Sialia currucoides

W North America (Alaska to c Mexico); winters to Baja Calif..

The breeding range of mountain bluebird extends from central Alaska,
central Yukon Territory, southern Mackenzie District, southern
Saskatchewan, and southwestern Manitoba; south along the eastern slopes
of the Coast Ranges to northwestern and south-central California; and to
central and southeastern Nevada, northern Arizona, southern New Mexico,
western Oklahoma, Colorado, western Nebraska, North Dakota, and
northeastern North Dakota [1]. Sightings of breeding mountain bluebirds
(paired with eastern bluebirds) have been reported in Minnesota [6,56].

Mountain bluebirds winter from southern British Columbia and western
Montana south to northern Baja California and neighboring islands,
Sonora, southern Chihuahua, central Nuevo Leon, extreme southwestern
Kansas, western Oklahoma, and western Texas. Occasional sightings in
western and northern Arkansas and northern Manitoba have been reported [1].

Breeding mountain bluebirds have been sighted in Wisconsin [43].
Transient and winter resident mountain bluebirds have been reported in
Vancouver, British Columbia [65].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

AK AZ AR CA CO ID KS MN MT NE NV NM ND OK OR SD TX UT WA WI WY

AB BC MB NT SK YT

MEXICO

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: BREEDING: central Alaska, southern Yukon to southwestern Manitoba, south in mountains to California, Nevada, northern Arizona, southern New Mexico, western Oklahoma, Colorado, western Nebraska, South Dakota, and North Dakota. NON-BREEDING: southern British Columbia, western Montana, south to central Mexico, southern Texas, east, at least casually, to eastern Kansas, western Oklahoma and central Texas.

Length: 18 cm

Weight: 28 grams

See Kaufman (1992) for detailed information on identification of bluebirds.

More info for the terms: cover, natural, snag

Nesting: Mountain bluebirds often use abandoned woodpecker (Picidae)
holes in dead or dying trees as nest holes [32,45]. Other cavities used
for nesting include holes in dirt banks, abandoned swallow (Hirundae)
nests, American dipper (Cinclus mexicanus) nests, hollow fenceposts,
mailboxes, holes in buildings, and nest boxes [29]. Crevices in cliffs
and mesas are also used [45]. Entrance hole orientation does not affect
nest site use [44]. In western Montana mountain bluebirds use whitebark
pine snags for nest sites at high elevations. At lower elevations
western larch (Larix occidentalis) snags are preferred, even though
Douglas-fir and lodgepole pine (Pinus contorta) snags are more abundant.
Preferred sites are open or semi-open. Average diameter of four snags
used by mountain bluebirds was 23 inches (58 cm); snag diameters ranged
from 10 to 29 inches (25.4-74 cm) [40]. In Wyoming mountain bluebirds
used an abandoned American dipper nest on the underside of a bridge.
Mountain bluebirds frequently nest in river banks in the area [14].

Nest Boxes: In south-central Washington mountain bluebirds used nest
boxes 0.3 mile (0.5 km) or more from ponderosa pine-Oregon white oak
(Quercus garryana) stands, but also used nest boxes near trees. They
showed less of a preference for nest box location than western
bluebirds, which always used boxes near trees or other cover [29].

Foraging: Perches near open, well-lighted areas with sparse ground
cover are favored foraging sites. Dead branches are preferred to living
ones, presumably for greater prey visibility. Where natural vegetation
is tall, mountain bluebirds prefer mowed to unmowed areas. Areas with
dry, nonfertile soils, low vegetation, and much bare ground are
preferred. Mountain bluebirds forage farther from perches than the
other two bluebird species and are occasionally found in open areas with
low perch densities [45].

More info for the term: cover

Mountain bluebirds normally occupy open woodland or edge habitat with
exposed perches and fairly sparse ground cover [29,45]. They are
attracted to burned areas, particularly with dead trees and/or snags
present [32,39,40]. For more information on the relationship of
mountain bluebirds to postfire environments see FIRE EFFECTS AND USE.
Hutto and others [33] listed 19 studies reporting increased mountain
bluebird populations in partially cut or clearcut forests. In northern
Arizona ponderosa pine stands, mountain bluebirds were present on
clearcut sites but not in light, medium, and heavily cut stands or in
uncut stands [60].

In Utah mountain bluebirds are common summer residents of high valleys;
they are uncommon winter visitors to lower valleys in southern Utah [25].

More info for the terms: density, shrub

Mountain bluebird occurs in several vegetative communities and is the
most ecologically tolerant of the three bluebird species. In most
communities, areas with snags (standing dead trees) are preferred over
snagless areas.

