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

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 km², 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 Existing information on rodents in Hong Kong was compiled from previous published and unpublished studies, and additional trapping was conducted at 17 non-urban sites.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.