Circannual variation in habitat use of the White-winged Snowfinch Montifringilla nivalis nivalis

High mountain areas are subject to strong seasonal fluctuations, and species inhabiting these particular environments show a high degree of habitat specialization to cope with extreme abiotic conditions. Estimates of habitat use are influenced by the spatial and seasonal scales at which they are evaluated, so studies at multiple scales are important in order to explore adaptive responses to seasonal environments. In the present study, we assessed habitat use of the White-winged Snowfinch Montifringilla nivalis subsp. nivalis (henceforth Snowfinch) during breeding and non-breeding seasons at three different spatial scales (diameters of 100, 250 and 500 m). Although Snowfinches clearly used high-elevation habitats in both seasons, there was evidence that they are less specific during the non-breeding period: the variance explained by habitat and topographical factors was lower in winter than in the breeding season. Moreover, our results suggest that the use of habitat is scale-dependent. This pattern was especially relevant in the breeding season, perhaps because habitat use might be more related to nest-site selection and specific foraging sites to provide food for nestlings. Snowfinches use high mountain habitats throughout the year, probably as a consequence of physiological and morphological specializations typical of high-elevation species, but in winter they show a certain flexibility in habitat use. Snowfinches might thus adopt a flexible specialist strategy. This could represent a trade-off to overcome possible effects on survival, condition and fitness, which can be particularly strong in harsh, unpredictable environments.