Abstract
Mountain ecosystems are inhabited by highly specialised and endemic species which are particularly susceptible to climatic changes. However, the mechanisms by which climate change affects species population dynamics are still largely unknown, particularly for mountain birds. We investigated how weather variables correlate with survival or movement of the white-winged snowfinch Montifringilla nivalis, a specialist of high-elevation habitat. We analysed a 15-year (2003–2017) mark-recapture data set of 671 individuals from the Apennines (Italy), using mark-recapture models. Mark-recapture data allow estimating, forgiven time intervals, the probability that individuals stay in the study area and survive, the so called apparent survival. We estimated annual apparent survival to be around 0.44–0.54 for males and around 0.51–0.64 for females. Variance among years was high (range: 0.2–0.8), particularly for females. Apparent survival was lower in winter compared to summer. Female annual apparent survival was negatively correlated with warm and dry summers, whereas in males these weather variables only weakly correlated with apparent survival. Remarkably, the average apparent survival measured in this study was lower than expected. We suggest that the low apparent survival may be due to recent changes in the environment caused by global warming. Possible, non-exclusive mechanisms that potentially also could explain sexual differential apparent survival act via differential breeding dispersal, hyperthermia, weather-dependent food availability, and weather-dependent trade-off between reproduction and self-maintenance. These results improve our current understanding of the mechanisms driving population dynamics in high-elevation specialist birds, which are particularly at risk due to climate change.
Highlights
Mountain ecosystems are inhabited by highly specialised and endemic species which are susceptible to climatic changes
Mountain ecosystems are recognised as global biodiversity hotspots, hosting highly specialized and endemic species[1,2,3] which are threatened by human-induced causes including climate change[4,5,6,7,8,9]
A long life span is characteristic for some alpine bird species
Summary
Mountain ecosystems are inhabited by highly specialised and endemic species which are susceptible to climatic changes. Non-exclusive mechanisms that potentially could explain sexual differential apparent survival act via differential breeding dispersal, hyperthermia, weather-dependent food availability, and weather-dependent tradeoff between reproduction and self-maintenance These results improve our current understanding of the mechanisms driving population dynamics in high-elevation specialist birds, which are at risk due to climate change. Warm temperatures (>25 °C in the European Alps) can be followed by cold temperatures and even snow storms within minutes Species inhabiting these variable environments must show a high physiological and behavioural flexibility to cope with sudden abiotic changes within short periods of time, while they need to be able to persevere with long-lasting inclement weather periods. Improving the knowledge of demographic parameters, such as survival and reproduction, of a variety of different mountain bird species would be a crucial step for understanding how life-history traits of mountain birds are shaped by their extreme environment, and understand the needs and vulnerability of their populations
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