Biologists have long puzzled over why certain mossy plants are found only in the Arctic and at the very tip of South America, but not in between. Now, a team of researchers has discovered that long-distance fliers like the American golden-plover (pictured), which migrate from their breeding grounds in the Arctic to South America, often harbor tiny parts of these spore-producing plants in their feathers. Birds are known to transport seeds internally and externally, but scientists had not linked them to the long-distance dispersal of microscopic plant spores, called diaspores. To do so, the researchers first collected down and contour feathers from 23 birds representing eight species that were nesting along two Arctic rivers. The scientists microscopically examined the washed and screened samples, revealing 23 plant fragments from mosses, liverworts, algae, and fungi—all believed able to grow into new plants, they report today in PeerJ. The plant bits had been attached to the feathers of seven birds from three species—semipalmated sandpipers, red phalaropes, and the golden-plovers. The birds likely picked up the fragments from the vegetation they used to line their nests, which are typically simple depressions they scrape in the ground. The diaspores, especially those of mosses, are known for their resilience and can likely survive the birds’ journey to South America, the scientists say. On arrival, the birds generally molt -- and in the process, drop off their tiny cargo, too. The scientists think that a new population of mosses can be established from a single, successful bird-dispersal event, because many moss species can self-fertilize and grow as clones.