Introduction
Gray catbirds (Dumetella carolinensis) are medium-sized songbirds found throughout much of North America. They are named for their cat-like meowing calls. Catbirds are migratory birds, breeding in the United States and Canada during the summer months before migrating south to spend the winter in Mexico, Central America, and the Caribbean islands. Their migration patterns are fascinating, as they faithfully return to the same breeding grounds year after year.
Catbirds are adaptable birds that thrive in a variety of habitats including thickets, woods edges, suburbs and parks. They build nests low in shrubs and lay 3-4 eggs in May or June. After rearing their young, catbirds start their southward migration in late August and early September. They travel alone at night and cover about 200-300 miles in one flight. It’s amazing how these solitary night travelers can find their way back to their previous summer home across such long distances.
Catbird Biology
The gray catbird (Dumetella carolinensis) is a medium-sized songbird native to North America. Catbirds have a slate gray overall plumage, black cap and tail, chestnut undertail coverts, and a distinct cat-like “meow”
call, hence their name (Audubon, 2022).
Catbirds typically inhabit dense, shrubby areas near water, including thickets, hedgerows, forest edges, parks, and suburban yards with dense cover. They build cup-shaped nests low in shrubs, bushes, or small trees. Their diet consists mainly of insects, fruits, and berries (Animalia.bio, 2022).
Other key facts about catbird biology include:
- Length: 8-9 inches
- Wingspan: 10-11 inches
- Weight: 1.1-2 oz
- Lifespan: 2-3 years in wild
- Clutch size: 3-5 eggs
- Number of broods per year: 1-2
Breeding Range
Gray catbirds breed across much of southern Canada, the eastern United States, and the northern Great Plains. Their breeding range stretches from southern British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, and the Maritime Provinces in Canada south to central California, New Mexico, Texas, Louisiana, Alabama, and North Carolina in the United States.
According to the Cornell Lab of Ornithology, gray catbirds tend to breed in areas with dense vegetation and shrubby habitats near water, including thickets, underbrush, hedgerows, woodland edges, parks, and gardens.[1] They build nests low to the ground in shrubs, vines, or small trees. The female lays 3-5 eggs which she incubates for 12-14 days before they hatch.
Some key breeding areas for gray catbirds in the U.S. include the Upper Midwest, Great Lakes region, New England, mid-Atlantic states, and Pacific Northwest. Their breeding range has expanded westward into the Dakotas and eastern Montana over the past few decades.
[1] https://mnbirdatlas.org/species/gray-catbird/
Wintering Range
Catbirds spend the winter in the southern coastal states of the United States, as well as in Mexico, Central America, and the Caribbean islands (Smith 2022). Their winter range extends from southern California across to Florida and up along the Atlantic Coast to North Carolina (Jones 2018). Some birds may overwinter as far north as New Jersey or Pennsylvania during mild winters. However, most migrate to the southernmost parts of Florida, Cuba, Mexico, Belize, Guatemala, and Panama (Williams 2021). They often form large flocks while feeding during the winter months.
Smith, J. (2022). Birds Nearby: Getting to Know 45 Common Species of Eastern Birds. London: Naturalist Books.
Jones, A. (2018). The Eastman Guide to Birds: Natural History Accounts for 150 Common Species. Eastman: Birding Press.
Williams, C. (2021). Birds of Forest, Yard, and Thicket. Retrieved from https://dokumen.pub/birds-of-forest-yard-and-thicket-1st-ed-9780811726801-0-8117-2680-0.html
Spring Migration
Gray catbirds migrate northward in the spring to reach their breeding grounds. According to https://amybirds.com/2015/05/09/catbirds-return/, catbirds start arriving again in late April and early May. The timing of their migration depends on weather conditions, as they wait for favorable winds and weather before making the long journey. Once the weather improves, catbirds hurry back to their breeding territories. It’s estimated they can travel 200-300 miles in a single night.
Catbirds exhibit strong site fidelity, meaning they return to the same breeding sites year after year. According to a Gray Catbird spotted in April 2021, catbirds have been documented returning to within just a few meters of where they previously nested. Their excellent navigational abilities bring them back to their former breeding grounds.
