Science for Saving Species Research findings factsheet Project 2.2.3/4.2.2

All the eggs in one basket: Are refuges securing an Endangered ?

In brief Background

The forty- is habitat loss due to land clearing, endemic to , where it has wildfire, competition from noisy been lost from most of its former miners, climate change, predation range, and is now largely confined (particularly by introduced sugar to a small number of offshore gliders), and a newly discovered . These islands are serving parasitic fly that kills nestlings. as refuges for the Endangered bird; however, what caused Which of the threats are most the contraction to these places significant to the species, if and and why they still support viable how they interact, and how they populations has not been well have driven local extinctions in understood. Forty-spotted pardalote nest. former parts of the bird’s range Image: Fernanda Alvez have not been previously assessed. This study assessed the range Furthermore, the security of the and severity of the threats to The forty-spotted pardalote remaining populations is uncertain. the persistence of the forty- (Pardalotus quadragintus) is an spotted pardalote, established its Endangered bird endemic to population status, and produced Tasmania that is non-migratory recommendations to guide the and hard to detect due to its planning of trial reintroductions of soft call, very small size and the species across its former range. resemblance to two other more common pardalote species We identified large areas of suitable (P. striatus and P. punctatus). habitat that are too distant for natural recolonisation. To protect It is considered a “specialist” as the species from the threat of it nests in tree hollows, primarily extinction, we recommend of species, and is that new populations of forty- dependent for food on white spotted pardalotes be established gums (Eucalyptus viminalis). immediately in these new sites The range of the species has via reintroductions while robust contracted severely over the past source populations still exist. century. Once widely distributed Figure 1. Current refuges and historical across Tasmania, it is now mostly locations of the forty-spotted pardalote confined to a few small offshore across Tasmania. Refuges are indicated by solid red squares, historical sites by black island refuges (see Figure 1). squares, and new sites identified during this study by open red squares. 1: ; Key threatening processes to the 2: ; 3: Tinderbox; 4: North Bruny persistence of the species include Island; 5: South . Research aims What we did

This research aims to support two To achieve our research aims of their range with land clearance. management priorities for the securing the forty-spotted pardalote, We modelled the suitability of species: 1) to prevent yet further we first assessed the key threats to habitat across Tasmania for noisy contraction of the forty-spotted the species, and then established miners, and based on the findings pardalote’s range; and 2) to the status of the pardalote from those models, we assessed examine the potential to expand populations in known refuges the environmental suitability of its range through reintroductions by surveying those populations forty-spotted pardalote refuges to suitable habitat across its using an occupancy modelling for noisy miners, and created a former range. framework. map that predicts suitable and unsuitable environments. To secure the pardalote’s future We looked at the impact of forest in these ways, we set out to loss as a result of land clearing, We assessed each threat for its likely increase our understanding of timber harvesting and wildfire, consequences to the species, and what it is exactly about the islands and estimated the total area of considered the potential impacts where the species is persisting potential habitat of the forty-spotted of climate change, in the context that has made them refuges for pardalote and the total area of of the likelihood of other known the bird. Although islands are habitat affected by deforestation threats worsening. disproportionately represented in over the past 30 years. Also, as the To determine the population species extinctions globally, they pardalote’s current and historical status of the forty-spotted pardalote, can conversely become critical distribution is highly fire-prone, we conducted baseline surveys refuges when key threatening we estimated the area of habitat on the known refuges of Maria processes are absent, which is affected by wildfire over this Island, North Bruny Island and apparently what we are witnessing period, and the likely future Flinders Island, which together in the case of the forty-spotted fire risk of each refuge. support almost 80% of the bird’s pardalote. Understanding what Noisy miners are not currently current habitat area. We used characteristics allow the species found in forty-spotted pardalote occupancy modelling to estimate to persist in an area will be refuges; however, they are numbers in critical habitat for valuable to identifying potential widespread on the Tasmanian each refuge as well as in other reintroduction sites across its and have expanded locations with sparser data. former range.

