BODY-MASS AND CARCASS COMPOSITION OF FALL MIGRANT OLDSQUAWS

We investigated body and organ mass and carcass composition of twenty- seven migrant Oldsquaws (Clangula hyemalis) killed when they collided with power transmission lines in northeastern Ontario in October 1986. Comparison of the first principal component (PC1) from eight structur al measurements indicated that adult male Oldsquaws were structurally larger than females; however, organ weights did not differ between sex es when PC1 was included as a covariate (ANCOVA, P > 0.05 in all cases ). Carcass composition was similar to that reported for spring migrant s. Ash-free lean dry weight (AFLDW) and ash were positively related to structural size, but did not differ between sexes when PC1 was includ ed as a covariate. Lipids comprised 17.5% of whole body mass of female s and 14.1% of males and were sufficient to fuel migration at least to the next likely staging area in the Great Lakes, Fall migrant Oldsqua ws must have stored substantial lipid and protein reserves after breed ing, suggesting that offshore feeding areas in James and Hudson Bay ar e critical.