Predicting suitable release sites for assisted colonisations: a case study of eastern barred bandicoots Citation: Rendall, Anthony R, Coetsee, Amy L and Sutherland, Duncan R 2018, Predicting suitable release sites for assisted colonisations: a case study of eastern barred bandicoots, Endangered species research, vol. 36, pp. 137-148. DOI: http://www.dx.doi.org/10.3354/esr00893 ©2018, The Authors Reproduced by Deakin University under the terms of the Creative Commons Attribution Licence Downloaded from DRO: http://hdl.handle.net/10536/DRO/DU:30111470 DRO Deakin Research Online, Deakin University’s Research Repository Deakin University CRICOS Provider Code: 00113B Vol. 36: 137–148, 2018 ENDANGERED SPECIES RESEARCH Published July 10 https://doi.org/10.3354/esr00893 Endang Species Res OPENPEN ACCESSCCESS Predicting suitable release sites for assisted colonisations: a case study of eastern barred bandicoots Anthony R. Rendall1,*, Amy L. Coetsee2, Duncan R. Sutherland1 1Research Department, Phillip Island Nature Parks, Cowes, 3922 Victoria, Australia 2Wildlife Conservation and Science, Zoos Victoria, Elliott Avenue, Parkville, 3052 Victoria, Australia ABSTRACT: Assisted colonisations are increasingly being used to recover endangered or func- tionally extinct species. High quality habitat at release sites is known to improve the success of assisted colonisations, but defining high quality habitat can be challenging when species no longer inhabit their historical range. A partial solution to this problem is to quantify habitat use at release sites, and use results to inform assisted colonisation in the future. In this study, we quanti- fied habitat use by the eastern barred bandicoot Perameles gunnii, functionally extinct on the Australian mainland, immediately after translocation to an island ecosystem. The release site, Churchill Island in Westernport, Victoria, Australia, has a mix of open woodlands and open pas- ture, providing a range of habitat conditions considered appropriate for nesting and foraging. A total of 16 bandicoots were radio-tracked for 30 d immediately post-release. Early survivorship was high (94%), with males found to have larger home ranges and move greater distances from their first nest than females. Males and females initially used structurally complex habitats for nesting and foraging; as they became more established, males moved further from their release point and both sexes increased their use of open habitats during nightly activity. Female home ranges had limited overlap, suggesting intra-sexual territoriality. Males exhibited larger overlap- ping home ranges. Our results assist in quantifying habitat use of bandicoots immediately post- release and will be used to inform future assisted colonisations of the species to larger islands, in the presence of feral cats. KEY WORDS: Assisted colonization · Island conservation · Endangered species INTRODUCTION the release group, (2) successful breeding by the release group and their offspring and (3) persistence Assisted colonisations are the intentional move- of the established population (Seddon 1999). In each ment and release of organisms outside their indige- case, the outcome is influenced by several factors nous range to avoid extinction of populations of the including presence of feral predators, release habi- focal species (IUCN 2013). They have become a criti- tats (Sheean et al. 2012) and captive naivety (Math- cal tool in the conservation of many endemic fauna ews et al. 2005). Habitat suitability is even more per- around the world as invasive species and anthro- tinent when considering the assisted colonisation of a pogenic influences continue to affect their survivor- species to a region outside of its indigenous range. ship. The motivations for assisted colonisation are Assisted colonisations are increasingly being used varied; however, their success or failure is deter- for endangered species where key threatening pro- mined through 3 key criteria: (1) the initial survival of cesses cannot be mitigated within their indigenous © The authors 2018. Open Access under Creative Commons by *Corresponding author: [email protected] Attribution Licence. Use, distribution and reproduction are un - restricted. Authors and original publication must be credited. Publisher: Inter-Research · www.int-res.com 138 Endang Species Res 36: 137–148, 2018 range. Islands provide ideal locations for assisted for nesting and open habitats for foraging (Dufty colonisations with an increased ability to successfully 1994, Cook et al. 2010, Winnard et al. 2013). eradicate invasive species in these ecosystems In 2015, eastern barred bandicoots persisted across (Phillips 2010). In Austra lasia, predator-free islands 5 geographically isolated populations (Parrott et al. have enabled the establishment of several species, 2017) ranging in size from ~60 individuals in the cap- including the golden bandicoot Isoodon auratus (Ot- tive insurance population to around 1000 individuals tewell et al. 2014), Tasma nian devil Sarcophilus har- at Mt. Rothwell (D. Sutherland unpubl. data), with all risii (Thalmann et al. 2016), western barred bandi- bandicoots, from all sites, being descendants of 19 coots Perameles bou gain ville (Short et al. 1998) and founder individuals (Weeks et al. 2013). In 2010, the kakapo Strigops habroptilus (Lloyd & Powlesland genetic diversity in the remaining mainland bandi- 1994). Although success has been achieved (Fischer coot population had dropped by 35 to 40% from the & Lindenmayer 2000), failures highlight the need to level in 1990. To prevent further loss of diversity, a understand the factors that enable or prevent these rapid population increase to 2500 individuals is populations from successfully establishing within required (Hill et al. 2010). To achieve this, the East- new environments (Kemp et al. 2015). ern Barred Bandicoot Recovery Team has initiated Selection of release sites is a critical component of projects to establish the species on fox-free islands, any reintroduction but can be difficult to identify for where threats can be managed effectively (Coetsee threatened species with reduced ranges. Habitat suit- 2016, Hill et al. 2018). ability for threatened species is often gauged by habi- In this study, we aimed to assess the survival and tat use within restricted or relic populations that may habitat use of bandicoots immediately post-release in inhabit sub-optimal regions at the peripheries of their a novel environment to help inform future assisted indigenous range (Osborne & Seddon 2012). Given colonisations of the species. Specifically, we aimed to the importance of release site suitability, understand- quantify habitat use through assessment of the im - ing habitat use immediately post-release when portance of structurally complex habitats, how habi- founders are adjusting to new environmental condi- tat use changed over the first 30 d post-release and tions may improve the success rate of future assisted whether there were sex- or origin-based differences. colonisations. The eastern barred bandicoot Perameles gunnii (mainland form, un-named sub-species) was once MATERIALS AND METHODS widespread throughout the tussock grasslands of western Victoria from the South Australian border to Study species and location Melbourne’s western suburbs (Seebeck 1979). Since European settlement, the species has undergone a Eastern barred bandicoots (hereafter ‘bandicoots’) significant reduction in its range, largely attributable are small marsupials, with adults weighing from 600 to habitat loss and predation by the introduced red to 1000 g. Bandicoots typically live 2 to 3 yr and can fox Vulpes vulpes (Seebeck 1979). Such population produce up to 5 litters of 1 to 4 young yr−1, if condi- pressures have resulted in the species being listed as tions allow (Dufty 1995). They are strictly nocturnal, endangered under the Commonwealth Environmen- nesting during the day in leaf litter or grass-lined tal Protection and Biodiversity Conservation Act 1999 nests hidden in a small scrape usually within struc- and as extinct in the wild by the Victorian Depart- turally complex habitats, then emerging at night to ment of Environment, Land, Water and Planning’s forage in open habitats (Dufty 1991, Winnard et al. (DELWP) Advisory List of Threatened Vertebrate 2013). Their diet consists largely of invertebrates on Fauna (Department of Sustainability and Environ- or under the soil surface such as earthworms, various ment 2013). In an attempt to re-establish viable pop- beetle larvae (coleopteran and lepidopteran) and ulations, reintroductions at 9 locations within the adults (Coleoptera), as well as vegetative material indigenous range have been attempted with varying including grass and roots (Reimer & Hindell 1996). levels of success (Winnard & Coulson 2008). Preda- Churchill Island (38° 29’ 59’’ S, 145° 20’ 19’’ E) is tion by red foxes V. vulpes is the primary reason for 52 ha in size, 91 km south-east of Melbourne beyond reintroduction failure, a prob lem exacerbated by the indigenous range of the species (Fig. 1). Chur chill poor quality habitat and drought (Todd et al. 2002, Island sits off the northern coastline of Phillip Island Winnard & Coulson 2008). Studies of habitat use and is connected by a 100 m concrete bridge. Biose- within the indigenous range have shown that bandi- curity measures are in place to prevent incursions of coots require a mix of structurally complex habitats introduced red foxes, feral cats and rabbits Oryctola- Rendall