Extreme drought decreases waterbird biodiversity in floodplain wetlands

Floodplain wetlands are crucial for waterbird survival and reproduction. Droughts can significantly reduce food availability and habitat quality for waterbirds, leading to a decline in their abundance and diversity. The aim of this study was to assess the impact of extreme drought on waterbird populations in Dongting Lake by analyzing alterations in hydrological, vegetation, and land use variables. We conducted waterbird surveys (2018–2023) and collected habitat data over six years to determine the effects of extreme drought on waterbird conservation. Key environmental factors influencing waterbird feeding guilds were identified, and their effects were analyzed across normal, extreme drought, and flood years. The results indicated that the Normalized Difference Water Index and water recession depth are critical hydrological variables that influence waterbird abundance. During extreme drought years, high-temperature vegetation dryness index values led to significant habitat and resource shortages, challenging waterbird survival. During normal and flood years, waterbird populations can partially buffered moderate drought effects by adjusting their foraging strategies and habitat selection. The temperature vegetation dryness index affected waterbird feeding guilds through multiple ecological pathways by altering habitat and water quality. This study also examined how environmental factors affected migratory bird guilds. These findings provide valuable insights into the spatial distribution of overwintering waterbirds and inform conservation efforts involving wetland ecosystems, highlighting the necessity for adaptive water management strategies to mitigate the adverse effects of drought and hydrological changes on waterbird populations.