Flying-Fox Roosting and Foraging Habitat in Australia
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CSIRO PUBLISHING Australian Journal of Zoology https://doi.org/10.1071/ZO20086 Threatened but not conserved: flying-fox roosting and foraging habitat in Australia Libby A. Timmiss A, John M. Martin A,B,F, Nicholas J. Murray A,C, Justin A. Welbergen D, David Westcott E, Adam McKeown E and Richard T. Kingsford A ACentre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia. BInstitute of Science and Learning, Taronga Conservation Society Australia, Bradley’s Head Road, Mosman, NSW 2088, Australia. CCollege of Science and Engineering, James Cook University, Townsville, Qld 4811, Australia. DThe Hawkesbury institute for the Environment, Western Sydney University, Richmond, NSW 2753, Australia. ECommonwealth Scientific and Industrial Research Organisation, 47 Maunds Street, Atherton, Qld 4883, Australia. FCorresponding author. Email: [email protected] Abstract. Conservation relies upon a primary understanding of changes in a species’ population size, distribution, and habitat use. Bats represent about one in five mammal species in the world, but understanding for most species is poor. For flying-foxes, specifically the 66 Pteropus species globally, 31 are classified as threatened (Vulnerable, Endangered, Critically Endangered) on the IUCN Red List. Flying-foxes typically aggregate in colonies of thousands to hundreds of thousands of individuals at their roost sites, dispersing at sunset to forage on floral resources (pollen, nectar, and fruit) in nearby environments. However, understanding of flying-fox roosting habitat preferences is poor, hindering conservation efforts in many countries. In this study, we used a database of 654 known roost sites of the four flying-fox species that occur across mainland Australia to determine the land-use categories and vegetation types in which roost sites were found. In addition, we determined the land-use categories and vegetation types found within the surrounding 25 km radius of each roost, representing primary foraging habitat. Surprisingly, for the four species most roosts occurred in urban areas (42–59%, n = 4 species) followed by agricultural areas (21–31%). Critically, for the two nationally listed species, only 5.2% of grey-headed and 13.9% of spectacled flying-fox roosts occurred in habitat within protected areas. Roosts have previously been reported to predominantly occur in rainforest, mangrove, wetland, and dry sclerophyll vegetation types. However, we found that only 20–35% of roosts for each of the four species occurred in these habitats. This study shows that flying-fox roosts overwhelmingly occurred within human-modified landscapes across eastern Australia, and that conservation reserves inadequately protect essential habitat of roosting and foraging flying-foxes. Keywords: bat, fruit-bat, pollinator, conservation, threatened species, Pteropus, vegetation community, mammal. Received 27 October 2020, accepted 8 February 2021, published online 3 March 2021 Introduction (Hayward 2011). Understanding species habitat requirements Globally, more than 8500 vertebrate species are threatened and use remains crucial for developing effective conservation with extinction (IUCN 2020). Habitat destruction and action plans. degradation, as a result of human land use, are largely Flying-foxes (Pteropus spp.) roost colonially, typically in considered the driving threats to biodiversity (Chaudhary and groups of thousands to hundreds of thousands of individuals, Mooers 2018; Powers and Jetz 2019). As such, habitat and often in habitat containing relatively large, emergent trees, protection is frequently prioritised in species conservation close to floral resources for nocturnal foraging (Granek 2002; planning (Possingham et al. 2002; Wintle et al. 2019). Gulraiz et al. 2015;Oleksyet al. 2015). Of the 66 Pteropus However, habitat protection is not always sufficient to ensure species globally, six are extinct and 31 are considered at risk species persistence, and a multitude of approaches are often (Vulnerable, Endangered, or Critically Endangered) on the necessary for the successful conservation of threatened species IUCN Red List (Todd 2019). Four species of flying-fox are Journal compilation Ó CSIRO 2021 Open Access CC BY-NC-ND www.publish.csiro.au/journals/ajz B Australian Journal of Zoology L. A. Timmiss et al. native to the Australian mainland: grey-headed (Pteropus fragmented landscapes (Welbergen et al. 2020). It could be poliocephalus), spectacled (P. conspicillatus), black argued that flying-foxes are ecologically more important in an (P. alecto), and little red (P. scapulatus) flying-fox. The anthropogenic landscape, as their foraging behaviour connects grey-headed flying-fox is recognised both nationally