Five to seven days of nonstop flight across an ocean, between continents. This mind-bending feat of endurance is undertaken twice each year by Upland Sandpipers (Bartramia longicauda) migrating between North and South America. For those of us who gear up for a two-hour car ride (complete with map and weather reports, coffee, snacks, and a queue of podcasts), a 20,000 km (~12,500 mile) annual journey seems almost impossible to comprehend. Especially when you consider that sandpipers are carrying nothing but the feathers on their backs.
Biologists have long known that Upland Sandpipers migrate between breeding grounds in the northern United States and Canada to their wintering grounds in the Pampas ecoregion of Uruguay and Argentina, but via which course and exactly when they traveled remained a mystery… until now. VCE’s recent paper in the Open Access journal Frontiers in Ecology and Evolution unveils surprising new information about the species’ migratory patterns.
In a first for this species, our team (myself, former VCE biologist Rosalind Renfrew, and Brett Sandercock of the Norwegian Institute for Nature Research, in Trondheim, Norway) used lightweight satellite tracking tag data (and some complicated math) from nine Upland Sandpipers to describe a series of new discoveries.
We learned that sandpipers regularly crossed major ecological barriers during migration, which included long oceanic flights, high elevation mountains, and tropical forests. We documented new staging sites at canefields in the mountain valleys of Colombia, grasslands in the Llanos of Venezuela, and at airports (e.g., Baltimore Washington International Airport, Maryland) along the Atlantic Coast of the U.S. Unlike many bird species who overwinter in a single location, individual Upland Sandpipers used multiple discrete areas up to 1,500 km apart on nonbreeding grounds. In one instance, a sandpiper tagged in Massachusetts overwintered in Brazil less than 100 km away from another sandpiper tagged in Kansas; and two sandpipers that were captured 27 km apart in Kansas overwintered ~2,600 km apart from each other in central Brazil and Uruguay.
Perhaps the most dramatic discovery, however, came from the Amazon rainforest. I don’t think anyone, including us, would have confidently predicted what we discovered: some of these Upland Sandpipers—a species thought to inhabit large open grasslands exclusively—spent the nonbreeding season on partially flooded river islands in the Amazon basin! Just as extraordinary, this area is almost 1,000 km north from the nearest site previously known to host overwintering Upland Sandpipers. Taken together, we hope this suite of discoveries moves the needle forward substantially in terms of adapting and improving the global conservation strategy for this shorebird species.
The full article, “Migration Patterns of Upland Sandpipers in the Western Hemisphere,” is freely available on the Frontiers in Ecology and Evolution website. In addition, all of the raw and processed tracking data are freely available for the public to view, and other researchers to use, at Movebank.org.
Funding for this research project was provided by the U.S. Department of Defense Legacy Resource Management Program (Project 15‐764).