Study on the occupancy model of urban mammals using camera-trapping techniques: a case study in Shenzhen, south China

Urbanization profoundly shapes regional biodiversity. Yet in-depth understanding of how urban wildlife respond to urbanization in China is limited due to the lack of concern and research regarding urban wildlife. In order to provide insights into how the urban biodiversity is maintained, we used an empirical dataset collected from 176 camera traps deployed between August and November 2022 to investigate mammal occurrence and habitat use in Shenzhen, a rapidly urbanizing megacity in south China. Single-season occupancy models were constructed to determine how species occupancy varied under the influence of habitat structure (vegetation cover and distance to rivers), human disturbance (nighttime light) and species interactions (free-ranging pet cats) on site scale in a typical urban region. A total of 10 species of terrestrial mammal (4 orders, 10 families) were detected during the period of survey. The results showed that leopard cats (Prionailurus bengalensis), wild boars (Sus scrofa), and Chinese ferret-badgers (Melogale moschata) have relative high occupancy and detectability in the study area, while rhesus macaques (Macaca mulatta) have the highest detectability rate with very low occupancy. Other mammals species exhibit medium to low occupancy and detectability. Vegetation cover is the most weighted factor in the occupancy models of the leopard cats, Chinese ferret-badgers, Indian civets (Viverricula indica), and Pallas’s squirrels (Callosciurus erythraeus). Distance to rivers exerts a stronger impact on the site occupancy of Malayan porcupines (Hystrix brachyura) compared to other species. Pallas’s squirrels and Chinese ferret-badgers present high tolerance to disturbance from human activities, since there is a slightly positive correlation between their site occupancy and nighttime light. The results of two-species occupancy modeling show that both Pallas’s squirrels and hog badgers (Arctonyx collaris) are less likely to co-occur with free-ranging pet cats. The spatial distribution of free-ranging pet cats and other 5 species including leopard cats, however, tend to overlap within the study area. Such an overlap could intensify habitat encroachment and resource competition which may pose a threat to urban wildlife. Our findings underscore the complexity of mammals’ response to anthropogenic features in urban areas, taxa-specific or even species-specific needs should be considered when formulating the ecological-based conservation and management strategies of urban biodiversity.