Some aspects of Chaffinch Fringilla coelebs biology, based on an analysis of individuals ringed during 1991 to 2003 in Norfolk, England.

Abstract

From 1991 to 2003, 2,954 Chaffinches Fringilla coelebs were caught and ringed, year-round, at Hilborough, Norfolk, England. The age and sex composition of Chaffinches varied between winters, but no systematic pattern was apparent. The age and sex composition of Chaffinches caught during winter did not vary significantly from that of Chaffinches caught during the breeding season. Chaffinch wing lengths and body weights did not vary significantly between seasons. Male Chaffinches had wings that were on average 6 mm longer than females and adult wings were on average 2-3 mm longer than immatures and juveniles. Male Chaffinches were on average 2 g heavier than females, Approximately 40% of Juvenile Chaffinches retained unmoulted greater coverts after their post juvenile moult, retaining 1.47 ± 0.04 and 1.67 ± 0,09 for males and females respectively, Compared to immature females, twice as many immature males retained juvenile greater coverts. Over the period of study, Chaffinches showed relatively consistent annual productivity, with captures of between 1.5 and 2 times as many juveniles or immatures as adults during the months following the breeding season. The higher productivity in some years was not explained by variations in average monthly temperature during the breeding season. The mean duration between initial and final capture on the study site was between 1.6 and 2.3 years, and the longest period between initial capture and last recapture was over ten years. Only 0.14% of Chaffinches were recorded moving distances greater than 5 km from the site of capture, confirming the sedentary nature of the species. This study shows that few, if any, continental immigrants supplement the local Chaffinch population at the study site in Norfolk.