External sexing and ageing techniques and population structure of the European starling (Sturnus Vulgaris Vulgaris L.)

External sexing and ageing criteria, and the population structure of the European Starling (Sturnus vulgaris vulgaris L.) were studied in Kings County, Nova Scotia during the winter of 1978-'79. Ramus colour, when distinguishable, was 100% accurate in sexing starlings but was only applicable to 22.8% of 566 birds. A discriminant function analysis combining iris ring and hackle iridescence length resulted in 93.8% of the birds being sexed correctly compared to an accuracy of 85.6% by iris ring only. Ninety-seven per cent of 346 known-age starlings were aged reliably by hackle iridescence length and rectrix shape; this is in contrast to an accuracy of 95.6% by the application of hackle iridescence length alone. Iridescence measurements used in ageing by previous researchers appear unsatisfactory.