Abstracts

Presented by Brian Davis - Email: brian.davis@msstate.edu

Scaup (Aythya spp.) are collectively the most abundant diving duck in North America. While their typical diet is composed mainly of invertebrates, migrating populations within the Mississippi flyway have been reported consuming large quantities of bait- and sportfish produced at aquaculture facilities, particularly in Arkansas. However, it is not well understood how scaup use these relatively new habitats provided by aquaculture or to what extent human-wildlife conflict exists. The objectives of our study were to investigate the foraging ecology and abundance of scaup using aquaculture facilities in Arkansas, and to estimate the total amount of bait- and sportfish consumed annually. During winters 2016-2017 and 2017-2018, we collected 529 lesser scaup and 19 greater scaup foraging on aquaculture ponds used to produce a variety of fish species. Using permutational multivariate analyses of variance, we detected significant differences in lesser scaup diets between winters and weather temperature categories. Specifically, fish did not appear in lesser scaup diets in winter 2016-2017, whereas fish comprised 18% of their diet in the colder, 2017-2018, winter. Chironomidae was the most common prey item found in lesser scaup, comprising 71% of their diet in winter 2016-2017 and 40% in winter 2017-2018. Additionally, we conducted 1,458 individual pond surveys between the two winters and created abundance models using polynomial regression to calculate total scaup use-days (SUDs) within our survey area and estimated total fish loss. During winter 2017-2018, our model predicted approximately 875,000 SUDs, resulting in an estimated 59,700 kg of fish consumed by scaup. We suspect that scaup increasingly exploit fish in colder winters because of birds increased energy demands, prey availability and ease of capture, or some combination of these. Although we cannot fully reconcile these nutrition and behavioral mechanisms at this time, scaup can inflict substantial losses on producers in some instances.