Breeding biology and nest characteristics of the Eurasian Kestrel in different environments on an Atlantic island

Abstrakti

We studied reproductive parameters, nest-site characteristics and breeding success of the Eurasian Kestrel (Falco tinnunculus canariensis) on Tenerife Island, Canary Archipel- ago. Kestrels typically breed in cliffs cavities (79.4%), and were present in all habitats from sea level to 2,400 m, except in shrubby heaths (rich in Myrica faya and Erica arborea) and laurel forests. The breeding cycle was variable and dependent on altitude. Mean laying date for the island was 21 March and we found a significant delay of 31 ± 7 days in mean laying dates in habitats above 1,000 masl, probably due to weather condi- tions. No interannual differences were found in mean laying dates between habitats. We found no differences in clutch size (mean 4.41, n = 133) between habitats or altitude. Lay- ing date and mean clutch size were correlated under 1,000 masl. Mean brood size at hatch- ing was 3.48 (n = 124). Mean brood size at fledging was 2.99 (n = 124) with no differences between habitats or years. Our results suggest that the stability of the island habitats of Tenerife favours stability of reproductive parameters between years.