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

Abstract

I observed the use of exotic plant species by native birds and bats in 8 km 2 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.

Fruit traits of vertebrate-dispersed alien plants: smaller seeds and more pulp sugar than indigenous species

“…While the fruit traits of some individual species have been studied in detail, and reasons for their invasive success explored (Sallabanks 1993;Vila and D'Antonio 1998;Gosper 2004;, little attention has been given to the traits of suites of co-occurring alien species, nor of how fruit traits of alien and indigenous species compare (but see Corlett 2005).…”

A Habitat-Classification Framework and Typology for Understanding, Valuing, and Managing Invasive Species Impacts

“…Alien species may also provide important resources for native species in urban areas -e.g. fruits of alien trees as food source for native birds (Corlett 2005). In heavily disturbed sites, ecosystem impacts by invasive species are difficult to disentangle from impacts by other disturbance factors (Didham et al 2005), and often invasive species are probably not the driver of ecosystem change (Maskell et al 2006).…”

Pollination implications of the diverse diet of tropical nectar-feeding bats roosting in an urban cave

“…Intense 50 landscaping often increases the species richness and homogeneity of plants in these urban areas 51 (Grimm et al, 2008;Kowarik, 2011). These plants support diverse assemblages of birds and bats 52 (Corlett, 2005; Aida et al, 2016), which in turn provide seed dispersal and pollination services, 53 and consequently aid in maintaining urban green spaces (Tan et al, 2000;Corlett, 2005; 54 Sheherazade et al, 2017). However, the preference for planting non-native species in parks and 55 household gardens for urban beautification and food may create competition for pollination 56 services which could affect the reproductive success and survival of native plants (Faeth et al, 57 2005).…”