Hidden Lifelines for Migratory Birds
Billions of migratory birds rely on Central America’s Five Great Forests as winter shelters and vital stopover points. These forests hold up to half the global populations of several declining species, making them irreplaceable. Rapid deforestation now puts their future at serious risk.
Every spring, the songs of Wood Thrushes and warblers return to parks and neighborhoods across eastern North America. Few people know that these birds spend most of their lives far to the south and depend on the remote forests of Central America for survival during the rest of the year.
A new study from the Wildlife Conservation Society and the Cornell Lab of Ornithology shows that the Five Great Forests, stretching from southern Mexico to northern Colombia, play a crucial role for many migratory species that connect the two continents. Researchers used detailed weekly bird-distribution data from millions of sightings submitted to the global eBird platform. They found that these forests support between one-tenth and nearly one-half of the global populations of 40 migratory species. Many of these species rank among the fastest declining birds in North America.
“These forests shape the fate of birds we cherish in the United States and Canada,” said Anna Lello-Smith, lead author and conservation scientist at WCS. “They form the core of migration and support many species for more than half the year. They provide the food and shelter that allow Wood Thrushes, Magnolia Warblers and many others to return north each spring.”
Key Findings Show High Bird Concentrations
The study reveals striking numbers. 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 lost more than 70 percent of its numbers since 1970, passes through these forests during spring migration.
The Selva Maya, which spreads across Mexico, Belize and Guatemala, and the Moskitia in Honduras and Nicaragua stand out as the most important regions. Yet both landscapes lose habitat at alarming speed. A quarter of their total area disappeared in only 15 years 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 vast region shelters jaguars, tapirs, scarlet macaws and millions of migratory songbirds. For birds travelling thousands of miles each year, these forests act as essential resting and wintering grounds.
“Every fall, billions of birds move south through the narrow land bridge of Central America,” said Viviana Ruiz-Gutierrez, director of Conservation Science at the Cornell Lab and co-author of the study. “The density of warblers, flycatchers and vireos in these forests is astonishing. Each protected hectare safeguards a disproportionate number of birds.”
Deforestation Threatens a Critical Habitat Network
These forests vanish at a dangerous pace. Illegal cattle ranching has already destroyed millions of acres. In the Moskitia alone, almost one-third of the forest disappeared in only 20 years.
“If we lose the last great forests of Central America, we lose the birds that define our eastern forests,” said Jeremy Radachowsky, Regional Director for the WCS Mesoamerica Program. “But we can still change this by supporting communities, governments and conservation partners on the ground.”
Across Central America, Indigenous and local communities restore damaged land, prevent forest fires and revive traditional livelihoods such as sustainable allspice and cacao production. They often face severe risks, yet their work remains essential for protecting the remaining habitat.
“Imagine linking with those efforts,” said Ruiz-Gutierrez. “We could work together across the Americas to bring back our shared migratory birds.”
Mapping How Birds Connect the Americas
For many years, international cooperation remained limited because scientists lacked clear information on how migratory birds link different regions throughout the year. To improve cross-border conservation, researchers used a framework developed by Partners in Flight and the Cornell Lab. They mapped “stewardship connections,” which show where species dependent on the Five Great Forests gather to breed.
The results reveal strong ties between the Five Great Forests and forest regions in the Appalachians, the Mississippi Delta, the Great Lakes, New England and the landscapes around New York City. Researchers call these linked regions “sister landscapes” because birds connect them during different stages of their annual cycle.
Protecting Forests Means Protecting Migratory Birds
The Five Great Forests act as tropical partners to North America’s eastern forests. They shelter the same forest-loving species, including Scarlet Tanagers, Kentucky Warblers, Golden-winged Warblers and Broad-winged Hawks, during the months when these birds remain far from their breeding grounds. Protecting these wintering and stopover sites remains vital for ensuring their return each spring.
“Every hectare we protect in Central America creates ripple effects for birds and people across the hemisphere,” said Lello-Smith. “The forests that support thrushes and warblers also sustain communities. If you love watching your birds return each spring, we invite you to discover the tropical forests they rely on for most of the year and help protect them.”
