Blackbirds are a group of medium-sized songbirds that belong to the genus Turdus. There are several different species of blackbirds found across North America, including the common or Brewer’s blackbird, the red-winged blackbird, and the rusty blackbird.
Do blackbirds migrate for the winter?
Yes, most species of blackbirds in North America are migratory and will migrate south in the winter to escape the cold weather and find more abundant food supplies. Different blackbird species have slightly different wintering grounds and migration routes based on their breeding habitats.
Common blackbird winter range
Common or Brewer’s blackbirds breed across much of North America and winter primarily in two main regions:
- Southern U.S. – From California east to Texas and south to the Gulf of Mexico
- Southwestern Mexico
During migration, common blackbirds form enormous flocks, sometimes containing several million birds! They migrate mostly at night and fly at lower altitudes than many other migratory songbirds.
Red-winged blackbird winter range
Red-winged blackbirds breed from coast to coast across the northern U.S. and Canada. They winter in the southern half of the U.S. and Mexico.
Their winter range includes:
- Southeastern U.S. from North Carolina to Texas
- Southern California and southwestern Arizona
- Mexico
Red-winged blackbirds migrate during the day in smaller flocks than common blackbirds. They migrate relatively early and can arrive on their wintering grounds as early as July.
Rusty blackbird winter range
Rusty blackbirds breed in Canada and Alaska and the far northern U.S. They are one of the last blackbird species to migrate south in the fall. Their winter range includes:
- Lower Mississippi Valley
- Gulf Coast region
- Southeastern U.S. from Virginia to Texas
Rusty blackbirds migrate in smaller flocks than other blackbird species, traveling mainly at night.
Why do blackbirds migrate in the winter?
Blackbirds migrate south in winter for a few key reasons:
Food availability
Blackbirds have a predominantly insect-based diet in the summer breeding season. As winter arrives, their insect food sources become scarce in northern regions due to cold temperatures. Migrating south allows them to access more abundant food supplies.
Survival
Remaining farther north during harsh winters decreases survival rates for blackbirds. Freezing temperatures and heavy snow cover make finding food extremely difficult. Predation rates also increase, as blackbirds become more conspicuous against snow-covered landscapes. Migrating south improves their chances of survival.
Breeding
Some migratory blackbird species migrate early to establish winter territories. Males arrive before females to establish and defend the best breeding territories for the following spring. Wintering farther south allows them to arrive on the breeding grounds early and maximize their reproductive success.
What is the blackbird migration route?
Migration routes and flyways used by blackbirds generally follow north-south orientations and major geographic barriers like mountain ranges or coastlines. Here are some of the main flyways used:
Central Flyway
The Central Flyway overlaps the Great Plains and follows the Mississippi River drainage. Many rusty blackbirds and common blackbirds use this migration route.
Mississippi Flyway
The Mississippi Flyway follows the Mississippi River valley and is used by many red-winged blackbirds and common blackbirds.
Pacific Flyway
The Pacific Flyway runs along the western coastline and is used by western populations of red-winged blackbirds.
Atlantic Flyway
The Atlantic Flyway covers the eastern seaboard and is used by rusty blackbirds breeding in eastern Canada.
What are some major blackbird wintering sites?
Some important wintering sites and regions for blackbirds include:
Wintering Region | States/Areas | Key Habitats |
---|---|---|
Lower Mississippi Valley | Arkansas, Mississippi, Louisiana | Flooded agricultural fields, marshes, swamps |
Florida | Southern Florida | Freshwater marshes, grasslands |
Gulf Coast | Coastal Texas and Louisiana | Coastal marshes, grasslands, agricultural areas |
Pacific Coast | Central and Southern California | Coastal marshes, wetlands, agricultural fields |
Northern Mexico | Coahuila, Nuevo Leon, Tamaulipas | Freshwater marshes, scrublands, agriculture |
These regions provide critical overwintering habitats for blackbirds, with abundant food sources and favorable climates.
How do blackbirds know when and where to migrate?
Blackbirds rely on a combination of innate behaviors and environmental cues to determine the timing and direction of migration:
Genetics
Migration patterns are inherited genetically and passed from generation to generation. First-year birds inherit the migration routes, timing, and destinations of their parents.
Changes in daylight
Blackbirds are very attuned to changes in day length, which signal the changing of the seasons. As days shorten in the late summer and fall, blackbirds begin hormonal and physiological changes needed for migration.
Weather patterns
Shifts in weather patterns, such as falling temperatures and increased storms, provide blackbirds with environmental cues that it is time to migrate south.
Orientation
Blackbirds use a combination of celestial cues, geomagnetic senses, and visual landmarks to orient themselves and navigate along established migration flyways.
How do blackbirds navigate during migration?
Blackbirds use a variety of amazing tools and abilities to navigate during their biannual migrations:
Senses
Blackbirds rely heavily on their vision and geomagnetic senses to orient themselves. They likely see landmarks from high altitudes and may sense the earth’s magnetic fields.
Sun and stars
On sunny days, blackbirds determine direction from the location of the sun. On cloudy days and at night, they get their bearings from stars and constellations.
Landscape
Major landscape features like coastlines or mountain ranges provide blackbirds with visual reference points during migration flights.
Smell
Research suggests blackbirds may also use their sense of smell to help locate specific wintering sites, particularly places they have migrated to before.
Conclusion
In conclusion, blackbirds migrate south each winter to find more favorable habitats and food sources. Different blackbird species follow established flyways like the Mississippi and Central Flyways to reach overwintering sites primarily concentrated across the southern U.S. and Mexico. Blackbirds rely on innate behaviors and environmental cues to determine when to migrate and navigate using the sun, stars, geomagnetic senses, and visual landmarks. Understanding the migration patterns and behaviors of blackbirds provides important insight into their ecology and conservation.