In western North Dakota's Little Missouri National Grasslands, mountain
bluebirds were summer residents (mean density 2.3 pairs per 100 acres
[2.3/40 ha]) in ash (Fraxinus spp.) woodlands but not in cottonwood
(Populus spp.), juniper (Juniperus spp.), or pine woodlands. The ash
woodlands were in upland draws surrounded by prairie with dense shrubs
on the edges [31]. Mountain bluebirds have been observed in nearly
treeless areas of the South Dakota Badlands [45]. In the Black Hills
mountain bluebirds occupy nesting areas in ponderosa pine (P.
ponderosa) woodlands [45]. In southeastern British Columbia mountain
bluebirds were present on shrub plots within dry Douglas-fir
(Pseudotsuga menziesii) forests; a small number was present in very
young conifer stands [51]. In Montana mountain bluebirds are present in
the Douglas-fir-ponderosa pine zone and in the cedar (Thuja
spp.)-hemlock (Tsuga spp.)-spruce (Picea spp.)-grand fir (Abies grandis)
zone of the Kootenai National Forest [23]. They are also present in
whitebark pine (Pinus albicaulis) stands [40]. In northern Utah
breeding mountain bluebirds used clearcut quaking aspen (Populus
tremuloides) sites [15]. In central Nevada mountain bluebirds were
present in the interface between the aspen (Populus spp.)-white fir
(Abies concolor) zone and the upper big sagebrush (Artemisia
tridentata)-grass zone [42]. In west-central Colorado mountain
bluebirds were observed in aspen-dominated stands [53]. Mountain
bluebirds were present in west-central Colorado in severely burned
lodgepole pine (Pinus contorta) stands with standing dead trees [49].

In Arizona mountain bluebirds were active nesters in old-growth
ponderosa pine at approximately 8,500 feet (2,591 m) elevation [52].
Bent [8] compiled the following reports of mountain bluebird breeding
habitat: During the breeding season mountain bluebirds are usually
found above 7,000 feet (2,133 m) elevation in Utah, Colorado, northern
New Mexico, and Arizona where aspen (Populus spp.) groves alternate
with burned pine (Pinus spp.) forests with abundant snags. In the
Sangre de Cristo Mountains of New Mexico, breeding mountain bluebirds
occurred in open quaking aspen groves at 10,300 feet (3,139 m)
elevation; mountain bluebird families have been seen up to 12,300 feet
(3,749 m) elevation.

REFERENCES :
NO-ENTRY

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the term: forb

104 Antelope bitterbrush-bluebunch wheatgrass
105 Antelope bitterbrush-Idaho fescue
107 Western juniper/big sagebrush/bluebunch wheatgrass
109 Ponderosa pine shrubland
110 Ponderosa pine-grassland
201 Blue oak woodland
202 Coast live oak woodland
207 Scrub oak mixed chaparral
314 Big sagebrush-bluebunch wheatgrass
315 Big sagebrush-Idaho fescue
316 Big sagebrush-rough fescue
322 Curlleaf mountain-mahogany-bluebunch wheatgrass
409 Tall forb
411 Aspen woodland

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: shrub

K001 Spruce-cedar-hemlock forest
K002 Cedar-hemlock-Douglas-fir forest
K003 Silver fir-Douglas-fir forest
K004 Fir-hemlock forest
K005 Mixed conifer forest
K006 Redwood forest
K007 Red fir forest
K008 Lodgepole pine-subalpine forest
K009 Pine-cypress forest
K010 Ponderosa shrub forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K013 Cedar-hemlock-pine forest
K014 Grand fir-Douglas-fir forest
K015 Western spruce-fir forest
K016 Eastern ponderosa forest
K017 Black Hills pine forest
K018 Pine-Douglas-fir forest
K019 Arizona pine forest
K020 Spruce-fir-Douglas-fir forest
K021 Southwestern spruce-fir forest
K022 Great Basin pine forest
K023 Juniper-pinyon woodland
K024 Juniper steppe woodland
K025 Alder-ash forest
K026 Oregon oakwoods
K027 Mesquite bosque
K029 California mixed evergreen forest
K030 California oakwoods
K031 Oak-juniper woodlands
K032 Transition between K031 and K037
K033 Chaparral
K034 Montane chaparral
K038 Great Basin sagebrush
K055 Sagebrush steppe
K056 Wheatgrass-needlegrass shrubsteppe
K095 Great Lakes pine forest

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES11 Spruce-fir
FRES15 Oak-hickory
FRES17 Elm-ash-cottonwood
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES25 Larch
FRES26 Lodgepole pine
FRES27 Redwood
FRES28 Western hardwoods
FRES29 Sagebrush
FRES34 Chaparral-mountain shrub
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

1 Jack pine
5 Balsam fir
16 Aspen
21 Eastern white pine
22 White pine-hemlock
51 White pine-chestnut oak
208 Whitebark pine
210 Interior Douglas-fir
211 White fir
212 Western larch
213 Grand fir
217 Aspen
218 Lodgepole pine
220 Rocky Mountain juniper
229 Pacific Douglas-fir
230 Douglas-fir-western hemlock
237 Interior ponderosa pine
238 Western juniper
243 Sierra Nevada mixed conifer
244 Pacific ponderosa pine-Douglas-fir
245 Pacific ponderosa pine
247 Jeffrey pine
250 Blue oak-foothills pine
255 California coast live oak

