Variation in breeding plumage, and relation to body condition, of Curlew Sandpipers Calidris ferruginea in Sivash, Ukraine

During northwards migration through Sivash, Ukraine, in the middle of May, 91% of males and 58% of females were in complete breeding plumage. Previously undescribed variations in the breeding plumages of male and female Curlew Sandpipers were examined in relation to body condition. “Pale” males were in better condition than “dark” males; in females this difference was in the opposite direction but was not statistically significant. The results suggest that the accumulation of energy reserves for migration to the breeding grounds is first priority, and development of a darker plumage is second. Questions that arise need to be resolved on the breeding grounds.