To give reintroduced populations Forty-spotted pardalote in tree hollow. Image: Dejan Stojanovic the best chance of survival it will also be important to determine which threats are the most critical to address at reintroduction sites and what conservation actions would be most effective (e.g., fire management, predator control, reservation, biosecurity). Key findings Table 1. Risk of potential threats over the next 30 years at current and former forty-spotted pardalote sites. Former sites were assessed to assist the identification of suitable reintroductions. We were able to establish baseline Climate Location Fire Deforestation population data and to quantify colonisation change the historical impacts and future Maria Island Very high Moderate Moderate Very high potential risks of threats to the North Bruny Island Very high Very high High Very high refuge populations of forty- Tinderbox Very high Very high Very high Very high spotted pardalotes. South Bruny Island Very high Very high High Very high Existing populations Flinders Island Extreme Low High Very high Southport Extreme Moderate High Very high We found that occupancy rates Large patches of intact are very high at two refuges (Maria Unknown Low Unknown Very high habitat in former range and Bruny Islands) but that the pardalote is almost extinct on secure from these threats despite their impact will depend on local Flinders Island, likely due to recent being extensively reserved. Fire forest structure; noisy miners wildfire. Over the period of the frequency, intensity and extent are particularly pose a potential threat to study, we recorded the pardalote expected to increase with climate Bruny Island pardalote populations, at 59 of 67 sites (88%) on Maria change, and as most refuge habit as most occupied pardalote Island, 55 of 61 sites (90%) on Bruny excluding Flinders Island has habitat on that island is nearby to Island and just 7 of 115 sites (6%) on not burnt for a long time, they fragmented agricultural land. The Flinders Island. No were found are supporting a high fuel load, forest on Maria Island is more intact; at any previously known sites on suggesting that severe fire is likely however, extensive livestock grazing Flinders Island; the detections were under suitable weather conditions. across large parts of Maria Island made at a new site on the island severely suppresses the understorey The impact of fire on the remnant that is separated from the previously vegetation, reducing or eliminating populations of the forty-spotted known refuge by more than 20 km cover, which may advantage pardalotes has the potential to of primarily agricultural land. We noisy miners. also found the species in a small be devastating, as evidenced by patch of habitat near Southport on the population findings from Parasitic fly the Tasmanian mainland, where the Flinders Island. Despite some While the parasitic fly can cause last record of their presence in the forest recovery, that location is high nestling mortality, the degree vicinity was more than 120 years still unoccupied by the pardalote of this threat is as yet unknown. ago, although data was too sparse over a decade later. Given the However, it is likely to vary in for modelling at these locations. small size of the refuges, they are time and space according to all at risk of being totally destroyed, environmental conditions, and may Threats with little chance of recolonisation. be exacerbated under post-fire Deforestation in refuges has abated conditions and climate change. in recent decades, and these areas Noisy miners We conclude that the current appear to currently support viable We found that the environmental distribution across island refuges is populations. However, according suitability for noisy miners is high unlikely to secure the species from to our overall risk assessment, across most of the former and extinction. While we identified large all refuges face high, very high present distribution of the forty- areas of potential habitat across or extreme risks from multiple spotted pardalote; and that noisy the species’ former Tasmanian threats (see Table 1). These are miners are well-established less mainland range, these are likely chiefly wildfire, colonisation by than 4 km from all refuges except too distant from source populations the hyper-aggressive noisy miner, Flinders Island, with the implication for natural recolonisation. They and climate change. of risk of expansion of their also are subject to the threatening range into those refuges. Fire processes discussed above that Our results indicate that the islands Given the preference of noisy allow the expansion of noisy that are serving as refuges are not miners for fragmented environments, miners and other aggressive birds. Recommendations

Our findings lead us to propose that establishing new populations of forty-spotted pardalotes via reintroduction is essential to secure the species, and that this is best achieved without delay while robust source populations still exist. Because of the current threats to refuges we believe any risks associated with translocations far outweigh the risks of not acting. Reintroduced should be sourced from wild populations; wild animals are likely to have a greater change of successfully establishing than captive-bred Forty-spotted pardalote. Image: Henry Cook individuals, as even slight genetic Although this is also climatically In particular we have identified adaptions from captivity can have suitable noisy miner habitat, these a negative effect over the long that refuge sites are at risk from birds are rarely found in the intact term on the size of wild populations severe fires and deforestation or interior of larger forest patches. and their genetic diversity. other habitat simplification such as Diagnosing the processes that have caused by grazing. Management at The most suitable reintroduction led to a species’ current distribution these sites should aim to mitigate sites are in white gum forest across is extremely valuable because sites these threats. the species’ former range. In total that have previously seen local these areas cover more than Targeted revegetation programs extinctions do not necessarily 1100 km2, about half of which may eventually increase the area remain permanently unsuitable. occurs in patches of greater than that the forty-spotted pardalote 1 km2 in area and which often form Likewise, the existing refuge sites inhabits, but this will not address part of larger forest remnants. may not provide long-term security. the immediate threats to its refuges.

Further Information Cited material Matthew Webb Webb, M., Alves, F., Tulloch, A., Shaw, J., Bryant, S., Stojanovic, D., [email protected] Crates, R. & Heinsohn, R. 2018 All the eggs in one basket: Are island refuges securing an endangered ? Austral Ecology 4(3), 523–33 (doi:10.1111/aec.12693).

This project is supported through funding from the Australian Government’s National Environmental Science Program.