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Victoria’s Rangelands: In Recovery or in Transition?

Report from a Parks Victoria Sabbatical Project

Peter Sandell 2011 0 | P a g e

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A sabbatical project

The restoration of degraded dry (non-eucalypt) woodlands, grasslands, saltbush mallee, and chenopod shrublands within natural areas of the Victorian Mallee is the largest single restoration project currently being undertaken by Parks Victoria. It is a partnership between Parks Victoria, the Department of Sustainability and Environment, the Mallee Catchment Management Authority, Trust for Nature (owners of Ned’s Corner Station), and the Commonwealth through the ‘Caring for our Country’ initiative. It is a program that commenced in 1990 and is continuing today, more than 20 years later.

The purpose of this treatise is to document the history of management of the Victorian rangelands particularly since destocking, to evaluate progress towards the goal of landscape restoration, and to guide future management. Are Victoria’s rangelands on the road to recovery, or are they in transition to an altered state?

This document is complemented by a DVD with video and still imagery illustrating the management interventions, and the changes to these Mallee landscapes over the course of two decades. Acknowledgements

My thanks to Parks Victoria, who through their sabbatical award for 2010/11, provided me with the opportunity to document some of the work undertaken over two decades to restore Victoria’s rangelands. In particular, Dale Antonysen (District Chief Ranger, Mallee) supported my application and the project generally.

The DVD ‘Rangelands Reflections 1990-2011’ was prepared by Tom Klein of O-Line Video. Thanks also to the following people who provided me with assistance in the preparation of the document and the associated DVD:

Mat Driscoll (DPI) – retrieval of achival material held by DPI. Bob Merlin (Mallee CMA) – collection of aerial photography. Daryl Walters (Contractor) / Phil Pegler (Parks Victoria) – comments on the manuscript. Kathryn Schneider (PV) – mapping and data analysis, and for backfilling my role in the Mallee District. Brendan Rodgers (PV) – also for holding the fort in the Mallee District. Frann Sette (Sunrise 21 Inc.) for mapping, although she refused to give up her golf on Wednesdays. Mark Doyle (DSE Weeds & Pests Initiative)– for leniency with regard to reporting on the ‘Mallee Woodlands – Bouncing Back’ initiative.

Parks Victoria Mallee District field staff (too many to list here) who collected much of the data presented in this report, and who continue to demonstrate a long term commitment to the restoration of our rangelands.

Dr Brian Cooke (Invasive Animals CRC) and Steve McPhee (Agricultural and Technical Services) have provided ongoing technical advice in support of the Mallee rabbit program and have instigated several rabbit research projects. Brian also provided comments on the draft of this report.

My wife Patsy for putting up with me around the house.

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Contents 1. INTRODUCTION ...... 5 The Victorian Rangelands ...... 5 Vegetation communities ...... 9 Previous land uses...... 11 Restoration of the Rangelands...... 11 Scope of the Victorian Rangelands ...... 12 2. HISTORICAL CONTEXT ...... 14 An historical perspective on the Victorian rangelands ...... 14 Why didn’t closer settlement proceed over the Victorian rangelands? ...... 20 3. CREATION OF THE NEW MALLEE PARKS ...... 22 Community attitudes towards reservation ...... 22 Condition of the rangelands at the time of reservation ...... 22 Management considerations post stock grazing ...... 27 4. FIRST STEPS TO RECOVERY ...... 30 Recovery strategy ...... 30 Manipulation of habitat ...... 32 5. THE MALLEE RABBIT PROBLEM ...... 35 Rabbit control in the period 1990-95 ...... 36 6. ARRIVAL OF THE RHD VIRUS IN MALLEE RABBIT POPULATIONS ...... 40 Changes in rabbit abundance ...... 40 RHDV epidemiology ...... 41 Evolution of resistance to RHDV ...... 43 7. VEGETATION CHANGES IN THE WAKE OF RHDV ...... 45 Investigation of changes in floristics / biomass at Hattah monitoring site ...... 45 Evidence of pine regeneration at Hattah monitoring site ...... 48 Buloke regeneration within Hattah-Kulkyne N.P...... 50 Revision of rabbit control targets ...... 50 8. STATEWIDE RABBIT RISK ASSESSMENT ...... 52 9. CONVENTIONAL RABBIT CONTROL ...... 54 Rabbit resurgence at Hattah-Kulkyne ...... 54 Possible role of fox baiting ...... 56 Mallee Woodlands Bouncing Back initiative and new partnerships ...... 58 Demonstration of best practice at Hattah-Kulkyne ...... 62 4 | P a g e

Private contractors ...... 69 10. OTHER GRAZERS AND WEEDS ...... 71 Kangaroo abundance and impact ...... 71 Goats ...... 75 Total grazing pressure and rainfall ...... 77 Weeds ...... 78 11. MONITORING AND EVALUATION ...... 81 Monitoring of vegetation response ...... 81 Threat monitoring ...... 85 Evaluations of rangeland recovery ...... 85 Fauna surveys...... 87 12. NEXT PHASES OF RANGELAND RECOVERY ...... 89 Restoration progress and strategy ...... 89 Management effectiveness ...... 90 Partnerships and risk management ...... 91 Some concluding thoughts …… ...... 92 Appendix 1...... 98 Examples of press reports in the period leading up to reservation of the Victorian rangelands...... 98 Appendix 2...... 105 Series of time-lapse photographs illustrative of changes in vegetation condition within representative unfenced sites that were reserved in 1991...... 105

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1. INTRODUCTION

The Victorian Rangelands Many people would not consider any area of Victoria to be within the extent of the Australian rangelands because the north-west corner of the State also falls within the cropping belt. However, the expansive chenopod shrublands, dry (non-eucalypt) woodlands, saltbush mallee, and grasslands fit within most descriptions of the Australian rangelands by virtue of their low and unreliable rainfall (Stafford-Smith and Morton 1990), high evaporation rates, and the dominance of slow growing perennials (Aerts and van der Peijl 1993). In terms of rainfall, the NW of Victoria is semi-arid with an average annual rainfall of generally 350 mm or less (refer to map facing page 8).

Belah (Casuarina pauper) woodland in the NW corner of Murray- Sunset N.P.

Cattlebush (Alectryon oleifolius) woodland in the NW corner of Murray- Sunset N.P.

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Buloke (Allocasuarina luehmannii) woodland exhibiting regeneration in Hattah-Kulkyne N.P.

Slender Cypress- pine (Callitris gracilis) woodland at ‘Pine Plains’ within Wyperfeld N.P.

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Bluebush (Maireana sedifolia) shrubland in the NW corner of Murray-Sunset N.P.

Saltbush mallee community in the NW corner of Murray-Sunset N.P.

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Facing page. Map of rainfall isohyets across South-eastern Australia. Source: Bureau of Meteorology.

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Vegetation communities Vegetation classifications used here are Ecological Vegetation Divisions (EVD) based on the definitions and distributions of communities as modified by White et al. in 2003. There are 6 individual EVDs which collectively are described here as being within the ‘Victorian rangelands’:

• Riverine woodland / forest • Chenopod shrubland • Dry (non-eucalypt) woodland • Saltbush mallee • Wetland (permanent or ephemeral) • Saline wetland

The component Ecological Vegetation Communities (EVCs) for each of these EVDs are listed below.

Chenopod Shrubland

102 Low Chenopod Shrubland

Dry Woodland (non-eucalypt)

66 Low Rises Woodland

90 Tea-tree Scrub

97 Semi-arid Woodland

98 Semi-arid Chenopod Woodland

826 Plains Savannah

828 Semi-arid Parilla Woodland

Wetlands (freshwater permanent & ephemeral)

104 Lignum Wetland

107 Lake Bed Herbland

291 Cane Grass Wetland

806 Alluvial Plains Semi-arid Grassland

807 Disused Floodway Shrubby Herbland

808 Lignum Shrubland

809 Floodplain Grassy Wetland

810 Floodway Pond Herbland

200 Shallow Freshwater Marsh

718 Freshwater Lake Mosaic

819 Spike-sedge Wetland 10 | P a g e

821 Tall Marsh

992 Water Body - Fresh

Riverine Woodland/Forest

103 Riverine Chenopod Woodland

106 Grassy Riverine Forest

295 Riverine Grassy Woodland

641 Riparian Woodland

811 Grassy Riverine Forest/Floodway Pond Herbland Complex

812 Grassy Riverine Forest/Riverine Swamp Forest Complex

814 Riverine Swamp Forest

815 Riverine Swampy Woodland

816 Sedgy Riverine Forest

817 Sedgy Riverine Forest/Riverine Swamp Forest Complex

818 Shrubby Riverine Woodland

946 Riverine Swampy Woodland/Lignum Wetland Mosaic

Saltbush Mallee

132 Plains Grassland

158 Chenopod Mallee

Saline Wetland

101 Samphire Shrubland

717 Saline Lake Mosaic

741 Salt Paperbark Woodland/Samphire Shrubland Mosaic

820 Sub-saline Depression Shrubland

940 Samphire Shrubland/Saline Lake Mosaic

991 Water Body - Salt

The distribution of these vegetation communities is as shown on the map on the facing page: ‘Mallee District Rangeland Vegetation Communities’.

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Previous land uses In common with the rest of Australia’s rangelands, the Victorian rangelands have had an extensive history of occupation for pastoral use with only an estimated 1% not thought to have been grazed by stock at any time (Table 1). The principal other use of the woodlands has been timber harvesting both for fuelwood and for fenceposts. There is generally less than 40% of the dry woodlands remaining due mainly to clearing for agriculture (White et al. 2003). Compared with neighbouring areas of South Australia and New South Wales, however, a relatively large proportion of the Victorian rangelands are now being managed for nature conservation.

The fact that a relatively large portion of Victoria’s rangelands is now reserved is due primarily to the history of land use in NW Victoria and to the Land Conservation Council (LCC) Reviews of 1977 and 1989. In those reviews, the LCC determined that the use of public land in NW Victoria for stock grazing should initially be subject to reduced tenure (1977 LCC review) and then ceased altogether for most areas (1989 LCC review). These decisions were based on judgements that:

• “ … grazing was inhibiting the survival and regeneration of the native grasslands, woodlands, and chenopod shrubland communities ... and was contributing to regional land degradation problems” (LCC 1989, p.8). • “ … continual grazing of domestic stock is detrimental to the floristic composition of Mallee communities and to the processes of regeneration of both the overstorey and the understorey … the lack of regeneration and re-establishment of native overstorey and understorey vegetation is due to combined grazing pressure … leading to further land degradation” (LCC 1989, p.8)

The LCC formed the view that ongoing intensive grazing (by a combination of stock, rabbits, and over-abundant kangaroos) was incompatible with the conservation of grasslands, dry woodlands, and chenopod shrublands. The LCC also determined that the progressive degradation of these communities on public land would contribute to wider problems for the Mallee region, particularly associated with soil erosion and increased groundwater recharge.

The Victorian Government adopted the LCC recommendations with the result that extensive areas of public land that had been subject to grazing tenure for nearly 150 years were, in 1991, reserved as national park. A new national park, Murray-Sunset N.P., of 633,000 ha was created and there was a major expansion of the existing Wyperfeld N.P. Stock grazing was phased-out in accordance with a schedule prescribed by the LCC. Under this schedule, all grazing tenures within the new national park areas were terminated by the end of 1996.

The expansive new Mallee parks were initially managed by the National Parks Service within the Department of Conservation and Environment (later re-named Natural Resources and Environment). From 1997 management of Victoria’s national parks was vested in Parks Victoria on behalf of the Department of Sustainability and Environment (DSE). Restoration of the Rangelands The approach to the management of the newly reserved rangeland areas is akin to ‘restoration ecology’ (Murdoch, 2005) rather than the more conventional concept of the conservation management of parks and reserves. The main difference between the two is that restoration ecology entails a narrower focus. Murdoch (2005) states that “Effective restoration requires a goal or policy that is clear, articulated and accepted by researchers, practitioners and end-users”. Management interventions are made for the overriding purpose of restoring vegetation communities and habitats that have been progressively degraded through stock grazing and high rabbit abundance.

The LCC 1989 review provided some guidance as to the goals of management post-reservation:

• “To maintain and improve the native perennial overstorey and understorey vegetation to reduce wind erosion, local and regional salinity problems, and other forms of land degradation – such as weed invasion – and to establish a sustainable (although not entirely 12 | P a g e

natural) ecosystem based on the key elements of the original vegetation communities.” (LCC 1989, p. 60)

The Mallee Parks Management Plan (National Parks Service, 1996) provided further direction for management:

• “As far as is practicable, areas of the Parks that have been degraded through past land management activities will be rehabilitated by … reducing the impact of pest animals and plants on native species and communities, addressing the current imbalance of kangaroo populations … active revegetation in areas of localised extinction and rarity …” (NPS 1996, p.7) This statement from the management plan implies that effective reduction of total grazing pressure should be the primary mechanism for restoring the degraded rangelands. However, the plan also suggested that in some areas, grazing management alone may not be sufficient and that more active revegetation measures may be required. Some questions were not specifically addressed in the Management Plan, such as:

• To what level should total grazing pressure be reduced to promote recovery (although rabbit abundance at less than 5/km was specified)? or • At what point should active revegetation measures be adopted?

The management plan noted that the communities at most risk from grazing were those vegetation types which occur on soils of relatively high fertility (e.g. Belah woodland), whilst communities of intermediate fertility (e.g. chenopod shrubland) were at moderate risk This provides as much basis as we have for a system of triage in the event that the available resources did not match the scale of the task. It is probably safe to say that, at the time of reservation, no-one had a clear understanding of what would be required to restore the Victorian rangelands in accordance with the vision provided by the LCC.

The restoration of degraded dry woodlands, chenopod shrublands, riverine woodland, and saltbush mallee within natural areas of the Mallee is the largest single restoration program currently being undertaken by Parks Victoria. It also involves DSE through their management of state forest and the statewide Weeds and Pests Initiative, the Mallee CMA, and Trust for Nature (Ned’s Corner Station). The program has also been supported by the Commonwealth through the ‘Caring for our Country’ initiative. Victorian rangeland restoration is a program that commenced in 1990 and is continuing more than 20 years later. Scope of the Victorian Rangelands The total area of rangelands in the NW of Victoria is estimated to be approximately 250,000 ha. Of this total, approximately 41,000 ha remains subject to licensed stock grazing. In half of that area, stock grazing is scheduled to be phased-out over the next few years as a result of the Victorian government adoption of the 2008 VEAC River Red Gum Investigation recommendations. Table 1 outlines the current status of Victoria’s rangelands. It should be noted that other important areas of remnant rangelands (not shown in Table 1) remain on private farmland in the areas between the major parks. The management of those areas is not within the scope of this paper.

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Table 1. The current extent and management of Victoria’s rangelands on either public land or Ned’s Corner Station.

Land status Approx. % Land manager Management summary Area (ha) National park / 174,000 70% Parks Victoria Being restored through conservation management of total grazing reserve declared as pressure (rabbit control and recently as 1991. kangaroo management). Ned’s Corner 30,000 12% Owned and managed De-stocked in 2002. Being Station acquired by by Trust for Nature restored through rabbit control. Trust for Nature in 2002 National park 21,000 8% Parks Victoria Remains subject to stock declared in 2010 as grazing with a scheduled a result of VEAC phaseout of existing licences investigation. between 2012 and 2014 State forest 20,000 8% Department of Generally remains subject to Sustainability and stock grazing with some Environment assistance provided to licensees with rabbit control. Yarrara and 2,790 1% Parks Victoria No history of stock grazing. Mallanbool Flora These areas were originally & Fauna reserves forest reserves to meet future timber needs. Regional park 900 ha 1% Parks Victoria Lake Albacutya Regional Park declared in 1980. remains licensed for stock grazing.

The recovery of our Victorian rangelands, particularly our dry woodlands, can be considered to be at a tipping point after a decade of below-average rainfall and the accelerating loss of overstorey trees which are now more than 150 years old. The purpose of this treatise is to document the history of management of these areas since the removal of stock grazing, to evaluate progress towards the goal of restoration, and perhaps to guide future management. Are Victoria’s rangelands on the road to recovery, or are they in transition to some other state?

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2. HISTORICAL CONTEXT An historical perspective on the Victorian rangelands Grazing occupation of the Victorian Mallee commenced in the late 1840s with the initial pastoral runs being along the Murray River and in the Pine Plains area (now part of Wyperfeld N.P.). Within 17 years, squatters had occupied almost the whole of the Mallee area (LCC, 1987). Grazing by sheep and cattle of the Victorian rangelands continued under various tenures until the early 1990s in most cases, although grazing tenures were terminated earlier in the central portion of Wyperfeld which was destocked in 1979 (Durham, 2001), Hattah-Kulkyne N.P. which was destocked in 1977, and the ‘Heitmans’ lease (now part of Murray-Sunset N.P.) was destocked in 1982. Some areas of public land, notably on the Murray River floodplain continue to be grazed under licence although most of these will also be destocked as a consequence of the VEAC River Red Gum Investigation of 2008.

The lack of water was obviously a limiting factor for grazing development in areas remote from the River, such as the present-day Murray-Sunset N.P. This was addressed in various ways including the construction of catchment dams that filled from surface run-off after rains. Some of these dams were thought to have been constructed on the sites of Aboriginal soaks or wells. These wells were apparently quite common at the time of European settlement (Bill Duncan, pers. comm.). The legacy of stock grazing can be seen in the form of old fences, stockyards, huts (notably at Wonga and Mopoke), shearers quarters (Taplan and Ned’s Corner), shearing sheds (Berribee and Ned’s Corner), tanks, ironclad catchments, and catchment dams.

Mopoke hut was built by the Henschke family as on-site accommodation whilst managing their cattle in the centre of the ‘Sunset Country’ at Mopoke. The Henschkes had a long tradition of occupation within the Sunset and remain as park neighbours in the Millewa. The hut is being maintained by Parks Victoria. Photo by Bruce Summerfield.

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Heitmans

Separate allotments west of Morkalla were transferred to the Heitman brothers (Fred and Jack) in 1925. The initial holding of 3149 acres was too small to be a viable grazing enterprise. They also discovered that it was too saline for wheat production. They managed to extend their combined holdings to about 20,000 acres after 1937 but in the process were required to surrender Selection Purchase conditions in favour of annual leasehold tenure. This meant that they were no longer eligible for water deliveries (except for their house dam) from the State Rivers.

Long Plain Tank is thought to date back to the 1890s (Jim O’Day quoted in Mallee CMA, 2010) and is an example of a pine tank constructed from two concentric rings of cypress pine posts with clay mounded in between. Water was originally pumped into the tank from a catchment dam, but for a period up until 1937 the State Rivers and Water Supply delivered water to Long Plain Tank from the Millewa channel system. The tank was shared by Ned’s Corner Station with the adjoining lessee (Fred Heitman) during the late 1920s and early 1930s. In a letter to the Lands Officer in 1930, Fred Heitman reported that “the concentration for many years of thousands of sheep for watering purposes around Long Plain Tank had caused the bush to be killed and the shallow topsoil to be blown away”.

Long Plain tank photographed in 1991.

Fred Heitman, an engineer by profession, was seconded during WWII to a senior post with the Ministry of Munitions in Adelaide. Although he owned land in South Australia, he preferred to live on the Morkalla lease. Fred and his wife raised four children, two of whom became doctors. They lived in a large iron ‘barn’ with a dirt floor for most of their period of occupation.

Jack Heitman was a bachelor and his holding was at Tunart (south of Morkalla) where he had no access to a channel-filled dam. All his water had to be carried. Official concerns were raised about the overgrazing of the Heitman Bros. leases as early as 1950. The Lands Officer at the time noted that “soil erosion is very bad in some places – especially in the area originally selected by Jack Heitman”. Another adverse report was made by the Soil Conservation Officer following an inspection in 1967. He found that “because of the severity of the erosion, it will be many years before the land recovers”.

Another inspection during the 1982 drought (Department of Crown Lands and Survey Memo of 21/12/1982) resulted in the termination of the Heitmans grazing licences. The Senior Land 16 | P a g e

Management Officer reported that “The condition of this licence is scandalous. I estimate that between 5 and 10,000 acres of the 20,000 acre licence area are in an advanced state of desertification”. On their departure, the children of Fred and Jessie Heitman erected a cairn with the following inscription: In Memory of the Heitman Family. Pioneer farmers and graziers of the area. 1923-1983. They never gave up their faith in this country, it was just taken away from them. So ends an Era.

The cairn constructed by the Heitman family on their departure from the lease west of Morkalla in 1984. The dismantled ‘barn’ can be seen in the background. Photo by Glen Burnell.

Sunset Pastoral Co.

The area to the west and south of Heitmans was an extensive grazing operation managed by the Sunset Pastoral Co. until their licence was revoked in 1989. The lease was expanded in 1958 with the transfer (for the reputed sum of £50,000) of an adjoining lease to the south held by the sons of Les Hart. Les Hart had occupied extensive leases totalling 322,000 acres below Ned’s Corner from about 1935. These leases extended as far south as the Rock Holes Bore, some 35 kms below Settlement Road. 17 | P a g e

Rock Holes Bore as it was in 1932. Photo courtesy of Mr Syd Wheeler.

It was originally intended that the land west to the South Australian border and south to the Rock Holes Bore be subdivided for closer settlement. The area on the South Australian side had already been cleared for cropping. Grazing rights were therefore issued only on an annual basis. In 1936, however, Les Hart was granted a 21 year lease over his main block of 186,000 acres which was stocked with 9,000 sheep. During this period he constructed a number of dams and extended the Millewa channel into three dams on the eastern side, including Woodbine Tank.

Predation of sheep by Dingos was a major problem for the early grazing operations. Les Hart reported killing up to 40 Dingos a night over a period of several years in the 1930s. A vermin proof fence was constructed along the southern boundary of the Ned’s Corner leasehold - presumably to protect against Dingos emanating from the Sunset Country. An earlier netting fence had been constructed from 1885 by the government near Beulah, to the south of the present-day Wyperfeld / Big Desert parks. This fence was reportedly for the purpose of containing wild dogs to the north and rabbits to the south (BeulahVictoria.com.au). Dogs (thought to be part Dingo) remain within the Wyperfeld / Big Desert complex but there is no evidence of them persisting in the area that is now Murray-Sunset N.P.

The extension of water reticulation by pipeline from South Australia allowed stocking rates on the Sunset Pastoral Co. Lease to be increased. Several adverse reports were made to the Lands Department on the condition of the lease. In 1967 the District Soil Conservation Officer reported that the lessee demonstrated “the most blatant disregard for soil or pasture management one could expect anywhere”. Following the 1977 review of public land by the Land Conservation Council, the tenure held by Sunset Pastoral reverted to an annual grazing licence.

The lease was again inspected during the 1982 drought by the Senior Land Management Officer (Department of Crown Lands and Survey Memo of 21/12/1982). The Officer found an area of 5,000 acres that had been “.... bared off totally. No rabbits or weeds exist, no kangaroos were seen and the soil was separated and drifted down to fine gravel components and stones.” The second LCC Mallee Area Review in 1987 resulted in a recommendation that the Sunset Pastoral Co. licence area be incorporated within a new Murray-Sunset N.P. The ‘Sunset Shearers Quarters’ remains as a relic of one of Victoria’s largest grazing enterprises which occupied a vast area of public land in the period 1936-1989.

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Ned’s Corner station

The area that became known as Ned’s Corner Station was first registered as a lease in 1847 on behalf of Edward (Ned) Bagot. He already owned holdings in South Australia and managed these as part of an integrated pastoral operation (Mallee CMA, 2010). The lease was transferred on several occasions before freehold was granted on some of the station area to a consortium of soldier settlers in 1938. In 1948 ownership transferred to the Kidman Pastoral Co. who managed both the freehold and extensive areas of leasehold that included the eastern half of Lindsay Island and the Lake Wallawalla area.

Jim and Barb Hart assumed management responsibility on behalf of Kidmans in 1978 until the property was sold in 1994. They are quoted in the The Millewa-Murray: An Oral History (Mallee CMA, 2010) as follows.

“We went to Ned’s Corner in 1978. It was blue bush and salt bush country – beautiful sheep country. We had about 20,000 head and 200 head of cattle, but the cattle only ran on the islands. We didn’t run sheep on Mulcra, Lindsay and Mullaroo, but the Schmidts before us did, and in those days when they mustered the islands they would burn them because they were all lignum and Noogoora Burr and Bathurst Burr and as they were coming out they’d heave a match in and the regrowth would be all fresh.”

