Wintering waterbirds in the middle and lower Yangtze River floodplain: changes in abundance and distribution

Abstract

SummaryThe middle and lower Yangtze River floodplain is a globally important wintering area for waterbirds in the East Asian-Australasian Flyway. Ornithologists have reported on wintering waterbirds in the floodplain since the 1950s. However, an integrated analysis of the long-term changes in waterbird diversity is not available. Here, we synthesise existing information on changes in wintering waterbird abundance and distribution in the floodplain, summarise possible influencing factors and propose some priorities for further research. Waterbird richness and abundance have declined over the past 60 years. Declining trends have been observed in a number of areas and species. Nevertheless, a few areas and species showed different trends. In addition, waterbirds have become more concentrated in a few suitable areas such as Poyang Lake and Dongting Lake. Land reclamation, hunting, dam operation and extensive aquaculture are probably the four major threats to wintering waterbirds, while establishment of nature reserves is beneficial to waterbird conservation. Our study suggests that waterbirds in the floodplain are vulnerable, and that effective conservation measures are needed to protect and restore the waterbird diversity of this area.

Seasonal Water Exchanges between China’s Poyang Lake and Its Saucer-Shaped Depressions on River Deltas

“…Second, the construction of sluices between the lake and the depressions will inevitably lead to substantial changes in water regimes and hydrological connectivity. Especially, the fishing method "Lake Enclosed in Autumn" is unique and commonly used in the Poyang Lake; the method involves constructing an embankment around the depressions [23,33]. Local fishermen often release water from the depressions to catch as many fish as possible during the low-water season.…”

“…As water flows into the depressions, it carries sediment and nutrients, the differences in the connection of shallow depressions with the main lake should determine the distribution of nutrients and habitat diversity in the floodplain. It has been shown that numerous waterfowl and fish species use depressions for spawning nursery and foraging habitats in Poyang Lake [33]. The changing patterns of the connectivity degree can largely determine habitat diversity and the availability of foraging sites for fish stocks and migratory birds.…”

Population trends, threats, and conservation recommendations for waterbirds in China

“…Some studies have exhibited diverse threats to waterbirds inland. For example, damming along rivers have changed hydrological condition of both river and lakes, aquaculture in lakes have caused a decrease of vegetable food for waterbirds, and illegal hunting is not uncommon in lakes (see review of Wang et al 2017). Moreover, the similar proportion of population decline between the migratory and resident species (both nearly one third population declined, higher than the global average of 23%) suggests that migratory birds suffered serious threats during their life history periods in China, as those resident birds that stay in China during their entire life history.…”

“…China's extensive wetlands support large numbers of waterbirds. For example, coastal wetlands in China provide critical stopover sites for millions of migratory shorebirds along the East Asian-Australasian flyway (Barter 2002;Bai et al 2015); Lakes in the middle and lower reaches of the Yangtze River are the largest nonbreeding region for waterbirds in East Asia (Cao and Wong 2007;Wang et al 2017). Swamps and lakes in northern China provide breeding sites for diverse waterbirds such as cranes, gulls, ducks, and geese (Chen and Ding 2008).…”

“…Waterbird conservation suffered increasing pressure from many aspects. For example, wetland reclamation and exploitation in large scale and high intensity have caused dramatic habitat loss and degradation (Yang et al 2011;Ma et al 2014;Wang et al 2017). Illegal hunting for waterbirds is not uncommon in both coastal and inland regions (Ma et al 2012;Wang et al 2017).…”