© Marcel Burkhardt
Schneider, A. (2017)
Influence of environmental factors on nestling growth of the white-winged snowfinch (Montifringilla nivalis nivalis).
Bachelor Thesis, Environmental Science ETH Zurich
High alpine bird species are thought to be particularly threatened by global warming. Among them, the snowfinch (Montifringilla nivalis) has received little attention. It is important to understand the basic biology to determine the conservation measures for future protection of this species. In this study we focussed on the nestling growth of the snowfinch at the Furka pass in the Swiss Alps. The nestlings were measured at least every third day. The measurements included the following body features: weight, wing length, the 8th primary feather length (P8), body length and tarsus. With the measurements the growth curves for mass gain and wing development of the nestlings could be drawn. To examine the food availability and the feeding rate every nest box was repeatedly observed for thirty minutes. We additionally measured the abundance of invertebrates at random points in a maximum distance of five hundred meters around the colony, which should give a reference value for the food availability in the landscape. In generalized additive mixed model the morphological data was combined with the weather data of a weather station. There is evidence that the growth rate of mass of the nestlings may be influenced by temperature. Furthermore, it seems that the impacts of night temperatures are more crucial for the growth rate of mass than the day temperatures. The temperatures seem to have less effect on wing development than on weight gain. However, due to the small sample size, these results should be treated as provisional. Our results provide insight on how environmental factors, such as temperature, may influence the nestling growth and can serve as basis for further research. With additional data the precision of the estimated effects can be enhanced to better understand how the snowfinch may react in times of global warming.