What do sea otters have to do with ptarmigan survival? Ask the eagles.
In their recently published paper in Ecology, Robert G. Anthony and others studied populations of bald eagles before and after a sea otter decline. They expected that the breeding population of eagles would decline as well because much of their nestlings’ diet is sea otters and other animals found in kelp forests.
Instead, they found that the breeding population remained stable and nest success did not decrease. Instead of declining, the eagles changed their diets. They responded to loss of kelp forests by hunting non-kelp fish and increasing the number of birds fed to their nestlings.
So save an otter, save a ptarmigan!
Work cited: Anthony, R. G., J. A. Estes, M. A. Ricca, A. K Miles, and E. D. Foresman. 2008. Bald eagles and sea otters in the Aleutian Archipelago: indirect effects of trophic cascades. Ecology 89(10): 2725-2735.