Migratory birds are among the forces that stitch the globe together. Biologists have long known that animals can carry seeds and spores on their bodies, or may eat them and spread them in their waste.
But researchers at the University of Connecticut have begun exploring in more detail the role of migratory birds in long-distance plant distribution. While studying mosses that occur only in the high northern and high southern latitudes, and nowhere in between, PhD candidate Lily Lewis pondered what forces could have produced such bipolar distribution.
High-altitude winds can carry pollen grains and spores thousands of miles. But the nature of global wind currents, influenced by the Earth’s rotation, inhibits wind-driven dispersal across the equator.
To test the hypothesis that migratory birds may be responsible for bipolar plant distribution, Lewis and her research team studied the feathers of shorebirds that migrate between the Arctic and southern Chile. They recovered more than 20 reproductive plant parts from the feathers of 23 birds they sampled in the Arctic.
More research is needed to determine if these plant parts can survive the many-thousand-mile journey between Arctic and South American regions. But the findings of Lewis and her colleagues mark the first concrete evidence that birds can and do spread plants over vast distances.
As migratory birds wing north over the Colorado Plateau during the coming weeks, they will be carrying springtime on their wings. Time, and further research, will tell if they’re also carrying plant hitchhikers from the southern latitudes.
Earth Notes is produced by KNAU and the Sustainable Communities Program at Northern Arizona University.
