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David Butler

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Using light-level geolocators to measure breeding propensity of mottled ducks in the Western Gulf Coast
Of the vital rates that determine recruitment, breeding propensity (i.e., the proportion of females that lay at least one egg) and nest success appear to have the greatest influence, but breeding propensity remains poorly studied. The few studies that have been conducted reveal it to be highly variable among years (15–77%), likely in response to environmental conditions (e.g., precipitation and wetland availability), and lower than estimates from other dabbling ducks. Thus, quantifying breeding propensity across the mottled duck range in the WGC and identifying factors responsible for its variation remain high priorities for future investigation. Breeding propensity is also among the most difficult vital rates to...
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The Western Gulf Coast (WGC) is home to approximately 90% of the worldwide population of mottled ducks (Anas fulvigula), a non-migratory species that must satisfy its annual cycle needs within a small geographic range. Available population data suggest the WGC mottled duck population has experienced a slight to moderate decline across its range since 1985 (Gulf Coast Joint Venture [GCJV] Mottled Duck Working Group, Unpublished report). Because of its population status and reliance on a restricted geography, the mottled duck has been identified as a focal species for the U.S. Fish and Wildlife Service, a priority species in Texas and Louisiana Comprehensive Wildlife Conservation Plans, and the subject of targeted...
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