Sexual differences in physical condition in the White-backed Woodpecker Dendrocopos leucotos

Abstract

Body-mass and wing-length of adult White-backed Woodpeckers Dendrocopos leucotos were measured in 57 males and 55 females in Surnadal community in western Norway during November-June from 1985 to 2001. The mean physical condition (ratio bodymass : wing length) of reproducing females in coastal areas was better than of females in inland areas. The physical condition of males was higher than that of females in each month. The mean condition of males was relatively stable during January-June, whereas that of females worsened slightly in the same period. The mean condition of females caught during March-April (just before egg laying) showed positive correlation with the mean temperature in January and February, whereas that of males did not.