THE CONDITION OF BEWICK SWANS CYGNUS-COLUMBIANUS-BEWICKII IN WINTER AS ASSESSED BY THEIR ABDOMINAL PROFILES

An Abdominal Profile (AP) scale was developed to assess body condition of Bewick's Swans in the field. Change in AP score for individual bir ds correlated significantly with change in their body mass; moreover A P was significantly correlated with condition indices that were design ed to remove the potential confounding effects of variation in size be tween individuals. This demonstrates, for the first time, that mass ca n be predicted from AP. There was considerable overlap between the val ues of adjacent profiles however, indicating that predictions for sing le birds may not be very precise. Generalised linear models were used to examine the variation in AP between birds; variables which statisti cally accounted for some of the variation included month, year, sex, s tatus, dominance-rank and the multiple effects of month x year, and mo nth x status. Females had significantly higher AP scores than males th roughout the winter. The effect of social dominance upon AP was opposi te for the two sexes; low-ranking single males had higher AP scores th an higher-ranking paired males, whilst low-ranking single females had lower AP scores than higher-ranking paired females.