Associated Species: Other species that may use habitat in a similar way and/or respond similarly to threats, management, and conservation activities include Flammulated Owl, Williamson's Sapsucker, Northern Flicker, Olive-sided Flycatcher, and Pygmy Nuthatch.

Distribution: Western Bluebirds breed in western North America from southern British Columbia south to southern Mexico, and as far east as eastern New Mexico. In Physiographic Area 87 in Colorado, they occur most abundantly in the Southwest.

Habitat Requirements: Western Bluebirds favor open ponderosa pine forests containing large trees and snags with nest cavities. They also frequent meadows, burns, and other open areas within closed ponderosa forests.

Ecology: Western Bluebirds remain year-round in the southwestern part of the state, and some overwinter in river valleys in the west. They initiate nesting by early May, and most young leave the nest by mid August. Their diet consists of invertebrates (grasshoppers, caterpillars, beetles) and berries.

Management Issues and Conservation Recommendations: As with all cavity-nesting species, loss of large trees and snags reduces nesting opportunities. Western Bluebirds and other bird species of open ponderosa pine forest also lose habitat as fire suppression practices allow the development of dense stands. Restore ponderosa pine forests to presettlement conditions of large trees and snags, in clusters, with open, grassy understory.

Status and Reasons for Concern: A very high proportion (estimated at 29.4%) of this species' total population occurs within Physiographic Area 87, indicating that this region has high responsibility for the conservation of Western Bluebirds. Within Physiographic Area 87, BBS data do not show a statistically significant annual rate of change between 1969 and 1996 (P = 0.75; n = 30). Western Bluebirds were present on an average of 10.44% (SE = 3.21) of the BBS routes run in Physiographic Area 87 in Colorado, at an average abundance of 0.54 (SE = 0.28) individuals per route. The mean number of routes run each year was 11.4 (SE = 1.55). This species is monitored by MCB with point transects.

Biological Objective: Maintain or increase the species' distribution and abundance based upon results of the BBS and MCB monitoring programs.

Selected References: Andrews and Righter 1992, Kingery 1998, Winternitz 1973.