AUTHORS: Benjamin Sullender*, University of Wisconsin-Madison and Audubon Alaska; Jeb Barzen, International Crane Foundation and Private Lands Conservation LLC; Janet Silbernagel, University of Wisconsin-Madison
ABSTRACT: Seasonal inundation drives productivity in flood pulse ecosystems such as Poyang Lake. Summer hydrological connectivity promotes biological productivity, but the time-lags between productivity and habitat use by migratory wildlife make it difficult to assess the role of flooding solely through within-season observations. Especially as human-caused alterations threaten Poyang Lake’s natural flow regimes, it is essential to identify the ecological importance of flooding. We used a series of scan and focal sampling techniques coupled with spatial analysis of long-term observation datasets to define suitable habitat for Eurasian Spoonbills (Platalea leucorodia) and determine inter-annual relationships between hydrology and habitat use. We developed a metric of summer connectivity using satellite imagery and field measurements to estimate the number of days in which summer overbank flow connected adjacent sub-lakes. We next constructed a series of regression models comparing habitat use across years with different levels of connectivity. Our results indicate clear foraging preferences, particularly in years with normal connectivity. In years with below-average and above-average summer connectivity, the relationship between spoonbill abundance and habitat extent becomes uncoupled. These results suggest that seasonal flood pulses have an important role in structuring Eurasian Spoonbill foraging habitat, and the duration of summer connectivity alters foraging conditions in the following winter.