Optimizing the timing of water level recession for conservation of wintering geese in Dongting Lake, China

Habitat suitability and selection are key concepts in wildlife management, especially in protection of critical habitat and conservation of sensitive and endangered populations. In recent years, many approaches have been developed to link habitat suitability with animal occurrence and abundance. These approaches typically involve identifying existing habitats, defining habitat quality metrics, and estimating the association between animal occurrence/abundance and measured habitat metrics. In this study, we first tested whether we could measure habitat quality at Dongting Lake, China, one of the most important migratory waterbird wintering sites in the East Asian Flyway, for a group of Anatidae using metrics derived from the freely available multi-temporal MODIS vegetation index. The results showed that goose counts could be sufficiently modelled using mean winter season EVI (enhanced vegetation index) and habitat size computed from EVI time series and topographic wetness index (TWI). We then quantified the relationships between hydrological regimes and the habitat quality metrics. Our findings suggested that the timing of optimal water draw down should be early to mid October to ensure quality food sources for the wintering geese in Dongting Lake. The results have direct conservation implications as water recession timing is highly manageable through water flow regulation.