Central America’s Five Great Forests Are Critical Lifelines for North America’s Migratory Birds

A new scientific study has highlighted something both fascinating and deeply urgent: the Five Great Forests of Central America are essential wintering and stopover habitats for many of the migratory birds that people in the United States and Canada know and love. These forests stretch from southern Mexico all the way to northern Colombia, forming a vast green corridor that supports birds for over half of their yearly life cycle. The study, conducted by scientists from the Wildlife Conservation Society (WCS) and the Cornell Lab of Ornithology, uses massive amounts of data from the eBird platform to quantify these connections with remarkable precision.

Below, I break down what the study found, why these forests matter, what’s threatening them, and additional context to help readers understand the broader ecological importance of these regions.

The Five Great Forests and Their Role in Bird Migration

The Five Great Forests are:

• Selva Maya (Mexico, Belize, Guatemala)
• Moskitia (Honduras, Nicaragua)
• Indio Maíz–Tortuguero (Nicaragua, Costa Rica)
• La Amistad (Costa Rica, Panama)
• Darién (Panama, northern Colombia)

Together, these forests roughly equal the land area of Virginia and serve as a critical habitat network for species traveling the long-distance route between the eastern United States, eastern Canada, and the tropical regions of Central America.

Birdwatchers often hear the familiar songs of species like the Wood Thrush, Magnolia Warbler, and Golden-winged Warbler every spring in North America. But what’s often overlooked is that these birds spend anywhere from one-third to one-half of the year far to the south in warm tropical forests. The Five Great Forests provide the food, shelter, and climate stability that allow them to survive winter and fuel up for their return to breeding grounds.

Using weekly data from eBird, the researchers were able to map where populations concentrate at specific times of the year. They discovered that these forests collectively support 10% to almost 50% of the global populations of 40 different migratory bird species. That scale is astonishing—especially given how small Central America appears on the map compared to the entire hemisphere.

Key Findings That Show How Dependent Birds Are on These Forests

Some numbers from the study stand out because they highlight the depth of this dependence:

• Over one-third of the global population of the Kentucky Warbler winters in these forests.
• Nearly one-quarter of all Wood Thrushes and Golden-winged Warblers spend the winter here.
• More than 40% of the global Cerulean Warbler population passes through these forests during spring migration. This species has declined by over 70% since 1970, making habitat protection even more urgent.

The research also identifies which of the forests hold the highest concentrations of migratory birds. Two regions were found to be particularly vital:

• Selva Maya
• Moskitia

Unfortunately, both of these forests are also suffering some of the highest rates of deforestation. Selva Maya and Moskitia have lost nearly one-quarter of their total area in just 15 years, mostly to illegal cattle ranching. Moskitia alone has lost nearly one-third of its forest cover in the past two decades.

This combination of biological importance and extreme vulnerability makes the situation especially concerning.

Why Losing These Forests Threatens Birds in North America

The study emphasizes something that conservation scientists have long suspected: events happening in tropical forests strongly influence bird populations thousands of miles away. If these forests disappear, many of the birds that currently migrate back to the United States and Canada each spring may decline even further or vanish altogether.

Birds such as Scarlet Tanagers, Broad-winged Hawks, Vireos, Flycatchers, and Warblers depend on these forests during the non-breeding season. The ecological pressures they face in Central America—like deforestation, reduced food availability, and habitat fragmentation—have ripple effects that extend up the entire migratory chain.

The researchers describe the Five Great Forests as mirror landscapes of eastern North America’s breeding forests. The same species that rely on Appalachian forests in summer depend on Selva Maya or Moskitia in winter. This creates what the researchers call “sister landscapes,” biological partnerships across borders where the same birds occupy different regions at different times of the year.

Understanding these linkages helps guide cross-border conservation planning, which has historically been difficult because scientists lacked detailed maps of how bird populations move across seasons.

Current Efforts to Protect These Forests

Although the deforestation trends are serious, conservation efforts are already underway. Indigenous and local communities are central to forest protection, with many groups actively restoring degraded land, creating sustainable livelihoods, and fighting forest fires.

Some promising community-led approaches include:

• Sustainable cacao production
• Allspice cultivation
• Ecotourism programs
• Forest protection patrols

These communities often take significant personal risks to protect forests from illegal encroachment. The study emphasizes that supporting these local groups—economically and politically—is one of the most effective ways to stop forest loss.

Additional Ecological Significance of the Five Great Forests

Beyond birds, these forests are home to:

• Jaguars
• Scarlet Macaws
• Tapirs
• Countless amphibian, reptile, and plant species

Their ecological value stretches well beyond any single species group. They store significant carbon, moderate regional climate, and protect freshwater systems that millions of people rely on.

From a broader ecological perspective:

• Forests like these buffer communities from droughts and storms.
• They maintain genetic diversity across wide geographic ranges.
• They serve as natural corridors allowing species to adapt to climate change.

Losing these forests would mean not only ecological collapse for migratory birds but deep, long-term impacts for Central American biodiversity and human well-being.

A Quick Look at Migratory Bird Ecology for Extra Context

To expand on the topic beyond the news story, here are some helpful points about migratory birds:

• Many species migrate because their breeding grounds in North America offer abundant food in summer but become unlivable in winter.
• Tropical forests provide more stable food sources, milder temperatures, and safe roosting habitats.
• Long-distance migrants can travel thousands of miles in only a few weeks, relying on energy reserves built up in forests like those in Central America.
• Habitat loss anywhere along this migratory route—breeding grounds, stopover sites, or wintering grounds—can cause major population crashes.

eBird has played an increasingly important role in tracking these trends. With millions of birdwatchers submitting checklists, scientists can now create high-resolution maps of migration movements, habitat use, and population density. This kind of participatory science is becoming a cornerstone of modern conservation.

Research Paper

Leveraging participatory science data to guide cross-border conservation of migratory birds: A case study from Mesoamerica’s Five Great Forests
https://doi.org/10.1016/j.biocon.2025.111551