© Marcel Burkhardt
Niffenegger, C. A. (2021)
Nest site selection of the White-winged Snowfinch Montifringilla nivalis in the Swiss Alps.
Master thesis, University of Bern
Time and place of reproduction are crucial determinants of the reproductive success, especially in mountain ecosystems where the diverse topography and pronounced seasonality result in a high degree of spatial and temporal variation of environmental conditions. Species inhabiting high-elevation ecosystems have thus evolved strategies to adjust their breeding effort according to the prevailing environmental conditions. In mountain environments, the pattern of snowmelt often determines the onset of the reproductive period by governing access to key resources such as food. Yet, climate change may disrupt the fine-tuned species-habitat associations because of altered snow conditions and therewith changes in food availability, modification of the microclimatic conditions or increased predation pressure. We used a combination of habitat mapping and satellite remote sensing to assess the small-scale and broad-scale nest site selection of the White-winged Snowfinch Montifringilla nivalis, a declining alpine passerine. We observed considerable temporal variation of nest site selection in response to environmental conditions. In the first half of the breeding season, Snowfinches selected weather-protected, morning sun exposed nest cavities while they used nest cavities according their availability later on. Nests were often located close to snow patches which typically offer abundant and accessible food supply. Our results highlight the risk of a phenological mismatch that may arise from ongoing shifts in spring snow conditions, which could increase the spatial disconnection between suitable nest sites and optimal foraging grounds, with potentially negative effects on reproductive success and population dynamics. We suggest that nest box supplementation could to some extent help Snowfinches to cope with climate change if installed with the right orientation and next to suitable foraging grounds.
keywords: species-habitat association, nest site selection, environmental conditions, mountain ecosystem, White-winged Snowfinch, snow cover