The leasehold areas of Neds Corner reverted to national park in 1991 with cattle grazing on Lindsay Island finally phased out in 1995. The new owner of the Ned’s Corner freehold after 1994 continued to graze cattle and sheep and also cleared an area of woodland for cropping. However, it was sold in 2002 to Trust for Nature and has since been managed to maintain and enhance its ecological value (Mallee CMA, 201). It remains the largest freehold property in Victoria at 30,000 ha incorporating extensive rangelands.

In another quirk of history, the saline shrublands of Lindsay Island, Mulcra Island, Wallpolla Is., and Neds Corner could have all been inundated under the waters of the proposed Chowilla Dam. The South Australian Government proposed in the 1950s to build a massive dam which would have extended some 90 km upstream of Chowilla across the S.A. border. The intention was to free South Australia of its dependence upon the upstream states by building a large storage on the lower Murray (Don Blackmore quoted in Mallee CMA, 2010). In expectation that the dam was going ahead, a lot of Red Gum and Black Box timber was harvested from Lindsay Island and a sawmill was established at Paringa on the basis of the opportunity for salvage logging. The plan for a dam was eventually scrapped and the Chowilla / Lindsay / Wallpolla floodplains are now an icon site under the Living Murray initiative of the collective Commonwealth and State governments.

Berribee

The Berribee lease was most recently managed by Amarina Pastoral who were based in the SE of South Australia. Berribee homestead and woolshed were located on public land in a scenic position on the Lindsay River. Their lease extended over the western half of Lindsay Island and an area to the west of Lake Wallawalla and north of the Sturt Highway. The homestead was purchased by the Victorian government at the time of the declaration of Murray-Sunset in 1991 although it fell outside the initial boundary of the national park. Condition of the lease was generally poor at the time of reservation (refer photos pages 23 & 24).

Pine Plains and Glencoe station

Other areas with extensive history of pastoral occupation were ‘Pine Plains’ to the west of Patchewollock (now part of Wyperfeld N.P.) and sections of Glencoe station (west of Hattah) which had leasehold extending through the eastern half of what is now Murray-Sunset N.P.

Pine Plains was occupied and stocked from 1848 and a series of lessees suffered hardships associated with lack of surface water, dingos, and rabbit plagues. One occupier was even forced off the lease in 1854 due to flooding of the Wirrengren Plain at the terminus of the Outlet Ck system (Durham 2001). 19 | P a g e

In 1917 Mr H. O’Sullivan and M.F. Kelly successfully tendered for the grazing rights (Shepherd 1985). Although Mr H.O’Sullivan died in 1926, the grazing licence remained with the O’Sullivan family for the next 70 years.

Pine Plains, for various reasons, was not subdivided for closer settlement although a number of blocks of freehold were granted to the O’Sullivan family and remain as inliers within Wyperfeld N.P. As late as 1967 the Lands Settlement Commission requested that the area be taken over by the Government for servicemen returned from the Vietnam War but this was refused (Shepherd 1985). The grazing licence was transferred to O.L.(Jack) O’Sullivan in 1957 and he was reportedly an honorary ranger for Wyperfeld N.P. for a period (Melb. Age 1989). His sons (Tim and Brian) continued the grazing tradition on public land until their licence was terminated in 1996.

Pine Plains seems to be particularly prone to rabbit infestation and Coman (1999) reports that one of the last of the Victorian rabbit trappers was still operating there in the 1960s. It was the venue of research by the Keith Turnbull Research Institute (KTRI) into the use of the European Rabbit Flea as a vector for myxoma virus (Shepherd 1985). Rabbit populations at Pine Plains were monitored by KTRI for an extended period between the early 1970s and the mid 1980s (Coman,1999). The results of this sampling are shown in Figure 1 and are illustrative of the ‘food limited system’ (Parer, 1977). That is, in the absence of effective control, rabbit numbers increase rapidly in good seasons only to crash during dry times when food becomes limiting. These data are also illustrative of the impact of predation once a population has been reduced to low levels as occurred following the 1982 drought. Coman (1999) notes that ‘foxes and cats can be useful allies in rabbit control”.

Historic rabbit counts Pine Plains 80 70 Rabbit flea 60 introduced 1982 50 drought 40 30 20 No Av. rabbitsAv. perkm 10 data 0 70 71 72 73 74 75 75 76 77 78 79 80 80 81 82 83 84 85 85 ------Jun Jun Jun Oct Oct Oct Apr Apr Apr Feb Feb Feb Dec Dec Dec Dec Aug Aug Aug

Figure 1. Historical rabbit counts at Pine Plains. The values on the Y axis are the average number of rabbits counted per km in spotlight counts. The average count cycled from as high as 60 to as low as 3 per km. Source: Keith Turnbull Research Institute.

Another very large grazing tenure at the time of the 1989 LCC Review was that held by the late Harold McArthur with holdings of 75,735 ha occupied since the 1930s. The Crown Lands inspection of 1982 found that the area west of the Raak Plain was “in fair condition all things being considered”. (Department of Crown Lands and Survey Memo of 21/12/1982). The licences to the west of the Meridian within Murray-Sunset N.P. were phased out in 1991, but Glencoe station continues to this day as a grazing operation on state forest west of Hattah managed by the McArthur family. 20 | P a g e

Why didn’t closer settlement proceed over the Victorian rangelands? It has already been noted that clearing of similar land systems proceeded over the border in South Australia (despite the Goyder line) whereas the Victorian rangelands and dunefields remained under pastoral tenure. In neighbouring N.S.W., different land use policies again were implemented. Overstocking, depredation of rabbits, growth of noxious shrubs, and the drought of 1894-1900 led to the 1901 Royal Commission into the ‘Condition of Crown Tenants in the Western Division of New South Wales’ (Condon, 2002). The Royal Commission resulted in the Western Lands Act of 1901. Condon (2002) notes that this was an Act of conservation in the sense that it made no further provision for the alienation of Crown lands and recommended strongly against agricultural development (Condon, 2002). Under the Act, Crown land was ‘leased subject to conditions, subsequently strengthened, to protect the environment’. Long term leasehold tenure remains in place for most of the Western Division of N.S.W. subject to enforceable conditions although this has not prevented further episodes of desertification such as during the 1920s and subsequently.

The fact that much of the Victorian rangelands remained uncleared and in public ownership, with the eventual removal of grazing tenures, is probably the result of historical circumstances and a reflection of long-term public policy. There was strong advocacy for closer settlement in the local press (Sunraysia Daily editorial of November, 1920):

“Sunraysia Daily would like to see a report by Mr Laing on that million acre stretch of land between Merbein and the South Australian border. Someday there will be half a dozen irrigation settlements on the frontages, but the back country is capable of immediate development, and it would support as large a population as any similar area of the Mallee. Why should the South Australian side of the border fence be covered with wheat fields in emerald and gold, when on the Victorian side the land supports a sheep to the dozen acres?” (Sunraysia Daily quoted in Mallee CMA, 2010).

Victorian policy with respect to closer settlement was clearly relatively conservative when compared with South Australia. Dr John Cooke of DSE notes in Mallee CMA (2010) that “In order to reduce the risk associated with closer settlement, Victorian governments ensured that the expansion of closer settlement, and hence cereal farming in the Mallee, was preceded by the establishment of transport and social infrastructure”.

The closer settlement of the Millewa between the Murray and the Sunset Country began in 1923 but was soon beset by problems mainly relating to insufficient rainfall and poor cereal prices. By 1945 fewer than 200 settlers remained of the original 1000 (Mallee CMA,2010). Settlement did not extend further west than North-South Settlement Road (approximately 15 km inside the S.A. border). The North-West Settlement Act of 1948 and a government inquiry resulted in reallocation of holdings into more viable enterprises. In 1961 the Act was further amended to provide for freehold titles.

It was proposed that the Sunset Country to the south of Settlement Rd also be opened to closer settlement (see Figure 2). A resolution carried by the Victorian Farmers Union Conference at Ouyen in 1924 urged the construction of a railway from Hattah towards the S.A. border to open up the 60 miles wide belt of the Millewa between the Murrayville and Millewa North railways (McLean & Jowett, 1974). Work on the construction of the Millewa South railway line began in 1928 westward from Nowingi but only extended for 24 miles towards Rocket Lake. In the following year the Closer Settlement Board declined to open further land for settlement and the line drifted over. The railway track beyond the 15 mile point was removed in 1942 to reclaim the steel for the war effort (McLean & Jowett, 1974). 21 | P a g e

Figure 2. Constructed and proposed railway lines for the support of closer settlement in the Victorian Mallee. Source: McLean & Jowett, 1974.

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3. CREATION OF THE NEW MALLEE PARKS Community attitudes towards reservation At the time of the reservation of most of the remaining Victorian rangelands in 1991, a total of 31 separate grazing tenures existed over the state forest which had been converted to national park. Most of the grazing licensees accepted the decision of government with good grace, whilst a few were antagonistic and predicted that the new parks would become a haven for vermin and weeds causing problems for neighbouring farms. There was considerable publicity at the time (refer Appendix 1).

A common theme in the local press was that “there is little worth in removing grazing cattle and sheep to encourage native tree regeneration if rabbits take their place”. Other concerns expressed were that kangaroo populations would increase and impact upon neighbouring farms, that increased grass growth would lead to increased incidence of wildfires, and that the scale of the task of managing the former grazing leases would be beyond the local agency (Department of Conservation and Environment) and would represent a major drain on the public purse. The impact of the LCC recommendations upon particular families who depended largely on their public land leases was also highlighted. Some landholder anger was directed at the new Aboriginal name that had been chosen by the Minister (Mr Steve Crabb). After vocal local protests, this new name (Yanga-Nyawi National Park) was abandoned and the name Murray-Sunset N.P. adopted (Appendix 1).

Some more in-depth media analysis noted that the Mallee Region was not a charismatic cause for conservation and would hence struggle to attract resources. An article in the Melbourne Age of 1st August 1989 stated that there was now a new vision for the Mallee. “After a century of being seen as an agricultural opportunity, it is now recognised as the last semi-arid vegetation in south-east Australia. The CSIRO describes .... belated acknowledgement by land managers of bad past practices. There is a new awareness of the link between tree cover and land degradation – the more you denude, the more you interfere with balanced systems”. In the same article, Tim and Brian O’Sullivan are quoted as blaming the degradation on them being “locked in a financial trap: not wanting to throw cash at land they could lose, yet risking that loss by not looking after their property”. The article also quotes the Victorian Farmers Federation; “Where will all the money come from for a million hectares, much of it in decline?” Condition of the rangelands at the time of reservation Concerns about the condition of the Mallee rangelands were by no means first expressed by the LCC. As noted above, the Department of Crown Lands and Survey (Memorandum of 21/12/1982) and the Soil Conservation Authority prepared periodic reports on the conditions of individual leases from the 1950s. Earlier, Zimmer (1944) reported on the lack of regeneration of Callitris sp. in the Yarrara forest prompting some regeneration experiments. He found rabbits, livestock and unsuitable soil conditions were all implicated. Allen (1983) assessed tree decline in Western N.S.W. by means of questionnaires, canvassing for information through newspapers, and by literature review. He found widespread evidence of insidious tree decline caused by grazing animals and expressed concern that the steady decline in tree numbers would lead “to an inevitable completely treeless landscape”.

At the time of reservation in 1991, the condition of Mallee grazing licences varied widely depending on stocking practices and the level of rabbit control. Some licensees had adopted conservative stocking practices which were reflected in the relatively good condition of their licence area. Other licences were in a highly degraded condition. No detailed assessment was made of the condition of licence areas at the time of reservation, although this information may have been useful in the subsequent interpretation of differing rates of rangeland recovery.

It is not possible to characterise the condition of all of the diverse rangelands at the time of reservation. The following images are representative of areas that exhibited land degradation or other issues that would require management. 23 | P a g e

Belah (Casuarina pauper) woodland north of the Sturt Hwy in the Berribee licence area. Photo taken in March 1990. There is a clear browse line on the trees, no evidence of any tree regeneration. The shrub layer is degraded and the field layer is absent. At the end of summer no palatable grasses or forbs remain for stock.

Grazing exclosure established on Sunset Pastoral licence area in 1968 and photographed here in 1989. Indicates regrowth of Slender Cypress-pine (Callitris gracilis) within the exclosure but not outside. 24 | P a g e

Cattlebush (Alectryon oleifolius) photographed on Sunset Pastoral licence area in 1990. There is no evidence of native tussock grasses in the field layer which is dominated by introduced annual weeds (Bromus spp. and Hordeum spp.) and Burr Medic (Medicago spp.).

Dunes immediately to the south of Lindsay Island photographed in April 1990. Areas close to the Murray River and anabranches historically had higher stocking rates. These areas coincided with areas of high Aboriginal cultural significance. In some cases, Aboriginal burials had become exposed by over grazing. 25 | P a g e

The lunette of Wirrengren Plain photographed in 1992. Loss of tree cover (Slender Cypress-pine) has exposed the lunette to wind erosion.

Area of Cypress-pine woodland north of the Sturt Hwy where most of the trees have been harvested for fuelwood or construction purposes.

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A network of catchment dams existed throughout the northern area of Murray-Sunset where soils generated runoff. These dams tended to be at the centre of a ‘piosphere’ effect with the level of grazing impact inversely proportional to the distance from the dam.

Many areas of state forest exhibited high densities of established rabbit warrens such as these visible from the air within the newly reserved Hattah-Kulkyne N.P. in 1980. 27 | P a g e

A large warren within the Sunset Pastoral Co. licence area immediately prior to reservation (1990).

It is safe to say that the degraded condition of the new Mallee parks had no precedent in the history of national park reservation in Victoria. Management considerations post stock grazing Whilst the LCC had determined that ongoing intensive grazing (by a combination of stock, rabbits, and over-abundant kangaroos) was incompatible with the conservation of grasslands, semi-arid woodlands, and chenopod shrublands, it could be that other factors might also be limiting upon any projected recovery of the Victorian rangelands.

Even with low levels of total grazing pressure, there may be insufficient sources of viable seed remaining to re-establish woodland trees in particular, or established weeds may outcompete the germinants of native species. In addition, the characteristics of the soil may have changed due to trampling, and prolonged deposition of nutrients such that conditions are now unfavourable for the original vegetation. A study on the effect of stock removal on woodlands in the Murray Mallee and Wimmera by Duncan et al. (2007) notes that “the capacity of soils to recover is not well known”, and that “the timeframe of nutrient decline is poorly understood”. This refers to evidence linking high soil phosphorous levels with a low diversity of native perennials.

Based on their analysis, Duncan et al. (2007) hypothesized that the probability of regeneration having occurred would increase with time since destocking. In a Mallee context, the elapse of further time is clearly also associated with progressive loss of overstorey trees (the seed source).

Only one detailed recovery plan has been prepared for the rangeland communities: namely for Buloke woodlands, including associations with Slender Cypress-pine (Cheal et al., in press). This plan remains as a draft and has yet to be released by the Commonwealth Dept. of Sustainability, Environment, Water, Population and Communities (David Cheal, pers. comm.).

In the Recovery Plan, the authors assess priorities for conservation based on standard criteria for conservation importance, size, intactness etc. They note that in the category of large, insecure ecologically, secure legally, and highly degraded are the “stands of (former and moribund) Buloke Woodland ..... in the larger national parks in Victoria, notably Albacutya, Hattah-Kulkyne, Murray- 28 | P a g e

Sunset and Wyperfeld. Throughout these parks, the Buloke Woodland has been eliminated or is highly degraded, with further degradation to extinction likely.”

The Recovery Plan notes that “Removal of historic overgrazing has not led to reinstatement of the typical field layer of pre-settlement Buloke Woodland” and “Furthermore, Buloke itself has not regenerated in Buloke Woodland (Sands) following removal of domestic stock.” This latter statement is based in part on B. Sc. Honours projects conducted at Wyperfeld in the period 1989-1990 (Raymond 1990, and Castle 1989). At the time of these studies, monitoring of Buloke communities over a period of approximately 22 years by rangers and Monash University Botany Department had failed to locate juveniles. This was despite the sequence of exceptional rainfall years from 1973-75 (Castle, 1989).

Regardless of the pessimistic prognosis contained in the draft Buloke Recovery Plan, the authors do prescribe some recovery actions and performance criteria for the land manager. These include the following:

Action Performance criteria Greatly reduce grazing impacts from • Replace introduced annual spp. In the field layer rabbits in the large parks. with native tussock grasses and native annuals typical of Buloke Woodlands. • Successful regeneration of associated woody species, notably Hakea spp. And shrubby chenopods. In-plant appropriate woody species • Re-incorporation of woody species typical of into Buloke Woodland (Sands) in Buloke Woodlands into remnant stands Albacutya, Hattah-Kulkyne, Murray- • Sunset and Wyperfeld Parks. Second generation regeneration of woody species in Buloke Woodland

• Consistent presence of woodland-dependent fauna (eg. White-browed Treecreeper), as determined by survey Manage populations of kangaroos to • Kangaroo population management strategies levels below which they will not developed, published and implemented significantly adversely affect • regeneration of and in Buloke Successful regeneration of woody species within Woodlands. Monitor outcome Buloke Woodlands

Coman (1999, p.19) noted that stock grazing favoured the spread of rabbits by maintaining the shorter pasture that rabbits prefer. With respect to the standard of rabbit control that might be required, the draft Buloke Recovery Plan cites the work of Lange & Graham (1983) and others who found that a density of rabbits as low as 0.5 per ha are capable of removing almost all seedlings of Acacia spp. in an arid zone woodland. Subsequent work by Murdoch (unpub.) at Hattah-Kulkyne has confirmed the low threshold of rabbit abundance at which the survival of Buloke seedlings is at risk.

Kangaroos could also be said to be beneficiaries of the era of stock grazing. The removal of the shrub understorey by stock is thought to have contributed to an increase in kangaroo densities post stock grazing. The density of Western Grey Kangaroos at Hattah-Kulkyne increased from an estimated park average of 25/km2 in 1983 to approximately 46/km2 in 1990 (Coulson 1990). This increase followed both the 1982-83 drought and the cessation of stock grazing in 1977.

The imperative of maintaining a high standard of total grazing pressure (rabbits, kangaroos and goats) is a common theme in the Mallee Parks Management Plan (NPS, 1996), the LCC Recommendations (1989), Restoring the Balance (1990), and the draft Buloke Recovery Plan (in press). It has largely 29 | P a g e been the responsibility of the land manager (initially the National Parks Service and since 1997, Parks Victoria) to implement a regime of low total grazing pressure at the scale required (approx. 250,000 ha).

There are few precedents for intensive grazing management on this scale elsewhere in Australia. Operation ‘Bounceback’ aimed at protecting and restoring the semi-arid environment of the Flinders, Gawler and Olary Ranges of South Australia is one example. This program also began in the early 1990s, with a focus on reducing threats to Yellow-footed Rock-wallaby populations in the Olary Hills and Flinders Ranges but has since expanded to include broadacre threat abatement including rabbit and goat control, as well as a suite of other management and monitoring activities. One of the managers (Peter Alexander) of ‘Bounceback’ made a presentation to Parks Victoria staff in 1999.

The South Australian Bounceback is a sophisticated program that links integrated feral animal control to natural recovery processes, weed control and strategic revegetation, and fauna recovery initiatives (Alexander, 1999). It arose under similar circumstances to those in the Mallee where the Flinders Ranges N.P. was declared in the mid 1970s but recovery was slow following destocking. Key lessons from their experience were the wide range of partnerships they have established and the establishment of key criteria for assessing ecological integrity and evaluating success. The obvious successes of ‘Bounceback’ give some cause for optimism that conservation programs on this scale can deliver positive outcomes and provide a good model for the Victorian Mallee in a similarly semi-arid environment.

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4. FIRST STEPS TO RECOVERY Recovery strategy It is important to reflect that the ultimate goal of land management post stock grazing has been to achieve recovery of the dry woodlands and other communities / habitats that have been assessed as being at risk from overgrazing. The key elements of the strategy to achieve that goal, flagged in the key planning documents listed above, can be summarised as:

1. Active control of grazers (rabbits, goats, and kangaroos) such that total grazing pressure is maintained below the threshold at which the regeneration of native perennial grasses, shrubs, and trees can occur and persist (given sufficient rainfall); 2. Passive control of grazers or manipulation of habitat such that the environment becomes less suitable for grazers. Within this category the obvious options are the closure of artificial waters within the Mallee parks and the fencing of boundaries to prevent goats and kangaroos from accessing waters on adjoining farmland; and 3. Active revegetation measures (direct seeding / planting / weed control) where grazing management alone is not sufficient to promote recovery. 4. Periodic evaluation of the effectiveness of recovery actions so that techniques, and indeed the entire strategy, can be revised as necessary.

These key elements of the recovery strategy are clearly not independent given that there is no point in undertaking active regeneration measures if the total grazing pressure remains high. In fact, the maintenance of low total grazing pressure underpins the strategy.

At an early stage in the management of previously grazed areas of the new Mallee parks, it was recognised that there was considerable scope for passive management measures which could lead to cost-effective and long term reductions in total grazing pressure. These included the closure (by some means) of artificial waters and the fencing of boundaries to prevent kangaroos and goats from accessing waters on neighbouring farmland. It made sense to fully explore and implement these in order to reduce the costs of the active control measures.

In terms of the evaluation of management effectiveness, it was decided at the outset to establish a network of paired grazing exclosures. These were 6.25 ha in area (250m × 250m) and were mostly built in 1991 although a few were built in 1989 at Sunset Plains under a NAP project and some within Hattah-Kulkyne / Glencoe were built in 1997 to specifically monitor the changes resulting from the arrival of RHD virus in the rabbit population.

The location of the grazing exclosures is as shown in Map on the facing page.

The purpose of the grazing exclosures was to act as reference areas against which the effectiveness of the management of total grazing pressure could be assessed. For instance, if regeneration was observed within the exclosures but not outside, this would be evidence that total grazing pressure needed to be further reduced in order to promote widespread recovery. Of course, this assumes that the grazing pressure within the exclosure remained very low relative to that outside. Unfortunately this was not necessarily the case for a number of the exclosures.

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Grazing exclosure at Bee Rack Hill in Wyperfeld photographed in 1994. Slender Cypress-pine has regenerated inside but not outside due to high total grazing pressure in advance of RHDV and kangaroo management.

The same location photographed in 2011 showing the emergence of seedlings outside the exclosure. 32 | P a g e

Manipulation of habitat

Fencing of the northern boundary of Murray-Sunset

Representations were made in the early 1990s by the farming community in the Millewa to the then Minister for Conservation (Mr Barry Pullen) about the need for a kangaroo-proof fence along the northern boundary of the newly declared Murray-Sunset N.P. Their concern was that high numbers of kangaroos were sheltering in the Park and feeding on their cereal crops. The traditional government mechanism for dealing with this problem for landholders was to issue ‘wildlife destruction permits’ for the culling of a defined number of kangaroos. The farmers argued that this was time consuming and did not address the underlying problem.

The relative prosperity of Western Grey Kangaroos, in particular, on the fringes of Mallee public land was recorded in the kangaroo censuse conducted by David Morgan (1992) within Murray-Sunset N.P. This relative abundance can be attributed to the availability of watering and feeding opportunities on the farmland combined with the shelter provided by park vegetation. Not only were relatively high densities of kangaroos on the fringe of the Park causing problems for landholders, they were also degrading the condition of vegetation inside the Park.

A trial electrified fencing project was initiated in 1992 as part of a “Good Neighbour” government initiative. It was managed as a cooperative venture between the Dept. of Conservation and Natural Resources and the Millewa-Carwarp Landcare Group. Under this arrangement, the government contributed $30,000 towards the cost of fence materials and the Landcare Group made an in-kind contribution valued at $17,000. The three adjoining landholders ( John Bowen, Alan Henschke, and Jack Symes) erected the fence to an agreed design and undertook to maintain it in working order. The first section of 29 km west from the Meridian was completed in October 1993 with the materials only cost being $1,620 per km. The remainder of the Park boundary west and north to the Sturt Hwy (a further 93 km) was completed in subsequent years although the original fence design was varied.

The Sunraysia Daily of 13/11/93 covered the launch of the new fence by the Member for Mildura (Mr Craig Bildstien). Mr Bildstien was quoted as saying that the kangaroo barrier was “a clear demonstration of what can be achieved when neighbours, government agencies and the community work together on a project”. The project facilitator for Dept. of CNR was Nick Ryan who is quoted as saying that “if I had to pick a group of people to complete a project like this, then a better bunch I would not find”. One of the farmers, John Bowen, said “This is the greatest thing to come to the Millewa since we got the pipeline. We can see the difference in the crops already”.

