Migrations can resemble an extreme endurance sport, in some cases taking animals thousands of miles across continents or oceans to feeding, breeding and overwintering grounds. New research shows these feats may offer a surprising benefit: protection from disease.
Ecologist Sonia Altizer, of the University of Georgia, and her colleagues first saw evidence of this among monarch butterflies. A single-celled parasite that plagues monarchs does not affect those that migrate to the same degree it infests year-round residents. By reviewing other studies, the scientists found evidence of similar phenomena among other animals.
Disease could potentially influence how far animals travel and how long they spend in a particular place, giving it a more prominent role in shaping migrations than scientists have recognized, Altizer says.