Every spring, the familiar songs of Wood Thrushes and warblers drift back into parks and neighborhoods across eastern North America. Few people realize that these birds spend most of their lives much farther south, relying on the lush and often remote forests of Central America to survive the rest of the year.
A recent study from the Wildlife Conservation Society (WCS) and the Cornell Lab of Ornithology (Cornell Lab), published in Biological Conservation, shows that the Five Great Forests of Central America — stretching from southern Mexico to northern Colombia — are essential for many migratory bird species that connect the two continents.
Using detailed information on weekly bird distribution, made possible by millions of sightings submitted to the Cornell Lab’s global eBird platform, researchers discovered that these forests collectively provide habitat for between one-tenth and nearly one-half of the global populations of 40 migratory species. Many of these birds are among the fastest declining in North America.
“What happens in Central America directly affects the birds we love in the United States and Canada,” said Anna Lello-Smith, lead author and conservation scientist at WCS. “These forests aren’t just tropical wilderness — they’re at the heart of migration, sustaining many of our birds for more than half the year. They provide the food and shelter that allow Wood Thrushes, Magnolia Warblers, and so many others to return north to fill our spring with song and color.”
Key Findings Reveal High Bird Concentration
Among the study’s most notable results:
- More than one-third of the world’s Kentucky Warblers and nearly one-quarter of all Wood Thrushes and Golden-winged Warblers spend the winter in these forests.
- Over 40 percent of the global Cerulean Warbler population, a species that has declined by more than 70 percent since 1970, passes through these forests during spring migration.
- The Selva Maya (spanning Mexico, Belize, and Guatemala) and the Moskitia (in Honduras and Nicaragua) are the most important forest regions for these species — yet they are losing habitat rapidly, with a quarter of their area cleared in just 15 years, largely due to illegal cattle ranching.
Together, the Selva Maya, Moskitia, Indio Maíz-Tortuguero, La Amistad, and Darién form a continuous ecological corridor roughly the size of Virginia. This region shelters not only migratory songbirds but also jaguars, tapirs, and scarlet macaws. For birds migrating thousands of miles each year, these forests serve as essential resting and wintering grounds.
“Every fall, billions of birds pour south through the narrow land bridge of Central America,” said Viviana Ruiz-Gutierrez, director of Conservation Science at the Cornell Lab of Ornithology and co-author of the study. “The density of migratory warblers, flycatchers, and vireos crowded into these five forests is astounding, and means that each hectare protected there safeguards a disproportionate number of birds.”
Rapid Deforestation Threatens Critical Habitat
These forests are disappearing at an alarming pace. Illegal cattle ranching has already destroyed millions of acres. In the Moskitia alone, almost one-third of the forest has vanished in only 20 years.
“If we lose the last great forests of Central America — and we are — we lose the birds that define our eastern forests in North America,” said Jeremy Radachowsky, Regional Director for WCS’s Mesoamerica Program. “But by supporting rural communities, governments, and conservation partners on the ground, we can still turn the tide.”
Across Central America, Indigenous and local communities are working to restore damaged lands, prevent forest fires, and revive traditional, bird-friendly livelihoods such as sustainable allspice and cacao production. They often face serious risks in doing so, yet these efforts remain essential for protecting remaining forest habitat.
“Imagine the possibility of linking with those efforts,” said Ruiz-Gutierrez, “so that we can work together across the Americas to bring back our shared migratory birds.”
Mapping How Birds Connect Regions Across the Americas
For years, international cooperation has been limited because scientists lacked clear information about how migratory birds connect different habitats and communities throughout the seasons. To support cross-border conservation, researchers used a framework developed by Partners in Flight and the Cornell Lab to map “stewardship connections” — regions in North America where species dependent on the Five Great Forests gather to breed.
These findings show that the Five Great Forests are closely tied to forest regions in the Appalachians, the Mississippi Delta, the Great Lakes, New England, and the landscapes surrounding New York City. Researchers refer to these paired regions as “sister landscapes” because they are linked by the same bird species at different points in the annual cycle.
Protecting Forests to Protect Migratory Birds
In many ways, the Five Great Forests serve as tropical counterparts to North America’s eastern forests. They shelter the same suite of forest-loving birds, including Scarlet Tanagers, Kentucky Warblers, Golden-winged Warblers, and Broad-winged Hawks, during the months when these species are far from their breeding territories. Safeguarding these wintering and stopover habitats is essential for ensuring that these birds continue to return north each spring.
“Every hectare we protect in Central America has ripple effects for birds and people across the hemisphere,” said Lello-Smith. “The forests that sustain thrushes and warblers also support communities. If you love watching your birds come back each spring, we invite you to discover the tropical forests they call home for most of the year — and help protect them.”
