Impact of weather on breeding success of the Eurasian Kestrel Falco tinnunculus in a semi-arid island habitat

In semi-arid ecosystems, rainfall and temperature induce changes in the food chain and affect breeding conditions of raptors. We examined the influence of rainfall and temperature on the breeding success of the Eurasian Kestrel Falco tinnunculus inhabiting xerophytic scrub on Tenerife Island, Canary Archipelago. Reproductive performance was recorded during five years, and food availability (arthropods, lizards, mice and birds) was monitored monthly during a wet and a dry breeding season. We found that increased rainfall in the previous autumn was associated with an earlier laying date and a more prolonged breeding season. Mean clutch size showed a positive correlation with rainfall in the month prior to laying. Hatching and fledgling success did not vary significantly between a wet and a dry year. Temperature did not influence breeding parameters. Despite the advanced laying date and larger clutch size observed, high prey availability during egg formation in the wet year did not result in higher overall breeding success. Stable between-year number of fledglings coincided with stable prey availability during the nestling or fledgling periods. Food conditions in the dry year were more stable and attuned to harsh weather conditions regardless of rainfall during the previous autumn and pre-breeding period.