Canada, and 31 percent in Mexico. They rate an 8 out of 20 on the Continental Concern Score. They are a U.S.-Canada Stewardship species, but they are not on the 2012 Watch List. These birds benefited from the westward spread of logging and grazing in the late nineteenth and early twentieth centuries, when the clearing of forest created open habitat for foraging. The subsequent waning of these industries, coupled with the deliberate suppression of wildfires, led to a dwindling of open acreage in the West and the decline of the species. More recently, as land-use practices have stabilized, so have Mountain Bluebird populations. Construction of nest boxes in suitable habitat has also provided a population boost. Populations are declining in areas where trees are too small to provide natural nesting cavities, and where forest and agricultural management practices have reduced the availability of suitable nest sites. Among birds that nest in cavities but can’t excavate them on their own, competition is high for nest sites. Mountain, Western, and more recently Eastern bluebirds compete for nest boxes where their ranges overlap. House Sparrows, European Starlings, and House Wrens also compete fiercely with bluebirds for nest cavities.
- Dunne, P. 2006. Pete Dunne’s essential field guide companion. Houghton Mifflin, Boston.
- Lukas, D. 2011. Sierra Nevada Birds: A Compact Field Guide Companion. Lukas Guides, Big Oak Flat, California.
- Power, H.W. and M.P. Lombardo. 1996. Mountain Bluebird (Sialia currucoides). In The Birds of North America Online, No. 222 (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York.
- Partners in Flight. 2012. Species assessment database.
- USGS Northern Prairie Wildlife Research Center. 2013. Attracting bluebirds and other cavity nesting songbirds in North Dakota: establishing bluebird trails.
- USGS Patuxent Wildlife Research Center. 2013. Longevity records of North American Birds.
- USGS Patuxent Wildlife Research Center. 2012. North American Breeding Bird Survey 1966–2010 analysis.
Short- to medium-distance migrant. Mountain Bluebirds breed across western North America as far north as Alaska; they spend winters in as far south as central Mexico. Migrating flocks may consist of 20 to 200 birds.
Mountain Bluebirds take readily to nest boxes. If you live in suitably open habitat within their range, consider putting up a nest box to attract a breeding pair. Make sure you put it up well before breeding season. Nest boxes should be located away from buildings, areas of heavy pesticide use, and dense woods, ideally in open rural country with scattered clumps of trees or low shrubs. Mount boxes in pairs at least 100 yards apart, with 10 to 20 feet between boxes in a pair. Aggressive competitors can nest in the first box, leaving the second for bluebirds. The entrance hole should be about 1.75 inches in diameter, located about 6 inches above the floor of the box. It should face away from prevailing winds, and in an easterly direction to avoid overheating by afternoon sun. Ideally, there should be a place to perch within about 100 feet of the box, for when fledglings leave the nest. Attach a guard to keep predators from raiding eggs and young. Find out more about nest boxes on our Attract Birds pages. Some retail outlets carry ready-made boxes, or build your own: you'll find plans for building a nest box of the appropriate size on our All About Birdhouses site.
Find This Bird
In the right places it can be a snap to find Mountain Bluebirds, as they are not shy of humans and live in fairly open country. They sit in the open on perches such as treetops, fence posts, and power lines. In summer in rural areas and ranches, particularly at higher elevations, you can often find them simply by driving rural roads and eyeballing such potential perches. In forested areas, look for them in large openings, particularly if there are aspen in the vicinity (aspen is a key cavity-providing tree in western montane forests). In winter, search for areas with berry-laden junipers and watch for flocks of birds feeding on