Range expansion due to urbanization: Increased food resources attract Grey-headed Flying-foxes (Pteropus poliocephalus) to Melbourne



Abstract  Urbanization profoundly alters the biota of areas that become cities and towns. Many species are introduced by humans while indigenous species often decline. Although these changes are well known, the long-term ecological effects of new species and their interactions are seldom considered and rarely documented. This study examines changes in diversity and temporal availability of the food resources of Pteropus poliocephalus (Grey-headed Flying-fox) in the Melbourne region using a variety of historical and current data sources. Our results indicate that urbanization has influenced the distribution, abundance and ecology of P. poliocephalus through a dramatic increase in the quantity and temporal availability of food resources. Prior to European settlement, only 13 species recorded in the range-wide diet of P. poliocephalus grew in the Melbourne area. Compilations of street-tree databases indicate that an additional 87 species have been planted on Melbourne’s streets and that there are at least 315 500 trees that are able to provide food for P. poliocephalus. Phenology records indicate that street trees have lengthened the temporal availability of food for P. poliocephalus. A period of natural food scarcity between May and August has been ameliorated by street trees which have provided nectar and a previously absent fruit resource. These changes are likely to be a major factor contributing to the recent range expansion of P. poliocephalus and the establishment of a permanent camp in Melbourne.