Bluebirds are beautiful little songbirds with bright blue plumage. They are a popular backyard bird that many people enjoy seeing during the warmer months. As winter approaches, bluebirds migrate south to escape the cold weather. However, some bluebirds have adapted to sticking around in certain areas if they have access to food and shelter.
Bluebird Migration
Most bluebirds that breed in the United States and Canada migrate south for the winter. The majority fly to the southern United States, Mexico, and Central America. Some travel as far south as Florida, the Bahamas, and even Cuba. Bluebirds start flocking together in late summer and early fall to prepare for migration. They gather in large groups called “migrating flocks” before making the journey south.
Bluebirds migrate during the day and travel mainly during daylight hours. They stop frequently to rest and feed. Bluebirds may migrate alone, in pairs, or as part of a larger flock. They can cover hundreds of miles over several weeks on their fall migration. The exact timing, distance, and duration depends on the individual bird, weather, and food availability along the migration route.
What Triggers Migration?
Several factors trigger bluebirds to migrate in the fall:
- Decreasing daylight hours
- Colder temperatures
- Declining food sources
- Genetic predisposition to migrate
Shortening daylight tells bluebirds that winter is approaching. Colder temperatures make it harder for them to survive, especially at night. Food also becomes scarcer in most parts of their breeding range. The combination of these seasonal changes motivates bluebirds to migrate south where conditions are more favorable.
Some Bluebirds Stay in the Winter
While most bluebirds migrate south in winter, some populations have adapted to stick around certain northern regions if they have a reliable food source and shelter.
Backyard Feeders Provide Food
Backyard bird feeders allow some bluebirds to find enough food to survive cold winter months in the north. Sunflower seeds, suet, mealworms, and other energy-rich foods can help sustain wintering bluebird flocks.
Nest Boxes Offer Shelter
Many people put up nest boxes to attract breeding bluebirds in spring and summer. But these nest boxes also provide crucial shelter for bluebirds trying to survive winter. They roost communally in cavities, using each other’s body heat to stay warm.
Fruit Trees Provide Food
Fruit trees and bushes like dogwoods, crabapples, and hawthorns provide an important winter food source. They persist on berries when insects become scarce. Backyards and parks with fruiting trees help support wintering bluebirds.
Winter Range of Bluebirds
With sufficient food and shelter, bluebirds can potentially survive winter across much of the southern United States. However, most wintering bluebirds concentrate in a few core regions:
- Mid-Atlantic coast
- Appalachian Mountains
- Lower Midwest
- Pacific Northwest
Milder climates, abundant backyard feeders, and plenty of nest boxes allow bluebird populations to persist year-round in these areas. However, their winter range depends on unpredictable factors like temperature, snow cover, and food availability.
| State | Estimated # of Wintering Bluebirds |
|---|---|
| Virginia | 45,000 |
| North Carolina | 35,000 |
| Tennessee | 30,000 |
| Arkansas | 25,000 |
| Missouri | 20,000 |
| Oklahoma | 15,000 |
Wintering Behavior
Bluebirds exhibit different behaviors in winter than the breeding season:
- Form large nomadic flocks up to 100+ birds
- Roost communally in cavities for warmth
- Frequent feeders regularly for food
- Eat more berries than insects
- Mixed flocks with other songbirds
- Range more widely searching for food
Challenges for Wintering Bluebirds
Winter is still an extremely difficult time for bluebirds that remain up north:
- Finding enough food
- Withstanding frigid temperatures
- Surviving winter storms
- Avoiding predators
- Competing with other birds
Supplemental feeding, roost boxes, and winter habitat can help counter these threats. But their populations are limited compared to summer due to the stresses of winter.
Food Limitations
Insects become scarce in winter, forcing bluebirds to rely more on fruits and seeds. But berries can get covered by snow or knocked down by wind and ice. Feeders may freeze or run out. Finding enough nutrition is an ongoing struggle.
Extreme Cold
Small birds like bluebirds are vulnerable to bitterly cold temperatures. They can lose heat rapidly. Prolonged exposure or being caught out overnight in extreme cold can be deadly. Hunkering down in cavities helps bluebirds conserve energy and share warmth.
Winter Storms
Heavy snow, ice, rain, and wind can be hazardous for bluebirds. Most winter mortality happens during storms. They can knock down fruit sources, cover feeders, and prevent bluebirds from foraging.
Predators
Predatory birds like Cooper’s hawks and Sharp-shinned hawks stay around in winter looking for food. Bluebirds are vulnerable to ambush at feeders, fruiting trees, and exposed roosts. Watching for predators and roosting safely helps bluebirds manage this risk.
Competition
Other birds like European starlings, robins, and House sparrows compete with bluebirds for winter food and cavities. Aggressive exclusion can limit bluebird access to feeders and prime roosting spots.
Preparing Your Yard for Wintering Bluebirds
You can make your yard more bluebird-friendly in winter by providing food, shelter, and protection:
- Supply suet feeders
- Offer mealworms
- Hang fruit like grape jelly
- Plant winter berry bushes
- Put up roost boxes
- Insulate boxes
- Clean out old nests
- Site boxes out of wind
- Heat roosts if possible
- Use predator guards
- Control competing birds
A little effort goes a long way toward supporting overwintering bluebirds and enjoying their beauty year-round.
Conclusion
While most bluebirds migrate south for winter, some populations along the mid-Atlantic, Appalachians, Midwest, and Pacific Northwest have adapted to stick around during the colder months. Backyard feeders, nest boxes, and fruiting trees help provide the food and shelter bluebirds need to survive winter in the northern portion of their range.
However, winter is still an extremely challenging time full of threats like starvation, exposure, storms, predators, and competition. Preparing your backyard habitat with roost boxes, winter feeders, and berry bushes aids bluebirds that try to overwinter in your area and provides enjoyment of their beauty year-round.
