Most ducks feed exclusively on foods high in protein (macroinvertebrates) during the breeding period and exclusively on foods high in carbohydrates (grains) during fall and winter. There is little information, however, regarding when ducks make the transition from selecting a diet high in carbohydrates to selecting a diet high in protein. Furthermore, there is little data to determine how the timing of this transition may vary among species with differing ecological adaptations. To better understand when ducks make the diet transition and how it differs among species, I am collecting mallards, gadwalls, ring-necked ducks, scaup, and blue-winged teal at 3 latitudes during different stages of spring migration. I will use esophageal contents from each duck to compare the diet of ducks to availability of food from selected and potential feeding sites to determine if the transition in selection of food types occurs during the spring migratory period. Data from this study will be used in a bioenergetics model to set habitat objectives for spring migratory ducks.
