Foraging habitat selection by Alpine White-winged Snowfinches Montifringilla nivalis during the nestling rearing period

Abstract

High-elevation species are expected to be vulnerable to climate warming and to experience dramatic range contractions in the coming decades. Indeed, climate change in high-altitude biota has proceeded at a faster pace compared to lowlands. Understanding basic ecological features of mountain species, such as their foraging ecology, may be useful to further our understanding of the mechanisms dictating species distributions and their responses to global warming, ultimately improving conservation strategies. In this study, we investigated foraging habitat selection of the poorly studied Alpine White-Winged Snowfinch Montifringilla nivalis during the nestling rearing period (June–July) in the Italian Alps. Pair members from 18 different nests were visually followed for 1 day or until we obtained 10 foraging locations. At foraging and control plots (equal numbers per breeding pair; control plots within 300 m of the nest, the average exploited radius according to literature) we recorded habitat variables (habitat types/heterogeneity, sward height, slope, solar radiation). We built models of foraging habitat selection and evaluated whether the selection of climate-related variables varied with temperature and season progression. Snowfinches preferred to forage at colder (low solar radiation) sites, with snow patches and short grasses, some boulders and bare ground, and shifted towards sites with increasingly lower solar radiation after the first week of July. Snow patches are likely to provide both arthropod fallout and suitable sites for invertebrates at their melting margins. Short herbaceous layers likely improved invertebrate detectability in addition to their abundance. These results suggested that climate change may impact on the foraging ecology of this species: warming may reduce the availability of snow patches and favor a denser and taller sward, and may reduce the time frame within which melting snow patches are highly profitable. Hence, the fine-scale habitat requirements of foraging Snowfinches highlight the species’ potential high sensitivity to anthropogenic climate warming.