Abstract
This study focuses on how avian migration is facilitated by changes in organismal metabolism, muscle structure, and muscle metabolism. These specific migratory changes were examined across the annual cycle on‐an organismal level by investigating whole body oxidative capacity (ability to use energy) and, on a tissue level by characterizing muscle tissue size and oxidative capacity. In order to quantify whole body oxidative capacity, summit metabolism was measured to determine the peak oxygen consumed by each individual. Birds were euthanized and the pectoralis (flight muscle) and gastrocnemius (leg muscle) were removed and weighed. Mitochondrial content of the muscle was quantified by measuring enzyme activity via citrate synthase and cytochrome oxidase assays to determine oxidative capacity of the muscles. Summit metabolism and flight muscle mass were greatest during southward migration compared to temperate breeding and tropical wintering. The Gray Catbird displays phenotypic plasticity during migration compared to non‐migratory periods suggesting that augmentation of the flight muscle and increased metabolism are necessary for migration.Grant Funding Source: Supported by NSF #IOS‐1257455 to PJS
Published Version
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