The Wood Thrush (Hylocichla mustelina) is a medium-sized North American thrush. Its breeding habitat is deciduous and mixed forests across eastern North America. The Wood Thrush has a large breeding range from southern Canada to northern Florida, and as far west as eastern Texas. However, its population has declined significantly in recent decades due to habitat loss and fragmentation. Understanding the geographic range of the Wood Thrush is important for conservation efforts.
Breeding Range
The Wood Thrush breeds in the eastern United States and southeastern Canada. According to the Cornell Lab of Ornithology, the northern limit of its breeding range stretches across southern Canada from southeastern Saskatchewan to southern Quebec and New Brunswick. The western edge of its breeding range goes from eastern North Dakota and Minnesota across southern Wisconsin and Michigan, and south through eastern Iowa, Missouri, and Arkansas. On the eastern side, its range covers all of the eastern U.S. states north to southern Maine.
In Canada, the core breeding range includes southern Manitoba, Ontario, and Quebec. The species breeds locally elsewhere in suitable habitat. In the U.S., the Wood Thrush’s breeding range covers all of the northeastern states south throughout the Appalachians and eastern interior highlands. It breeds west locally to the eastern Great Plains. The southern limit of its breeding range stretches across the southeastern states from eastern Texas to northern Florida.
Key Breeding Areas
Some key areas that support breeding Wood Thrush populations in the northern part of the range include:
- Southern Ontario
- Southern Quebec
- New York
- Pennsylvania
- Maryland
- Northern Virginia
- Eastern West Virginia
- Western North Carolina
In the core southern part of the breeding range, abundant summer populations can be found in:
- Western North Carolina
- Eastern Tennessee
- Northern Georgia
- Northern Alabama
- Northwestern South Carolina
- Western Virginia
- Eastern Kentucky
High elevation areas like the Appalachian Mountains and parts of the Allegheny Plateau support especially large breeding populations. Moist hardwood forests in river valleys and upland areas provide prime Wood Thrush habitat.
Wintering Range
The Wood Thrush migrates to southern Mexico and Central America to spend the winter. Its winter range extends from southern Veracruz in eastern Mexico, through Guatemala and Belize, to central Panama. Most winter farther south in Costa Rica and western Panama.
In Mexico, the Wood Thrush winters primarily in the states of San Luis Potosí, Hidalgo, Veracruz, Oaxaca, Tabasco, Chiapas, and the Yucatán Peninsula. It is scarce in the northern part of its Mexican winter range.
In Central America, the core wintering range covers the highlands of Guatemala, Honduras, Nicaragua, and Costa Rica. It is uncommon on the Caribbean slope and scarce on the Pacific slope. Panama marks the southern limit, where it is most abundant in Chiriquí and Veraguas Provinces.
Key Wintering Sites
Important wintering sites supporting large numbers of Wood Thrush include:
- The highlands and interior valleys of Chiapas, Mexico
- The central plateau of Chiapas
- The central highlands of Guatemala
- The mountains of western Honduras
- The central mountains of Nicaragua
- The Talamanca highlands of Costa Rica
- The highlands around Boquete, Panama
The Wood Thrush favors shady coffee plantations, wooded ravines, and forest borders during winter. Its winter habitat is generally between 3,000-8,000 ft (914-2,438 m) elevation.
Migration Range
The Wood Thrush is a long-distance Neotropical migrant. It migrates through the eastern U.S. to reach its Central American wintering grounds. In fall, birds start heading south in September and October. Spring migration north occurs between early April and mid-May. These thrushes fly around 180 miles (290 km) per night during migration.
During fall migration, Wood Thrushes follow two main routes. Birds west of the Appalachians migrate southwest down the Mississippi Flyway or through Texas to the Yucatan Peninsula. Birds east of the Appalachians follow the Atlantic Flyway along the U.S. East Coast and Caribbean islands like Cuba and the Bahamas. They converge in Central America before continuing into South America.
In spring, Wood Thrushes generally take a more direct northbound route through the U.S. interior rather than following coastlines. They make extensive use of habitat corridors like river valleys during migration. Major U.S. migration stopovers include:
- Appalachian Mountains
- Ozark Plateau
- Lower Mississippi Valley
- Upper Mississippi Valley
- Great Lakes region
These routes concentrate large numbers of Wood Thrushes along their migration pathways in both spring and fall. Conservation of stopover habitats is critical to their successful migration between breeding and wintering areas.
Range Map
This map shows the breeding, wintering, migration, and year-round ranges of the Wood Thrush:
Image credit: Birds of the World, Cornell Lab of Ornithology
The green area depicts the summer breeding range, blue shows the winter range, yellow indicates migration ranges, and purple represents year-round range. As the map shows, there is little overlap between summer and winter ranges for this migratory songbird.
Season | Range |
---|---|
Breeding (summer) | Eastern North America from southern Canada to the southeastern U.S. |
Wintering | Southern Mexico through Central America to Panama |
Migration | Through eastern U.S. via Atlantic and Mississippi Flyways |
Year-round | Very limited, only in souther FL and extreme south TX |
This table summarizes the seasonal distribution across the Wood Thrush’s range.
Range Changes Over Time
The Wood Thrush has experienced significant breeding range contractions and population declines in recent decades. According to the North American Breeding Bird Survey, it declined in abundance by 63% from 1966 to 2015 across its range. The core forest habitat it depends on has been degraded and fragmented by human land use changes like logging, development, and agriculture. Climate change may also be shifting its range northward.
Based on breeding bird atlas data, the northern limit of its range has retracted southward in states like Wisconsin, Michigan, Vermont, New Hampshire, and Maine. Its breeding range has also contracted from the western side in Minnesota, Iowa, and Missouri. In Canada, it has declined significantly in Ontario and no longer breeds in Prairie provinces like Manitoba.
