Effects of rainfall and temperature on timing and breeding performances of a threatened large falcon: case study of the lanner falcon ( Falco biarmicus feldeggii ) in Italy

The use of environmental cues such as temperature and rainfall for the timing of breeding and as an indicator of plentiful food much later in the season is thought to have a great influence on breeding success and productivity rates. We tried to assess effects of such cues on timing and performance of the lanner falcon ( Falco biarmicus feldeggii ), a threatened large falcon in Italy. We ascertained success and productivity of 178 breeding attempts in 38 breeding sites distributed in central Eastern Sicily and along the Apennine peninsula. In Sicily alone, we checked each nest annually to ascertain the number and age of chicks and also post-hatching mortality. We overlaid nest locations in order to add attributes of temperature and rainfall for each month and year. Breeding populations from Sicily to the Apennine peninsula showed no significant difference in all breeding parameters except distribution of brood size. Annually, breeding pairs tried to synchronize the hatching in a precise favourable period that increased nestling survival. February rainfall was the main abiotic factor that greatly influenced all lanner falcon reproductive parameters with a positive effect as cues for breeding decisions by parents. Conversely, intense rainfall caused nesting failure through a delay in laying dates. Our study confirmed the importance of environmental cues such as temperature and rainfall on breeding decisions by lanner falcon pairs inhabiting the whole Italian territory. We discuss our results and compare them with prior studies in terms of their potential conservation implications for this threatened subspecies.