Birds move higher up mountains as the climate warms
University of Helsinki
image:
Bird species are shifting to higher elevations over time, likely in response to climate change. The red line represents the mean elevation of birds, which has moved uphill after 20 years.
view moreCredit: Image and image processing: Jani Närhi
Many bird species have moved toward colder areas in the mountains of Europe as the climate has warmed over the past two decades. Sunny southern slopes attract birds to live at higher elevations than do shadier northern slopes.
A new study examined 177 bird species in four large mountain ranges: the Alps, the Pyrenees, the Scandinavian Mountains, and the British Highlands. Of these species, 63 per cent moved uphill. This uphill movement has averaged about half a metre per year in the 2000s.
The fastest change happened in Scandinavia and the Alps — for example, the northern wheatear has shifted an average of 33 metres uphill in the Scandinavian mountains since 2001. No significant uphill shift was observed in Great Britain or the Pyrenees. This indicates that the causes behind range shifts, such as the intensity of climate change and human land use, vary from region to region.
In mountainous areas, local climatic conditions, or microclimates, can vary considerably even over short distances. For example, the northern mountain sides receive less sunlight than the southern sides, resulting in cooler and wetter conditions. These differences affect the habitats of species.
"Sunny slopes attract birds to higher elevations because vegetation zones and food resources are located higher up. However, birds are also moving uphill at the same rate on shady slopes, which suggests that warming temperatures are affecting the entire mountain landscape", explains PhD researcher Joséphine Couet from the Finnish Museum of Natural History, University of Helsinki.
The results show that broader climatic trends are driving birds to move uphill in the mountains across Europe. Slopes that are less exposed to solar radiation could serve as refuges, but these small-scale advantages are not enough to counteract large-scale uphill movements.
"Mountain areas are not only majestic landscapes, but also hotspots of biodiversity, home to many species that depend on specific climatic and habitat conditions. This information is crucial for conservation planning in complex terrains where local conditions vary greatly", Couet emphasizes.
The study was published in the journal Global Ecology and Biogeography and is based on bird monitoring data from eight European countries between 2001 and 2021.
Northern Wheatear
Credit
Jani Närhi
Journal
Global Ecology and Biogeography
Article Title
Solar Radiation Affects Bird Distributions but Not Elevational Shifts in European Mountains
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