Rare Bits 37, June 2000

Number 37 June 2000 RARE BITS THE NEWSLETTER ABOUT THREATENED SPECIES WORK This newsletter is produced FEATURE ARTICLE primarily as a vehicle for information exchange between departmental staff South Island kaka research involved in threatened species recovery and from Ron Moorhouse ecological restoration Last summer was a watershed for kaka you can protect them. Once Fenn trap- programmes. In recognition of wider interest, however, research in Nelson Lakes National Park. lines were established we stopped “Rare Bits” is also provided We’ve finally monitored enough nesting localised nest protection so that we could to non-departmental groups attempts to answer the key question of evaluate this more widely applicable on request. The newsletter’s our research: can predator control method of stoat control in combination informal style may reverse the decline of kaka? with the existing bait-station grid. occasionally lead to Baseline research by DSIR/Landcare in Six of the 8 nesting attempts completed misunderstandings for some of those readers. Views Big Bush Conservation Area documented since the establishment of Fenn trap-lines expressed by the authors are the previously appalling productivity of have been successful. The 2 nests that not necessarily those of the kaka there in the absence of predator failed did so because of predation on Department of control. Only 2 of 20 nesting attempts nestlings and eggs, no female birds were Conservation. monitored over an 11-year period were killed. Even without including our first successful, producing just 4 young. Over season’s data, the difference between the same time period 4 of 7 radio-tagged these results and the DSIR/Landcare data females were killed on the nest by is so great that probability of it occurring predators, probably stoats. by chance is only about 1 in 1000. To CONTENTS Three season’s data has now been exclude the possibility that we had struck FEATURE ARTICLE South Island kaka research 1 collected since the beginning of predator years of unusually low predator numbers SPECIES ROUNDUP control in the Rotoiti Nature Recovery we concurrently monitored kaka nesting Weta 3 Project (RNRP) area, literally just over success at Lake Rotoroa (20 km from the Dactylanthus 3 the road from Big Bush. In the first RNRP area) where there was no predator CONSERVANCY NEWS season of our study a poison bait-station control. At the same time that most pairs Northland 4 Auckland 5 grid was in place to control rats and were nesting successfully at Rotoiti, 9 of Waikato 7 possums, but, because Fenn trap-lines 10 nesting attempts at Lake Rotoroa failed Bay of Plenty 8 for stoats were not yet in place, we used due to predation on eggs, nestlings, or East Coast/Hawke’s Bay 9 aluminium tree ‘bands’ and a ring of Fenn nesting females. The probability of this Wanganui 10 traps around each nest to protect these difference in nesting success between the Wellington 11 Nelson/Marlborough 14 from stoats. RNRP area and Lake Rotoroa being due West Coast 16 All four nests monitored that season were to chance is about 1 in 100. Otago 17 successful, fledging 12 young. While they From the population perspective it is the Southland 19 seemed effective, the localised nest predation of nesting females that is the OTHER BITS protection measures we used that season most damaging. Last summer alone we Successful bat skills workshop 20 are relatively impractical because you lost 3 of 5 nesting females to predators Argentine ant – a new pest? 21 Island Roundup 22 need to know where the nests are before at Lake Rotoroa. The RNRP area is a net producer of kaka, female nesting just outside the RNRP a marked turnaround from the appalling boundaries produced a clutch of 8 eggs, productivity figures recorded by DSIR/ twice the usual clutch size. Two females Landcare in the absence of predator resident in the RNRP area are currently control. Excluding last season’s fledglings renesting after fledging young earlier this which are still at risk of predation and year and another female at Rotoroa was those that we can’t find, 17 (61%) of the killed on the nest attempting to do the 28 fledglings radio-tagged at Rotoiti in same thing. Attempts to raise a second the previous two breeding seasons are brood in the same season have not still alive at present. previously been recorded in kaka. Although about a third of the young In January 1999 we transferred 4 female fledged have been lost to predators, more kaka from Whenua Hou (Codfish Island) than enough have survived to to the RNRP area in an effort to increase compensate for adult mortality which is our sample size. One of these nested last low (1 of 5 radio-tagged females at Rotoiti summer – only a year after her