Mountain areas often hold special species communities and are thus in the high priority list of conservation. Changes in human land use, such as grazing pressure and afforestation, and especially in climate have been suggested as major threats for biodiversity in the mountain areas, because species have difficulties to find new suitable habitats in circumstances. Despite the special species communities very little is known about the population trends of species in mountain areas [1,2]. Here we studied population trends of 44 bird species in four major European mountain regions: Fennoscandia, UK upland, south-western (including Pyrenees) and south-central mountains (including Alps), covering 12 countries. We predicted that more species should show negative trends due to unfavourable environmental conditions. We also predicted the declines to be more severe in mountain specialists compared to mountain generalists, which are also found in the lowlands. We found in accordance with our predictions that mountain bird species have experienced significant declines (c. -7%) during 2002–2014. Mountain specialists showed a significant c. -10% decline in population numbers, and the slope for generalists was also negative but not significantly so. The slopes of specialists and generalists did not differ from each other. Fennoscandian and south-western populations were on average declining, but UK or south-central mountain birds showed on average stable situations. Our findings support the hypothesis that mountain species are declining. Thus more efforts should be undertaken to identify the causes of decline in order to protect these populations.

[1] Lehikoinen, A., Green, M., Husby, M., Kålås, J. A. & Lindström, Å. 2014: Common montane birds are declining in northern Europe. Journal of Avian Biology 45: 3–14. [2] Scridel, D., Brambilla, M., Martin, K., Lehikoinen, A., Iemma, A., Anderle, M., Jähnig, S., Caprio, E., Bogliani, G., Pedrini, P., Rolando, A., Arlettaz, R. & Chamberlain, D. E.: The effect of climate change on holarctic mountain and upland birds: a review and meta-analysis. Ibis (in press).