An initial evaluation of whether the fence had achieved the objective of decreasing kangaroo densities to more natural levels within the fringes of Park was conducted in 1995. It relied upon measurement of kangaroo abundance by means of pellet counts along both fenced and unfenced sections of the boundary. Results were equivocal and the evaluation was effectively invalidated by the presence of artificial waters within the Park in close proximity to the fenced section, as well as ongoing culling of kangaroos by landholders in the unfenced section.

A second evaluation of the Millewa fence was conducted by Farrow in 2001. By this time, the dams inside the Park had been closed and the fence had been extended along the entire boundary. The method of this evaluation involved comparing the index of kangaroo abundance currently with that in 1995. In his evaluation Farrow (2001) found that the density of kangaroo pellets was, on average, 85% less in 2001 than had been the case 5 years earlier. The Park neighbours (John Bowen, Alan Hentschke, and Jack Symes) were all interviewed as part of the 2001 evaluation and each considered that the fence had been a success in terms of cost-effective reduction in kangaroo grazing pressure on crops and pasture. In addition to reducing kangaroo grazing pressure, the Millewa fence has prevented any stock trespass into the Park that might have otherwise occurred, and it has prevented goats from accessing water on farmland. There is little doubt that this has led to a reduction in goat impacts within the northern portion of Murray-Sunset N.P. 33 | P a g e

The first stage of the Millewa kangaroo fence after completion in 1993. This electrified sloping fence has proved very effective at reducing kangaroo damage to crops and pasture. It has also reduced kangaroo abundance within the fringes of the national park.

Closure of catchment dams in Murray-Sunset N.P.

The LCC (1989) recommended that dams not required for community use (principally fire protection) be closed because they support feral animals and artificially high numbers of native herbivores. This recommendation was not implemented pending the completion of the park planning process to identify any dams that should be retained. The Mallee Parks Management Plan (NPS 1996) noted that there were an estimated 100 catchment dams within Murray-Sunset N.P. and that these were preferentially located in Pine-Buloke Woodland, Belah Woodland, and Savanna Mallee vegetation communities, all of which are at risk from ongoing grazing.

A remote catchment dam in Murray- Sunset.

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Previously, in 1991, two dams in the southern half of Murray-Sunset had been fenced as a trial to assess whether this was a viable means of reducing grazing pressure whilst still providing watering opportunities for some species of birds. Favaloro (1966) had recorded that a number of birds were favoured by reliable water supplies, including White-plumed Honeyeater, Brush Bronzewing, Crested Pigeon, and Red-rumped Parrot. The trial fencing of waters raised animal welfare issues with large numbers of thirsty kangaroos and goats congregating around the fences and it was abandoned.

Advice from fire management officers was that the catchment dams were not useful for fire suppression because it was difficult to extract water from them, and they were often dry at the critical time. A few tanks on pipelines were installed as alternative water supplies in the NW corner of Murray-Sunset. Many tanks were then modified by installing banks where the catchment drains entered the dam. A summer deluge in January 1999 breached most of these banks allowing the dams to refill. Rangers continued to report grazing impacts associated with goats throughout the Park.

After further public consultation, it was decided that the fabric of a few dams, including Sunset Tank and Henschke Tank, should be retained for their historic significance. Others were bulldozed flat under a contractual arrangement with Mildura Rural City Council in 1999/2000. The few that remain open are in wilderness areas where it is not possible to deploy machinery. It is assumed that these will silt up over time.

Most of the available evidence from rangeland studies suggests that the widespread availability of water from artificial sources has led to increased grazing pressure by large herbivores (kangaroos and goats) and that this has led to declines in biodiversity. Whilst some species (increasers) are found to be more abundant in close proximity to water, another group (decreasers) can now only be found at distances of 8 or more kms from water points (Landsberg et al. 1997). In terms of overstorey plants, understorey plants, birds, and reptiles, Landsberg et al. (1997) found that most species were in the category of ‘decreasers’. They found a tendency for palatable perennial grasses to be replaced by unpalatable species or by unpalatable shrubs such as Dodonaea spp.

Although comparable studies have not been undertaken in the Victorian rangelands, both the closure of catchment dams and the fencing of the northern boundary of Murray-Sunset would appear to have generated lasting benefits. Grazing pressure has clearly been reduced and there has been regrowth of the field layer in areas that were previously denuded in the vicinity of catchment dams. The application of habitat manipulation in these cases also has been more cost-effective than the alternative of direct control of kangaroos and goats. This raises the question of whether there should be wider application of habitat manipulation measures, such as kangaroo / goat proof fencing of other boundaries of the large Mallee parks.

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5. THE MALLEE RABBIT PROBLEM

Rabbits, of course, are not a new problem for the Mallee. Rolls (1969) quoted in Shepherd (1985) suggested that by the early 1870s the Mallee was one of the five main breeding centres for rabbits in Australia. During the Victorian Crown Lands Commission of 1878-1879 rabbits were blamed for many crop failures in the Mallee (Shepherd 1985). Most control efforts in the early days were ineffective and involved poisons, such as strychnine, that were highly toxic to other fauna.

The introduction of Myxoma virus in the early 1950s initially reduced the number of rabbits by about 99% in the Mallee but the country still had a very high rabbit potential (Shepherd 1985). In the longer term some scientists have suggested that, in dry regions, the current density of rabbits might be 25% of that which prevailed prior to Myxo (Coman 1999). In 1962 a coordinated baiting program using 1080 carrots was commenced by the Lands Department (Shepherd 1985). The European Rabbit Flea was trialled at Pine Plains in the early 1970s but, in common with mosquitoes, it tends not to persist in drier conditions. This led to the introduction by Dr Brian Cooke of the Spanish Rabbit Flea in 1993 and Coman (1999) reported that it has proved to be persistent in semi-arid regions.

Significant rabbit control programs were conducted within Mallee national parks and State forests for some decades prior to the major park expansion of 1991. At Hattah-Kulkyne in 1982/83 (soon after park declaration) the rabbit problem was so severe that it was decided to conduct aerial baiting with 1080 carrots in the Kramen, Cantala, and Mournpall blocks. The Hattah airstrip was constructed for this purpose (Dennis Ward, pers. comm.). Aerial baiting was again conducted in about 1987 (Damian Kerr, pers. comm.). Large quantities of carrot 1080 baits were also distributed using superspreaders (David Christian pers. comm.). The death of two Red Kangaroos at Kramen at this time was attributed to 1080 poisoning (David Major, pers. comm.). In a separate incident baiting by the Lands Department in the Outlet Ck area of Wyperfeld resulted in the poisoning of a number of Brush-tailed Possums. This experience led to temporary withdrawal of authority to bait within national parks in about 1987 (David Christian, pers. comm.). As a consequence of this decision, populations at Hattah- Kulkyne grew rapidly in the late 1980s.

It was envisaged at the time that the use of 1080 would cease after the major poisoning programs and that the level of resources needed for rabbit control would decrease dramatically once the heavy knockdown phase at Hattah-Kulkyne had been completed (Ward and Cooke, 1987). In fact baiting did resume subject to a strict national park policy on 1080 use with a series of management approvals required before any field application. The need for local guidelines resulted in the preparation of Mallee Resource Protection Guidelines-Rabbit Control which was revised in 2000 by NRE (2000).

A key element of the rabbit control strategy at Hattah-Kulkyne in the early 1980s was the construction of rabbit proof fences to both divide the Park into manageable units, and to prevent re-colonisation of treated areas (Ward and Cooke 1987). Approximately 60 km of fencing was installed at that time and continues to be maintained to this day. In fact, rabbits are relatively sedentary and generally travel no more than a few hundred metres from their warrens (Coman 1999). Despite occasional instances of mass dispersal, the problem tends to be a home grown one. To be effective, a rabbit control program needs to achieve a 95% + kill. Coman (1999) notes that an 80-90% population reduction can be replaced by breeding in a single good season.

Over time, the conventional methods of rabbit control have improved particularly with the introduction of large tractors for warren ripping, pressure fumigation with chloropicrin (introduced in the 1950s), fumigation with aluminium phosphine tablets (1960s), and efficient bait layers for 1080 oats or carrots. Ward and Cooke (1987) found that the use of phosphine tablets was labour intensive and ineffective due to the lack of sufficient soil moisture. This is an opinion shared by many current Parks Victoria staff who find pressure fumigation with chloropicrin to be the better method (Rob McNamara, pers. comm.). Field trials have found little difference between the effectiveness of the two fumigation techniques (Brian Cooke, pers. Comm.). More recently, the use of implosion devices 36 | P a g e

(Rodenator or Rodex) which pump a mixture of propane and oxygen into the warren before ignition has become popular with some staff whilst others do not rate it highly.

Some of the existing rabbit control techniques have come under increasing scrutiny both from an animal welfare and an OH&S perspective. The use of Chloropicrin by staff or contractors of Victorian government agencies was banned in 2011 on OH&S grounds. The use of Chloropicrin is due to be prohibited nationally from 2013. Ripping is now precluded from extensive areas in the Mallee on the grounds of the risk to Aboriginal cultural sites. Parks Victoria was declined permission by DPI to evaluate the effectiveness of a ‘Rodenator’ implosion device on the grounds that the device does not have animal welfare endorsement. A landholder in the Mallee who had been granted support under the Bush Tender program was told that ripping of warrens did not conform with the program guidelines although warrens could be excavated by hand! (Phil Murdoch pers. comm.). There are grounds to suggest that the limitation of available rabbit control techniques may be due to a growing disconnect between the perspectives of our largely urban population and a realistic appreciation of the devastation that rabbits cause to our natural environment. Rabbit control in the period 1990-95 With the launch of the new Mallee parks in 1991, the Victorian government announced initiative funding of $1.5M per year for the management of the park additions. Although this funding was for all management activities, it was clear that most of the funds would be needed for rabbit control in areas that had recently been destocked. One of the first areas where broadscale rabbit control was implemented was the NW of Murray-Sunset because stock grazing had already been phased out from Heitmans and Sunset Pastoral Co. licences, with other licences to follow. Control works actually began in the Heitmans block in the mid 1980s – soon after the licence was relinquished.

The total area of the NW corner of Murray-Sunset N.P. (north of Settlement Rd) was approx. 215,000 ha of which 90,000 ha was assessed as requiring intensive rabbit control. This in turn represented about 40% of the overall area of the new Mallee parks in need of intensive rabbit control works. A NW Sunset Rabbit Control Plan was prepared by the Pest Plant and Animal Planning Officer with Dept. Conservation & Natural Resources (Daryl Walters) in May 1990. The plan subdivided the NW Sunset into management units and prescribed a sequence for control activities for the period 1990-95.

The target set for an acceptable level of rabbit control was maintenance of abundance below 5 per spotlight km or approx. 2 per ha. An extensive system of spotlight transects totalling 130 km in length was established and monitored on a quarterly basis. It was known from earlier studies such as that by Cooke (1987) in the Coorong N.P. that densities of rabbits as low as 3 per ha were capable of preventing the regeneration of sensitive perennial trees and shrubs, and Lange and Graham (1983) where only 1 or 2 rabbits per ha were capable of removing all Acacia spp. seedlings in the arid zone. The target of 5 or less per km was considered as one that was realistically achievable for NW Sunset in the short term given the history of neglect in these areas.

The initial ‘knockdown’ control works predominantly involved broadscale ripping of warrens either by Departmental staff or by contractors. Consideration was given to a large scale baiting program but the judgement at the time was that the rabbit population was already collapsing due to a lack of food (Daryl Walters, pers. comm.). The population did in fact collapse of its own accord over the summer of 1990/91. Smaller 40 hp tractors with a single tyne ripper were found not to be up to the task of ripping large warrens, particularly in copi soils. Most of the ripping was soon contracted out to a 240 hp Cat Challenger operated by Des Thompson. This tracked machine had 9 tynes, with the 5 rear tynes being 750 mm in length. It could travel at speeds of up to 30 kph between warrens. The initial success of the Cat Challenger was attributed to the depth of ripping, the speed at which it was able to cover the ground, the large mass of the machine causing warrens to collapse, and to the fact that the open landscape meant that virtually no warren was inaccessible (Daryl Walters, pers. comm.). 37 | P a g e

The Cat Challenger operated by Des Thompson ripping large warrens in the NW of Murray- Sunset N.P.

At the time there were policy concerns about the environmental risks associated with widespread use of 1080 in national parks following the earlier experiences of off-target impacts at both Hattah- Kulkyne and Wyperfeld national parks. However, some targeted baiting was used in areas of high rabbit abundance. The newly prepared Natural Resource Protection Guidelines were applied as part of the plan to minimise the risks of undue impacts upon either environmental or cultural values. Under these guidelines, for instance, ripping of warrens in areas of Aboriginal cultural significance was precluded.

With each year of the program, smaller areas required knockdown control but progressively larger areas required follow-up maintenance. This involved fumigation and, in some cases, secondary ripping. A review of the initial program conducted by the National Parks Service in 1995 (unpub.) recorded that within the former Sunset Pastoral Co. area, the Cat Challenger was used to rip 15,589 large warrens within an area of 9,614 ha (1.6 warrens per ha). Only very limited pre-poisoning was undertaken. The cost of the initial ripping was approx. $10 per ha. An initial evaluation one month after completion in mid 1991 found that only 1-2% of warrens had re-opened but that an estimated 5- 8% of warrens had been missed. Overall strike rate was hence assumed to be 90-94%. Follow-up fumigations were conducted by Departmental staff at intervals of between 6 & 12 months at a cost of $2.68 per ha.

Three years after the initial ripping, the density of warrens was assessed as being as high as 25% of the original density. A secondary ripping program was conducted at an estimated cost of $6.60 per ha. A further assessment 18 months later found that the secondary ripping had only marginally reduced warren density in some areas and that pine ridges with light sandy soil were the areas most prone to re-openings. The knockdown works were suspended for a year in 1993/94 to allow greater focus on maintenance works in the form of fumigation, poisoning, and maintenance ripping at an aggregated average cost of $4.20 per ha.

The total expenditure on both knockdown and maintenance rabbit control for the 5 year period from 1990/91 to 1994/95 in the NW of Murray-Sunset was $1,754,313 of which 68% was for Departmental works through direct employment and 32% was for contract ripping. The total area of knockdown control was 63,890 ha whereas a slightly larger area (71,890 ha) was subject to maintenance control. The 1995 review of the program estimated that $400,000 per annum would be required for a full maintenance program in the NW Sunset area. In fact, total expenditure had reduced from $411,000 in 38 | P a g e year 1 to $204,000 in year 5. Figure 3 is a representation of the area subject to either knockdown and maintenance control in each year and the average expenditure on all works per ha.

80000 16

70000 14

60000 12

50000 10 Knockdown area (ha) 40000 8 Maintenance area (ha) Area (ha)Area 30000 6 Cost perCostha($) Total cost per ha ($) 20000 4

10000 2

0 0 1990/91 1991/92 1992/93 1993/94 1994/95

Figure 3. This chart shows the reducing area of knockdown ripping whilst the area of maintenance control increased. The change in the balance between knockdown and maintenance control is reflected in reduced expenditure per ha.

After the first 5 years, levels of rabbit abundance in the NW Sunset were variable. Areas north of the Sturt Highway near Lake Wallawalla periodically had spotlight counts as high as 40 per km because knockdown control had yet to be implemented. In the Heitmans block where works had commenced nearly 10 years earlier, counts of less than 3.5 per km were being maintained. The changes in the average spotlight counts over the aggregated 130 km of transects is shown in Figure 4.

16.0

14.0

12.0

10.0

8.0 Av. rabbits per km 6.0 Target 4.0

2.0

0.0 90 90 91 91 91 92 92 92 93 93 93 94 94 94 95 95 95 ------Apr Apr Apr Apr Apr Dec Dec Dec Dec Dec Dec Aug Aug Aug Aug Aug Aug

Figure 4. Average spotlight counts for NW Sunset for the period 1990-95 relative to the target of 5 per km. Knockdown control works had not extended to all areas by 1995. 39 | P a g e

Key recommendations arising from the 1995 review of the NW Sunset program were:

• That initial ripping should only be conducted after a pre-poisoning (and perhaps shooting) had been completed to reduce the surface rabbit population and increase the likelihood that rabbits would be occupying warrens at the time of ripping. • That fumigation should be completed no later than 3 weeks after ripping (knockdown or maintenance).

Despite the 1995 review finding some scope for improvement in practices, the control work conducted in the NW Sunset before 1995 has stood the test of time. Rabbit abundance in this area declined dramatically following the arrival of RHD virus in 1996 and has remained at low levels (<1 per km) over the subsequent 15 years (refer Chapter 9).

The regional Pest Plant and Animal Planning Officer from that time recollected that the initial effectiveness of the broadacre rabbit control did raise alarm bells with some staff who had previously worked for Crown Lands (Daryl Walters, pers. comm.). He was summoned to a meeting of staff at Hopetoun where they expressed concern that they might soon be out of a job! 40 | P a g e

6. ARRIVAL OF THE RHD VIRUS IN MALLEE RABBIT POPULATIONS Changes in rabbit abundance Rabbit Haemorrhagic Disease (RHD), also known as Rabbit Calicivirus Disease (RCD), is a disease specific to the European rabbit and was first described in domestic rabbits in China before spreading to Europe in 1988. The causative agent is the Rabbit Calicivirus and this virus was introduced for field trial as a biocontrol on Wardang Island in South Australia in October 1995. It subsequently spread to the mainland and was first observed within Mallee rabbit populations in the NW of Murray- Sunset N.P. in March 1996.

The RHD virus caused an immediate and dramatic decline in rabbit abundance across the Mallee that was independent of rainfall (Cooke 1999). An investigation of the implications of RHDV for the Hattah area of NW Victoria (Hattah-Kulkyne N.P. and areas of State forest west of Calder Hwy) began in 1996. It was a joint Parks Victoria and NRE project which was initially sponsored by ANZECC / ARMCANZ as part of the National RHD Monitoring and Surveillance program. As the project manager, Peter Sandell was appointed to the National RHD Science Sub-committee which collated data from ten national sites with the objectives of:

• improving the understanding of the contribution of RHDV (and other factors) to the maintenance of effective rabbit control; and • improving the understanding of the implications of reduced rabbit abundance for biodiversity.

The National RHD Monitoring and Surveillance program continued to be sponsored nationally by ANZECC / ARMCANZ for only three years post release but was maintained longer at some sites, including at Hattah, through state government support. In Victoria the epidemiological sampling and other work was sponsored by the Victorian ‘Rabbit Buster’ program until 2002/03.

The dramatic effect of the initial arrival of RHDV in the Mallee is illustrated in Figure 5 which displays the change in the average spotlight count pre and post-RHDV for aggregated sampling sites within Hattah-Kulkyne N.P. 41 | P a g e

20 250 18 16 200

14 Arrival RHDV 12 150 10 8 100 Rabbits per km per Rabbits 6 4 50 Quarterly rainfall Annuello (mm) Annuello rainfall Quarterly 2 0 0 91 92 93 94 95 96 97 98 98 99 00 01 02 ------Jan Jan Jan Jan Jan Jan Jan Jan Dec Dec Dec Dec Dec

Figure 5. Rabbit spotlight counts (line) from the combined Boolca and Kramen sites of Hattah- Kulkyne N.P. 1991-2002 relative to rainfall (columns) at Annuello (nearest BoM recording station). Source of data: Parks Victoria staff Hattah-Kulkyne N.P.

The spotlight data from four sites in the Hattah area (national park and State forest), from the NW Sunset, and from Pine Plains provided consistent evidence of the effectiveness of RHDV in reducing Mallee rabbit abundance by approximately 95% (Sandell unpub.). The evidence of spotlight counts and surveys of active entrances suggested that the greatest level of population reduction was achieved where complementary ripping of warrens had been undertaken prior to, or soon after, the initial RHD epizootic in 1996. McPhee and Butler (2010) corroborated this experience in a statewide study where they found that systematic ripping with heavy machinery was highly effective at a time when biological controls (RHD and Myxo) had reduced the capacity of populations to recover.

In those areas of the Mallee where ripping had been completed, spotlight counts remained below 1 per km for at least the first 5 years following the arrival of RHDV. In the case where ripping was conducted later (Glencoe east) counts cycled as high as 1.5 per km, which was still low when compared with the pre-RHDV experience (Sandell unpub.). The high level of rabbit control was achieved independent of rainfall conditions. Winter rainfall conditions were particularly suitable for rabbit breeding in 1999 and 2000 but populations failed to respond. RHDV epidemiology As part of the RHD monitoring program at Hattah, rabbit populations were sampled at each site for the presence of RHDV antibodies using the shot sample method; hence rabbits less than 3 months of age were not sampled. Sampling between June 1996 and June 2000 was conducted at quarterly intervals, but only at half-yearly intervals between 2000 and 2003. A total of 1534 rabbits were sampled over the 7 year period. Collected serum was analysed at the Victorian Institute for Animal Science (VIAS) for the presence of RHDV antibodies using the “Capucci” competition ELISA. Rabbit eyeballs were also collected so that the eye lens could be weighed as a measure of the age of each rabbit. Rabbits that tested positive to RHDV antibodies (sero-positive) were the survivors of 42 | P a g e infection. The trend in the proportion of the population that was sero-positive between 1996 and 2003 is shown in Figure 6.

1.20 Prop. Pos

1.00 4 per. Mov. Avg. (Prop. Pos)

0.80

0.60

0.40 Proportion of sample positiveofsample Proportion 0.20

0.00 96 96 97 97 98 98 99 99 00 00 01 01 02 02 03 ------Jun Jun Jun Jun Jun Jun Jun Jun Dec Dec Dec Dec Dec Dec Dec

Figure 6. Changes in the proportion of the serum sample from the combined Hattah sites which tested positive to RHDV antibodies between June 1996 and June 2003. Source of data: VIAS, Attwood.

A pattern of winter / spring epizootics of RHDV emerged for rabbit populations in the southern arid and semi-arid regions of Australia (Cooke, 1999). At the Hattah monitoring site, there was evidence of widespread epizootics in spring of each year from 1996 to 1999 inclusive. This was supported by field observations (blowflies around warrens and sudden declines in rabbit activity) and by the serological data. In each of the years 1996 to 1999, the population of young rabbits (< 1 yr old) exhibited a higher proportion that were sero-positive when sampled in December relative to a cohort of younger rabbits sampled six months earlier. Of 49 rabbits sampled in March 2000, all were found to be sero-positive (they were all the survivors of infection). This confirmed that, at the time, the virus was being effectively transmitted through populations and that almost all rabbits were likely to be challenged before they reached 1 year of age (Sandell unpub.).

The proportion of the sample found to be sero-positive subsequently declined to 50% or below (total sample). In 2001, only 50-60% of adult rabbits (more than 12 mths of age) were found to be sero- positive. These data would suggest that poorer transmission of the disease in 2000 and 2001 may have led to a reduction in overall effectiveness. The observed patterns of epidemiology of RHD virus tend to be variable, and appear to be influenced by the timing of rainfall events and hence the breeding cycle (Coman 1999). Although the routine collection of rabbit serum ceased at Hattah in 2003, field observations have confirmed that there have been subsequent widespread RHD epizootics in most years since then.

There is still a need to understand how RHDV persists and whether a lack of virus is a major limitation on the effectiveness of RHDV as a biological control agent in some parts of Australia (Cooke 1999). Given the recurrent epizootics of RHD in Mallee it seems that persistence of the virus is not an issue locally. Effective transmission of the virus within populations relies upon there being a sufficient pool of susceptible rabbits and the right environmental conditions for spread of the disease. 43 | P a g e

Whilst a number of insects (mosquitoes, flies, fleas) have been capable of infecting rabbits with the virus in an experimental setting, the mechanisms of spread in the field are not well understood (Cooke 1999).

