Short-Lived Species Move Uphill Faster Under Climate Change

Abstract Climate change is pushing species ranges towards poles and mountain tops. Although many studies have documented local altitudinal shifts, knowledge of general patterns at a large spatial scale, such as a whole mountain range, is very limited. From a conservation perspective, studying altitudinal shifts is particularly important as mountain regions often represent biodiversity hotspots and are among the most vulnerable ecosystems. Here, we examine whether altitudinal shifts have occurred among birds in the Scandinavian mountains over 13 years and assess whether such shifts are related to species’ traits. Using abundance data, we show a clear pattern of uphill shifts in the mean altitudes of the bird species’ abundances across the Scandinavian mountains, with an average speed of 0.9 m per year. Out of 77 species, 54 shifted their ranges uphill. In general, the range shift was faster when the altitudinal range within the area was wider. Importantly, the altitudinal shift was strongly related to species’ longevity: short-lived species showed more pronounced altitudinal uphill shifts than long-lived species. Our results show that the altitudinal range shifts are not only driven by a small number of individuals at the range boundaries, but the overall bird abundances are on the move. This highlights the wide-ranging impact of climate change and the potential vulnerability of species with slow life-histories, as they appear unable to timely respond to rapidly changing climatic conditions.