Abstract
Along the East Asian-Australasian flyway (EAAF), waterbirds are threatened by a wide range of human activities. Studies have shown that wintering populations of many species have declined in Australia and Japan; however, long term data along China’s coast are limited. In this study, we analyzed data collected from monthly bird surveys to quantify population trends of wintering waterbirds from 1998 to 2017 in the Deep Bay area, South China. Of the 42 species studied, 12 declined, while nine increased significantly. Phylogenetic comparative analysis revealed that population trends were negatively correlated to reliance on the Yellow Sea and body size. Further, waterbird species breeding in Southern Siberia declined more than those breeding in East Asia. These findings, coupled with a relatively high number of increasing species, support the continual preservation of wetlands in the Deep Bay area. This study provides another case study showing that data collected from wintering sites provide insights on the threats along migratory pathway and inform conservation actions. As such, we encourage population surveys in the EAAF to continue, particularly along the coast of China.
Highlights
Studying population trends of threatened species to identify drivers of population change is crucial for conservation
We identified species traits of waterbirds that correlated with their population trends, which shed light on the threats they experience across their breeding, migratory, and wintering grounds
We found that species that rely on the Yellow Sea declined more than other species, which agrees to previous studies along the East Asian-Australasian flyway (EAAF) (Amano et al, 2010; Clemens et al, 2016)
Summary
Studying population trends of threatened species to identify drivers of population change is crucial for conservation. Many waterbird species travel across hemispheres annually, and their populations can be impacted by a wide range of environmental and anthropogenic factors in breeding grounds, stopover sites, and wintering grounds (Amano et al, 2010; Catry et al, 2013; Clemens et al, 2016; Howard et al, 2020). Waterbirds of the EAAF experience a wide range of other threats (Wang et al, 2018), including hunting (Gallo-Cajiao et al, 2020), alien invasive species (Gan et al, 2009), pollution (Zhao et al, 2016), and climate change (Iwamura et al, 2013; Wikramanayake et al, 2020)
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