The susceptibility of rabbits to RHDV varies with age. Cooke (1999) states that “Maternal antibodies may inhibit natural infection of young rabbits. .... Young rabbits, with protection from both natural resilience and maternal antibodies, mostly survive infection.” This suggests that caution should be applied to any release of virus in populations with a significant proportion of young rabbits which might become immunised as a consequence. Evolution of resistance to RHDV As with all biological controls, it is to be expected that the host will develop resistance through the process of natural selection. There may also be co-evolution of the virus such that it becomes less pathogenic, although work being conducted in South Australia by Ron Sinclair (Cooke, pers. comm.) has found that field strains of virus still remain relatively virulent infecting most rabbits and causing high mortality (around 80%). This suggests that the virus is evolving to try to keep up with increasing rabbit resistance (Cooke pers. comm.). However, Dr Cooke (pers.comm.) notes that “even small changes in mortality from about 90% to 80% might be enough to tip the scales in favour of the rabbits”. Evidence from the Victorian Mallee is that the period during which RHDV was most effective were the 6 years from 1996 to 2002. After 2002, increases in rabbit abundance were observed at some locations, notably at Hattah-Kulkyne N.P. and at Pine Plains (refer Figures 7 & 15).

Aggregated rabbit spotlight counts HKNP

12.0

10.0

8.0 RHDV 6.0

4.0 Average km count per Average 2.0

0.0 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 ------Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar

Figure 7. Aggregated spotlight counts from Hattah-Kulkyne N.P. for the period 1993-2011 showing a steady increase in abundance post 2002 and declining abundance after 2009. Dotted line is moving average over 4 periods. Source: Parks Victoria staff at Hattah-Kulkyne N.P.

44 | P a g e

In response to concerns that RHDV was becoming less effective at Hattah-Kulkyne in particular, Dr Brian Cooke (Invasive Animals CRC) and Steve McPhee (Agricultural & Technical Services) collected a small sample of sero-negative rabbits from the Park in 2006. Seven sero-negative rabbits from Hattah-Kulkyne were subsequently challenged with a low dose of RHDV and all survived, whereas with unselected laboratory rabbits given the same virus dose, eight out of 12 rabbits became infected and died (B. Cooke, pers. comm.). This provided the first concrete evidence of the development of resistance to RHDV within Mallee rabbit populations. Dr Cooke (pers. comm.) has advised that in general, rabbits in areas of 250 - 400 mm annual rainfall have been found to be more resistant to laboratory challenges with RHDV than rabbits from very wet areas or very dry areas. Although the reasons for these differences are not clear, one would expect that those regions where the virus was most effective initially, such as the Mallee, are where resistance might evolve earliest.

The explanation of the resurgence in rabbit populations at Hattah-Kulkyne is complicated by a number of factors, including the fact that investment in conventional control had declined substantially in the wake of RHD. This is discussed in more detail in Chapter 9.

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7. VEGETATION CHANGES IN THE WAKE OF RHDV

The RHD Monitoring and Surveillance Program included the investigation of a range of possible implications of the sudden collapse in rabbit populations for biodiversity across the ten national sites. In particular, studies of predator-prey relationships investigated whether there had been changes in the abundance or activity of foxes and cats (so called prey-switching), whether any native prey species may have been disadvantaged by prey-switching, and whether native predators might have been disadvantaged by reduced availability. The initial results of these studies are outlined in Sandell and Start (1999) and are generally outside the scope of this report. Investigation of changes in floristics / biomass at Hattah monitoring site The biodiversity questions considered here relate to the rabbit – vegetation interactions, specifically:

• Has there been a measurable reduction in total grazing pressure as a result of reduced rabbit abundance, or have other herbivores (for example, kangaroos) increased in abundance as a consequence of RHD? • Has there been any measurable recovery in the structure, biomass or floristic composition of native vegetation, or in the level of weediness due to reduced rabbit abundance?

The short term focus of the investigation of the role of reduced rabbit abundance in vegetation recovery at Hattah was upon elements of the pasture layer, eg. perennial grasses and subshrubs, where measurable changes might be expected within a time frame of 5 years. Floristic changes are likely to provide a better measure of any recovery than fluctuations in total biomass, which are strongly influenced by rainfall (Hodgkinson and Freudenberger 1997). In a rangelands case study, Landsberg et al. (1997) found that ‘species response groups’ were more useful than ‘species richness’ for interpreting the impact of grazing on plant and animal communities.

Pasture species can be categorised as either: 1) ‘decreasers’ (that is, species intolerant of high grazing pressure); or 2) ‘increasers’ (that is, species favoured by a regime of intensive grazing). 1. “Decreasers” (all of which are native plants) were sub-divided into four categories: 1.1. Group 1 - perennial grasses (eg. Austrodanthonia sp., Poa spp. Austrostipa spp.); 1.2. Group 2 - native dicotyledons (eg. Actinobole uliginosum, Brachyscome lineariloba, Chenopodium pumilio, Ptilotus spathulatus, Rhagodia spinescens, Zygophyllum ammophilum); 1.3. Group 3 - all native pasture species (combination of groups 1 and 2); and 1.4. Group 4 - selected native pasture species (eg. Bulbine semibarbata, Austrodanthonia sp., Austrostipa spp., Enchylaena tomentosa, Wurmbea doica).

2. “Increasers” (all of which are exotics) were sub-divided into four categories: 2.1. Group 1 - all exotics; 2.2. Group 2 - selected increasers (eg. Bromus spp., Critesion spp., Brassica tournefortii, and Hypochoeris glabra); 2.3. Group 3 - introduced annual grasses (eg. Avena spp., Bromus rubens, Critesion murinum ssp. leporinum, Pentaschistis airoides, and Vulpia myuros); and 2.4. Group 4 - dicotyledon weeds (eg. Asphodelus fistulosus, Brassica tournefortii, Erodium cicutarium, Hypochoeris glabra, Medicago minima, Silene nocturna, and Salvia verbebaca).

Floristic sampling was conducted within 1m2 permanent quadrats systematically located within and outside grazing exclosures between 1997 and 2001 (no pre-RHD data) at four sub-sites (refer Figures 8 and 10). Existing rangeland monitoring techniques were adapted to the task of measuring vegetation attributes given that grazing pressure was the main dependent variable. The sampling method 46 | P a g e

involved a qualitative assessment of the standing dry weight for all pasture species using a comparitive yield table (t’Mannetje and Haydock 1963; Green et al. 1994). The field sampling in the first two years was conducted by a single observer (Dr Ian Sluiter of Ogyris Ecological Research) engaged under contract to Parks Victoria (Sluiter 1997a, Sluiter 1997b). Subsequent sampling was conducted by Parks Victoria staff and the results summarised in Sandell (2002).

Fenced plot 250m * 250m or 6.25ha Unfenced pair

Floristic Photo points quadrats 1m*1m

Approx. 70m 200m*25m belt transects for initial record of tree species

Figure 8. Layout of transects and quadrats at Boolca sub-site (not to scale). Note pseudo-replication within exclosure.

The outcomes of the floristic sampling need to be interpreted in the context of the extant grazing regime at each sub-site. At the two sub-sites within Hattah-Kulkyne N.P. (Boolca and Kramen), kangaroo densities were being maintained within the range 5-10 individuals per km2. At these sub- sites there was a general improvement in the ratio of decreasers to increasers over the 5 year period, although the biomass of native perennial grasses in the unfenced treatment at Boolca was low relative to the fenced treatment. There was a greater diversity of native annual and perennial grasses in the Boolca fenced treatment. Dicotyledon weeds exhibited relatively more biomass in the Boolca unfenced treatment. The biomass of native dicotyledons did not differ significantly between the fenced and unfenced treatments at either site. 47 | P a g e

Estimated Marginal Means of DECR3 3.4

3.2

3.0

2.8

2.6

2.4 TRTMNT

2.2 All grazers excluded

2.0 Unfenced 4321 5 876

SEASON

Figure 9. Plot of estimated marginal means of dry weight biomass for gp. 3 decreasers (all native pasture species) at Boolca sub-site for the period April 1997 – April 2001. Fenced treatment (red) and unfenced treatment (green). Source of analysis: Dr Duncan Mackay, Flinders University.

The third sub-site (Raak) was located within the eastern part of Murray-Sunset N.P. where rabbit populations had also declined dramatically but there was no management of kangaroos or goat populations. In this case, the grazing exclosure design included a rabbit-only treatment (K) and a kangaroo only treatment (R), as well as the total grazing exclusion (F) and the unfenced (U).

K treatment – ringlock to F treatment – ringlock and R treatment – rabbit 2m netting netting to 900mm.

Photo points

100m * 25m belt Floristic / biomass transect for initial sampling quadrats Unfenced control record of tree species

Figure 10. Layout of transects and quadrats at Glencoe and Raak subsites (not to scale). One of two replicates. Fenced plots are 140m*140m or 1.95ha. 48 | P a g e

Data from the unfenced treatment at Raak provided evidence of a general improvement in the status of decreasers (native dicotyledons and perennial grasses) relative to increasers (dicotyledon weeds and introduced annual grasses). A downward trend in the biomass of dicotyledon weeds (unfenced treatment) was found to be significant at the .05 level. There was regrowth of chenopods (Atriplex vesicaria) and tussocks of Austrostipa sp. resulting in higher levels of cover compared with those that existed immediately post-RHD. Whilst rainfall in the period 1999 – 2001 was considerably higher than that in the preceding three years (1996 – 1998), it was concluded that reduction in rabbit grazing was an important factor in the observed recovery. The relative improvement in the status of decreasers provided support for this conclusion.

The final sub-site (Glencoe state forest) was subject to ongoing stock grazing. The same grazing exclosure design as Raak applied. Data from the unfenced treatment provided evidence of an improvement in the status of native dicotyledons, but a relative decline in native perennial grasses compared with the fenced treatments at Glencoe (Figure 11). In neither case were these trends found to be statistically significant. The floristic data at Glencoe was difficult to interpret. On balance, there appears to have been relatively little floristic benefit in the unfenced treatment at this site. The relative weediness of some of the fenced treatments (particularly K) was considered to be possibly related to the long history of grazing disturbance at this site and a depleted seedbank of native pasture species.

Estimated Marginal Means of DECR1 3.5

3.0

2.5

2.0 TRTMNT

1.5 All grazers excluded

1.0 Kangaroos excluded

.5 Rabbits excluded

0.0 Unfenced 87654321

SEASON

Figure 11. Plot of estimated marginal means of the dry weight biomass for gp. 1 decreasers (native perennial grasses) at the Glencoe sub-site for the period April 1997 – April 2001. All grazers excluded (red), kangaroos excluded (green), rabbits excluded (blue), and unfenced (purple). Source of analysis: Dr Duncan Mackay, Flinders University. Evidence of pine regeneration at Hattah monitoring site Belt transects (0.25ha or 0.5ha in area) were installed within each treatment at all sub-sites in 1996. An initial survey of the transects was completed in April 1997 and the results documented (Morgan and Sluiter 1997). The basal circumference, crown diameter, and approximate height of each tree were recorded. An assessment of browsing was also made for smaller trees. This information was recorded for a total of 3611 individual woody perennial plants. The initial sampling of belt transects for the combined subsites highlighted the general lack of woody perennials in the smaller size classes. For instance, only 0.6% of all stems had a basal circumference 49 | P a g e of less than 0.2m and only 2.1% of stems had a basal circumference of less than 0.3m (Morgan and Sluiter 1997). The belt transects were sampled again in 2002 and comparisons made between the age class distributions for each period and for each treatment. In the case of Slender Cypress-pine, Figure 12 highlights the general increase in stems in the smaller age classes from 1997 to 2002 for the combined treatments (fenced and unfenced).

Figure 12. Size class distribution of Callitris gracilis stems in 1997 and 2002 at Boolca and Kramen sub-sites (combined fenced and unfenced treatments). Although new seedlings of Callitris gracilis were recorded in both the fenced and unfenced treatments they were more numerous in the fenced treatment (Figure 13 for the Boolca sub-site).

Figure 13. Size class distribution of Callitris gracilis live stems at Boolca in 2002 (fenced and unfenced treatments). 50 | P a g e

Buloke regeneration within Hattah-Kulkyne N.P.

In the course of her PhD study in June 2004, Fiona Murdoch conducted a survey over 135 km of belt transect to record the presence of Buloke (Allocasuarina leuhmannii) regeneration within the Park (Murdoch 2005). Through this process she was able to record 69 separate patches of Buloke recruitment. Her analysis determined that this recruitment had occurred on a number of occasions since 1996 and had become visible to local staff from 2000. Genetic analysis determined that the recruitment was all seedlings in origin and not due to sucker regrowth (Murdoch 2005).

This record of isolated (not widespread) Buloke seedling regeneration at Hattah-Kulkyne was highly significant for a number of reasons. It occurred despite generally below average rainfall conditions for the period 1996-2005 which included some very dry periods: 1997-98 and 2001-2004. Other Mallee studies, notably those of Castle (1989), Raymond (1990), and Chesterfield and Parsons (1985) had not recorded regeneration of woodland casuarinas even after the wet period of 1973-75. Murdoch (2005) has postulated that the post RHDV regeneration events at Hattah-Kulkyne are the first time Buloke has regenerated on this scale since the mid 1950s at which time Myxomatosis would have similarly reduced rabbit abundance.

Fiona Murdoch conducted a subsequent investigation into the effects on Buloke regeneration of increased browsing by rabbits (Murdoch unpub. 2007). In this study she revisited a subset of the original sites and some new sites to evaluate rabbit impacts in 2005 and again in 2007. She confirmed that regeneration had continued post 2004 but that seedlings were increasingly being impacted by rabbit browsing. Some areas of regeneration were fenced by Parks Victoria and the Mallee CMA between December 2006 and March 2007. Fiona Murdoch then assessed the browse damage and related this with the current rabbit abundance. She found that the level of browse damage was closely related to rabbit abundance and that very few seedlings showed signs of kangaroo browsing alone (Murdoch unpub. 2007). Where rabbit abundance was measured as being <3 per spotlight km or <1 active entrance per ha, browse damage was low. At > 6 rabbits per km seedlings were severely affected by rabbit browsing with the loss of very small seedlings with small seedlings unable to progress to a larger size.

Revision of rabbit control targets

There was already recognition by Parks Victoria staff that 5 rabbits per spotlight km was not an adequate level to which rabbit populations should be managed, and that post-RHD, a higher standard of rabbit control was both necessary and achievable. There was also the consideration that investment in rabbit control was most cost-effective when populations were in low growth and when there was less chance of breeding out-competing the reductions due to control work. Coman (1999) cites an example from Wagga in the 1960s where, by adopting a ‘rabbit-free’ approach, the per acre costs of rabbit control were reduced by some 80% over a 6 year period. The zone of effective control is well illustrated in Figure 14 from Williams et al. (1995). Once rabbit abundance has been reduced to a very low level natural mortality, particularly due to predation, has a major impact (Coman 1999).

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Figure 14. Hypothetical growth curve for a rabbit population and periods of effective / ineffective control from Williams et al. (1995). This graph illustrates that for the same time interval (t1-t2) there is a large increase in the population (w) during the high growth phase of the population, relative to the small increase (v) during the low growth phase.

Fiona Murdoch’s investigations at Hattah-Kulkyne confirmed that it was rabbit browsing, not rainfall or kangaroos, that was limiting upon Buloke regeneration. Without improved rabbit management that is able to maintain abundance below 1 active entrance per ha there is no prospect of new seedling regeneration and small extant seedlings will progressively be lost.

Some of the key recommendations from the work of Fiona Murdoch at Hattah-Kulkyne were:

• Management targets for rabbits must be <3 per spotlight km or 1 active entrance per ha to allow current Buloke seedlings to survive, whilst an even higher standard of control is probably required to enable recruitment of new Buloke seedlings. • Capacity to control rabbits within the Park (funding, training, planning, techniques) needs to be increased to achieve newly defined targets. • A long term rabbit management strategy needs to be developed and costed.

The implications of even moderate densities of rabbits upon regeneration of Buloke was discussed in a detailed summary analysis by Murdoch, McPhee, and Cooke (unpub.). ‘How many rabbits are too many? – Monitoring grazing pressure and regeneration of semi-arid woodlands’ reinforces the need to maintain rabbit abundance below a threshold of 1 active entrance (or less than 1 rabbit) per ha in order to promote woodland recovery.

In light of the work of Murdoch et al. at Hattah-Kulkyne, the studies conducted elsewhere in the arid zone (e.g. Lange and Graham 1983), and the other considerations noted above, rabbit control targets of 1 rabbit per spotlight km and < 1 active entrance per ha have been adopted for the Mallee District. These targets have been included in rabbit management strategies for both Hattah-Kulkyne and Wyperfeld National Parks and in agreements reached with DSE on the implementation of the major government-funded rabbit control initiative: ‘Mallee woodlands - bouncing back’. The four year ‘Mallee woodlands - bouncing back’ initiative of the Victorian government under the Weeds and Pests Initiative began in 2007 and has resulted in considerable investment in a landscape scale rabbit control program. Hence three of Fiona Murdoch’s key recommendations have been adopted. The post-RHDV rabbit program is discussed further in Chapter 9.

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8. STATEWIDE RABBIT RISK ASSESSMENT

In order to prioritise Statewide investment in rabbit control, Parks Victoria in 2002 commissioned the Arthur Rylah Institute for Environmental Research (ARIER) to undertake a comprehensive rabbit risk assessment (Long et al. 2003). Each of 32 ecological vegetation divisions (EVDs) across the State was assessed in terms of susceptibility to rabbit disturbance. Dry (non-eucalypt) woodland and chenopod shrubland were the two EVDs assigned to risk category 1 – communities most susceptible to rabbit disturbance Statewide. Murray-Sunset N.P. was ranked as the national park most at risk from rabbits Statewide. It was assessed as containing 64% of the total area (or 69,800 ha) of vegetation / habitat in the highest risk category.

Long et al. (2003) found the key factors predisposing dry woodlands to high risk from rabbits included the fact that the typical tree dominants (spp of Callitris and Casuarina; and other non- myrtaceous and often non-sclerophyllous genera, such as Alectryon, Myoporum, Santalum) are relatively palatable as seedlings. Mutze et al. (2008) note that, under a Mediterranean climatic regime, rabbit grazing on woody seedlings is most severe in late summer when there is little alternative green feed available.

The evidence with Buloke regeneration at Hattah-Kulkyne N.P. (Murdoch, 2007) suggests that regeneration within dry woodlands is not primarily episodic, but continuous. This renders the canopy species at risk of elimination by rabbits as typical seasonal drought concentrates rabbit browsing on tree seedlings. Every stratum is susceptible to rabbits and every stratum is dominated by palatable species (Long et al. 2003).

The ARIER risk assessment determined that 91,000 ha of the Mallee parks was in the highest risk category, and 264,000 ha of the Mallee parks was in risk categories 1-4. These areas have now expanded due to reservations since 2002. The risk categories assigned by ARIER for WesternVictoria are illustrated in the map on page 53 (source: Long et al. 2003).

This prioritisation for rabbit control within Victorian national parks begs the question: what if the dry woodlands have changed irreversibly from their original condition, e.g. lost their tree cover? Would they then still warrant the highest priority for resource allocation? 53 | P a g e

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9. CONVENTIONAL RABBIT CONTROL

As noted above, progressive increases in rabbit abundance were observed at Hattah-Kulkyne from 2002. There was a lesser increase at Pine Plains – another very rabbit prone environment. In the case of Pine Plains, spotlight counts exceeded 1 per km for a period in 2002/03 before a more sustained increase in 2005/06 (refer Figure 15). Although an upswing in rabbit abundance to 3.5 per km was experienced at Pine Plains, these counts are still very low compared with the historical experience – refer Figure 1. Average counts in the NW area of Murray-Sunset N.P. remained below 1 per km and, in fact, have not exceeded that target for since 1996 (refer Figure 18).

Aggregated spotlight counts Pine Plains (Wyperfeld NP) 5 Increased investment in 4 conventional control 3 RHDV

2

1 Av. no. perrabbits km Av.

0 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 ------Jul Jul Jul Jul Jul Jul Jul Jul Apr Mar Mar Mar Mar May May May

Figure 15. Rabbit spotlight data from Pine Plains (Wyperfeld N.P.) for the period 1995-2011 relative to the target of 1 per km. Counts averaged over the aggregate of 16 transects with a total length of 118km. Source: Parks Victoria staff at Wyperfeld N.P. Rabbit resurgence at Hattah-Kulkyne The evidence at Hattah-Kulkyne, Wyperfeld and some other areas of the Mallee from 2002 highlighted the need for re-investment in integrated conventional rabbit control works. Reliance upon biological control (RHDV and Myxomatosis) was no longer a viable strategy – if it ever had been. The level of discretionary funding of conventional rabbit control works had declined to low levels with only $29,000 being available at Hattah-Kulkyne in 2002/03. This was clearly insufficient to deal with the escalating rabbit problem in the Park.

Aside from the low level of resourcing in the early 2000s, there are some unique challenges to effective rabbit control at Hattah-Kulkyne. The dry woodlands occur on Aeolian dunes that are interspersed with riverine woodland vegetation – dominated mainly by Black Box (Eucalyptus largiflorens). The distribution of dry (non-eucalypt) woodlands is as shown in the map facing page 10. The dunes themselves became extensively colonised by Hopbush (Dodonaea spp.) after being heavily denuded in the 1982 drought. This primary coloniser provides ideal harbour for rabbits who readily establish warrens at their bases. Hopbush thickets make access for baiting and fumigation difficult. In addition, rabbits have established large warrens in the adjoining Black Box woodlands where they can be difficult to access and destroy. 55 | P a g e

The damage associated with increasing rabbit abundance at Hattah-Kulkyne became increasingly visible in 2006 with the Buloke seedlings that had emerged between 1996 and 2002 now being heavily browsed or even ringbarked (Murdoch unpub. 2007).

Slender Cypress-pine ringbarked by rabbits at Hattah-Kulkyne post 2006.

The level of rabbit impact in the Park in 2006 prompted the development of a Rabbit Management Action Plan (Pegler 2007) and the adoption of an emergency response. Areas of Buloke regeneration were fenced with netting, and rabbit control stepped up over summer with spot baiting, ripping, and shooting (Phil Pegler pers. comm.). The net effect of these works was to ensure the survival of discrete areas of juvenile Buloke and to reduce the average spotlight count in 2007 to 2 per km. However, spotlight counts again increased in 2008 and peaked in 2009 at an average of close to 10 per km.

From 2002 the level of discretionary funding available for rabbit control works at Hattah-Kulkyne, and on Mallee public land generally, rose steadily (Figure 16). There was a spike in funding at Hattah-Kulkyne in 2006/07 when Parks Victoria redirected resources to the emergency response effort.

$ 400000 350000 300000 250000 200000 $ 150000 100000 50000 0 02/03 03/04 04/05 05/06 06/07 07/08 08/09 09/10 10/11

Figure 16. Amount of discretionary funding available for rabbit control works at Hattah-Kulkyne N.P. from 2002 – 2011 under a series of Victorian Government initiatives and more recently (2009- 11) from the ‘Caring for our Country’ Program managed through the Mallee CMA. 56 | P a g e

Possible role of fox baiting The growth in rabbit populations at Hattah-Kulkyne coincided with a project to evaluate the cost- benefit of fox baiting in the Park. This adaptive experimental management (AEM) project involved intensive fox baiting in the western half of the Park (treatment area) from March 2002 until 2006. The effect of the baiting program was to cause an estimated 89% reduction in fox activity in the treated area, but also an estimated 74% reduction in the non-treated area (Robley and Wright 2004). Hence the treatments were not independent and foxes were migrating from the non-baited area and taking baits. The evidence of the rabbit spotlight counts for this period (Figure 17) suggests that the reduction in fox activity may have released the rabbit population from a ‘predator pit’.

Rabbit counts for fox-baited v's non-baited areas of HKNP

12.0 Fox baiting ended 10.0 Fox baiting 8.0 started

6.0

4.0

2.0 Average km count per Average

0.0 1/3/93 1/1/95 1/12/96 1/12/98 1/12/00 1/12/02 1/12/04 1/12/06 1/12/08 1/12/10

Figure 17. Rabbit spotlight counts for transects within the fox baited treatment (line) and the non- baited treatment (bars) at Hattah-Kulkyne. Source of data: Parks Victoria staff at Hattah-Kulkyne N.P.

