Carotenoids in the eggs of american coots: associations with size of eggs, local environment, and diet

American Coot (Fulica americana) Science Article 9


I studied carotenoids in the eggs of American coots (Fulica americana) from 3 study sites in Saskatchewan, Canada. I supplemented two diet types designed to reduce
carotenoids in the diet of laying coots to investigate the relationship of carotenoids and the size of eggs and to examine the allocation of carotenoids into eggs. In chapter 2, I examined influences of local environment, food quantity and food quality on egg size. Carotenoid content and stable nitrogen and carbon isotopes in yolk
were measured and used to elucidate whether variation in type of food eaten contributes to egg size. By analyzing isotopes in coot tissues, I confirmed that coots use
endogenous lipid reserves for egg formation but not endogenous protein reserves, and the size of eggs is more dependent on exogenous sources of nutrients. My data
demonstrate that carotenoids are not causal in egg size, but are components of natural, high quality diets

USNE J. BUTT, Department of Biology University of Saskatchewan Saskatoon, 2005

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