Associated Species: Other species that may use similar habitat components or respond positively to management for the Eastern (Azure) Bluebird are: Northern Goshawk (Apache), Acorn Woodpecker, Strickland’s Woodpecker, Northern Flicker, Bridled Titmouse, White-breasted Nuthatch, Montezuma Quail, Black-throated Gray Warbler, Hutton’s Vireo, Ash-throated Flycatcher and Scott’s Oriole.

Distribution: This subspecies of the Eastern Bluebird is a year-round resident from south-central Arizona (Santa Rita, Pajaritos, and Huachuca mountains) south along the Sierra Madre Occidental to Guerrero (AOU Checklist 1957). During breeding, it is found in the mountains of southern Arizona south to Jalisco, Oaxaco and Vera Cruz (Bent 1949 from AOU Checklist 1931). Monson (1981) lists the following areas for breeding: Huachuca Mountains west to the Pajaritos; the Chiricahua Mountains; Happy Valley east of the Rincon Mountains in Pima and Cochise Counties; and at Bear Canyon in the Santa Catalina Mountains. Recently, (1993, ’94, ’96 and ’97) in both Pima and Cochise Counties, breeding has been confirmed through the Arizona Breeding Bird Atlas Project.

Ecology: The Azure Bluebird is a resident of southeastern Arizona and essentially non-migratory (Monson 1981). It is an occasional cooperative breeder-- young from previous broods help at the parent’s nest (Ehrlich and others 1988). Frugivorous and insectivorous, its diet includes earthworms, snails, and other invertebrates as well as berries. The young are fed primarily insects, which are caught "on the wing" by the adults. In the winter, berries are the most important food source (Ehrlich and others 1988). Bluebirds are secondary cavity nesters, often using woodpecker-excavated holes, but will also use crevices, cracks and natural cavities in trees and rocks. Nests consist of a loose cup of grass, weed stems, pine needles, and twigs, occasionally with hair or feathers (DeGraaf and Rappole 1995, Ehrlich and others 1988, Phillips and others 1964). As a cavity nester, it is a rare cowbird host (Ehrlich and others 1988, Woodward 1979).

Habitat Requirements: The Azure Bluebird is found at elevations of 1000-2000 m (3280-6560 ft) in the pine-oak forests of southeastern Arizona (Monson and Phillips 1981, Phillips and others 1964). It has also been found at lower elevations, nesting in cottonwoods at Patagonia, Arizona, but not in recent years (Monson and Phillips 1981, T. Corman, pers. observ.). Oaks are the primary tree species utilized, including Emory, Arizona white, silverleaf and Mexican Blue oaks mixed with some Apache and Chihuahua pine. They frequent areas of open canopy with scattered trees, forest edges, and burned or cut-over woodlands (DeGraaf and Rappole 1995). The mid- understory is open and ground cover is mainly forbs and grasses with low foliage and stem densities. Snag density is high, as the species is a secondary cavity nester and uses mature to late succession forest patches for both foraging and nesting. During winter, small flocks may wander from breeding areas and can sometimes be found in the Tucson area, but usually remain in the mountains (Monson 1981, Russell and Monson 1998).

Habitat and/or Population Objectives:

The distribution of this subspecies across the landscape is patchy and localized, but may have always been so, as this excerpt from Swarth (1914) in Bent (1949) indicates "rare in summer in the high mountains of extreme southern Arizona, not of common occurrence in either of these mountain ranges where S. Mexicana bairdi [Western Bluebird] is the common breeding bluebird". Adults require low perches for hawking and catching insects near the ground (Ehrlich and others 1988). Nest cavities are also low, often within meters of the ground (Russell and Monson 1998). An abundance of snags are needed for nesting, therefore uncontrolled fuelwood cutting and the taking of larger trees results in loss of nesting substrates. Felling dead trees and removing dead branches decreases availability of cavities and low perches and increases competition with other cavity nesting species (Ehrlich and others 1988). Ligon (1969) also suggests that the availability of cavities may limit this species, possibly because they begin breeding activities later than other cavity nesters.

Because this species is insectivorous, mainly aerial, loss of grasses and forbs due to heavy grazing pressure may result in lowered food supply, although light grazing may enhance habitat by decreasing the shrub layer (Ligon 1969). Where both fire and grazing have been excluded, heavy undergrowth and dense foliage may be responsible for the scarcity of this bird (Ligon 1969). In open park-like forests of northern Mexico, the bluebird is more common (Marshall 1963 in Ligon 1969). Ligon (1969), referring to the Southwestern Research Station in the Chiricahua Mountains, reported that "heavy grazing by cattle near the research station has destroyed much of the undergrowth, producing a more open woodland than is found in areas where both fire and cattle have been excluded". This information was collected in 1965 and it is uncertain if this population of bluebirds is still present at the research station, although they are seen occasionally and in small numbers in the surrounding areas.

Management should include low intensity fires which will: 1) "fire prune" oaks, thus making them less susceptible to larger wildfires; 2) result in a mosaic of vegetation; 3) be of such an intensity to maintain openness of habitat, allowing more growth of forbs and grasses; and 4) decrease shrub layer. Research needs include determination of tree size needed for nesting, cavity size and availability, including identification of competitors (starlings?), and cavity height requirements (much of this information is known for the bluebirds in the eastern United States, but research comparing the needs of this subspecies is lacking). Nest box programs have been very successful in the eastern United States for bluebirds, but their use in the West is not common. Ligon (1969) reported that within two days of placement of a nest box, it was occupied by a pair of Azure Bluebirds that successfully reared young from the box. Research is needed on nest box usage to determine if a nest box program should be implemented in certain areas. Since this bird has disappeared from some areas of southeastern Arizona, research on abundance and reproductive success could be useful in determining population centers.

Eastern (Azure) Bluebird management issues are listed in italics. Below each issue are the Arizona Partners in Flight Conservation Recommendations.