As winter closes in across much of North America, migratory birds are heading south to warmer climes and more abundant food. But until recently, scientists didn’t have a good understanding of exactly where they went.

Researchers from the Wildlife Conservation Society (WCS) and the Cornell Lab of Ornithology U.S. analyzed observations from eBird, a global citizen-science database of sightings submitted by bird-watchers. They found that in 2022 more than half of the 314 migratory bird species they studied went to the five great forests of Central America.

They write that 5 billion migratory birds funnel through Central America each year. Many stop in the rainforests, alpine wetlands and mangroves of the five great forests: Selva Maya in Mexico, Belize and Guatemala; Moskitia in Honduras and Nicaragua; Indio Maíz-Tortuguero in Nicaragua and Costa Rica; La Amistad in Costa Rica and Panama; and the Darién in Panama and northern Colombia. Collectively, these forests cover more than 10 million hectares (2.5 million acres), the researchers write.