A group of researchers from the University of Turin in Italy has undertaken extensive survey work to understand the effect of avalanches on bird communities in the Alps.
Riccardo Alba led the team in surveying 240 sites in the western Italian Alps near Turin in spring 2021. Half of the sites surveyed had been affected by avalanches at some point in the last few decades.
Rock Bunting takes advantage of areas cleared by avalanches (Paul Cools).
The danger presented by sudden, large-scale movements of snow to human life are clear, but the long-term effects on the birds of the affected area have received little attention. It is obvious that avalanches periodically flatten swathes of forest occupied by woodpeckers, tits, finches and thrushes, but the team wanted to understand whether the newly sculpted slopes go on to boast more bird diversity.
Alba said of the study: "I didn't expect to find such [high] diversity."
The fresh growth in the wake of an avalanche creates ideal habitat for pipits, buntings and chats. By adding more rocks, shrubs and grass to an area, the 'footprint' of an avalanche complements surviving high-canopy woodland, to give rise to a rich bird community. Lower altitude slopes, with their taller trees, saw the biggest changes.
A richer variety of bird species was found at sites that had seen recent avalanches, with 62 species compared to 55 in unaffected areas. Species typically found at the tree line, such as Black Grouse and Rock Bunting, were found to be taking advantage of the opportunities presented by the open habitat. Furthermore, species composition varied in relation to the frequency of avalanches in the area, and the time passed since the last event.
Whether avalanches will become more frequent as the climate changes is a debated topic in the research community. Alba says it is important to go ahead with further research into their effect on mountain ecosystems, as it is possible that changes in snow precipitation driven by climate change will have an impact on how often mountain slopes are cleared.
Reference
Alba, R, Oddi, L, Rosselli, D, & Chamberlain, D. 2023. Avalanches create unique habitats for birds in the European Alps. Journal of Ornithology: 1-12. DOI: https://doi.org/10.1007/s10336-022-02039-3