and fragmented vegetation (see Westcott et al. 2015;Welbergen internationally as Vulnerable to extinction (TSSC 2001;IUCN et al. 2020). Studies assessing flying-foxes’ foraging 2020), and the spectacled flying-fox is nationally Endangered behaviour report that nightly movements predominantly occur in Australia (TSSC 2019). Globally, a lack of understanding within a 25 km area surrounding roosts (Roberts 2012; regarding flying-fox roosting behaviour and habitat Welbergen unpub. data) and landscape scale movements of up requirements hinders population assessments and conservation to 300 km in a night (Welbergen et al. 2020). planning. For the four mainland Australian flying-fox species, we Historically, Australian flying-fox roosts have described the location and species composition of known predominantly been described as associated with natural diurnal roosts supporting colonies. We then assessed the land habitats including mangroves, wetlands, rainforests and, to a classification of each roost: protected, urban, or agricultural. lesser extent, dry sclerophyll eucalypt (Palmer and Woinarski We also assessed the vegetation classification associated with 1999;Fox2011; McClelland et al. 2011). In recent years, each roost. Lastly, we assessed the land classification and however, colonies have increasingly become associated with vegetation type within the surrounding 25 km of each roost. urban landscapes (Williams et al. 2006;Plowrightet al. 2011; Tait et al. 2014). Several urban ‘benefits’ have been proposed. These include night-time lighting improving navigation, Methods altered climatic suitability of urban areas, and a mixture of The four mainland Australian flying-fox species are distributed native and exotic plants providing more reliable nectar and across tropical regions in the north to the warm-temperate fruit resources year-round (Vardon and Tidemann 1999; regions of eastern Australia (Fig. 1)(Parishet al. 2012). Grey- McDonald-Madden et al. 2005). However, the exact causes for headed flying-foxes have the southernmost distribution of any an increased use of urban areas by flying-foxes are yet to be flying-fox species, spanning from Queensland around to South determined, as little is known about the roosting and foraging Australia (Westcott et al. 2011). The black flying-fox is a habitat preferences of flying-foxes in urban environments. predominantly tropical species, ranging the northern coastline Flying-fox roosts located close to urban areas are of Australia, and over the past two decades has spread south commonly criticised by the public for being loud and odorous, from Queensland along the east coast of New South Wales and posing a disease risk (Edson et al. 2015;Curreyet al. (Welbergen et al. 2008; Roberts et al. 2012) with vagrant 2018). Conflict can lead to ineffective and potentially records in Victoria. Little red flying-foxes have the most damaging management strategies such as roost dispersal extensive distribution, spanning from Western Australia across (Roberts et al. 2011; Lentini and Welbergen 2019). Conflict the north of Australia to Queensland and south to Victoria. may also occur in agricultural areas, with flying-fox foraging Spectacled flying-foxes have the most restricted distribution of damaging crops (Divljan et al. 2011). These conflicts are the four species, being found in the wet tropics and Cape York exacerbated by patterns of roost occupancy that appear to be in north Queensland in Australia (Garnett et al. 1999;Fox driven by local foraging resources (Giles et al. 2016; 2011). Vanderduys et al. 2020). At times, local flowering can lead to large temporary influxes of flying-foxes, which can lead to or exacerbate conflict (Lentini and Welbergen 2019). An extreme Flying-fox colonial roost data example of this has been observed in response to mast The National Flying-fox Monitoring Program (NFFMP) flowering of spotted gum (Corymbia maculata)where (Westcott et al. 2011) has produced a spatial dataset of the ~250 000 grey-headed flying-foxes moved to the Water location of known roosts for the four mainland species of Gardens roost located in Bateman’s Bay, New South Wales, flying-fox across Australia, with a focus on grey-headed and where the community responded with intense calls for spectacled flying-fox colonies. As part of the NFFMP, all dispersal of this vulnerable species (Welbergen and Eby 2016). known roosts were surveyed quarterly for flying-foxes At present, it is unknown on what basis flying-foxes choose between November 2012 and February 2017 (n = 18 surveys). their roost sites, which renders management agencies unable to Roosts were added during the survey period; these could be design ‘carrot solutions’ that help reduce conflict by creating newly occupied by flying-foxes or have previously been more