Duck Non-Breeding Body Condition Differs by Sex, Age, and Year on the Texas Mid-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 body condition patterns for these birds has important implications for overwinter survival, breeding success, and population regulation. This is especially true for females, which are typically the limiting sex in ducks. Herein, we an- alyze sex- and age-specific differences in body condition of non-breeding dabbling ducks over the winter hunting season in coastal Texas. We collab- orated with hunters over two winters to salvage, weigh, and measure 1255 dabbling ducks, including blue-winged teal (Spatula discors), green-winged teal (Anas crecca), northern shoveler (Spatula clypeata), gadwall (Mareca strepera), and northern pintail (Anas acuta). Using a modern body condition index calculation, we found that females were in better body condition than males for four of the five species studied (i.e., blue-winged teal, northern shoveler, gadwall, and green-winged teal), although this effect depended on year for green-winged teal. Body condition differed between immatures and adults, although the direction of that difference varied between the two winters. Ducks generally declined in body condition across the winter hunt- ing season and body condition was typically higher in 2017–2018 than 2018–2019. Yearly differences in body condition may be due to major differences in precipitation, with our results suggesting differential responses by sex, age class, and species to increased availability of temporary habitats when precipitation was greater.

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