Alarming global-scale declines of bird numbers are occurring
under the changing climate1, and species belonging to alpine
and Arctic tundra are particularly affected2,3. Increased nest
predation appears to be involved4, but the mechanisms linking
predation to climate change remain to be shown. Here we
test the prediction from food web theory that increased primary
productivity (greening of tundra) in a warming Arctic
leads to a higher risk of nest predation in tundra ecosystems.
By exploiting landscape-scale spatial heterogeneity in areas
of primary productivity across alpine tundra ecotones and
supplied with experimental nests in sub-Arctic Scandinavia,
we found that predation risk indeed increased with primary
productivity. The productivity-predation risk relation was
independent of the simultaneous effects of rodent population
dynamics and vegetation cover at nest sites. Predation
risk also increased steeply with altitude, implying that species
at the high-altitude end of the alpine tundra ecotones are
particularly vulnerable. Our study contributes to an improved
understanding of how climate change may affect Arctic and
alpine ecosystems and threaten endemic biodiversity through
a trophic cascade.
