New is not always better: low breeding success and different occupancy patterns in newly built nests of a long-lived species, the white stork Ciconia ciconia

Abstract

Capsule An increase in new nest building in a white stork population revealed that they were built further from human settlement and on non-typical structures; such nests had lower breeding success resulting from later breeding. Aim To determine why some birds build new nests rather than occupy older ones, and how new nests affect breeding performance compared to old nests, in a long-lived bird, the white stork. Methods We compared new nest construction in 2010 with a long-term data set on white stork in Western Poland from 1974 to 2009. For data from 2010, we analysed nest location and breeding biology in detail. Results Since 1974, the proportion of new build nests was ca. 1.6%; in 2010 this was 13.2%. Pairs in new nests bred later than pairs in old, and had smaller clutches and lower breeding success. New nests were located further from settlements and tended to be built on different structures. A significantly lower proportion of new nests were re-occupied in subsequent years. Conclusions Pairs may build new nests to gain experience in nest building, cooperation and foraging for subsequent seasons or because of competitive pressure when the environment is close to carrying capacity. Breeding success can be initially very low.