Evaluation of Regression Methods to Estimate Nutritional Condition of Canvasbacksand Other Water Birds

摘要

Regression equations that use mensural data to estimate body condition (i.e., thegeneral health of a bird based on body reserves of fat or protein) have been developed for several water birds. These equations often have been based on data that represent different sexes, age classes, or seasons, without being adequately tested for intergroup differences. When compared to methods using total fat or moisture content, mensural equations frequently provide poor fits to measures of condition, or use body measurements that do not appreciably increase a model's precision. The authors used proximate carcass analysis of 538 adult and juvenile canvasbacks (Aythya valisineria) collected during fall migration, winter, and spring migrations in 1975-76 and 1982-85 to test regression methods for estimating body condition.