Annual cycle in body mass and organ size in long-tailed duck Clangula hyemalis
LE3 .A278 2016
Bachelor of Science
Organ use varies throughout the annual cycle of various organisms. Tradeoffs between functional importance and cost of organ maintenance therefore change at different time periods. Many migratory birds have cycles of atrophy and hypertrophy in different organs to accommodate these tradeoffs, thereby adjusting nutrient allocation to tissues to match their energetic needs. These cycles have not been studied yet in long-tailed ducks (Clangula hyemalis). This study focused on adjustments in organ size and body mass during three distinct time periods in the lifecycle of long-tailed ducks: pre-breeding, breeding, and migration. Over 150 long-tailed ducks were collected at several Canadian field locations over a period of three years, and from those carcasses I conducted dissections, recorded body mass and the size of hearts, gizzards, and livers. Results indicate that overall body mass increases over the year, heart size does not change, and liver and gizzard atrophy during breeding and hypertrophy during migration. Patterns were similar for females and males. This study provides support for the hypothesis that adjustment of organ size throughout the annual cycle is an adaptive trait exhibited by long-tailed ducks.
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