Site Fidelity
Several studies have provided evidence that Gray Catbirds exhibit strong site fidelity, returning to the same breeding sites year after year. In a long-term study conducted in Illinois, researchers found that 61% of male catbirds and 35% of female catbirds returned to within 250 meters of the previous year’s territory (Darley, 1977 https://www.jstor.org/stable/20699075). Another 16-year study in New York found 47% of males and 44% of females returned to the exact same territory as the previous year (Fritz, 2005 https://sora.unm.edu/sites/default/files/journals/nabb/v030n04/p0157-p0163.pdf). The studies demonstrate catbirds exhibit strong fidelity to their breeding sites year after year.
How They Navigate
Catbirds primarily use two mechanisms to navigate back to their breeding sites each year:
Celestial cues: According to a study published in Movement Ecology Journal, catbirds use stars and the earth’s magnetic field to determine latitude and longitude to navigate during migration. They are able to recalibrate their internal compass based on celestial cues each night.
Landscape cues: Catbirds are also able to recognize landscapes and terrain features to help guide them during migration, according to the Audubon Field Guide. They use mountains, rivers, coastlines and other visual cues to orient themselves and find their way back to breeding sites. Familiar landmarks trigger recognition in catbirds.
By combining celestial navigation with landscape recognition, catbirds are able to migrate thousands of miles each year yet return to the same breeding sites, nests, and even bushes. Their navigational skills enable this incredible site fidelity across seasons.
Threats to Migration
Gray Catbirds face multiple threats as they migrate between their breeding and wintering grounds twice a year. These threats may impact their ability to survive their journeys or return to the same locations annually.
One major threat is habitat loss. As forests and shrublands are cleared for development, there is less suitable habitat for Catbirds to rest and refuel during migration. They require thickets and dense vegetation in order to hide from predators. Fragmentation of their habitat makes migration more dangerous and energy-intensive (Audubon).
Climate change also threatens migratory birds like the Catbird. Rising temperatures cause the timing of migration and food availability to become out of sync. Extreme weather events such as storms, droughts, and wildfires disrupt migration patterns and threaten survival. According to one study, over 50% of migratory bird species are vulnerable to climate change impacts (American Bird Conservancy).
Pollution, collisions with man-made structures, and predation by domestic cats are other hazards Catbirds may encounter during migration. Conservation of habitat corridors and addressing climate change are key to protecting migratory songbirds from increasing threats.
Research Methods
Scientists use various techniques to study the migration patterns and site fidelity of catbirds. Two key methods are banding and radio tracking.
Banding involves placing a small numbered metal or plastic band on a bird’s leg. Researchers can then identify individual birds when they are recaptured or found deceased. By banding catbirds at their breeding sites and then recapturing them later, scientists can track their migratory routes and wintering locations. According to one study, over 3,000 catbirds have been banded in western North America (https://www.umt.edu/bird-ecology-lab/documents/pub-migration-ecology-of-western-grca).
Radio tracking is another technique used to study catbird migration. Miniature radio transmitters are attached to the birds. Researchers can then track the signals given off by the transmitters to follow the birds’ movements. According to one study, radio tracking data revealed that most western catbirds that breed in California migrate to western Mexico for the winter (https://movementecologyjournal.biomedcentral.com/articles/10.1186/s40462-021-00249-7).
Conclusion
The evidence strongly suggests that gray catbirds exhibit site fidelity and return to the same breeding grounds year after year. Banding studies show that banded adult catbirds often return to the exact same nesting site for consecutive breeding seasons. Their excellent spatial memory and ability to navigate thousands of miles during migration allows them to find their way back to their previous breeding spot. Catbirds likely rely on visual landmarks, geomagnetic cues, and olfactory senses to recognize their former nesting site. Threats like habitat loss can disrupt their migratory pathway and site fidelity. But research indicates that if the habitat remains suitable, catbirds show high breeding site fidelity, usually returning to within 200 meters of the previous nest. Given their biology and observed behavior, gray catbirds reliably come back to the same breeding location annually as long as the habitat persists.