Interactions between birds, fruit bats and exotic plants in urban Hong Kong, South China

I observed the use of exotic plant species by native birds and bats in 8 km² of urban Hong Kong. Twenty-nine plant taxa were used repeatedly. Five species accounted for most interactions with birds: Cinnamomum camphora (10 bird species), Ficus religiosa (6), Livistona chinensis (7) and Pyracantha crenulata (6) provided fruits, while Bombax ceiba (6) supplied nectar. Panicum maximum (2) and C. camphora (1) provided seeds for granivorous birds and Leucaena leucocephala is host to a psyllid consumed by small insectivores in winter. Most trophic interactions between exotics and fruit bats involved the fruits or flowers of Syzygium jambos, while Livistona chinensis provided roosting sites for Cynopterus sphinx. The fruiting phenologies of the exotic species differed from the local flora, with fruit of some species available for the majority of the year. Fruit characteristics for the most commonly eaten species are within the range for native fruit species, although most are larger and have a lower seed load than the medians for native species. Seed dispersal by birds and/or fruit bats is a necessary, but not sufficient, condition for the naturalization of fleshy-fruited plants in Hong Kong, but S. jambos is the only naturalizing exotic species that needs vertebrates for pollination.