Hattah rabbit management strategy

The failure to maintain rabbit abundance within the target range prompted a detailed review of rabbit control operations at Hattah-Kulkyne in 2008. The reviewer (Peter Sandell) sought the advice of Park staff and outside experts: Dr Brian Cooke of Invasive Animals CRC, and Steve McPhee of Agricultural and Technical Services. Findings from the review are summarised below:

• There was no coherent strategy for an integrated approach to rabbit control across the Park at the scale required. • Control works had focussed on the central Mournpall Block where the primary treatment in recent years had been contract fumigation. This approach had been continued despite an evaluation in 2003 that found approx. 30% of warrens were being missed. There had also been considerable investment in use of the Rodenator although this device was generally unproven as a control technique. • Similarly, the ripping work undertaken in Mournpall did not appear to have been very effective due to poor timing – it was generally conducted in winter / spring when rabbits were 57 | P a g e

relatively abundant. Ripping was not preceded by comprehensive baiting as part of a more integrated approach. The lack of consistent follow-up after ripping was contributing to high rates of re-opening. • Control effort was not able to reduce the population in any one area to a very low level. Rather, operations had generally been within populations that were in a rapid growth phase and hence the works were being overrun by high rates of breeding. • Baiting conducted in recent years had been on a very small scale relative to the extent of the rabbit problem. The management response generally did not take sufficient account of the scale of the problem. • The supervision of contractors was inadequate, e.g. insufficient feedback to contractors on the proportion of missed warrens. Hourly rate contracts did not require the contractor to achieve a specified standard of control. An alternative approach would be to issue longer term incentive-based contracts where the contractor is rewarded for achieving a prescribed standard.

Following this review, a 3 year rabbit management strategy was developed for the Park in consultation with Park staff, Dr Fiona Murdoch (restoration ecologist), Dr Brian Cooke (IA CRC) and two Traditional Owner representatives (Parks Victoria 2008). The objective was to ‘optimise the management of rabbits to achieve regeneration of our dry woodlands’. Investment was made in new infrastructure and equipment including the installation of a 7 tonne silo for the storage of grain used in large scale 1080 oat baiting, and the purchase of new precision bait layers. In 2010, Parks Victoria leased three 180 hp log skidders each equipped with a 4 tyne ripper. The implementation of the Hattah-Kulkyne rabbit management strategy is being reviewed at half-yearly intervals.

One of three 180 hp skidders acquired by Parks Victoria in 2010 for ripping warrens in the Mallee.

Earlier rabbit control initiatives

The $10 M Victorian ‘Rabbit Busters’ program from 1996-2000 had combined monitoring and operational funding with the objective of maximising upon the benefits of RHDV. This was an 58 | P a g e important initiative at a time when there was general complacency about the need for conventional rabbit control. It included the preparation of Rabbit Action Plans for the Mallee and Wimmera CMA regions. ‘Rabbit Busters’ allowed for the continuing collection of rabbit serum and tissue samples within the Mallee parks beyond the expiry of the national RHD monitoring and surveillance program. With the conclusion of the ‘Rabbit Busters’ program in 2000, there was less capacity to address the resurgence in Mallee rabbit populations that came after 2002. Government agencies had ‘dropped the ball’ perhaps because of misplaced confidence in the ongoing effectiveness of RHDV.

A new Victorian initiative ‘Keeping a lid on Mallee Rabbits’ applied from 2004-2007 and was based upon a landscape approach to rabbit control in the Mallee with more funding for conventional control works. With the benefit of hindsight, the title ‘keeping a lid’ sent the wrong message. The aim should be ‘rabbit free’ because the threshold of rabbit damage is so low in semi-arid environments. Nevertheless, the additional funding allowed more control works to be undertaken across Mallee public land, mainly through the agency of private contractors. Parks Victoria developed a panel of 15 ‘preferred suppliers’ for rabbit control that could be engaged at short notice to undertake baiting, ripping, and fumigation. This arrangement has a number of benefits in that it provides some assurance of ongoing work for contractors who can develop their own capacity, it allows rapid response to undertake works, and contractors are not constrained (as staff are over the summer months) by fire management responsibilities. Casual employees were also hired for similar reasons to operate Parks Victoria equipment. Mallee Woodlands Bouncing Back initiative and new partnerships The ‘Mallee woodlands – bouncing back’ initiative was launched in 2008/09 with a four year timeframe to achieve defined targets for rabbit control and measurable improvements in the condition of the dry woodlands. Funding of $2.4M was approved by the Expenditure Review Committee of Cabinet (ERC) for expenditure over 4 years. The initiative provided a clear purpose for rabbit control works, woodland recovery, but the program under the umbrella of the DSE Weeds and Pests Initiative had broader defined outcomes:

1. Communities engaged to influence governments to assist with solutions in/on environmental stewardship issues for their unique landscapes; 2. Increased, sustained capacity and knowledge within agencies and the community to address threats to key biodiversity assets; 3. Demonstrated efficiency of management and change in the condition and viability of dry woodlands; 4. An integrated approach to pest control across public and private land, including the indigenous community resulting in a reduced threat of rabbits on environmental, social and economic values in the Mallee; 5. Persistent program of biological rabbit control on the ground; and 6. Increased ecosystem resilience. This ambitious program has been managed by Parks Victoria in partnership with DSE, The Mallee CMA, Trust for Nature (Ned’s Corner), and a panel of private contractors. The scope of the program was defined as four separate areas which encompassed almost all the rangeland areas of the Mallee at risk from rabbits and being managed for conservation (refer map on next page).

• ‘Millewa North’ encompasses the NW corner of Murray-Sunset N.P., Ned’s Corner Station and areas of State forest on the River frontage (most of which have now been included in Murray-Sunset as a result of the VEAC Red Gum investigation). • ‘Hattah’ area encompasses Hattah-Kulkyne N.P., Glencoe Station (State forest), and the eastern end of Murray-Sunset N.P. • ‘Cowangie-Pink Lakes’ encompasses the Pink Lakes region of Murray-Sunset N.P. and the Cowangie State Forest. • ‘Wyperfeld – Patchy’ includes both the Pine Plains and southern regions of Wyperfeld / Lake Albacutya parks as well as areas of state forest and reserves in the Patchewollock area. 59 | P a g e

Map showing the four separate areas of landscape scale rabbit control activity under the ‘Mallee woodlands – bouncing back’ initiative.

The achievements of the ‘Bouncing Back’ initiative to date are summarised briefly below under the headings of each of the intended outcomes.

1. Communities engaged to influence governments to assist with solutions in/on environmental stewardship issues for their unique landscapes. o There has been publicity generated about the threat to assets posed by increasing rabbit abundance and the need to actively control populations now that the effectiveness of RHDV is declining. o A Mallee Rabbit Taskforce was formed with membership of all the relevant agencies to foster improved collaboration. o Field days / workshops have been conducted for staff, landholders, and contractors to promote best practice control techniques.

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2. Increased, sustained capacity and knowledge within agencies and the community to address threats to key biodiversity assets. o Specific rabbit management strategies have been developed for those areas (Hattah- Kulkyne and Wyperfeld) where effective control has proved most problematical. o Rabbit abundance data collected half yearly across all four areas has been converted to a spatial layer to highlight problem areas where works need to be scheduled. o A partnership has been forged with the Invasive Animals CRC to assist staff through mentoring and research.

3. Demonstrated efficiency of management and change in the condition and viability of dry woodlands. o Rabbit abundance has been reduced through conventional control works and in 2010 the target of average spotlight counts of 1 or less per km was achieved in all areas. o The unit costs of control are gradually being reduced as there is a transition from knockdown to maintenance control within lower-growth populations. o Contractor innovation is being promoted through the issue of a performance-based maintenance contract at Hattah-Kulkyne. o A demonstration site for best practice rabbit control was established at Hattah-Kulkyne with support from the Invasive Animals CRC (refer Chapter 9). o The application of a ‘rapid assessment’ technique for analysis and reporting upon treatment and control outcomes has been piloted with the use of Trimble ‘Juno’ PDAs. o Changes in the condition of dry woodlands are being evaluated in terms of improvements in both the understorey (floristic changes) and the overstorey (recruitment of new tree seedlings).

4. An integrated approach to pest control across public and private land, including the indigenous community resulting in a reduced threat of rabbits on environmental, social and economic values in the Mallee. o A memorandum of understanding has been agreed with Trust for Nature in relation to cooperative rabbit control works in the Ned’s Corner area and surrounding national park. Under this agreement, baiting and other works have been jointly conducted over the last 2 years. o The Mallee Natural Resource Protection Guidelines have been applied to control operations such that any off-target risks to environmental or cultural values have been minimised.

5. Persistent program of biological rabbit control on the ground. o There has been collaboration with Invasive Animals CRC in their ‘RHD Boost’ initiative. Current data collection in the Mallee is being supported by Parks Victoria staff with the objective of gaining an understanding of the current effectiveness of RHDV.

6. Increased ecosystem resilience. o Through prolonged maintenance of low rabbit abundance, there has been a demonstrated reduction in fox abundance (Figure 18). The maintenance of low fox activity is likely to be associated with wider biodiversity benefits. o Progressive restoration of understorey vegetation is improving the quality of habitat for a range of fauna taxa.

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Contrasting experiences in rabbit control at NW Sunset and at Hattah-Kulkyne

It may be useful to reflect on the contrasting post-RHDV rabbit abundance between NW Sunset (Figure 18) and Hattah-Kulkyne (Figure 7). Current investment in conventional rabbit control in the NW area of Murray-Sunset N.P. is relatively low (estimated to be $1.80 per ha of vegetation at risk) compared with Hattah-Kulkyne N.P. ($9 per ha at risk). The NW Sunset area is no less susceptible to rabbit infestation based on the ARIER risk assessment.

16.0 1.2 Av. rabbits per km 14.0 1.0 12.0 Av. foxes per km 0.8 10.0 RHDV

8.0 0.6

6.0 0.4 Rabbits per km per Rabbits 4.0 0.2 2.0 km per counted foxes

0.0 0.0 95 96 97 99 00 01 02 03 04 05 06 07 08 09 90 91 92 93 98 ------Apr Jan Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Mar Aug Sep Aug Sep May Period of count

Figure 18. Chart of the changes in the spotlight counts of both rabbits and foxes for the NW area of Murray-Sunset for the period 1990-2010. These data demonstrate the maintenance of a high standard of rabbit control (<1 per km) over 15 years and the subsequent reduction in fox abundance after a long lag period. Source of data: Staff of Murray-Sunset N.P. based at Werrimull.

The long lag period (approx. 6 years) before fox counts declined to low levels as shown in Fig. 18 is counter-intuitive given the relatively short lifespan of foxes in the wild (18-24 months). The experience at Pine Plains was that there was no obvious decline in fox abundance post-RHDV although fox counts have remained low (<0.15 per km) relative to those in NW Sunset. There has been no fox baiting at either location.

There are grounds to argue that the contrast in rabbit abundance between NW Sunset and Hattah- Kulkyne can be explained largely in terms of the recent management histories for the respective areas, although differences in landform probably also played a part. The NW Sunset was comprehensively ripped using the Cat Challenger with 750mm tynes in the period immediately prior to the arrival of RHDV. Being an open area, very few warrens were inaccessible. Daryl Walters (pers. comm.) observed that the combined speed and weight of the Cat Challenger caused large warrens to visibly collapse. 62 | P a g e

By contrast, Hattah-Kulkyne was not comprehensively ripped during this period and the ripping work that was conducted used smaller agricultural tractors with 600mm tynes. There remain large warrens at Hattah-Kulkyne, particularly within Black Box communities, which appear never to have been ripped. Fumigation was relied upon in some areas as the primary treatment at Hattah-Kulkyne whereas ripping has remained the primary method of control in the NW Sunset.

Follow-up after ripping was more systematic in the NW Sunset under the terms of a strategic plan. A comprehensive fox control program was implemented at Hattah-Kulkyne from 2002 to 2006 which may have released the low level rabbit population. There is more or less permanent water in the Hattah Lakes and rabbit warrens are in greater density within close proximity to the lakes. There has been a relatively high turnover of staff at Hattah-Kulkyne whereas there has been greater staff longevity within Murray-Sunset N.P. These differences may collectively explain why the decline in rabbit abundance post-RHDV was maintained for much longer in Murray-Sunset (> 15 years) when compared with Hattah-Kulkyne (only 6 years). Demonstration of best practice at Hattah-Kulkyne One of the objectives of the ‘Mallee Woodlands - Bouncing Back’ initiative was to establish a demonstration site for best practice rabbit control at Hattah-Kulkyne. This was done in 2009 in partnership with the Invasive Animals CRC who contributed $20,000 to the overall cost of the project and guided the project design.

The project set out to evaluate the relative cost- effectiveness of two different rabbit conventional integrated control strategies in the Kramen block of Hattah-Kulkyne. One strategy involved pre- baiting with 1080 oats whilst the other involved only ripping and fumigation. Outcomes were compared with an untreated control.

Map illustrating the distribution of dry woodland interspersed with riverine woodland across Hattah- Kulkyne N.P. The location of the Kramen demonstration site (northern area) and separate control (southern area) are shown in orange. 63 | P a g e

This map shows the ‘treatment’ and ‘control’ areas which are separated by low-lying land which supports Black Box woodland. Of the 6 blocks of 50ha within the treatment (upper) area, blocks 2,3 & 6 were pre-baited whilst 2,4 & 5 were only ripped and fumigated. The 3 blocks within the control (lower) area received no treatment. Warrens of less than 5 entrances are shown as pink dots, whereas larger warrens are shown red dots.

The costs of each operation were calculated on the basis of all-inclusive contract rates. The results will be used to demonstrate and promote the most cost-effective combination of conventional control techniques in the context of the Hattah-Kulkyne N.P.

Baiting practice

Baiting of blocks 2, 3, & 6 was completed in the period 5-20 May 2009. Three free feeds at 3 day intervals were followed by 1080 oat baiting at 4kg/km. Sterile oats were used and the baited oats were dyed green to minimize the attractiveness of oats to birds. Oats were not laid until the afternoon on each occasion. A total of 60 km of trail was laid at a density of approx. 20 linear km per km2. Dead rabbits were collected off the trail on the first and second mornings after baiting. The trails were then covered. Experience showed that there was significant bait uptake on the second night after 64 | P a g e baits were laid (presumably due to sub-dominant rabbits coming late to the trail). The total number of dead rabbits collected from the trail was only 42 and it is assumed that most rabbits died within warrens. No off-target impacts were recorded. The contractor (Daryl Walters) reported that there was a high uptake of oats by rabbits despite the presence of green pick at the time of baiting. Emus were also removing oats from the trail but this was reduced by a light covering of soil over the oats in the trail. This was achieved by means of use of a chain dragged behind the bait-layer. Minimum temperatures overnight were in the range 7-120 C.

Ripping practice

Ripping of the treatment area (blocks 1-6) and immediate surrounds commenced on 16 June and was completed on 3 July 2009. Ripping work was undertaken by an experienced contractor (Jack Pryse) using two 140 hp log skidders each with 4 rear-mounted tynes 600 mm in length, and a single spotter on a bike. The tynes were modified at the tip with a ‘winged keel’ design which reportedly improved that lateral extent of the rip and aided with cross-ripping and turning. After each warren had been cross-ripped in a ‘zig zag’ pattern, the front blade on the skidder was used to smooth the restore the ground surface as level as possible. A surface with relatively few banks is considered to be important in minimizing the risk of re-openings. Using the skidders it was possible to access virtually all warrens found. Large logs were pushed aside. In the case of warrens close to trees, ripping was conducted radially away from the tree to minimize damage to tree roots.

There had been rain prior to commencement of works and the soil moisture conditions were not ideal for ripping. The contractor recorded each warren using a GPS and the waypoints were subsequently downloaded and mapped. The total area of ripping was 1227 ha – ripping extended outside the area shown on the map. The total number of warrens ripped was 2607 over 11 days of operations by the two machines. This equated to 2.1 warrens per ha on average.

Fumigation practice

Fumigation using a pressure fumigator (chloropicrin) commenced by contract (Les Lidden) on 21/7/09 (3 weeks after ripping) and was completed on 27/7/09. The contractor used dogs to flush rabbits into warrens and locate them in logs. A total of 326 warrens were found and treated. Most of these were re-openings from the earlier ripping but the proportion of warrens that had not been ripped was not recorded. Subsequent monitoring found a relatively high level of re-openings in block 5 of the treatment area. This was re-fumigated 2 weeks later with a further 16 warrens being treated by the same contractor. Total number of warrens treated was therefore 342 over an area of 993 ha. This equated to 0.34 warrens per ha on average.

Fallen logs pushed aside to rip a warren with the area subsequently bladed flat. Kramen demonstration site.

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Control costs

The contracted rate for the laying of 3 free feeds (3 day intervals), subsequent 1080 baiting, pick-up and burial of carcasses was $123 per km of completed trail. Hence the cost of baiting 60 linear kms was $7380. Costs of consumables were $1,872 for free-feed oats (720 kg @$2.60) and $1,238 for 1080 oats (240 kg @ $5.16 per kg). The total cost of baiting was $10,480 and the unit cost was $35.00 per ha.

Costs of ripping were based on an all-inclusive hourly rate of $275 charged by the contractor (Jack Pryse) for his two 140 hp skidders. Included in the rate for the combined skidders and operators was the spotter on a quadbike. The cost calculation is therefore: $275 per hr (for 2 skidders plus spotter) * 9 hours (average hrs worked per day) * 11 days. Total cost of ripping amounted to $27,225 for an area of 1227 ha and 2601 warrens. This equated to unit costs of $10.44 per warren or $22.18 per ha.

Costs of fumigation were estimated on the basis of the hourly rate of the contractor ($45 for each of two operators with quadbikes and dogs) plus the cost of fumigant (chloropicrin). The cost calculation for the treated area was: 6 days × 2 persons × 10 hours per day @ $45 per hour, plus the cost of the fumigant (6 × larvacide 500mm @ $42.27). The total cost of treating 326 warrens over 1227 ha was $5,657. This equates to unit costs of $17.29 per warren or $4.60 per ha.

Hence the aggregated cost for the ‘ripping +fumigation’ treatment was $26.78 per ha. The comparable cost for the ‘baiting+ripping+fumigation’ treatment was $61.78 per ha, or more than twice the cost of the non-baited treatment. These costs need to be seen in the context of the initial high level of rabbit abundance: more than 2 warrens per ha.

Relative effectiveness of two treatments

Measurements were made of the relative rabbit abundance in each of the treatments between April 2009 ( prior to treatments) and April 2011 (21 months after the initial treatments). Both spotlight counts and warren counts were undertaken, although spotlight counts were not continued after January 2010 in the treatment blocks and no measurements were possible in the control blocks after 9 months because general rabbit control works had extended to this area by that stage.

The results of the spotlight and warren counts present a consistent picture of the relative effectiveness of the alternative treatments. Both treatments resulted in dramatic initial reductions in rabbit abundance relative to the control. After 1 month, the density of active entrances was measured as having been reduced by 99.2% within the baited treatment and by 95.7% in the non-baited treatment relative to the densities pre-treatment. After 21 months, however, the relative reductions were 97% and 79%. The populations in each of the treatments had recovered at the same rate, but the greater initial reduction associated with baiting (although the difference was less than 4%) meant that the population in the baited area would take longer to reach the threshold at which damage to regrowth could be anticipated. Results are summarised in Figures 19 and 20.

Whether the longer period of recovery in rabbit abundance within the baited treatment justified the extra cost of $35 per ha would need to be the subject of economic analysis. However there is no doubt that earlier and probably more frequent intervention will be required in the non-baited area in order to maintain populations below the threshold at which environmental damage will occur.

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Kramen spotlight counts 3.5 3.0 2.5 2.0 Ripped only 1.5 Baited and ripped 1.0 Damage threshold

Rabbitscounted perkm 0.5 0.0

Figure 19. Changes in rabbit abundance as measured by spotlight counts for the alternative integrated control strategies at the Kramen demonstration site: baited and non-baited.

Kramen warren counts 1.20 1.00 0.80 0.60 Non-baited 0.40 Baited 0.20

Active Active entrancesperha Threshold 0.00

Figure 20. Changes in rabbit abundance as measured by density of active entrances for the alternative integrated control strategies at the Kramen demonstration site: baited and non-baited.

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Summary of best practice rabbit control

Based on the evidence from the literature, from the Kramen demonstration site, and from the advice of experienced practitioners, best practice rabbit control for Hattah-Kulkyne has the following characteristics:

• The objective should be for ‘rabbit-free’ and the initial reduction in abundance should be greater than 97%. Ongoing investment should be maintained even at low levels of abundance. The goal is community and habitat restoration and the cost-effective use of resources. The rabbit abundance threshold for environmental damage is very low. • Works should be conducted at the optimal time in the rabbit breeding cycle. In general, the optimal time for knockdown control is over summer when breeding has ceased and the population is already under stress. Refer Table 2. • Where rabbits are relatively abundant (e.g. above 5 per km), pre-baiting is recommended to maximise the effectiveness of the subsequent treatments (refer figures 19 & 20). • The destruction of warrens by ripping is the key to any integrated control program (refer notes from ripping workshop). Follow up fumigation should be initiated soon (preferably within a month) after ripping. • Adequate data should be collected (e.g. GPS plotting of warrens) at the time of each treatment to facilitate an effective evaluation of outcomes. This would involve subsequent inspections of a sample of treated warrens. • Routine monitoring should be conducted in order to detect incipient change within populations such that a management response can be implemented before damage occurs. • Best practice should be refined for each location through the maintenance of demonstration (research) sites.

Month Rabbits Rip Fumigate Bait RHDV Myxo breeding warrens active active January

February

March

April

May

June

July

August

September

October

November

December

Table 2. Adaptation for the Mallee of a similar calendar prepared by the Department of Primary Industries and Fisheries, Queensland (2008). It indicates the best time of year to undertake control activities. 68 | P a g e

Ripping workshop

A workshop was convened in Mildura in November 2009 to discuss ripping practice for rabbit control. Scientists from IA CRC, interstate agencies, PV staff and contractors were present.

It was recorded that warren ripping is the most cost-effective method of rabbit control used by land managers in Australia and also the method with the greatest innovative change in recent years. It is the key to controlling rabbits on a wide scale, particularly in arid, semi-arid and open grazing and cropping areas of Australia. It was widely used in major programs such as Operation Bounce-back, West 2000 (NSW) (Ferraro and Burnside 2000) and Rabbit Busters (Victoria) and a major rabbit control project at Bulloo Downs in Queensland (Dave Berman, pers. comm.). New machinery ranging from large bull-dozers to Bob-cat excavators is increasingly being used. Surprisingly little has been published in recent times on these trends or the benefits generated. Since the release of RHDV, rabbits have less capacity to quickly regain numbers and McPhee et al (in press) show that long-term benefits have accrued from ripping in the those years whilst RHDV kept rabbits low.

There are many examples suggesting that warren ripping can have long-lasting effects. For example, warren ripping in ‘trap-rock’ country in south-eastern Queensland carried out before the spread of RHDV has lasted for about 30 years (Berman, pers. comm.). This raises the strong probability that ripping done effectively can give long-lasting results and this should be the aim of investing in this form of rabbit control. It is not a good policy, especially in sensitive areas like National Parks to be re- ripping too often and ripping should aim to keep rabbits low for at least 10 years without the need for retreatment to justify its use. But to do this it is important to maximize effectiveness by paying attention to the following:

• Summer is the optimal time for ripping when soils are dry and run into deeper leads. In some instances (heavy clay) this may not work. This is also the time when rabbit populations are approaching their low points for the year, after myxomatosis and RHDV have taken their toll, and a lightly occupied warren has a lower probability of reopening than one that is heavily populated. • Spotters working closely with the machine operator are essential. They must communicate well with driver by using easily seen markers (e.g. bamboo pole, toilet paper) to mark outlying holes and indicate the size of the warren to be ripped (e.g. two-way radio, holding up fingers indicating number of holes) and be trained to find 1 hole warrens as well. The spotter checks ripping as well as directing the driver to the next hole. • Cross-ripping to ensure complete warren destruction has always been regarded as essential. With a small tractor, cross ripping helps get greater depth. However, many large machines are now designed to minimize this (e.g. two-way rippers and winged tynes). There is no simple formula for deciding on the most economical configuration of tynes on a machine. Going from 4 to 3 tynes may cost 30% more but could also allow longer tynes to be pulled through the soil. Nonetheless, it would be worth re-evaluating the value of cross-ripping now that heavy equipment is widely used. • Tyne depth should be 600 mm minimum, although a depth of 900 mm is preferable in deep sands. It was noted that the Aboriginal Heritage Act in Victoria precludes ripping deeper than 600mm on dunes. Heavy machines also crush warrens and this can be beneficial. • It is essential to rip beyond the perimeter of obvious warren entrances. General consensus was that ripping one machine width outside apparent surface signs of each warren was the best practice. However, this may be excessive if using a D8 dozer which may have a ripping bar width of ~ 3-4 m. • Smoothing soil on a ripped warren surface, also known as back-blading, is considered time well spent not only for aesthetic purposes but also because it reduces sites where rabbits might shelter and begin new excavations. Log-skidders have scrub rakes for pushing dead trees off the warren surface and blades for smoothing the warren surface after ripping. • Dogs can be used to drive rabbits below ground prior to ripping warrens. Dave Christian (Parks Victoria) was enthusiastic about the effectiveness of using dogs to drive rabbits 69 | P a g e

underground prior to ripping or fumigation. Moseby et al (2005) suggest that dogs are much more effective than human activity in driving rabbits below ground. Shooting of surface rabbits during ripping operations was also discussed but there are no data on likely effectiveness.

