Waterbird diversity and abundance in response to variations in climate in the Liaohe Estuary, China

Birds are sensitive to environmental change and thus good indicators of biodiversity and ecosystem health. Because birds fill a variety of functional roles, understanding their diversity patterns is important to inform and support conservation management. This study focused on the diversity and abundance of waterbirds occupying the Liaohe Estuary, an internationally important habitat, and migratory stopover in northeast China. Analyzing data from 42 monitoring stations/transects collected over ten years, we determined the seasonal abundance and distribution of waterbirds throughout the estuary and surrounding lands and looked for associations with climatic data shown to influence bird populations. Results showed that although global populations of waterbirds are decreasing, bird abundance, richness, and alpha diversity increased in the Liaohe Estuary during our 10- year study. Distinct annual patterns of species distribution were detected during spring and autumn with population lower in spring than autumn. Analyses with non-metric multidimensional scaling (NMS) showed that spring populations had a strong and positive relationship to temperature variables including spring mean temperature and cumulative temperature days. There was a clear distribution of waterbird species along the axis of the spring temperature range and precipitation. Whereas in autumn, waterbird populations had a strong and negative relationship to precipitation variables including annual precipitation, autumn precipitation, and autumn maximum precipitation. These findings indicate that waterbird diversity in this region and others may be responsive to climate change, especially in spring season. We discuss the ramifications of these shifts in terms of future utilization of the estuary by waterbirds in the region. We project that as temperatures continue to warm and precipitation decreases, there may be increasing migratory stopover and breeding in the Liaohe Estuary and thus populations may continue to increase in the future.