The Effects of Sex, Age, Time, Habitat, and Management on Body Condition of Wintering Duck Populations on the Texas Gulf Coast

Waterfowl are of significant cultural, economic, and conservation importance along the Texas Gulf coast. Millions of ducks utilize this region as they move along the Central Flyway each winter. Understanding of body condition patterns for these birds and their relationships with habitat management techniques has important implications for recruitment, breeding success, and population regulation. This is especially true for females, which are typically the limiting sex in ducks, and juveniles, which are critical for recruitment. In this study, we collaborated with hunters over two years to salvage over 1800 of the most popularly hunted dabbling duck species along the Texas Gulf coast and interviewed managers to document habitat type and management techniques. Mass, linear measures, and fat scores were collected along with sex and age of each individual. We found that females were typically in better body condition than males, especially at the beginning of the hunting season. Body condition differed between immatures and adults, although the direction of that difference was year-dependent. Ducks generally declined in body condition across the winter hunting season and body condition was typically higher in the year 2017-18 than 2018-19. Body condition differences by habitat type and in relation to management intensity were species-dependent, but these factors were important predictors of body condition for the majority of species. Our results suggest that wintering female and immature dabbling ducks are doing well in comparison to their counterparts (i.e. males and adults), but that sex- and age-specific differences in relation to yearly precipitation patterns, habitat, and management intensity suggest differential responses to resource availability. Future research should explore sex- and age-specific foraging patterns and habitat usage on the wintering grounds