Private contractors The proportion of discretionary funds expended on contract works has generally increased in recent years to the point that in 2009/10 at Hattah-Kulkyne, nearly 80% of discretionary funds ($270,000) were directed to contract works. The balance of funds was used for casual employment of plant operators and for the purchase of materials, e.g. oat baits. Engagement of preferred suppliers is on the basis of agreed hourly rates. Contractors are required to submit the waypoints of all warrens they treat either by ripping or fumigation. In the case of baiting contractors, they submit track logs of their bait trails. The spatial data can be used to evaluate the cost-effectiveness of works, e.g. cost per warren, rates of re-openings, and proportion of missed warrens.

The piloting of longer term performance-based rabbit maintenance contracts is an objective of the ‘Mallee woodlands – bouncing back’ initiative. The advantages of this approach are seen as (1) fostering custodianship on behalf of the contractor who will become very familiar with the area and hence efficient, (2) encouraging innovation in terms of strategies and techniques of control within agreed constraints, and (3) providing a direct incentive to the contractor to exceed defined standards through bonus payments. The first contract of this type was issued for the 5,000 ha Cantala block of Hattah-Kulkyne in July 2010. Key elements of the contract brief are:

• Integrated rabbit control by baiting, ripping, and fumigation had been completed over the Cantala Block within the previous 12 months and abundance was low although it did not meet all the standards required of the contractor at the time the contract was issued. Any area of large warrens that were found by the contractor, within the first few months, to have been missed in the initial treatment were the responsibility of Parks Victoria to rip. • The contract was issued for 1 year with the option of 2 × 1 year extensions by mutual agreement. • The contractor has access to the area at any time but is required to keep a log of all days on which works were conducted, along with the waypoints of all warrens treated or bait laid. • The contractor is required to conduct works on a minimum of 1 day per calendar month. • Given the initial low rabbit abundance, the anticipated methods of control are fumigation and ripping or implosion of remnant warrens. Shooting will also be permitted by agreement with the contract supervisor. The contractor may use other methods, e.g. spot baiting, by prior agreement with Parks Victoria. The contractor may also crush, disperse, or burn rabbit harbour subject to an agreement on the timing and methods to be used. • The objective is to maintain rabbit abundance below the thresholds defined below. Parks Victoria will conduct measurements half-yearly (as a minimum) to assess compliance with these standards. o Spotlight counts generally of 1 or less rabbits per km and of no more than 3 per km, based on the higher of two counts conducted on separate nights from transects at least 10km in length. The average spotlight count is to be less than 1 rabbit per km; o An average pellet count of less than 10 pellets per quadrat (0.25m2), based on sampling of 15 quadrats per site with a minimum of 30 sites distributed systematically across the area (minimum of 450 samples); and o An average of less than 1 active entrance per ha, based on sampling of a minimum of 25 × 1 ha plots distributed systematically across the area. • If the contractor achieves all 3 of the above standards, payment will be made at 125% of the scheduled rate. This payment will be retrospective back to the date of the previous evaluation. If the contractor achieves 2 of the above standards, payment will be made at 100% of the scheduled rate. If the contractor achieves only 1 or none of the above standards, a notice of non-compliance will be issued. If three notices of non-compliance are issued within 70 | P a g e

the contract period, the contract will be terminated and the contractor will not be eligible to any further payments.

In the case of the Cantala pilot, the contractor achieved two of the three standards at the first measurement (December 2010) and hence continued to receive payments at 100% of the contract rate. He subsequently (March 2011) exceeded all three standards and was paid 125% of the contract rate. The rate determined through competitive tender was $10 per ha per annum. This is an all-inclusive cost (apart from monitoring). It is assumed that the contractor margins would improve over time as rabbit abundance is reduced to very low levels. There are currently insufficient funds to issue maintenance contracts over all areas of dry woodlands (approximately 100,000 ha). The intention of outsourcing rabbit maintenance in some areas is to provide Parks Victoria staff with the opportunity to focus their management on a reduced area and hence implement more consistent follow-up control works.

In reality there is only a small pool of contractors to bid for maintenance contracts, partly because of the DPI requirement that contractors hold a Commercial Operators Licence (COL). The other options for maintenance rabbit control are: use of agency staff, employment of casual staff, or contracting out on an hourly rate basis. Within this mix there appears to be scope for issue of more performance- based contracts subject to the success of the current pilot at Cantala Block.

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10. OTHER GRAZERS AND WEEDS Kangaroo abundance and impact Kangaroo management is considered here only in the context of the potential of kangaroo browsing to limit or prevent rangeland recovery. The phenomenon of increasing kangaroo abundance post the removal of stock grazing in the Mallee has been experienced widely (Coulson 2007) and has been clearly demonstrated for the Mallee parks through the conduct of annual kangaroo censuses.

The rapid increase in the density of Western Grey Kangaroos at Hattah-Kulkyne in the early 1980s has been characterised as a response to the end of the severe 1982 drought and reduced competition from other grazers (DCNR 1994). The proportion of breeding females doubled between 1982-83 and 1983-84 (Coulson and Norbury 1988). The localised abundance of Western Grey Kangaroos at Hattah-Kulkyne was the highest recorded for mainland Australia (Coulson 1990). Stock grazing ceased in the Park in 1977 but the kangaroo censuses only began in 1983.

Cheal (1986) noted that in 1984 there was no discernible difference between the rabbit-infested and rabbit-free areas of the Park. Both were severely denuded and over-grazing by kangaroos was implicated in the loss of native grasses and forbs, and the inhibition of tree regeneration. Coulson and Norbury (1988) demonstrated that browsing of woody plants by kangaroos significantly increased when the biomass of grass in the field declined below approximately 400 kg DW ha-1.

Based on the collective evidence of overgrazing by kangaroos and the fact that there was some regeneration of Slender Cypress-pine and Hooked Needlewood (Hakea tethrosperma) within fenced plots, it was concluded that kangaroos were preventing regeneration. A kangaroo control program for Hattah-Kulkyne National Park, ‘Restoring the Balance’ (DCE 1990) was developed. The independent plan (Coulson 1990) recommended that “the population of Western Grey Kangaroos be reduced and maintained at a target density indicated by monitoring and modelling of the situation”. The threshold of a minimum of 400 kg DW ha-1 of grass biomass was the guiding principle.

Kangaroo management was initially applied within the fenced Mournpall Block from 1990 and later extended to the balance of the Park in 1996. The Kangaroo Technical Advisory Committee (KTAC) provides independent advice to Parks Victoria and DSE on annual targets and management practices. For Hattah-Kulkyne a target density of 5 kangaroos km-2 was adopted and detailed monitoring was conducted by the Department of Natural Resources and Environment between 1992 and 1996 to model the relationship between grass biomass, rainfall and kangaroo density (Sluiter et al. 1997).

This evaluation concluded that “only in high rainfall years would the non-mallee or woodland areas of Hattah be capable of sustaining 5 kangaroos km-2 (Sluiter et al. 1997). Densities at the time of this study were in excess of 10 kangaroos km-2. Nevertheless, the target of 5 kangaroos km-2 was retained and densities within Mournpall reduced to that target in 1992 (Figure 21). No kangaroo culling was conducted in any of the Mallee parks in 2009/10 or 2010/11 due to low kangaroo abundance in those years. Parks Victoria field staff observed high levels of kangaroo mortality associated with extremely high temperatures in February and November of 2009. 72 | P a g e

Western Grey Kangaroos at Hattah-Kulkyne

90 Kangaroo mgt Mournpall 80 Kangaroo mgt 70 outside Mournpall 60 Mournpall Block 50 Outside Mournpall 40 30 20 10

Estimated density (kangaroos persqukm) 0 83 84 86 87 88 89 91 92 93 94 96 97 98 99 01 02 03 04 06 07 08 09 ------Jul Jul Jul Jul Jul Jul Jan Jan Jan Jan Jan Oct Oct Oct Oct Oct Oct Apr Apr Apr Apr Apr Year of census

Figure 21. Estimated densities of Western Grey Kangaroo (Macropus fuliginosus) at Hattah-Kulkyne N.P. inside and outside the Mournpall Block. Kangaroo management commenced within Mournpall in 1990 and outside Mournpall in 1996. Chart compiled by Lorraine Ludewigs on the basis of results of annual censuses conducted by Assoc. Prof. David Morgan and Parks Victoria.

Kangaroo censuses in the central area of Wyperfeld N.P. began in 1972 and it was recorded that the densities of Western Grey Kangaroos in the vicinity of Outlet Ck and the terminal lakes had remained sufficiently high to prevent regeneration of woody perennials such as Slender Cypress Pine (Morgan 1994). This area had been destocked in 1979 (Durham 2001).

A model for estimating carrying capacity at Wyperfeld was developed by Assoc. Prof. David Morgan (1995). Inputs to the model are current kangaroo abundance and rainfall from the two preceding years. Kangaroo management in the central area of Wyperfeld commenced in 1998 and the estimated density of kangaroos has been in the range of 5-15 km-2 since that time (Figure 22).

Kangaroo management extended to the Pine Plains area of Wyperfeld in 2000 following the cessation of stock grazing in 1996 and a decision of KTAC based on an ‘ecological rationale for kangaroo management at Pine Plains’ (Wouters 2000). The Western Grey Kangaroo population at Pine Plains had increased from 5.4 kangaroos km-2 in 1997 to 10.5 km-2 in 1999. Kangaroo densities in both central Wyperfeld and Pine Plains have generally been within the range 5 – 15 km-2 since 2003 (Figure 22).

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50 Western Grey Kangaroos at Wyperfeld N.P. 45 Kangaroo mgt 40 at Pine Plains RHD 35

30

25

20

15 Destocking Central Pine Plains 10 Wyperfeld Pine Plains Estimated density (kangaroos persqu)km 5

0 1972 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009

Year of census Figure 22. Estimated densities of Western Grey Kangaroo (Macropus fuliginosus) at Wyperfeld N.P. (central Wyperfeld and Pine Plains). Chart compiled by Lorraine Ludewigs on the basis of results of annual censuses conducted by Assoc. Prof. David Morgan and Parks Victoria.

There are two sources of data on kangaroo abundance for the NW area of Murray-Sunset: rabbit spotlight counts conducted from 1990 in which kangaroo numbers were also recorded, and the annual kangaroo census which commenced in 1992. Stock grazing ceased in the Taparoo area (south of Sturt Hwy) in 1990 or earlier but not until 1992 in the Berribee area (north of the Sturt Hwy).

Kangaroo spotlight counts NW Sunset

180 Kangaroo mgt RHD 160 De- 140 stocking 120 100 80 60 40 20 Av. WGKs WGKs Av. countedpertransect 0 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Figure 23. The average number of Western Grey Kangaroos counted per transect per year in the NW of Murray-Sunset. Data were collected from 5 separate rabbit spotlight transects with a total length of 130km and suggest a response to destocking in 1990/92 and rabbit control. Kangaroo management commenced in 2000. Source of data: Parks Victoria staff of Murray-Sunset N.P.

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The annual kangaroo census data for the NW of Murray-Sunset N.P. indicate that the density of Western Grey Kangaroos was as high as 25 km-2 in 1999. Red Kangaroos (Macropus rufus) also commonly occur in this area but at lesser densities. The ‘ecological rationale for kangaroo management at Murray-Sunset N.P.’ (Wouters 2000) found that ongoing kangaroo grazing was having adverse consequences for vegetation recovery. “Sites with relatively high kangaroo densities have exhibited less Cattlebush regrowth”. Kangaroo management for the relevant areas of Murray- Sunset N.P. was subsequently approved by KTAC and commenced in 2000. Management targets were similar to those applied at Hattah-Kulkyne N.P. The results of annual censuses for the Berribee and Taparoo areas of Murray-Sunset are illustrated in Figure 24.

Western Grey Kangaroos in NW of Murray-Sunset 40 Kangaroo 35 management 30

25 Berribee (Neds corner) 20 Taparoo

15

10

5

Estimated density (kangaroos persqu)km 0

Year of census

Figure 24. Estimated densities of Western Grey Kangaroo (Macropus fuliginosus) in Murray-Sunset N.P. (Berribee and Taparoo). Chart compiled by Lorraine Ludewigs on the basis of results of annual censuses conducted by Assoc. Prof. David Morgan and Parks Victoria.

Figures 21 to 24 show that the high kangaroo densities experienced after destocking have now been reduced through management to what are considered to be more sustainable levels in the context of a rangeland restoration program, although in some cases this reduction is only relatively recent (Pine Plains and NW Murray-Sunset). Murdoch (2007) found that kangaroos at the prevailing density of 5- 10 km-2 were not inhibiting the survival of Buloke seedlings at Hattah-Kulkyne. Sluiter et al. (1997) had earlier suggested that a density of 5 km-2 did not allow the minimum prescribed threshold of grass biomass to be retained in a year of median rainfall. In a 2007 review of vegetation change within both NW Murray-Sunset and Hattah-Kulkyne, Cheal et al. (2007) recommended that there be a review of kangaroo management throughout those areas.

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Goats There have been longstanding goat populations across Mallee public land, but relatively little data have been collected on their abundance or movements. Goats are thought to be in greater concentrations in the mallee and woodland communities of both Hattah-Kulkyne and Murray-Sunset compared with Wyperfeld (National Parks Service 1996). The reasons for the lower population density in Wyperfeld is not known but the presence of wild dogs and the relative absence of free water in the Wyperfeld / Big Desert complex are thought to be factors.

Feral goats can breed twice a year, although usually every 8 months (Henzell 1992). Twins and triplets are common and a population of feral goats can increase by about 75% per year. A once-a- year goat cull must remove 43% of the population to return it to the level of a year before (Henzell 1992). Goat browsing has a high environmental impact as they can browse to a height of 1.8 m. They are capable of removing palatable perennial plants of less than 2 m in height and of generally degrading land and habitat.

Evidence of goat browsing on a clump of Emu bush (Eremophila longifolia) in the Sunset Plains area of Murray-Sunset in 2002.

Goat browsing has severely inhibited the development of this cypress pine photographed in Murray- Sunset N.P. in 2002.

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Three aerial censuses of goats have been undertaken in the southern half of Murray-Sunset N.P. The first of these was in 2000 (Macdonnell 2000) when the population density in that area was estimated to be 1.3 goats km-2. The total population for the southern half of Murray-Sunset was estimated to be in excess of 4,200 animals because some goats are not detected in a helicopter survey. Subsequent aerial surveys over the same area estimated the density to be 0.55 goats km-2 in 2002 and 0.36 goats km-2 in 2004. These estimates tend to be in the lower range of goat densities recorded for semi-arid rangelands, e.g. in eastern South Australia (mean annual rainfall of 240 mm) where densities of up to 5 goats km-2 have been recorded (DEWHA 2008).

45

40

35

30

25 Mounds with scats 20 Mounds with prints 15

10

5 No. mounds with evidence ofgoats evidence mounds with No.

0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Figure 26. Evidence of changes in goat abundance derived from data stored on the national Malleefowl database. Volunteers from the Victorian Malleefowl Recovery Group record the presence of goat prints or scats on more than 1000 mounds over the summer.

Goats feed in woodland areas but tend to retreat to mallee or mallee-heath vegetation for shelter. Goats need to drink every two to three days in summer but can otherwise extract most of their water needs from their food (DEWHA 2008). However, some Parks Victoria staff have observed that goats in Murray-Sunset N.P. are less reliant upon free water (Robert McNamara, pers. comm..). The potential extent of goats across the Mallee District is estimated to be 880,000 ha. Hence the control or eradication of goats would be a massive undertaking.

Since 2003 Parks Victoria has entered into a partnership with the Sporting Shooters of Australia (SSAA) for the supervised shooting of goats in Murray-Sunset N.P. Under that partnership a total of 2795 goats were shot by Nhill SSAA between 2003 and 2011 (Robert McNamara pers. comm.). Whilst this level of culling will have been beneficial, it is not likely to constitute effective control given the fertility of goats and the evidence from Malleefowl monitoring. Aerial shooting (as practiced in South Australia) is another control option being considered but there are a number of regulatory hurdles in Victoria. Passive measures such as fencing of the southern boundary of the Park are also worthy of consideration given the apparent effectiveness of the fence on the northern boundary. Effective goat control is currently hampered by a lack of information on current densities, movement patterns, and water dependence. 77 | P a g e

Total grazing pressure and rainfall A summary of the collective data on rabbit and kangaroo abundance could conclude that the periods when there was a coincidence of low rabbit abundance (<1 per spotlight km) and low kangaroo abundance (<10 km-2 ) were in Hattah-Kulkyne from 1996 to 2002 and in NW Murray-Sunset from 2004 to 2010. In the case of Pine Plains, both rabbit and kangaroo abundance were relatively low from 2007-2010. In each of these areas, rabbit abundance was particularly low post 1996 for at least 6 years.

The periods 1996-1998 and 2001-2009 were of generally below average rainfall, whilst 1999-2000 and 2010 were wetter periods in the Mallee.

Annual rainfall at Annuello 600

500

400

300 Rainfall 200 Mean

100

0

Figure 25. Annual rainfall (mm) relative to the mean annual rainfall recorded at Annuello in the Victorian Mallee from 1996 to 2010. Over this 15 year period, only 3 years experienced above- average rainfall, whilst in 8 years the rainfall was below-average. Source: Bureau of Meteorology.

The inclusion of the rainfall data suggests that the ‘regeneration windows’ may have been further restricted to 1999-2000 at Hattah-Kulkyne, and perhaps only the current period of 2010/11 in the case of NW Sunset and Pine Plains because of the relatively high kangaroo densities which prevailed prior to 2004. However, the previous importance attached to above-average rainfall as a trigger for regeneration was not borne out in the study by Fiona Murdoch (2005) where she found that Buloke seedlings established in several years post-1996 and did not appear to be related to any particular rainfall event.

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Weeds Stock grazing has also left a legacy of weed infestation across the Victorian rangelands. The field layer in most areas at destocking was predominantly annual weeds such as barley grass (Hordeum spp.), brome grass (Bromus spp.), burr medic (Medicago spp.), turnip (Brassica spp.), and Paterson’s curse (Echium plantagineum). A number of perennial weeds such as onion weed (Asphodelus fistulosus) and horehound (Marrubium vulgare) were also very widespread. The evidence from some of the monitoring (refer Chapter 7) is that many of these weeds (increasers) have declined relative to a range of native decreasers such as spear grass (Austrostipa spp.), ruby salt bush (Enchylaena tomentosa), and the copperburrs (Sclerolaena spp.). However, the relative abundance of increasers and decreasers still varies widely depending on seasonal conditions. Duncan et al. (2007) note that the “gradual shift back to a native, if species poor, system is generally attributed to a decline in soil nutrient levels”.

Many of the original weed species are still widespread and periodically abundant. Chemical control of these weeds is not seen as a viable option at the scale of the rangelands, but some species are targeted on the basis of their limited extent, risks to agriculture, or for amenity reasons. No clear strategy exists for broadscale weed control other than the maintenance of low total grazing pressure so that decreasers can compete with introduced species.

Against the trend of other annual weeds, ward's weed (Carrichtera annua) has become the predominant ground cover species in large areas of calcareous soils in the NW of Murray-Sunset NP. It seems to have supplanted (at least temporarily) other annual weeds such as barley grass and brome grass. It also seems to have outcompeted native perennial grasses (Austrostipa sp.) since 1998. There is anecdotal evidence of a relative absence of regeneration of woody perennials, e.g. slender cypress pine, in those areas where C. annua has become the dominant ground cover. The possible role of ward's weed in preventing regeneration of woody perennials is of concern. This invasive weed may also be implicated in the degradation of habitat for a range of fauna, including pavement termites. This issue is the subject of current research by the Dept. Environment and Climate Change in N.S.W. (James Val, pers. comm.).

Field layer at a fenced monitoring site in the Berribee Tank area in spring 1998 comprises a mixture of introduced annuals (C. annua) and native perennial grasses (Austrostipa spp.). 79 | P a g e

Field layer at same site by spring 1999 is a dense sward of C. annua with virtually no other species present.

Same site in spring 2000 with C. annua still representing the bulk of the biomass although some native chenopods (Sclerolaena spp.) have also become established. 80 | P a g e

By 2011, after an extended period of above-average rainfall, most of the biomass in the field layer is again native tussock grasses (Austrostipa sp. and Austrodanthonia sp.).

It has been speculated that C. annua may have benefited in some way from the reduction in total grazing pressure, particularly post-RHDV. Most of the seed is held in pods, although some seed is stored in the soil. A study by Julia Cooke (2003) found that competition from native perennials reduced C. annua seed production, particularly post-fire. However, the native grasses are more palatable than ward's weed and will be preferentially grazed over time. In her Hons Thesis, Julia Cooke (2003) has suggested that reduction in total grazing pressure and burning should be elements of an integrated management approach.

A field trial of the use of fire to remove the pod seed bank has been conducted in the Flinders Ranges (Cooke 2003). In this case fire effectively removed the pod seed bank and germinations the following year were equivalent to the size of the much smaller soil seed bank. Based on this evidence, it has been proposed to use fire in the NW of Murray-Sunset as a means of reducing the dominance of ward’s weed in the field layer. An area of 14,600 ha has been nominated to the Fire Operations Plan of 2012/13 – 2014/15 for repeated burning.

David Eldridge and James Val of the Department of Environment and Conservation in N.S.W. have commenced a study of the relative persistence of C. annua and Austrostipa spp. at Mallee Cliffs N.P. The study encompasses an investigation of the effects of wards weed on termites, reptiles and soil function in semi-arid grasslands. The results of this study are likely to influence management strategy in the NW of Murray-Sunset.

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11. MONITORING AND EVALUATION

The Mallee parks management plan (NPS 1996) included the following strategy: Monitor the effectiveness of control and rehabilitation programs. The rehabilitation program essentially involved the reduction in total grazing pressure to “a level which allows the native perennial species to regenerate and Park landscapes generally to recover”. Hence the basic requirement was to monitor both the threats (abundant rabbits and kangaroos) and the vegetation response. Vegetation monitoring in the Mallee goes back to the initial declaration of Hattah-Kulkyne N.P. in 1980. Monitoring of vegetation response Mueck plots at Hattah-Kulkyne The Mueck plots (named after the initiator – botanist Steve Mueck) were established to monitor the effect of rabbits (and subsequently kangaroos) upon vegetation recovery in HKNP. This was also extended to include monitoring of VROT species (see below). The study was initiated in 1980 with a number of subsequent revisions. The plots were sampled at irregular intervals (1980, 1981, 1982, 1983, 1984, 1985, 1987, 1991 1993 and 1996). Plots were established in the following sequence: 1980: 35 unfenced plots were established across three areas, the 'southern', 'central' and 'northern' sectors. 4 rabbit and 4 total grazing exclosures were erected along the Mournpall Track. 1983: controls for each exclosure were established. 1984: a total grazing exclosure and control plot were established to protect a population of Rhyncharrenna linearis (Purple Pentatrope). 1985: a 70 ha area (the Conservation Plot) was fenced off excluding kangaroos and rabbits, in which 14 plots were established. 1986: 9 total grazing exclosures of varying sizes were erected to protect rare and endangered species (Eremophila bignoniiflora, Psoralea tenax, Sida fibulifera, Scaevola depauperata, Comesperma scoparium, Sida ammophila, Swainsona phacoides, Lepidium monoplacoides)

Surveys were conducted from the end of October to the beginning of December, noting the presence of every species as well as assigning a cover abundance value using the Braun-Blanquet Scale. Photographs of plots were taken to monitor structural changes. Broad findings to date are (refer Mueck 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, Hills 1994.)

