Seasonal variation in weight, body measurements and condition of free-living Teal

Abstract

The weights and measurements of almost 7000 Teal captured in Abberton Reservoir, Essex during 1969–85 were analysed. Teal showed significant differences between the first year and adult birds and between males and females in tarsus and wing length, but significant differences only between the sexes in skull length. Weights were corrected for body size using wing length to give a condition index. The index of condition increased in all age and sex classes from September to reach maximum values late in the year, before falling to lowest levels in February. Female birds show more marked responses by the reduction in January condition index to hard weather than males and, indeed, the proportion of females caught at Abberton significantly declines with increasing severity of weather conditions. The significance of these sex related responses are discussed in the light of known features of the ecology of the species.