Food Supply and External Cues Limit the Clutch Size and Hatchability in the White Stork Ciconia ciconia
2008
Djerdali, Sofia | Tortosa, Francisco S. | Hillström, Lars | Doumandji, Salaheddine
Clutch size is an important life history trait, and factors such as nest predation and food availability can both be of crucial importance for its variation in nature. The aim of the present study was to evaluate the effects of extra food on clutch size, laying date and hatching success in the White Stork. Three different colonies of White Storks were studied in northern Algeria over a three-year period (2002––2004) that was characterised by considerable variation in both food availability and precipitation. This study demonstrated that an extra food supply during the pre-laying period had a positive effect on clutch size - nests with extra food had larger clutches. There was also an advance in laying date and a greater hatching success in nests with access to extra food. In addition to food supply, clutch size was independently affected by the year, which could have been due to differences in rainfall. Furthermore, the results of this study suggest that extra food during the incubation period could help the parent birds resolve the conflict between incubation behaviour and minimizing the time off the nest, i.e. increasing nest attentiveness in nests with extra food and enhancing hatching success.
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