Factors affecting Grey-headed Flying-fox (Pteropus poliocephalus: Pteropodidae) foraging in the Melbourne metropolitan area, Australia

Factors affecting the foraging of mobile native fauna in highly fragmented urban landscapes have seldom been quantified at large spatial scales. We investigated factors affecting foraging by Grey-headed Flying-foxes (Pteropus poliocephalus; 'flying-foxes') in the greater Melbourne metropolitan area. Flying-foxes established a continuously occupied colony site in the Royal Botanic Gardens Melbourne in 1986, and the size of the colony has subsequently increased greatly. We used a stratified-random sampling design to examine the importance of six variables on the detection of foraging flying-foxes: (i) distance from the colony site (0-10, 10-20 and 20-30 km); (ii) distance from the Yarra River (0-5 and 5-20 km); (iii) the relative tree density of the municipality; (iv) whether the site was a park or street; (v) whether there was a relatively high or low density of trees at the site; and (vi) whether food was or was not detected at the site. We surveyed 240 sites within a 30-km radius of the colony site for foraging flying-foxes in both May and October 2002. The probability of detecting a foraging flying-fox declined with increasing distance from the colony site, but increased with increasing tree cover, and was higher for parks compared with streets and when food was present. Flying-foxes were observed foraging in a number of plant genera that have no species that naturally occur in the Melbourne area. Flying-foxes in Melbourne thus forage on planted resources that are widely distributed within a fragmented landscape, and are an example of a positive response by a native species to the process of urbanization