Prey availability is a crucial factor for the reproductive success of apex predators and the analysis of their dietscan provide meaningful information about the quality of their habitats. In Sicily the declining lanner falcon Falcobiarmicus feldeggii and the increasing peregrine falcon Falco peregrines brookei share similar habitats and trophicneeds. By studying their current and past diets, we have investigated whether the characteristics of their foragingecology could explain these different demographic trends. In 2014-2016, we identified 805 peregrine and 250lanner Vertebrate prey from 15 peregrine and 6 lanner nests, and compared our dataset with previous data fromSicily (Peregrine 1978-81; Lanner 1981-88). The average number of Vertebrate prey in peregrine nests (53,7 ± 28,7) was higher than in lanner nests (42,0 ± 25,6). Expectedly, peregrine preyed exclusively upon birds, while lanner upon birds (92,9%), small mammals (4%), and reptiles (2,4%). Orioles and common swifts were significantprey for the former, while the european rabbit was important for the latter in terms of biomass. Pigeons, starlingsand magpies formed the majority of prey for both species, and collared dove, previously absent in Sicily, appearsin their current diet. The average avian prey was smaller for peregrine (97,7 g) than for lanner (122,5 g). Overdecades, the lanner richness of prey species (S) decreased (from 55 to 33) while the one of peregrine increased(from 38 to 63). Alfa-diversity index showed a similar figure, while dominance as expressed by the Simpson index(1-D) was lower in present lanner diet (0,83) than in past lanner, as well as in past and present peregrine diets (allindexes >0,90). Trophic niche overlap between the past and present datasets is medium according to Whittaker'sindex (0,44 peregrine; 0,48 lanner; 0,42 peregrine/lanner past; 0,48 peregrine/lanner present). Lanner preyed alsoon insects in both periods, with considerable differences (npast = 341 and ncurrent = 2) which can be attributed todifferent seasons of data collection. The two predators are responding to variations in habitats and preypopulations; however the more aerial-hunting peregrine, demonstrates to be flexible and more successfullyadapted to the alteration of traditional agro-ecosystems.
|Number of pages||2|
|Publication status||Published - 2017|