Abstract:

As an important land and water transition zone on Earth, wetlands are good places for birds to breed and roost. Bird monitoring has become an important index for assessing the biodiversity and ecological environment of a region. Nansha Wetland Park in Guangzhou is rich in biological resources and provides an important resting and wintering ground for global migratory birds as it is located on their migration route from East Asia to Australasia. To understand the migration patterns and annual dynamic changes of birds in the Nansha Wetland Park, line- and point-transect surveys were conducted to collect bird species and abundance data from January 2014 to December 2018. First, our results showed that 139 birds were recorded during the study period, of which migrant species were dominant. Combined with the available literature, a total of 186 bird species were recorded, belonging to 17 orders and 49 families. Of these bird species, 165 are under various levels of protection. Second, while the interannual changes in bird abundance were substantial, those of bird species richness were not, indicating that bird species tended to reach maximum abundance in bird communities. When compared to bird abundance in 2015, the number of individuals was relatively stable in other years of investigation, and the number of investigated species was the highest in 2017. Finally, monthly changes in bird species were in accordance with the annual rhythms of migration. Specifically, bird species richness increased rapidly during the wintering period, but remained constant during the breeding period. In addition, the migration time of waterbirds tended to increase over time. This may be related to a warming climate that prompts birds to migrate earlier. Differences in habitat patches are important influencers of bird feeding habits, and thus bird distribution and habitat. Among the habitat patches investigated, birds were primarily distributed in shallow tidal flats with rich food sources and in tall and lush mangrove communities, such as those containing the species Sonneratia apetala. Notably, the number of Platalea minor, a key indicator bird species, has increased steadily, with an increase of 346.15% from 26 in 2014 to 116 in 2018. The annual and monthly dynamic changes of birds in different areas showed subtle changes in individual numbers but generally showed a stable trend, which may be related to the environmental capacity of the habitat. The number of species and individuals that can be sustained by the environment tended to be saturated; that is, the maximum number of species that can be accommodated by the Nansha Wetland Park. Taken together, these findings suggest that bird species diversity could be promoted by expanding the area of tidal flats, increasing the planting area of mangroves, reasonably reclaiming wetlands, and maintaining the proportion of shallow water tidal flats and mangroves.

Key words: Nansha Wetland Park, avian community, biodiversity, migration patterns, habitat selection