Data linking climate change to observed changes in arctic marine and terrestrial wildlife populations are scarce, despite substantial changes in sea ice and arctic vegetation that constitutes wildlife habitat. Here, we mine observational records from the Alaskan Arctic to identify changes in distribution or behavior of many terrestrial wildlife species during the last century.
Results/Conclusions
We show that the increase in productivity of arctic vegetation and expansion of deciduous shrubs resulting from longer and warmer summers starting in the mid-1800s triggered the establishment of novel tundra herbivores moose in the 1930s and snowshoe hares in the 1970s, both which depend on shrubs protruding above the snow for forage in winter. Earlier spring onset has led to a 3-10 day earlier return of 16 species of migratory birds since 1964, though the effect of the altered timing on population sizes is unknown. We expect that other boreal species such as lynx, beaver, or red fox are also shifting into treeline and tundra habitats. The decline in shrub-free tundra is meanwhile reducing habitat for endemic tundra species such as the Alaska marmot, caribou, and a variety of small mammals and birds, which will also have to contend with new competitors arriving from the south. Complicated interactions associated with predation, disease, trophic mismatch, competition, and other factors complicate predictions that are not based on past observations, underscoring the need to analyze observed wildlife changes and to maintain long-term studies.