The Mountain Bluebird (Sialia currucoides) is a small thrush that is found in open country and forest edges in western North America. They are known for their brilliant blue plumage and melodious song. Some key facts about the Mountain Bluebird:
Identification
The Mountain Bluebird has bright turquoise-blue upperparts and pale blue underparts. The male has a darker blue throat and chest. Females are duller blue overall. They have a long tail and straight dark bill. Juveniles have speckled breasts. The Mountain Bluebird is similar in appearance to the Eastern and Western Bluebird, but its range does not overlap with theirs across most of its range.
Range
The Mountain Bluebird breeds from Alaska and western Canada south to Nevada and New Mexico. They winter as far south as Mexico. They are found at elevations up to 12,000 feet in open meadows, burned areas, forest clearings and openings, ponderosa pine forests, aspen stands, and alpine tundra.
Nesting
The Mountain Bluebird is one of the earliest spring migrants, arriving at breeding grounds by late February. They choose open sites for nesting, often nest boxes or natural cavities in trees, stumps, cliffs, or old woodpecker holes. They will also use holes in buildings. The female builds the nest out of grasses and pine needles, shaping a neat cup. She lays 5-7 pale blue eggs and incubates them for 13-17 days. The chicks hatch over a 2-4 days and fledge after about 21 days in the nest.
Diet
The Mountain Bluebird is primarily an insectivore, feeding on beetles, grasshoppers, caterpillars, ants, bees, and other small invertebrates. They will also eat some seeds and berries. They often perch on a high vantage point like a tree branch or fence post and swoop down to catch insects on the ground or among vegetation.
Migration
The Mountain Bluebird is one of the earlier migrants, arriving at its breeding grounds by late February or March. They start migrating south again by late August or September to wintering grounds in the southern U.S. and Mexico. Some birds may linger as far north as Canada in mild winters. The Mountain Bluebird often migrates in loose flocks of a dozen or two birds.
Interesting Facts
- The Mountain Bluebird population declined in the early 1900s due to competition from European Starlings and House Sparrows for nest sites. The provision of nest boxes helped their numbers recover.
- They can have up to three broods per breeding season, especially if the first nest fails.
- They are very tolerant of cold and have been seen sun-bathing in below zero F temperatures.
- They have unusually long tongues (up to 1.5 inches) for catching insects.
- Mountain Bluebirds hover and dive like flycatchers to catch flying insects.
- They are monogamous, pairing off in lifelong mateships.
- The oldest known wild Mountain Bluebird was 12 years 9 months old.
Threats
The main threats facing Mountain Bluebirds are:
- Loss of nesting cavities to introduced birds like Starlings and House Sparrows
- Reduction in insect prey due to pesticide use
- Extreme cold weather or late spring storms reducing nesting success
- Habitat loss and fragmentation of open meadows and clearings they prefer
Providing suitable nest boxes in appropriate habitat can help offset the loss of natural nesting sites for Mountain Bluebirds.
Conservation Status
The Mountain Bluebird has a large range and population, estimated at 1.5 million birds. Trend data from 1966-2015 indicates a population increase of +2.7% annually. Due to its large and growing population, the Mountain Bluebird is classified as Least Concern on the IUCN Red List.
Where to See Mountain Bluebirds
Some top places to spot Mountain Bluebirds include:
- Grand Teton National Park
- Rocky Mountain National Park
- Going-to-the-Sun Road in Glacier National Park
- Mount Rainier National Park
- Craters of the Moon National Monument
- San Juan Mountains, Colorado
Look for them perched on tree snags, fences, or overhead wires along open roads or meadows. Nest boxes along forest roads, campgrounds, and mountain trails may also host breeding bluebirds.
How to Attract Mountain Bluebirds
Here are some tips to attract Mountain Bluebirds to your backyard:
- Put up nest boxes designed specifically for bluebirds on fence posts or trees at the edge of open habitat.
- Ensure nest boxes have a 1.5 inch diameter entrance hole to exclude larger birds like Starlings.
- Face the entrance hole southeast towards morning sun and prevailing winds.
- Keep nest boxes 50-100 feet apart to avoid competition.
- Clean out old nests in autumn to prepare for spring.
- Provide a perching platform like a fence or wires near the nest box.
- Supplement natural food sources with mealworms offered in platform feeders.
Key Points About the Mountain Bluebird
- Known for its bright turquoise blue plumage and melodious song
- Found in open habitats and forest edges in western North America
- Migrates north to breed in early spring, raising up to three broods per summer
- Nest in cavities in trees, cliffs, nest boxes; female builds nest
- Population increased with addition of nest boxes after decline from competition with introduced birds
- Eats mainly insects and some seeds and berries
- See them in National Parks like Glacier, Grand Teton, Rocky Mountain, and Mount Rainier
- Attract to backyards with nest boxes designed specifically for bluebirds
Conclusion
With its brilliant turquoise plumage and melodic voice, the Mountain Bluebird is a stunning and welcome visitor to open habitats across western North America. This member of the thrush family migrates north in early spring to breed, nesting in cavities and raising up to three broods over the summer. Its diet consists mainly of insects like beetles, ants, and grasshoppers. After nesting box initiatives helped recover populations that declined due to competition with introduced birds, the Mountain Bluebird now has a large and growing population. See these blue beauties for yourself by spotting them perched on fences, overhead wires, and snags in places like National Parks, or attract them to your own backyard with proper nest boxes.