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Montana Field Guide

Montana Field Guides

Eastern Bluebird - Sialia sialis

Potential Species of Concern

Global Rank: G5
State Rank: S4B

Agency Status
USFWS: MBTA
USFS:
BLM:
PIF:


 

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Copyright by Borror Laboratory of Bioacoustics, Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, all rights reserved.
 
General Description
The Eastern Bluebird is a small thrush (16 to 21 cm long) with a wingspan of approximately 33 cm. The male has a bright blue back, head, wings, and tail. The throat, sides of the neck, and upper breast are orange, with the orange on the breast extending down the flanks. The white belly is bright and apparent. The female is similarly colored, but is duller overall. The head and back are more of a gray or gray-blue than blue, but the wings and tail are primarily blue. Unlike the male, the female has a white throat. On both sexes, the eye is black, and the bill is dark and stout, with a yellow gape (Gowaty and Plissner 1998, Sibley 2000).

Vocalization of the Eastern Bluebird is described as a song of mellow whistles sounding somewhat like "chiti WEEW wewidoo" or "Tu-a-wee" (Gowaty and Plissner 1998, Sibley 2000). The male sings loudly from high, conspicuous perches, sometimes during flight (Gowaty and Plissner 1998).

For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.

Diagnostic Characteristics
The plumage of the male Eastern Bluebird is most similar to that of the Western Bluebird. The Eastern Bluebird is discernable by its white belly, orange throat and blue scapulars, while the Western Bluebird has a blue belly and throat and chestnut scapulars. The features distinguishing the female Eastern, Western, and Mountain Bluebirds are less distinct. The Eastern Bluebird female is distinguishable from the Western Bluebird by the white throat, rufous on the sides of the neck, and more distinct rufous flanks. The Eastern Bluebird is darker overall than the Mountain Bluebird, with more rufous-orange on the flanks, upper breast, and sides of the neck. The Western Bluebird and Mountain Bluebird females lack the white throat. In addition, the bill of the Eastern Bluebird is thicker and stouter than that of the two other bluebird species.

Species Range
Montana Range

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eBird Occurrence Map

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Courtesy of eBird and Cornell Lab of Ornithology
 


Summary of Observations Submitted for Montana
Number of Observations: 111

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

Breeding
(direct evidence "B")


Breeding
(indirect evidence "b")


No evidence of Breeding
(transient "t")


Overwintering
(regular observations "W")


Overwintering
(at least one obs. "w")



 

(Observations spanning multiple months or years are excluded from time charts)



Migration
Based upon limited records, spring arrival occurs in May. Records indicate that birds are present through August, and fall migration begins soon after. In 1990, the presence of an individual bird was recorded at Long Pines, Carter County as late as October (Montana Bird Distribution Committee 2012).

Habitat
Limited specific information exists on habitat use by Eastern Bluebirds in Montana, but the species may generally be limited to the deciduous trees (primarily cottonwood, Populus spp.), along the rivers of eastern Montana, which can provide significant habitat where nest boxes haven't supplanted these natural nesting sites (Johnsgard 1986, Gowaty and Plissner 1998).

Other frequently used habitats can include pastures, roadsides, farmlands, meadows, yards, and other open grassy areas that might provide adequate foraging habitat (Northern Prairie Research Center 2003). Reports of breeding in the state indicate the use of nesting boxes, with other potential nesting sites including old woodpecker holes and natural cavities in riparian forests, shelterbelts, farmsteads and city parks (Johnsgard 1986, Montana Bird Distribution Committee 2012).

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.  If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2012.  Mammals of Montana.  Second edition.  Mountain Press Publishing, Missoula, Montana.  429 pp.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
No information regarding food habits exist for Eastern Bluebird in the state. Other studies outside of Montana indicate Eastern Bluebirds eat mainly insects, but will also consume other invertebrates and small fruits. Primarily a ground-forager, this bird will perch on a branch, post, or wire and swoop to catch prey items on or near the ground (Northern Prairie Research Center 2003). Orthoptera and beetles comprise a large portion of the Eastern Bluebird's diet (Terres 1980). While foraging fruit, which this species consumes primarily in late summer and into winter, the bird will land on the stalks of fruiting bushes or in trees to pluck fruit from the perch (Gowaty and Plissner 1998). Eastern Bluebirds may also be observed gleaning insects from foliage.

Ecology
No Eastern Bluebird ecological information is available from Montana. Studies from other areas in the species' range state that Eastern Bluebirds are a territorial species and are known to prefer nesting boxes that are at least 100 yards from other bluebird nests (Gowaty and Plissner 1998). Nesting territories range from 1.1 to 2.0 hectares in size, and decrease as the nesting season advances, possibly in response to an increase in food availability or the need for parents to more closely protect the nestlings (Gowaty and Plissner 1998).

Ectoparasites of the Eastern Bluebird include lice (Philopterus sialii, Ricinus sp.); mites (Analgopsis sp. and Dermanyssus prognephilus) (Gowaty and Plissner 1998); flies (Ornithomyia anchineuria); eye worms (Oxyspirura pusillae) (Gowaty and Plissner 1998); nasal mites (Sternostoma siliphilus and Boydaia spatulata) (Gowaty and Plissner 1998); and trematodes (Collyriclum faba) (Kibler 1968, Gowaty and Plissner 1998). Predation by chipmunks (Tamias sp.), and Northern Flying Squirrels (Glaucomys volans) on the Eastern Bluebird is common, the former species raids the nests and eats eggs or young. Adults, nestlings, and/or young can become prey to the House Sparrow, European Starling, domestic cat (Felis domesticus), American Black Bear (Ursus americanus), Raccoon (Procyon lotor), and American Kestrel (Falco sparverius) (Gowaty and Plissner 1998).

Reproductive Characteristics
Given the rarity of records in the state, relatively numerous nesting observations exist for Montana. The breeding records indicate that at least three eggs have been produced (when eggs have been observed) and on more than one occasion four fledglings have been noted. Four breeding accounts indicate that nesting took place in nest boxes, with breeding dates ranging from May to July (Montana Bird Distribution Committee 2012).

Management
Other than the placement of nesting boxes in appropriate habitat, no management activities designed specifically for the Eastern Bluebird in Montana are known.

References
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Citation for data on this website:
Eastern Bluebird — Sialia sialis.  Montana Field Guide.  .  Retrieved on , from