Apparent survival and spatial movement of Snowfinches (Montifringilla nivalis) in Austria

The annual apparent survival is an important parameter determining the development of populations. Depending on different factors such as weather, food supply, predators, etc., there are sometimes strong differences between the individual years, but averaged over several years, trends may indicate major changes in habitat suitability. The aim of the study was to measure long-term changes in annual apparent survival of Snowfinches in Austria. This species is a songbird specialized in high alpine habitats that are particularly affected by climate change. Thus, records of a total of 2423 marked and recaptured birds from 1966 to 2021 from the Austrian Alps serve as the basis for calculating the survival rate. The markrecapture method used allows an estimate of the probability that an individual will remain and survive in a study area within a given interval (one year). We estimated the apparent survival rate, averaged over all years, to be 0.55-0.70 (95% uncertainty interval) for male Snowfinches and 0.36-0.64 for females. The regression line indicating the trend over the years is negative for both sexes, although the decrease is much more pronounced in females. Furthermore, the data allowed to evaluate stationarity and movement tendencies. Most recaptured individuals were found at the same place where they were marked. Some of them may travel distances between 10-50km and some individuals even travelled several hundred kilometers. The decline in survival of Snowfinches certainly indicates that something must have changed over the last 60 years, and a causal relationship between climate change definitely needs further investigations.