Threatened but not conserved: flying-fox roosting and foraging habitat in Australia

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.