• Seasonal conditions strongly influence the species compostion of the groundflora. The predominance of particular *species in the groundflora appears to be both transitory and cyclical in nature. *Stipa spp, Brassica tournefortii, Sclerolaena diacantha, Myriocephalus stuartii and Vittadinia spp. • Significant regeneration of woody perennials, e.g. Callitris gracilis, Alectryon oleifolius and Allocasuarina luehmannii, had not been recorded for the period 1980 to 1985 (immediately after the first abortive kangaroo management attempt in 1984). • However the general condition of the vegetation has improved in areas where grazing pressure from kangaroos and rabbit has been reduced. Herbaceous species such Swainsona microphylla and Corynotheca licrota have become locally common inside the Mournpall Block. • Species richness was high for 1996, comparable with previous 'good season' surveys. 82 | P a g e

• Photopoint data shows the establishment of Hopbush shrublands (Dodonea viscosa subsp augustissima) on many of the open dunes, some mature individuals have senesced during the study. Mallee parks grazing monitoring project

The ‘Mallee parks grazing monitoring project’ was in fact initiated in 1991 before the release of the management plan. The null hypothesis was: “That the maintenance of low total grazing pressure will result in no significant long term improvement in vegetation condition as measured by both structural and floristic attributes” (Sandell et al. 2002). The basis for the monitoring methods and sampling design are outlined in the report ‘Vegetation Recovery in the Victorian Mallee Parks 1991-1998’ published by Parks Victoria in 2002 (Sandell et al.). An overview of the findings of the grazing monitoring project are also to be found in Sandell (2006).

At the core of the project was a system of grazing exclosures at 10 locations which were to act as reference areas against which the effectiveness of the management of total grazing pressure could be assessed. The system of grazing exclosures was expanded in 1997 with the addition of new exclosures at Raak, Glencoe, and Boolca (refer Chapter 7, and map facing page 30).

In practice, the management of the grazing exclosures became a weakness of the system because a significant proportion (about half) were not well maintained with increasing rabbit incursions. This meant that conclusions based on fenced and unfenced comparisons were invalidated at many of the sampling sites. Nevertheless, the report for the period 1991-98 was able to draw a number of conclusions, particularly from longitudinal changes. These included:

• An increase in the shrub component of the understorey: principally the chenopods Sclerolaena obliquicuspis and Enchylaena tomentosa. • Extensive regeneration of Slender cypress-pine in the southern area of Wyperfeld. • Extensive regeneration of Sugarwood in the NW area of Murray-Sunset. • Limited regeneration of other woody perennials. • A trend towards reduced levels of weediness in the field layer.

Half yearly sampling of the original fenced and unfenced sites involved the collection of fixed point photographs as well as floristic sampling (refer Chapter 7). Structural measurements (stems of woody perennials) were made within belt transects at establishment and again at most sites in 1995 and in 1998 for the purpose of recording any regeneration. Ballentine (1998) contains a summary of the regeneration of tree species within Murray-Sunset in both fenced and unfenced plots at that time. This summary shows that at 5 exclosure sites within Murray-Sunset in 1998, 298 emergent tree and shrub species were recorded within fenced plots and 113 in unfenced plots.

The Mallee parks grazing monitoring project was discontinued in favour of independent periodic (5 yearly) condition assessments conducted by the University of Ballarat from 1997. However, the data from the original sampling may still be useful as a baseline for future assessments. Repeatable photographs have continued to be collected from some sites. Comparisons between unfenced and fenced treatments are likely to be informative for those sites where the exclosures have been well maintained. A series of photos illustrating temporal changes in vegetation condition at a subset of unfenced plots can be found in Appendix 2.

Hattah-Kulkyne vegetation monitoring project

This vegetation monitoring project at Hattah-Kulkyne began in 1992 in support of the kangaroo management program which commenced in the same year. Data collection ceased after 5 years in 1996 mainly as a result of personnel changes within the Department of NRE (Flora & Fauna) who had carriage of the project. The results of monitoring are documented in Sluiter et al (1997). Data was collected at quarterly intervals from 416*1m2 plots generally located at 100m intervals on fixed transects. Sites were stratified according to habitat type (“dunefield” / “floodplain”) and level of 83 | P a g e kangaroo grazing pressure (consplot / Mournpall / outside Mournpall). Biomass levels were quantified using a comparitive yield - dry weight rank method. A mass of 400 kg ha-1 was adopted as the threshold for monocotyledon biomass below which kangaroos were likely to impact upon the regrowth of perennial woody vegetation. This standard was developed by Coulson and Norbury (1988) in earlier work at Hattah-Kulkyne N.P. In practice, the threshold was exceeded in dunefield habitat for a short period in Mournpall and for a longer period in the Consplot. It was not achieved at all outside Mournpall where kangaroo densities were higher. Multiple linear regression analysis of data demonstrated that kangaroo density was a major influence over the total standing monocot biomass. Some weed species were found to be positively associated with kangaroo density.

Summary of findings (refer Sluiter et al 1997):

• For all grazing conditions, the total dunefield biomass declined over the study period with the greatest relative decline in the Consplot. Total biomass is most strongly influenced by rainfall over the previous 12 months. • High kangaroo density is negatively correlated with monocotyledon biomass. • Absolute dunefield monocot biomass exceeded the 400kg/ha threshold inside Mournpall between Dec. ‘92 and Mar. ‘94 but did not exceed 330 kg/ha outside Mournpall for the duration of the study. • The proportion of dunefield biomass contributed by native grasses (Austrostipa spp) remained much greater in Mournpall and the Consplot than outside (no change over period). • Asphodelus fistulosus (onion weed) was the dominant monocot of dunefields outside Mournpall but remained relatively unimportant in both Mournpall and the Consplot (no change over period). • Absolute floodplain monocot biomass did not exceed 200kg/ha except within the Consplot. • Dicotyledons remained dominant in floodplains outside Mournpall and to a lesser extent inside. • Austrostipa and Austrodanthonia spp. were very important components of floodplains in Consplot but markedly less so in the grazed areas. Periodic vegetation condition assessments for Wyperfeld, Murray-Sunset, and Hattah-Kulkyne

Parks Victoria, in the late 1990s, initiated a Statewide process for vegetation condition assessment within the framework of the Environmental Management System. A pilot assessment was completed at Wyperfeld N.P. in 1998 by the University of Ballarat (Miller et al. 1998). This involved quantitative assessment of condition which is defined as “the extent to which land use / human activity has modified the natural ecology”. The process requires a comparison to be made with a suitable standard so that changes in condition due to land use / human activity can be isolated from those due to stochastic events such as drought or wildfire. Benchmarks of condition in this case were areas judged to be the best available examples for a given EVC. Because the benchmark areas may have differing fire histories (or other disturbance) reference sites were established at a number of locations to define the full range of floristic variation within a given EVC.

Vegetation was classified based on similarity to the benchmark using a number of parameters of vegetation condition, including plant health, species richness and abundance, floristic composition, intactness of strata, mixture of age classes, and weediness. Measurements of each feature were converted to a score and combined into an index of overall condition on a scale of 0-10. This information was then mapped by interpolating between quadrats.

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Brief findings of the initial assessment at Wyperfeld (Miller et al. 1998) were:

a) Of the three riverine EVCs surveyed (Red Gum / Black Box, Pine / Buloke, and lakebed herbfield), the lakebed herbfield had (on average) the lowest condition index (CI) value; b) The Red Gum / Black Box woodland had the lowest indigenous species proportion by cover; c) Strata were found to be intact for all three communities; d) Overstorey was assessed as being healthy for the two woodland EVCs (no dieback); e) Areas of lakebed herbfield in best condition were within Lake Wirrengren; f) Areas of Red Gum / Black Box in best condition were at Lake Werrabean and condition found to be progressively worse further downstream; and g) Condition of Pine / Buloke generally average with isolated pockets in good condition.

There was no interpretation of the survey results in the report prepared by University of Ballarat. It is not clear why the best examples of lakebed herbfield were found in Lake Wirrengren whilst the lakebed herbfields in the smaller lakes were generally in poor condition. The transition of Red Gum / Black Box woodland from good to poor condition with increasing distance downstream could be related to flood frequency. Pine / Buloke was assessed as generally in average condition, the notable exception being the lunette to Lake Wirrengren (poor condition) which may relate to the grazing history.

After the pilot condition assessment at Wyperfeld, subsequent baseline assessments were also completed at Hattah-Kulkyne in 2002 and in Murray-Sunset in 2003. A repeat condition assessment was undertaken at Wyperfeld in 2004 (Gowans & Gibson, 2005). In the repeat assessment, the vegetation condition indices for River Red Gum / Black Box woodland, for Pine-Buloke woodland, and for Lakebed Herbfield were all found to have increased in comparison with the original assessment in 1998. The parameters which exhibited most improvement over the 6 year period were ‘native plant species richness’ and ‘strata intactness’. The woodland communities exhibited higher levels of overstorey dieback in 2004. Regenerating Slender Cypress-pine, with stem diameters of 1 cm or less, were recorded in 12 of the 56 quadrats (21%) within the Pine-Buloke community (Gowans & Gibson, 2005). Regeneration of Buloke was found in only one quadrat.

Review of vegetation monitoring by CSIRO

In 2000, Parks Victoria commissioned Dr Ken Hodgkinson of CSIRO Wildlife and Ecology to review vegetation monitoring in the Mallee parks (Hodgkinson and Baker, 2000). In his review Dr Hodgkinson referred to the difficulties experienced by rangeland managers in collecting meaningful information on long-term changes within naturally variable systems. This challenge has been addressed across the grazed rangelands by use of a number of approaches. There is scope for Victoria to learn from the monitoring systems in place elsewhere in the Australian rangelands, although the purposes of those monitoring systems are likely to be designed for different circumstances than apply to the restoration of the Victorian rangelands.

Dr Hodgkinson assessed the four Mallee monitoring projects against a number of criteria including: relevance to management, sampling efficiency, selection of suitable measures of change, a design that allows analysis of interacting influences, scientific rigour, and meaningful interpretation of results in reports. When assessed against each of these criteria, Dr Hodgkinson found that the new Mallee parks (Wyperfeld and Murray-Sunset) grazing monitoring project was the most robust and best designed to meet the future needs for information on vegetation recovery in the Mallee parks. The vegetation condition assessment conducted initially at Wyperfeld in 1998 was also found to be robust but the design did not allow for the analysis of interacting factors (notably grazing pressure). It relied only on the perceived difference from the benchmark sites. 85 | P a g e

Threat monitoring The monitoring of grazer abundance (rabbits and kangaroos) has been maintained throughout the restoration program and the results of this monitoring have been reported in Chapters 6,9 and 10. These datasets which extend, in some cases, over 20 years have become valuable in terms of understanding longer term trends in grazer abundance and risk. Under the auspices of the ‘Mallee woodlands – bouncing back’ initiative, rabbit monitoring (spotlight transects) has been expanded to include Ned’s Corner and areas of state forest. This program encourages a tenure-blind landscape approach to rabbit control. Four areas including most of the non-eucalypt woodlands have been defined and form the focus of monitoring and reporting upon rabbit abundance against a target of 1 rabbit per spotlight km. Within each of these areas, the results of half-yearly spotlight counts have been represented spatially as a means of highlighting areas of higher risk or incipient change.

The annual kangaroo monitoring program is managed by PV with management targets varying depending on location (refer Chapter 10). The annual kangaroo census is conducted either aerially, or by ground transects depending again on location. The Mallee District in 2009 commissioned Assoc. Prof. David Morgan to conduct a review of kangaroo monitoring (Morgan 2009). As part of this review, David Morgan assessed existing methods and found the aerial method to be generally less accurate and less precise than ground censuses. Another approach based on ‘catch effort’ is also being explored by Parks Victoria in partnership with University of Melbourne (Dr Yung en Chee). This approach has a number of advantages including greater sampling efficiency and currency. Evaluations of rangeland recovery 2006 review of woodland condition Hattah-Kulkyne and northern Murray-Sunset

Parks Victoria sponsored a review by University of Ballarat (UB) and Arthur Rylah Institute (ARIER) of ‘vegetation change in the Victorian Mallee parks’. This review encompassed the non-eucalypt woodland areas of northern Murray-Sunset and of Hattah-Kulkyne. It was completed in mid 2007.

David Cheal (ARIER) summarised the findings of the review of woodland condition as follows:

What has been achieved – 1. Conversion of annual field layers (ground cover) to perennial tussock grasses or hop-bush shrublands (in Hattah-Kulkyne) and chenopod shrubs (in Murray-Sunset). The landscapes are now (more or less) stable, c.f. the eroding and unstable landscapes of the 1980s. 2. A regeneration cohort of Sugarwood and Cattlebush – the first regeneration for these species in perhaps a century or more. 3. First steps of restoration of dune woodlands in Hattah-Kulkyne. 4. First steps of regeneration of semi-arid woodlands in Murray-Sunset. 5. Temporary recovery of palatable rare and threatened species (many of which have since gone backwards as a result of increasing browsing pressure and the recent droughts).

What has not been achieved – 1. Restoration of function in semi-arid woodlands. 2. Regeneration of the key dominant trees, notably Belah, Buloke and the two pine species. 3. Regeneration of associated woody shrubs of semi-arid woodlands across all landscapes. 4. Restoration of semi-arid woodland habitats for dependent fauna and flora. UB and ARIER concluded that the extent of recovery was insufficient to keep pace with progressive tree loss and that woodlands continue to decline. 86 | P a g e

Key recommendations from UB / ARIER review were as follows:

• Continue to monitor species recovery/disappearance from the landscape. • Review management practices (e.g. rabbit control in HKNP and kangaroos throughout). • Maintain a long term commitment to grazing programs. Review and maintain targets (to keep rabbit numbers low), so that when ideal regeneration conditions recur, regeneration follows. • Where the parent (seed stock) trees have died, replace these tree and shrub species in the landscape, either by direct seeding or replanting. • Investigate the current abundance of Ward’s Weed (Carrichtera annua), its relationship to grazing intensity and its impact on native species and communities. A workshop was convened by PV in June 2007 on the topic of the ‘most appropriate variables / methods for monitoring of woodland condition’. It involved a range of PV / DSE staff and independent experts (Ian Sluiter, Steve Mueck, UB, ARIER). The focus was upon refining goals for woodland condition and the best means of measuring progress towards those goals. It was agreed that management effort should be directed as a priority towards the maintenance of areas of good quality woodland (e.g. those exhibiting regeneration). These areas will provide a source of ‘germplasm’ for regeneration in surrounding areas, refuges for dependent fauna, and a demonstration of what can be achieved through effective grazing management. A second order priority is the halting of further deterioration in condition in areas that are subject to ongoing decline.

2011 woodland condition assessment at Pine Plains

In 2011 Parks Victoria commissioned an independent woodland condition assessment at Pine Plains. The intention was to address the recommendation from the 2007 review by UB and ARIER to monitor ‘species recovery / disappearance’. The brief required the development and piloting of a suitable method for ground survey and spatial analysis. The project was designed to meet the need for greater quantification of the extent of tree regeneration within Pine-Buloke woodlands. The ground survey also incorporated threat monitoring in the form of the density of active rabbit warrens.

The ground survey found that there were only very isolated instances of Buloke regeneration (two instances only) and none of these were actually within quadrats. By comparison, 33% of the study area exhibited regrowth of Slender Cypress-pine. This regrowth was mostly on sand dunes and lunettes. The proportion of all sites categorised as either Slender Cypress-pine woodland or Pine- Buloke woodland was 72% of all sites. Hence regrowth of Slender Cypress-pine was recorded at 46% of all sites where this species occurred. A proportion of these sites would have had no or insufficient live trees as seed sources for regrowth.

The ground survey in this case was complemented by a separate aerial photo interpretation (API) using 2009 photography. This is seen as a possible supplementary means of broadacre assessment of the extent of woodland recovery.

The API survey measured crown cover for both tree canopy and shrubs using 6 categories with the lowest being no trees in the polygon (none) to the highest being crowns occupying 70-100% of the polygon area (heavy). The second lowest category is ‘trace’ with crowns occupying up to 9% of the polygon area. Woodland polygons were only defined as such if they had at least a ‘trace’ of Slender Cypress-Pine or Buloke and/or evidence of dead fallen trees. The area estimated as having lost all tree cover was 791 ha and the area with a trace of trees and no regrowth was estimated to be an additional 2,540 ha. These data suggest that the area of Pine Plains in need of replanting is of the order of 3,300 ha.

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Key findings from this most recent condition assessment can be summarised as follows:

• Regrowth of Slender Cypress-pine (combination of seedlings, and juvenile trees that emerged post-RHDV) now extends over approximately one third of the woodland area at Pine Plains (Sunraysia Environmental, 2011). • Regrowth of Buloke remains virtually absent at Pine Plains. • The measured level of threat from rabbits remains low with an average of only 0.2 active entrances per ha across Pine Plains. • A significant area of dry woodland (approx. 3000 ha) will require intervention in the form of direct seeding or planting if tree cover is to be restored (due to loss of seed trees). Fauna surveys Breeding surveys of Major Mitchell’s Cockatoo

Pine Plains is considered to contain the largest single breeding population of Major Mitchell’s Cockatoo (Lophocroa l. leadbeateri) in Victoria and a program of monitoring was initiated by DSE in 1995 (Victor Hurley, pers. 87omm..). Field sampling found that the Major Mitchell’s Cockatoo was heavily reliant upon nest hollows within Slender Cypress Pine: less than 1% of nests were recorded in trees other than Callitris gracilis. The progressive loss of suitable nesting trees through senescence therefore represents a major risk to the Victorian population.

Sampling of nest hollows by DSE recorded that nest occupancy by MMCs declined dramatically between 1995 and 2004. Since 2004 there has been a slight recovery but current levels are still only about 50% of those first recorded (Hurley 2011). Over the period of sampling, there have been 4% fewer hollows per annum that are suitable for MMCs due to tree loss. The average age of trees with suitable hollows was estimated to be 130 years. Hurley (2011) also found increasing competition for remaining hollows from Galahs.

Decline of White-browed Treecreeper

The White-browed Treecreeper (Climacteris affinis) is a species nominated by Cheal et al. (in press) as being a good indicator of land manager performance in managing Pine-Buloke woodlands. The Mallee CMA has commissioned a number of surveys of threatened Mallee birds, including the White- browed Treecreeper. A survey in 2006 by Hurley and Cheers found evidence of ongoing decline in populations of White-browed Treecreeper populations which had been surveyed in 1997. In the recent survey, 47 woodland patches in which White-browed Treecreepers had previously been recorded were re-surveyed. In 1997, 24 of these 47 patches had contained White-browed Treecreepers. Hurley and Cheers (2006) found that birds had disappeared from 11 of these original 24 patches, but they were present in 4 patches where they had not been recorded in 1997 (Hurley and Cheers 2006). Hence the net result was a 25% loss in the number of recorded populations over the course of a decade.

In discussion of their findings, Hurley and Cheers (2006) stated:

The apparent widespread loss of White-browed Treecreepers from semi-arid woodland blocks surveyed in this study may be due, in part, to continuing drought …. Alternatively, it may be the beginnings of a second wave of bird extinctions following the much earlier large scale clearing of mallee and semi-arid woodland habitats across North-west Victoria.

Victor Hurley (pers. comm.) has attributed the ongoing loss of the White-browed Treecreeper across its range in Victoria to ‘extinction debt’ associated with earlier clearing and grazing. Extinction debt is the concept that loss of a species can be due to events in the past – such as fragmentation of habitat.

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Woodland bird surveys

An initiative of Birds Australia led to the establishment of a program of half-yearly monitoring of bird populations in dry woodlands from 2006. A total of 15 sites were selected within both Murray-Sunset and Hattah-Kulkyne national parks for surveying. The sites were stratified into high or low quality (due to a legacy of stock grazing and high rabbit numbers). Sampling was conducted mostly by a local volunteer birdwatcher (Michael Mack) using the Birds Australia 20 minute 2 ha area search method. One purpose of the sampling was to assess whether improvements in woodland condition might cause improvements in the avifauna.

Birds Australia released a report on the first two years of the monitoring in 2009. This showed that 60 individual species of birds had been recorded between 2006 and 2008 (Birds Australia 2009). The following threatened species were recorded in the course of the surveys. Major Mitchell’s Cockatoo (Threatened in Victoria) Regent Parrot (eastern subspecies) (Vulnerable nationally; Threatened in Victoria) White-browed Treecreeper (eastern subspecies) (Threatened in Victoria) Slender-billed Thornbill (eastern subspecies) (Threatened in Victoria) Hooded Robin (south-eastern subspecies) (Threatened in Victoria) Crested Bellbird (southern subspecies) (Threatened in Victoria) Apostlebird (Threatened in Victoria).

Sampling as part of the Birds Australia project ceased in 2009 but the Mallee CMA has recently resolved to undertake another round of sampling in 2011/12 which will add value to these existing data.

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12. NEXT PHASES OF RANGELAND RECOVERY

In the Mallee District, we are engaged in the largest land restoration project ever undertaken by Parks Victoria. 250,000 ha of degraded rangelands (80% of which are now reserved) requires varying levels of management intervention. It is critical that that intervention is well targeted and integrated. To quote Restoration Ecologist Fiona Murdoch: “Effective restoration requires a goal or policy that is clear, articulated and accepted by researchers, practitioners and end-users”. Restoration progress and strategy Our current strategy and goals are largely threat-based:

1. Recovery through active control of grazers (rabbits, goats, and kangaroos) such that total grazing pressure is maintained below the threshold at which the regeneration of native perennial grasses, shrubs, and trees can occur and persist (given adequate rainfall); o We now have a good understanding of the standards of rabbit control required to promote woodland recovery. The aim should be to virtually eradicate rabbits from these areas. Although this is becoming more difficult in the post-RHDV environment, the Kramen trial has demonstrated that a high standard of control can be achieved if resources are available and best practice is implemented. Maintenance of very low rabbit abundance will reduce unit costs in the longer term. o Whilst there is scope to improve kangaroo management processes, the targets established through the ‘Restoring the Balance’ plan are still valid based on the available evidence. o Goat control measures have been implemented in partnership with the SSAA since 2003 in some areas, but there is a need for a more strategic approach to this issue. There has been no census of goat populations since 2004, making it difficult to evaluate current management effectiveness.

2. Recovery through passive control of grazers or manipulation of habitat such that the environment becomes less suitable for grazers. Within this category the obvious options are the closure of artificial waters within the Mallee parks and the fencing of boundaries to prevent goats and kangaroos from accessing waters on adjoining farmland; o Considerable progress has been made in this area with the closure of most artificial waters and the earlier fencing of the northern boundary of Murray-Sunset N.P. However, more consideration should be given to fencing of the boundaries of the large parks, particularly where goats are an ongoing problem. This would need to be considered as part of an integrated goat management strategy based on sound research and in partnership with park neighbours.

3. Recovery through active revegetation measures (direct seeding / planting / weed control) where grazing management alone is not sufficient to promote recovery. o There have been some minor direct-seeding and weed control trials but this goal largely remains to be implemented. The potential for carbon sequestration in this area remains untapped (see below). Zones for active revegetation will need to be based on sound prioritisation given the costs of broadscale works.

The goal expressed by the LCC in 1989 of establishing “a sustainable (although not entirely natural) ecosystem based on the key elements of the original vegetation communities” is still relevant. Implicit in this goal is the acceptance that it may not be possible to fully restore the original rangeland ecosystems to the point where locally extinct fauna species could be re-introduced. However, there will certainly be biodiversity benefits associated with a more sustainable and productive landscape. 90 | P a g e

There will also be the wider benefits associated with reduced soil erosion, lowered regional groundwater levels, the sequestration of carbon, and a more attractive landscape for visitors.

Some 15 years after the release of the Mallee Parks Management Plan, the time is right for development of a new ‘rangeland restoration strategy’ for the Victorian Mallee. This new strategy should build from a basis of effective control of total grazing pressure. It should determine what additional measures, or combination of measures (further habitat manipulation, direct seeding, weed control) might be needed to promote recovery under the range of current conditions (tree cover lost, woody regeneration absent, weedy field layer, no shrub layer etc.). Adaptive management trials could be useful in selecting the preferred management options for the next phase of rangeland recovery. A new hierarchy of conservation objectives should be developed in the strategy with the original LCC vision of sustainable rangeland ecosystems.

