Abstract
The timing of breeding and nest location in colonial birds may have fitness consequences. In particular, it has been demonstrated that peripheral breeders perform less well than core breeders. To determine whether environmental factors such as date of breeding and nest position influence reproductive success, we studied the breeding ecology of a large colony of White Stork Ciconia ciconia at Dréan, northeast Algeria, during 2011 and 2012. Mean egg-laying dates varied significantly between years and differed between core and peripheral nests with more precocious laying occurring in the center. Egg-laying in larger nests started earlier than in smaller ones in the core area but neither nest size nor nest position along the core-periphery gradient had any influence on studied breeding parameters i.e. clutch size, hatching success and chick productivity. There was no yearly difference in clutch size which averaged 4.7 ± 0.7 eggs (N = 156 clutches). Mean chick productivity was higher in 2012 (2.85 ± 1.21 chicks) than in 2011 (2.29 ± 2.28 chicks) and was marginally associated with egg-laying date. In contrast, nesting success declined with delayed onset of breeding. Results suggest that a low predation rate, abundant resources and a possible trade-off between fitness components may confound adaptive breeding-habitat selection in White Stork.