Habitat suitability of Hong Kong's urban parks for Short-nosed fruit bats Cynopterus sphinx

Abstract

Hong Kong has experienced rapid urbanisation over the past century. In urban areas, urban parks act as biodiversity hotspots which enable species to thrive. Cynopterus sphinx, a fruit bat inhabits most of Hong Kong’s urban parks. Little is known about the habitat requirement of C. sphinx in Hong Kong. The aim of my study is to look at the habitat suitability of Hong Kong’s urban parks for C. sphinx in order to inform management of urban parks to benefit conservation of the species. I surveyed 10 urban parks of varying size (1.68 – 19 ha) from November 2018 to February 2019 to investigate the roosting behaviour and foraging ecology of C. sphinx. I assessed whether abundance of roosts and average roost size were dependent on park size, abundance of Chinese fan palms and chiropterochorous food resources. I recorded the fruits that made up the diet of C. sphinx and the species in the parks that could potentially provide food resources to the bats throughout the year. Two urban parks were surveyed in March and April 2019 to look at factors (height of palm trees, abundance of green and dry fronds, distance from nearest path, ground cover and the location of palm trees in cluster or not) that might influence roost tree selection. For the first time in Hong Kong, I recorded C. sphinx roosting in Dracaena draco and Syagrus romanzoffiana. I also found 3 previously unrecorded fruits that made up their diet namely Bischofia polycarpa, Ficus rumphii and Roystonea regia. Every month I surveyed 622 Chinese fan palms. During each survey, I recorded an average of 2.30 ± 0.24 SE roosts per park and 11.32 ± 1.29 SE fruiting and flowering chiropterochorous species per park. The abundance of roosts in urban parks was significantly dependent on the abundance of chiropterochorous food resources (GLMM: test statistics, p = 0.041) and not on park size or abundance of Chinese fan palms. Average roost size was not dependent on any of the variables. In Kowloon Park, C. sphinx preferred to roost in tall palm trees (Mann-Whitney U = 15.5, p < 0.01) that had more green fronds (Mann-Whitney U = 62.5, p =0.005) although these were not significant in Tin Shui Wai Park (perhaps due to uniformity of tree height and number of green fronds in this park). I found that most parks could provide food resources to bats throughout the year. I recommend that to better conserve the species in urban parks, park managers should ensure that urban parks have Chinese fan palms distributed throughout the parks. That fan palms are tall and that their green fronds are not pruned. Also, urban parks should have enough food resources available to the bats throughout the year.