Rodent Diversity in a Highly Degraded Tropical Landscape: Hong Kong, South China

Abstract

The diverse ecological roles played by different rodent species mean that the loss of some species and superabundance of others could potentially influence a wide range of ecological processes. Hong Kong (22°N, 114°E), with seven million people in a land area of 1100 km 2 , could be considered a 'worst case scenario' for the survival of mammalian diversity. Existing information on rodents in Hong Kong was compiled from previous published and unpublished studies, and additional trapping was conducted at 17 non-urban sites. The rodent fauna of modern Hong Kong consists of eight species of rats and mice (Bandicota indica, Mus caroli, M. musculus, Niviventer fulvescens, Rattus norvegicus, R. rattus, R. tanezumi, R. sikkimensis: Muridae), one porcupine (Hystrix brachyura: Hystricidae), and one recently introduced tree squirrel (Callosciurus erythraeus: Sciuridae). Six of the murids are urban or agricultural commensals, so only the porcupine and two murids, N. fulvescens and R. sikkimensis, are likely survivors of Hong Kong's pre-deforestation native rodent fauna. The two murids co-dominate in forest and shrubland, but can also move through grassland, which has probably enabled their survival through repeated cycles of fragmentation and regrowth. Additional forest rodents that may have inhabited Hong Kong in the past are tentatively identified from information on their recent distributions in the region. One possible ecological consequence of Hong Kong's depleted rodent fauna is a shift in the balance between seed predation and seed dispersal, in favor of the former.

Seed dispersal in Hong Kong, China: past, present and possible futures

“…The 1102 native species with non-fleshy fruits have received much less attention. Of those investigated, 46 tree species (hoarding; Table 1), mostly in Fagaceae, have large, wingless, dry fruits, without a flesh reward, that were probably once dispersed by scatter-hoarding rodents, but now appear to be largely undispersed in Hong Kong (Chung 2005;Chung & Corlett 2006). Smaller numbers of species show clear adaptations for dispersal by attachment to fur, feathers, or clothing (exozoochory), mechanical dispersal, or floating in the sea or freshwater.…”

Invasive aliens on tropical East Asian islands

“…On both islands, alien plants dominate only in disturbed urban and agricultural areas, although this dominance can apparently persist on some sites after disturbance is halted (e.g. for Hong Kong-Corlett 1992b;Dudgeon and Corlett 2004;Leven and Corlett 2004;Chung and Corlett 2006;for Singapore-Corlett 1988, 1992aTan et al 2007). In contrast, only single alien plant species, Syzygium jambos in Hong Kong (Leung et al 2009) and Clidemia hirta in Singapore (Teo et al 2003), have signiWcantly invaded native, closed-canopy forests.…”

“…Buddhist releases have been less common in Singapore, but may be 1 C the source of the only widespread avian forest invader there, the white-crested laughingthrush (Garrulax leucolophus) (Wang and Hails 2007). The exotic squirrels in both Hong Kong (Callosciurus Xavimanus; Chung and Corlett 2006) and Singapore (C. Wnlaysonii; Baker and Lim 2008) were probably also established from deliberate releases. In Hong Kong, where no native squirrel species survived deforestation, C. Xavimanus has successfully invaded native forests, but in Singapore, which has high densities of native tree squirrels, the exotic species is currently conWned to suburban areas, although this may simply reXect its relatively recent introduction.…”

Exotic plant invasion in the highly degraded upland landscape of Hong Kong, China

“…For example, two native species of murid rodents dominate 1 C semi-natural upland plant communities on Tai Mo Shan and elsewhere, while six additional species occur only as urban or agricultural commensals, and are presumed to be exotic (Chung and Corlett 2006). The birds, however, provide a striking exception to this pattern, with many of the introductions of the last few decades being conWned to closed woody vegetation-the precise opposite of other taxa (Leven and Corlett 2004).…”