Abstracts

Presented by Aaron Pearse - Email: apearse@usgs.gov

The Nebraska Sandhills can attract hundreds of thousands of nesting duck pairs annually. Yet, a limited number of studies conducted in this region have reported low recruitment potential. Biologists monitored duck nests at Crescent Lake National Wildlife Refuge in the southwestern Sandhills for >2 decades. We summarized this unique time series and modeled temporal variation in nest survival of upland-nesting ducks. Nests from 5 species were found, with blue-winged teal (Spatula discors) as the most common species. Annual variation in nest survival was considerable during 1991-2018, ranging between 2% and 22% and averaging 8% (SD=5). Annual variation correlated with temporally varying environmental factors such as changes in wetland conditions, comparable to results from studies in the Prairie Pothole Region. Average and maximum nest survival was lower than estimated in the PPR, with predator community differences the likely mechanism. Bullsnakes (Pituophis catenifer) are present and known to eat duck eggs; therefore, grassland management that reduces abundance of larger snakes could have a positive effect on nest survival in this region. Under certain conditions the Nebraska Sandhills can recruit ducks at rates comparable to the PPR with annual variation affected by similar environmental factors. These results further support the notion that annual fluctuations in precipitation patterns affect predator communities which, in turn, influences recruitment potential of upland-nesting ducks.