Carbon sequestration

The effective control of rabbits in itself will result in carbon sequestration given the proven capacity of rabbits to selectively remove woody seedlings from semi-arid ecosystems. A ‘land carbon reforestation’ public land business case prepared for DSE by URS Australia in 2009 considered a pilot re-establishment of 2,100 ha of semi-arid woodland by means of fencing, weed control and direct seeding. URS found that this project would be marginally positive in net revenue terms and would generate revenues of around $3 million for an investment of a similar amount (URS 2009). This calculation assumes revenues generated from the CPRS (or similar carbon trading scheme). When environmental benefits are factored in, the benefit / cost ration increases substantially. Management effectiveness Without effective rabbit control, rangeland recovery will not proceed any further and, indeed, current gains will be lost. The new restoration strategy will need to give detailed consideration to the best means of achieving and maintaining high standards of rabbit control with the objective of achieving ‘rabbit-free’ status across the Victorian rangelands. In the post-RHDV environment, the task of conventional control will not get any easier. However, there is still the prospect of new biocontrol agents in the form of other strains of RHDV becoming available. ‘RHD boost’ is a current project of the Invasive Animals CRC which aims to identify and introduce other rabbit calici-viruses to which Australian rabbits have so far not been exposed. Epidemiological sampling of the Hattah-Kulkyne rabbit population has recently resumed for the purpose of collecting baseline information in advance of the possible release of new viral strains. The Victorian land managers need to cooperate closely with IA CRC to ensure that we benefit to the maximum extent possible from the ‘RHD boost’ initiative.

There is also scope for ongoing improvements in the practice of conventional rabbit control in the Victorian Mallee, both in a strategic and operational sense. From a strategic point of view, the Kramen demonstration site has given us a better appreciation of the value of baiting as part of an integrated control program. Optimal scheduling of works and the best use of contractors has also been discussed in some detail in Chapter 9. The results of the pilot performance-based contract which commenced in Cantala block at Hattah-Kulkyne in mid-2010 will be instructive as to the longer term value of this approach compared with the more conventional hourly rate basis for contractor engagement. There may well be other ‘market-based’ solutions that have yet to be considered.

Rabbit control operations conducted by either staff or contractors tend to be poorly evaluated due to the constraints on staff time or capability. The evaluations which have been done, particularly of fumigation treatments, have found that a relatively high proportion of warrens were missed or re- opened soon after treatment. In the case of an evaluation of fumigation works at Hattah-Kulkyne by Sandell et al. (2003) it was found that only 38% of warrens were actually treated and of those that were treated, 29% had re-opened within 12 months. Practice at that time did not constitute effective rabbit control as evidenced by the population increase from 2004. 91 | P a g e

There is scope for better use of digital data to evaluate effectiveness of treatments and to alert management to incipient change. As it is, the locations of all warrens either ripped or fumigated are collected. These data can be used in several ways. One of which is for the purposes of an evaluation by sampling a proportion of the warrens and calculating the rate of re-openings. If these are above a prescribed level (e.g. 10%) a secondary treatment would then be scheduled. The locations of known warrens could also be provided to contractors so that they can all be visited during the course of treatments.

Parks Victoria has recently pioneered the use of Trimble ‘Juno’ and ‘Nomad’ units for field data capture. These have been useful in assessing the standards of rabbit control by application of the ‘rapid assessment’ sampling techniques developed by Dr Brian Cooke. However, there are other digital devices that could also be used to display known warren locations to field staff and contractors. This approach is likely to reduce the risk of warrens being missed in the course of control treatments.

Parks Victoria is the lead agency responsible for delivery of effective rabbit control across the bulk (80%) of the Victorian rangelands. Responsibility cannot be delegated to contractors, but contractors will continue to play an important role. Parks Victoria needs to be geared at all levels for this responsibility. This means developing capacity through staff training, research and development, infrastructure and equipment. Conflicting priorities, e.g. in relation to the demands of fire management, need to be resolved. For rabbit control to be effective, it needs to be conducted by a combination of contractors and staff who have been quarantined from fire duties over summer - the optimal period for conduct of rabbit control.

The level of investment in rabbit control has fluctuated with much lower funding whilst RHD virus was effective. The lesson from that experience was that the areas where works were not done to maximise upon the benefits of RHDV were also the areas where population resurgence first occurred. There needs to be broad acceptance of the need to maintain investment in a high standard of rabbit control at a landscape scale for the benefit of both biodiversity and agricultural assets. Persistence and application of best practice will ultimately lead to a reduction in the unit costs of rabbit control across the Mallee. Investment in rangeland recovery will in fact need to be broadened in the next phase to encompass other elements of an integrated restoration program such as active revegetation. Partnerships and risk management There is an expectation of Parks Victoria that it will implement the management, conduct the monitoring, and commission any research that is needed with respect to rangeland recovery. Parks Victoria may not necessarily be best-placed to undertake all of those roles. For instance, a different skill set is needed for operational rabbit control than for monitoring. There may be grounds for monitoring to be conducted independently, particularly where the contractor remuneration depends upon the outcome.

The ‘Mallee woodlands – bouncing back’ initiative from 2007-2011 has been important in the development of a broader landscape approach to rabbit control. The Mallee CMA, ‘Caring for our Country’ initiative, and Trust for Nature have become important partners in the broader restoration of the rangelands. There is scope, however, for further development of these and of new partnerships. Our partners in this enterprise may not have a good appreciation of our broader goals, and hence Parks Victoria may not have been able to attract as much external investment / involvement as would otherwise have been possible. We could undoubtedly benefit from the experience of others who have been engaged in similar rangeland restoration programs, such as the South Australian Bounceback initiative, but tend to retain a Victorian focus.

The rangelands are generally classified as being either ‘fire influenced’ or ‘fire sensitive’ in a fire ecology sense. Fire in these communities represents both a risk and an opportunity. As the recovery progresses, so will the level of fuel hazard and the consequent risk of wildfire under adverse circumstances. There is a need for a ‘rangelands restoration strategy’ to consider the introduction of fire in a manner which can be to the benefit of native vegetation and habitats (and to the disadvantage of introduced species), and in a manner which reduces the risk of catastrophic wildfire. 92 | P a g e

Some concluding thoughts ……

Any impartial observer of progress to date with implementation of the 1989 LCC Mallee Area recommendations would be hard-pressed to argue that most of the claims made in the Press at the time of reservation were borne out by the experience to date. The new Mallee parks have not deteriorated through over-grazing by rabbits and kangaroos. Total grazing pressure has been significantly reduced since the early 1990s. There is evidence of vegetation recovery in the form of widespread (but not universal) regeneration of the key woody perennials. This has occurred despite the fact that the past two decades have been relatively dry. By the same token, it is unlikely that the observed landscape recovery would have occurred without the presence of RHD virus in rabbit populations from 1996.

Neighbours of the new Mallee parks have not experienced increased problems associated with pest animals, over-abundant kangaroos, or increased incidence of wildfire as was feared by some. Nevertheless, the parks have periodically struggled to attract adequate resources for rabbit control – particularly in the wake of the RHD virus. This may have been (as was predicted in the Melbourne Age of 1989) because rangeland recovery in the Mallee is not as charismatic as some conservation causes.

I do not suggest that the task of rangeland restoration in the Mallee has been completed, or that it is even well-advanced. We are merely at the end of the initial phase of the process. We now have prescriptions for the standard of grazing management needed, and a general appreciation of how to achieve those standards. The next phase of recovery will necessitate the development of new goals and new capacities, such as the application of active revegetation.

The vision of restoring sustainable ecosystems as espoused by the LCC in 1989 can only be reached through ongoing and intensive management intervention - but it remains achievable. The evidence of the last two decades is that these landscapes are remarkably resilient. Despite the fact that much of the original tree and shrub cover has been lost or is senescent, and the likelihood that rainfall will decline as a consequence of climate change, it is still within our collective powers to restore our rangelands to something resembling their earlier condition. It remains a matter of choice whether we choose to meet the challenges involved or whether we are prepared to accept irreversible change and the loss of tree and shrub cover from these landscapes. If we adopt the latter course there will be wider consequences in terms of further loss of biodiversity, erosion, increased groundwater recharge, and the loss of the opportunity to sequester carbon over a large area.

Peter Sandell

May, 2011.

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References:

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Department of Conservation and Natural Resources (1994) A Review of the comparative ecology of Red and Western Grey Kangaroos in Australian Rangelands. An evaluation of the likely impact on the vegetation at Hattah-Kulkyne National Park. Flora Fauna and Fisheries Unit, Mildura, April 1994. Department of Crown Lands & Survey (unpub.). Memorandum to Director Crown Land Management by G.F. Leitch, Senior Land Management Officer. Dated 21/12/1982. DEWHA (2008) Threat Abatement Plan for competition and land degradation by unmanaged goats. Department of the Environment, Water, Heritage, and the Arts. Biodiversity Conservation Branch, Canberra. Duncan, D., Moxham, C. & Read, C. (2007) Effect of Stock Removal on Woodlands in the Murray Mallee and Wimmera Bioregions of Victoria. Prepared on behalf of the Mallee and North Central Catchment Management Authorities by Arthur Rylah Institute for Environmental Research and the School of Botany University of Melbourne. 2007. Durham, G. (2001) Wyperfeld: Australia’s First Mallee National Park. Published 2001 by the Friends of Wyperfeld National Park Inc. Elsternwick, Victoria. Farrow, M. (2001) Evaluation of the Effectiveness of the Millewa Kangaroo fence on the Northern Boundary of the Murray-Sunset N.P. Unpublished report to Parks Victoria prepared by Mick Farrow, student at Sunraysia Institute of TAFE, Mildura 2001. Favaloro, N.J. (1966) Honeyeaters of the Sunset Country. Proc. R. Soc. Vic. 79:621-6. Ferraro, T. and Burnside, D. (2000) WEST 2000: A case Study of Natural Resource Management Investment in the NSW Rangelands. Gowans, S., and Gibson, M. (2005) Vegetation condition assessment Wyperfeld National Park. Report to Parks Victoria by the Centre for Environmental Management. University of Ballarat, Victoria. Green, D., Hart, D., and Prior, J. (1994) Site Selection and Field Measurement Procedures. Rangeland Study Site Manual, Part 1. Soil Conservation Service, Department of Conservation and Land Management. Condobolin. Revised January 1994. Henzell, R. (1992) Goat Biology and Environmental Impacts – Implications for Eradication. In: Feral Goat Seminar Proceedings. Edited by Lindsay Best, National Parks and Wildlife Service, South Australia. April 1992. Hodgkinson, K. and Freudenberger, D. (1997). Production pulses and flow-ons in rangeland landscapes. In: J. Ludwig, D. Tongway, D. Freudenberger, J. Noble and K. Hodgkinson (Eds.) Landscape Ecology,Function and Management: Principles from Australia’s Rangelands. CSIRO. Hodgkinson, K. and Baker, B. (2000) Review of vegetation monitoring in the Mallee parks, Victoria. Unpublished report prepared for Parks Victoria by CSIRO Wildlife and Ecology. April 2000. Hurley, V.G. and Cheers, G. (2006) Survey of White-browed Treecreepers in the Victorian Mallee 2006. Report to the Mallee CMA, Mildura. Hurley, V.G. (2011) Results from the 2010 breeding survey of Major Mitchell’s Cockatoo (Lophocroa l. leadbeateri) Pine Plains, Wyperfeld N.P. An unpublished report for the Department of Sustainability and Environment, Mildura. Land Conservation Council (1987) Mallee Area Review (Pub. Land Conservation Council, Melbourne, Victoria) Land Conservation Council (1989) Mallee Area Review Final Recommendations (Pub. Land Conservation Council, Melbourne, Victoria) Landsberg, J., James, C. and Morton, S. (1997) Assessing the effects of grazing on biodiversity in Australia’s rangelands. Australian Biologist, 10 (3). 95 | P a g e

Lange R. T., Graham C. R. (1983) Rabbits and the failure of regeneration in the Australian arid zone. Australian Journal of Ecology 8, 377-382. Long, K. Robley, A., Cheal, D., White, M., Carter, O., Tolsma, A. And Oates, A. (2003) Prioritisation of Rabbit Control within the Parks Victoria Estate; Reducing Risks to Environmental Values. Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, Melbourne. Report to Parks Victoria. Macdonnell, P. (2000) Feral goat (Capra hircus) helicopter survey in Murray-Sunset National Park, March 2000. Unpublished report, Parks Victoria, Mallee District, Mildura. Mallee CMA (2010) The Millewa-Murray: An Oral History. Compiled by Terry Gange on behalf of the Mallee Catchment Management Authority, Mildura. McLean, B. & Jowett, D. (1974) Rails West to Nowhere. Australian Railway Historical Society Bulletin. Vol XXV, No. 444. November, 1974. McPhee, S.R. and Butler, K.L. (2010) Long-term impact of coordinated warren ripping programmes on rabbit populations. Wildlife Research, 2010, 37, 68-75. Melbourne Age article: Cinderella Syndrome: The Victorian Mallee has been abused and ignored. Can this be changed asks Leith Young. Published 1/8/1989. Miller, J., Gibson, M., Westbrooke, M., Wilcock, P. and Brown, G. (1998). Condition of Vegetation in the Riverine Woodlands of Wyperfeld National Park. Report prepared for Parks Victoria by the Centre for Environmental Management, University of Ballarat, Victoria. Morgan, D.G. (1992) Yanga-Nyawi (Murray-Sunset) National Park Kangaroo Populations, July 1992. Unpublished report by University of Melbourne, Victoria. Morgan, D.G. (1994) Wyperfeld National Park Kangaroo Populations, July 1994. Unpublished report by University of Melbourne, Victoria. Morgan, D.G. (1995) Kangaroo populations in the Mallee following the cessation of stock grazing. In: Proceedings of the North West Ecological Management Workshop (Ed. G. Horner), held at Walpeup Research Station, 29-30 November 1995, National Parks Service, Victoria pp 13-23. Morgan, D.G. and Sluiter, I.R.K. (1997) Perennial woody plants in permanent belt transect plots in the Hattah area, north-west Victoria. Ogyris Ecological Research Report No. 97/10 to Parks Victoria, Melbourne. Morgan, D.G. (2009) Kangaroo Population Monitoring Methods in the Mallee Parks. Report to Parks Victoria. University of Melbourne Department of Zoology, June 2009. Murdoch, F.A. (2005) Restoration Ecology in the Semi-arid Woodlands of North-west Victoria. PhD Thesis, School of Science and Engineering, University of Ballarat. Murdoch, F.A. & Murdoch, P.J. (unpub. 2007) Evaluating the effects on Buloke regeneration of increased browsing by rabbits: Hattah-Kulkyne N.P. Report to the Dept. Of Sustainability and Environment and Parks Victoria. October 2007. Murdoch, F.A., McPhee, S.R, and Cooke, B.D. (unpub.2007) How many rabbits are too many? – Monitoring grazing pressure and regeneration of semi-arid woodlands. Report to Invasive Animals CRC. Mutze, G., Bird, P., Cooke, B., and Henzell, R. (2008) Geographic and Seasonal Variation in the Impact of Rabbit Haemorrhagic Disease on European Rabbits, Oryctolagus cuniculus, and Rabbit Damage in Australia. In: Lagomorph Biology: Evolution, Ecology, and Conservation: 279-293. Eds. Alves, P.C., Ferrand, N. and Hacklander, K. Springer-Verlag, Berlin,2008. National Parks Service ( unpub. 1995) Review of the Rabbit Control Program in the NW Sector of Murray-Sunset National Park 1990-95. Prepared by Peter Sandell, National Parks Service, Victoria, 1995. 96 | P a g e

National Parks Service (1996) Mallee Parks Management Plan (Pub. Department of Conservation and Natural Resources, East Melbourne, Victoria) NRE (2000) Resource Protection Guidelines – Rabbit Control (Mallee). Revised by Leigh Ahern on behalf of Department of Natural Resources and Environment, 2000. Parer, I. (1977) The population ecology of the wild rabbit Oryctolagus cuniculus in a Mediterranean- type climate in New South Wales. Australian Wildlife Research 9: 427-441. Pegler, P. (2007) Mallee District Rabbit Management Action Plan. Parks Victoria, January 2007. Raymond, K. L. (1990) The Regeneration Biology of Allocasuarina leuhmannii (R.T. Bak.) L. Johnson at Wyperfeld National Park. B.Sc. Honours Thesis, Monash University. Robley, A. and Wright, J. (2004) Adaptive Experimental Management of Foxes. Annual Report July 2003-June 2004. Parks Victoria Technical Series No. 20. Parks Victoria, Melbourne. Rolls, E.C. (1966) They All Ran Wild. Angus and Robertson, Sydney. Sandell, P. (unpub.) The Implications of RHDV for Vegetation Condition at Hattah-Kulkyne N.P.. Final Report to the Victorian Rabbit Busters Program prepared on behalf of Parks Victoria and Dept. NRE. Mildura, 2003. Sandell, P.R. and Start, A.N. (1999) Rabbit Calicivirus Disease Program Report 4: Implications for Biodiversity in Australia. A report of research conducted by participants of the Rabbit Calicivirus Disease Monitoring and Surveillance Program and Epidemiology Research Program. Prepared for the RCD Management Group. Bureau of Rural Sciences, Canberra. Sandell, P.R. (2002) Implications of Rabbit Haemorrhagic Disease for the short-term recovery of semi-arid woodland communities in north-west Victoria. Wildlife Research 29, 591-598 Sandell, P.R. (2006) Promoting woodland recovery in the Victorian Mallee Parks. Proceedings of the Royal Society of Victoria. 118(2): 313-321. ISSN 0035-9211. Sandell, P., Ballentine, M. and Horner, G. (2002) Vegetation Recovery in the Victorian Mallee Parks 1991-1998 (Parks Victoria, Melbourne, Victoria) Shepherd, R.C.H. (1985) Studies of a wild rabbit, Oryctolagus cuniculus (L.), population in the Mallee Region of Victoria following the release of the European Rabbit Flea, Spilopsyllus cuniculi (Dale). Thesis presented for the degree of Master of Agricultural Science in the University of Melbourne. Sluiter, I.R.K., Allen, G.G., Morgan, D.G. and Walker, I.S. (1997) Vegetation responses to stratified kangaroo grazing pressure at Hattah-Kulkyne National Park, 1992-96. Flora and Fauna Technical Report No. 149. Department of Natural Resources and Environment: East Melbourne. Sluiter, I.R.K. (1997a) Biomass and floristic monitoring of belt transects at Hattah-Kulkyne National Park, September 1997. Report No. 97/17 by Ogyris Ecological Research for Parks Victoria. Sluiter, I.R.K. (1997b) Biomass and floristic monitoring, Hattah-Kulkyne National Park, September 1997. Report No. 97/18 by Ogyris Ecological Research for Parks Victoria Stafford-Smith, D.M. and Morton, S.R. (1990) A framework for the ecology of arid Australia. Journal of Arid Environments 18, 255-278. Sunraysia Environmental (2011). Spatial assessment of the condition of a non-eucalypt woodland in the Mallee: Pine Plains, Wyperfeld National Park. Unpublished report to Parks Victoria. Mildura, June 2011. t’Mannetje, L. and Haydock, K.P. (1963). The dry-weight rank method for the botanical analysis of pasture. Journal of British Grassland Society, 18: 268-275. 97 | P a g e

Ward, D.J. and Cooke, J.W. (1987) The control of a pest animal (Rabbit) in an arid environment: A case study. Working paper at the Australian Vertebrate Pest Control Conference 1987. Coolangatta, May 1987. Convened by Queensland Rural Lands Protection Board. Williams, K., Parer, I., Coman, B., Burley, J. and Braysher, M. (1995). Managing vertebrate pests: rabbits. Australian Government Publishing Service, Canberra White, M., Oates, A., Barlow, T., Pelikan, M., Brown, J., Rosengren, N., Cheal, D.C., Sinclair, S. And Sutter, G. (2003) The vegetation of north-west Victoria: A report to the Wimmera, North Central and Mallee Catchment Management Authorities. Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment: Melbourne. Wouters, C., Wright, J. and Pegler, P. (2000) Ecological rationale for kangaroo management at Pine Plains area of Wyperfeld National Park. Unpublished report by Parks Victoria, March 2000. Wouters, C., Wouters, M., Macdonell, P. and Pegler, P. (2000) Ecological rationale for kangaroo management at Murray-Sunset National Park. Unpublished report by Parks Victoria, July 2000 Zimmer, W.J. (1944) Notes on the regeneration of Murray Pine (Callitris spp.). Transactions of the Royal Society of South Australia 68, 183-190

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Appendix 1.

Examples of press reports in the period leading up to reservation of the Victorian rangelands.

Article in the Sunraysia Daily of 23/9/1988 taking issue with the lack of consultation with grazing licensees and the ‘pre-emptive’ declaration of a new national park.

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Article from Sunraysia Daily of 21/9/1988 highlighted concerns of the McArthur family that their lifelong investment of time and money in their grazing lease was now to be lost. 100 | P a g e

Tim and Brian O’Sullivan photographed in the Melbourne Age of 1/8/1989 highlighted the ‘catch 22’ situation where uncertainty over tenure since 1977 had prevented them from investing in rabbit control. 101 | P a g e

The same article from the Melbourne Age of 1/8/1989 raised the concern that it would always be difficult to attract resources for the conservation management of the ‘uncharismatic’ mallee lands. It also noted that 6 of the 20 families affected by the LCC recommendations were totally dependent upon public land.

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This article from the Weekly Times in January 1991 in the lead up to the declaration of the new Mallee parks later that year raised concerns about the capacity of the Department of Conservation and Environment to manage the vast new areas and, particularly, contain the rabbits which would otherwise impact on neighbouring properties.

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Part 2 of the Weekly Times story includes claims by the MLA for Mildura that the declaration of the new parks was a massive over-reaction to previous land management problems and did not have the support of staff from the Departmental Regional Office. 104 | P a g e

Sunraysia Daily of 16th July 1991 105 | P a g e

Appendix 2.

Series of time-lapse photographs illustrative of changes in vegetation condition within representative unfenced sites that were reserved in 1991.

Buloke woodland in central Murray-Sunset N.P. (Mopoke) soon after declaration in autumn 1992.

Understorey remains bare following a dry year (1997). 106 | P a g e

Some shrub regrowth is apparent in autumn 2000.

Understorey remains relatively bare in spring 2008 following another dry period. No evidence of tree regeneration. 107 | P a g e

In June 2011, after the high rainfall of the previous 18 months, the field layer contained a diverse mix of native tussock grasses and sub-shrubs. Still no evidence of tree regeneration.

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Saline shrubland in central Murray-Sunset N.P. (Mopoke area) is dominated by Atriplex sp. in September 1992.

No apparent change in September 1997 following extended dry period. Artificial waters in the Mopoke area were closed about this time.

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No apparent change in vegetation condition in spring 2000.

By June 2011, after 18 months of well-above average rainfall, there is less bare ground but no other obvious changes. 110 | P a g e

Belah (Casuarina pauper) woodland in the NW corner of Murray-Sunset N.P. in spring 1991, soon after reservation. Extensive areas of bare ground with some annual weeds.

In spring 1994 some native tussock grass (Austrostipa sp.) is apparent in the field layer. 111 | P a g e

By spring 1998, following a dry period, bare ground is again predominant with some evidence of chenopod sub-shrubs (Sclerolaena sp.).

By spring 2005 native tussock grasses have re-emerged. 112 | P a g e

Same site in 2011 after above-average rainfall. Field layer is now dominated by native tussock grasses and chenopod shrubs.

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Field layer at Tower Paddock (NW of Murray-Sunset N.P.) is dominated by introduced barley and brome grass soon after reservation in spring 1992.

Chenopod sub-shrubs (Enchylaena sp. and Sclerolaena sp.) dominate the field layer in spring 1994.

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In spring 2000, sub-shrubs continue to dominate the field layer and tree regeneration of Cattlebush (Alectryon oleifolius) can be seen in the background.

By spring 2009, the field layer is dominated by Wards weed (Carrichtera sp.) and tree regeneration of both Sugarwood (Myoporum parvifolium) and Cattlebush can be seen in the background. 115 | P a g e

By 2011, Wards weed comprises only a small proportion of the field layer biomass relative to chenopod sub-shrubs.

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The field layer of this Slender Cypress-pine (Callitris gracilis) woodland at Bee Rack Hill in southern Wyperfeld N.P. was mainly bare ground in spring 1994.

In 1997 there is evidence of remnant native tussock grasses.

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By spring 2000, the field layer is a mixture of tussock grasses and introduced annual weeds. There is no evidence of tree regeneration.

By 2011, the emergence of seedlings of Slender Cypress-pine is apparent in the foreground.