Climate determinants of breeding and wintering ranges of lesser kestrels in Italy and predicted impacts of climate change

Climate warming would theoretically create conditions for the breeding range expansion of pseudo-steppe Mediterranean and long-distance migrant species and provide the possibility for these to overwinter in the same breeding areas. However, contemporary changes in rainfall regimes might have negative effects on the climate suitability and in turn, shrink species potential range. The lesser kestrel, Falco naumanni, is highly sensitive to rainfall oscillations and has recently extended its Italian breeding range towards northern latitudes and increasing its wintering records. We modelled the effects of temperature and rainfall on current and future climate suitability for lesser kestrels in both the breeding and wintering periods by using MaxEnt. Models were based on the distribution of 298 colonies and 45 wintering records. Future climate suitability was assessed under eight different scenarios. Spring rainfall amount resulted as the main determinant of breeding climate suitability, so its predicted reduction will determine a shrinkage in suitable areas (-42.10% in 2050; -32.07% in 2070). Specifically, the 66.05% of Italian colonies will be outside the climatically suitable area by 2050. However wide areas, suitable under current climate conditions, are still not occupied by lesser kestrel and allow the potential expansion of its Italian breeding range in the short term. Temperature seasonality mainly determined the species’ winter climate suitability, which is overall predicted to boost in the next decades (+145.03% in 2050; and +123.91% in 2070). All but one future scenarios predicted a northward shift of about 40 km for both breeding and wintering climate suitability. Despite its recent expansion, we have found that climate change will pose conservation concerns for the Italian breeding population of lesser kestrels. Indeed, changes in non-climate factors will also outline the future suitability of the Italian range for lesser kestrels in both seasons with effects that might both strengthen or mitigate climate effects.