Tropical birds are declining in the Hainan Island of China

摘要

Understanding biodiversity trends and the factors that influence those trends is crucial for effectively reducing global biodiversity loss. The biodiversity trends in tropical areas are largely unclear. In addition, habitat loss and fragmentation and illegal wildlife use threaten biodiversity in these regions. Herein, we report abundance and species richness trends for birds in the tropical Hainan Province (Island), China, based on extensive transect surveys conducted in 10 km x 10 km grid cells across the majority of the island between 1997-1998 and 2012-2013. We also quantified the effects of changes associated with land use, natural forests, agriculture, human populations, protected areas and wildlife-rearing farms on the abundance of birds. We found that 145 bird species suffered significant declines in abundance and species richness between two time periods of the survey. 28 species exhibited a decline in abundance, while 33 species showed an increase. Other species showed no significant changes in abundance. More common bird species declined more rapidly than less abundant species. The abundance trend in a grid cell (log ratio: 2012-2013/1997-1998) increased with the proportion of protected area but decreased with a reduction in natural forests and an increase in the number of wildlife-rearing farms. These results suggest that the avian decline on Hainan Island is mainly due to deforestation and illegal wildlife use. To slow this decline, it is necessary to increase protected area coverage and networks on the island, strengthen natural forest protection, and reinforce regulations to reduce habitat destruction and illegal wildlife use by wildlife-rearing farms. (C) 2016 Elsevier Ltd. All rights reserved.