On the southern edge of the breeding range, the Wood Thrush has declined in states like Kentucky, Tennessee, and Georgia due to forest loss. Its winter range in Central America has remained relatively stable thus far. But continued declines on the breeding grounds will likely lead to shrinking wintering range in the future.
Ongoing habitat loss and fragmentation pose the biggest threat to the future extent of the Wood Thrush’s range. Maintaining large forest blocks will be crucial for preserving breeding populations across its current geographic distribution.
Habitat
The Wood Thrush breeds in mature, deciduous and mixed forests across eastern North America. It prefers large tracts of forest with a closed canopy and tall trees. Ideal breeding habitat includes moist, shady hardwood stands with a well-developed understory. It favors forests with a mix of large trees and openings.
Common nesting sites include upland hardwood and mixed forests, riparian corridors, wooded wetlands, and shady forested slopes. Stands of beech, maple, and oak seem to be preferred. The Wood Thrush also inhabits pine-oak woodlands in parts of its range.
During the winter, it occurs in tropical evergreen forests, shade coffee plantations, wooded ravines, and forest borders. It is often found near small mountain streams in humid highland forests. The Wood Thrush migrates through a variety of wooded habitats like bottomland hardwoods, wooded yards, and parks.
Breeding Habitat
Specific types of forests used for nesting include:
- Deciduous forests: oak, maple, beech, birch, poplar, elm
- Mixed deciduous-coniferous forests
- Riparian woodlands along streams
- Forest wetlands: bottomland hardwoods, cypress swamps
- Eastern hemlock stands
- Pine-oak woodlands
- Moist wooded slopes and coves
Ideal breeding habitat has a high, closed canopy dominated by mature trees. A variable density understory with gaps for foraging and dense thickets for nesting provides optimal conditions.
Wintering Habitat
Typical wintering habitats include:
- Tropical evergreen and cloud forests
- Shade coffee plantations
- Heavily wooded ravines and slopes
- Forest borders and edges
- Partially open woodlands
- Forest clearings and gaps
The Wood Thrush favors humid highland forests mixed with tree plantations. Proximity to streamsides and wet forests is common during the winter period.
Migration Habitat
Migration stopover habitats include:
- Deciduous and mixed forests
- Pine-oak woodlands
- Riparian forests along rivers
- Coastal woodlands
- Parks and wooded suburban areas
Migrating Wood Thrushes use a variety of wooded habitats that provide food and cover. Riparian forests are particularly important migration corridors. Urban parks and greenspaces also provide stopover habitat.
Territory Size
Wood Thrushes are highly territorial on both their breeding and wintering grounds. A breeding pair defends a territory around their nest site, while wintering birds defend individual non-breeding territories.
On the breeding grounds, estimated territory sizes range from 1.2 acres up to 4 acres (0.5-1.6 ha). Wood Thrushes exhibit high site fidelity, returning to the same nesting territories year after year. Males establish territories shortly after arriving at the breeding grounds in spring.
Territories are advertised and defended through vocalizations and chasing intruders. Anything encroaching on the territory, including other Wood Thrushes, is aggressively chased out. Both males and females participate in territorial defense.
In migration and wintering areas, Wood Thrushes defend smaller non-breeding territories averaging around 0.25 acres (0.1 ha). Competition for limited habitat resources leads to more tightly packed territories compared to the breeding season. However, individuals still react aggressively towards intruders.
The size of Wood Thrush territories is influenced by habitat quality, population density, presence of predators, and pressure from competing species. For instance, territories tend to be smaller in marginal habitat and higher elevation wintering sites.
Population and Conservation Status
The Wood Thrush has an extensive breeding range and large overall population size. However, its numbers have declined significantly in recent decades. The global breeding population is estimated at 15 million birds.
According to the North American Breeding Bird Survey, the Wood Thrush population across its U.S. and Canadian breeding range declined by over 60% from 1966 to 2015. It is listed as a species of conservation concern by several state and federal agencies.
Partners in Flight estimates a global breeding population of 15 million, with 79% spending part of the year in the U.S. They estimate a breeding population of 11.7 million birds in the continental U.S. and 1.1 million in Canada based on Breeding Bird Survey data.
The species rates an 11 out of 20 on the Continental Concern Score. Wood Thrush populations are vulnerable throughout their range due to ongoing habitat loss and fragmentation. Conservation efforts are needed to protect key breeding habitats.
Population Threats
Major threats to Wood Thrush population health include:
- Habitat loss and fragmentation of breeding and wintering forests
- Forest management practices like clearcutting
- Increased nest parasitism from edge-adapted brood parasites like Brown-headed Cowbirds
- Climate change affecting migration and breeding phenology
- Acid rain degrading breeding stream habitats
Protecting large intact forest blocks will be critical for the future of Wood Thrush populations. Limiting forest fragmentation through sustainable selective harvest and conservation incentives for private landowners could benefit Wood Thrush breeding habitat.
Conclusion
In summary, the Wood Thrush breeds across eastern North America from southeastern Canada through the eastern U.S. It winters in southern Mexico through Panama. This migratory songbird has declined significantly due to habitat loss and fragmentation on its breeding grounds. Conservation efforts focused on protecting mature, intact deciduous forests will be key to preserving Wood Thrush populations across their breeding range.
Understanding the geographic range dynamics of the Wood Thrush provides important insights into its habitat needs and population trends. As a forest-dependent Neotropical migrant, its range and population health reflect broader patterns of avian diversity and forest ecosystem health across the Americas. Monitoring and maintaining populations of the Wood Thrush can indicate the effects of environmental changes and guide conservation of migratory bird species and their habitats.