release. has died in 3 years, apparently of natural Unfortunately, her eggs and a recently causes). However, we may have to hatched nestling were preyed on, increase the size of the protected area if probably by rats, but the fact that she we are to achieve a local recovery of nested so soon after her release is kaka. At present, most of the young evidence of the adaptability of kaka to produced within the RNRP’s boundaries different habitats. Three of these birds disperse into surrounding unmanaged left the RNRP area after their release but habitat where they are unlikely to breed remained local. One subsequently died successfully. but the other 3 are alive and well. Since Since kaka bred in only 6 of the 11 years only 1 settled within the RNRP DSIR/Landcare worked in Big Bush boundaries it looks like it is possible to we’ve been fortunate that there has been reliably transfer adult female kaka into breeding every year we’ve been working an area of several thousand hectares but at Rotoiti. The DSIR/Landcare research not of several hundred hectares. revealed that nesting only occurred when We now have robust evidence that the beech seed was available. I thought there RNRP is working for kaka. If there is had been pretty big beech mast the breeding next season we plan to use previous summer but last summer’s time-lapse video gear to identify beech-seed crop was bigger still. This predators so that we can target these probably explains the unprecedented more effectively. productivity of kaka last summer. A RARE BITS No. 37. July 2000 2 SPECIES ROUNDUP WETA ‘transferees’ had started to moult, so they from Andrea Booth (Northland), will be released when they have Jason Roxburgh (Waikato), and completed moulting, and when the John Lyall (West Coast) weather gets a bit warmer. Transfers Surveys for Deinacrida talpa, an alpine Auckland tree weta have recently been species, continued this summer with four released on Limestone Island; a 40-ha trips above the bushline along the scenic reserve in the upper Whangarei Paparoa Ranges locating a couple of new Harbour. After first listening for weta over sites. This followed on from last year’s several nights, weta were deemed survey, which extended the known range absent, probably owing to a century of north, and south along the range. No habitat removal, industrial activity and further work is planned. the presence of rats. DACTYLANTHUS Following the removal of rats and the from Bec Stanley (Auckland), Paul planting-up of the island over the last Cashmore (Bay of Plenty), and 10 years, it was considered viable to Graeme La Cock (Wanganui) release the weta into old remnant puriri What’s new? trees that could provide suitable roosting Two new sites for Dactylanthus taylorii sites. On-going monitoring of breeding were located by Graeme Atkins, Sid success will consist of artificial roost sites, Marsh, and volunteers on Hauturu in built by science students from Whangarei April. This brought the number of known Boys High School, and lengths of areas on Hauturu to 6, widely scattered bamboo capable of hiding juvenile weta. over the whole island. The research The Middle Island tusked weta (MITW), group was attempting to use kiore gut previously only found on Middle Island contents as a survey technique, because (Mercury Island Group), now has two possums, pigs, and rats are used on the new homes. Over a 2-week period, 150 mainland. It didn’t end up being a useful 4th instar MITW were released onto Red technique – we were surprised by the Mercury and Double Islands. These early flowering this year and so the islands are figured to give the weta their survey was a bit late, and also kiore greatest chance of establishing new seemed to chew the Dactylanthus quite populations, and will also indicate the finely and it was not visible in the optimal habitat of this species. stomachs. The new populations were The weta were welcomed to their new located by the old ‘look at the ground’ home by kaumatua of Ngati Tamatera, method. and have been monitored over the last A recent historic record of Dactylanthus few weeks. A perspex cover was was followed up in the Waitakere Ranges designed for the weta released onto Red with no success. The plan is to use the Mercury, to stop the risk of predation possum gut content technique next year by little spotted kiwi. Most weta have if funding allows. since vacated their perspex motels. In March staff were shown a new A few critters were released into a Dactylanthus site on the edge of the purpose built enclosure on Red Mercury, southern part of Whirinaki Forest Park and these animals will be monitored to adjoining Kaingaroa pine compartments. assess whether breeding occurs.

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