Bird Lore: Mountain Bluebird

Although Mountain Bluebirds breed in Eastern Washington, they can wander quite a bit in spring migration and can be seen in small numbers in Western Washington. An adult female appeared at Brackett’s Landing North on April 19th. The third and fourth photos are of her. It was only the second sighting that we know of in Edmonds. One was previously seen in the same vicinity in September 1999.

The Mountain Bluebird winters from Central California south and across the Southwest to West Texas. It migrates north to breed in the U.S. West, Western Canada and into Alaska. In summer this species can be found from low elevations to the high meadows of alpine zones. It inhabits open terrain with some trees in summer. It prefers tree hollows for nesting but will use holes in cliffs and dirt banks when tree hollows are unavailable. With the loss of a sufficient number of snags with nest cavities, the Mountain Bluebird has adapted to using nest boxes. In winter it can be found in juniper-pinyon woods but also inhabits treeless country.

As with many other birds, insects and berries make up the bulk of the Mountain Bluebird diet. It feeds most heavily on insects such as grasshoppers, beetles, crickets, caterpillars, ants, and bees. Berries are important to its winter diet and include mistletoe and juniper berries, as well as hackberry. It forages by hovering over a field and then dropping to the ground once it spots prey. It will also forage like a flycatcher, perching on a rock, fence post, or low branch and darting out to catch flying insects.

The female is more attracted to a good nest site than she is to the particular male. She selects her mate on the basis of the location and quality of the nest site, not on his looks or his ability to sing or engage in courtship flights. Both adults probably build the nest, which is a loose cup of twigs, grass, pine needles, and similar materials. It is either inside a natural cavity, one excavated by other birds such as woodpeckers, or in a nest box. The female Mountain Bluebird incubates her five to six eggs for about two weeks. Both adults feed the chicks, which do not leave the nest until about three weeks after hatching.

The male provides food for the female while she is incubating the eggs and brooding her young. When the male arrives with food, the female may beg like a young chick, opening her bill, quivering her wings and making begging calls. When she is ready for food, she waits until her mate is perched nearby and then flicks her wing that is farthest away from him. This signal sends him off to hunt for her.

Bluebirds are not able to excavate their own nest cavities so they are dependent upon finding cavities that have already been excavated by other species. The oldest Mountain Bluebird of record was a female and at least nine years old when she was recaptured and re-released during a banding operation in Alberta. There are not any collective nouns specific to the three bluebird species.

The Mountain Bluebird is a species of low concern for conservation purposes. Between 1966 and 2015, its population declined about 24 percent. Nonetheless, the estimated global population is 4.6 million, with 80 percent spending at least part of the year in the U.S. The Mountain Bluebird benefited from the spread of logging and grazing in the Western U.S. in the 19th and early 20th centuries because those activities created open habitat that is preferred by the species. As these activities waned and government policies began to favor the deliberate suppression of wildfires, open acreage dwindled and the species declined somewhat. As land use practices stabilized, so did the Mountain Bluebird population. The construction and maintenance of nest boxes for the several bluebird species has also aided a stable Mountain Bluebird population.

You can listen to the dawn song of a Mountain Bluebird here:

— By Carol Riddell

Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.

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