Reproductive consequences of early arrival at breeding grounds in the White Stork Ciconia ciconia

CapsuleThe phenology of arrival at the breeding grounds and reproductive output of White Storks were studied in central Poland between 2000 and 2011. Although, in general, there was a strong negative relationship between the number of fledglings raised and arrival date, pairs in which both partners arrived at breeding grounds very early in spring (before 5 April) reared lower number of fledglings in comparison to pairs that arrived slightly later (between 5 and 14 April). In the studied population, the negative reproductive effects of exceptionally early arrival were associated with higher probability of entire brood loss. The probability of brood loss in pairs that arrived before 5 April was estimated at 0.22, which decreased to 0.10 in pairs that arrived between 5 and 14 April.