Systems

• Terrestrial

Comments: Subalpine meadows, grasslands, shrub-steppe, savanna, and pinyon-juniper woodland; in south usually at elevations above 1500 m. In winter and migration also inhabits desert, brushy areas and agricultural lands. Nests are built in natural tree cavities, or abandoned woodpecker holes. May also use bird box, old swallow's nest, rock crevice, or old mammal burrow. Tree Swallows, flickers, wrens, and chickadees may compete for nest sites.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Mountain bluebirds are primarily insectivorous, but also consume fruit
when insects are inactive (in early morning and in the cooler seasons).
Contents of 66 adult mountain bluebird stomachs were 92 percent animal
matter, which was 30 percent beetles, 23 percent grasshoppers, 14.5
percent caterpillars, 13 percent ants, 8 percent weevils, 4 percent bees
and wasps, 4 percent true bugs, and less than 1 percent flies [7].

Insect Prey: In south-central Washington, beetle consumption decreased
during the nestling period. Nestling foods are mostly grasshoppers,
crickets, and caterpillars [29].

Plant Foods: Mountain bluebirds eat mistletoe (Phoradendron spp.),
hackberry (Celtis spp.), Saskatoon serviceberry (Amelanchier alnifolia),
and buffaloberry (Shepherdia spp.) berries in the nonbreeding season
[61].

Foraging Strategies: Mountain bluebirds adjust foraging strategies to
habitat and ground vegetation conditions [45]. Mountain bluebirds
usually forage from elevated perches. When prey is spotted a mountain
bluebird drops to the ground to capture it [29]. Mountain bluebirds
hover in search of prey and have been observed foraging on the ground
(hopping-gleaning) in grazed valleys with sparse vegetation [45].

Comments: Insectivorous. Feeds on beetles, ants, bees, wasps, caterpillars, grasshoppers, etc. Also consumes some berries and grapes seasonally. Hovers and drops to ground while foraging or darts out from a low perch to catch prey.

More info for the term: competition

Mountain bluebirds are preyed upon by many raptors including Cooper's
hawk (Accipiter cooperi), red-tailed hawk (Buteo jamaicensis),
sharp-shinned hawk (A. striatus), northern harrier (Circus cyaneus), and
possibly American kestrel (Falco sparverius). In addition, American
crow (Corvus brachyrhynchos) may prey on eggs, nestlings, and adults.
Adult mountain bluebirds are sometimes killed by house sparrows (Passer
domesticus) in competition for nest sites; a deer mouse (Peromyscus
maniculatus) was suspected in the death of an adult female mountain
bluebird whose nest box she had usurped. Deer mice destroy eggs and
nestlings in nest boxes, as do eastern chipmunks (Tamias striatus) and
red squirrels (Tamiasciurus hudsonicus). Nestlings have also been
destroyed by infestations of ants [37].

More info for the terms: density, fire exclusion, snag

Mountain bluebirds are strongly attracted to early postfire (1-2 years)
communities, particularly those with many standing dead trees.
Woodpecker activity in these communities provides many nest cavities
[32]. Fire initiates a tree-hole nesting cycle in Grand Teton and
Yellowstone National Parks. Woodpeckers concentrate in newly burned
areas to feed on insects (particularly bark beetles) and to nest in
standing dead trees [62], especially those with decay prior to fire
[50]. Mountain bluebirds and other secondary cavity nesters use the
holes after the woodpeckers abandon them. In northern Wyoming, northern
three-toed woodpeckers (Picoides tridactylus) and black-backed
three-toed woodpeckers (P. arcticus) begin leaving burned areas about 4
to 5 years after the fire. Hairy woodpeckers (P. villosus) continue to
excavate holes for years, until snags finally decay to the point of
falling down. At around 50 postfire years, tree-hole nesting species
usually leave the area even if a few snags are still present [62].

A 1982 study in the Little Firehole River watershed within Yellowstone
National Park indicated that mountain bluebirds were only common in a
222 acre (90 ha) area that burned in 1949. The authors speculated that
mountain bluebird numbers were high in the late 1700's and early 1800's
because up to 50 percent of the area was covered by early postfire
stands; as forests matured into the twentieth century mountain bluebird
numbers probably decreased [48]. In other areas of Yellowstone National
Park, mountain bluebirds were observed in burned areas in the first
postfire year [22]. Mountain bluebirds were associated with postfire
plots in severely burned lodgepole pine stands in Yellowstone National
Park. By the second postfire year mountain bluebirds were nesting in
holes excavated by northern three-toed woodpeckers. Peak mountain
bluebird breeding density occurred on 12-postfire year plots with a
small peak on 30-year-old plots. There were no mountain bluebirds on
57-year-old and older plots [62]. In Grand Teton National Park,
mountain bluebirds were present in the first postfire year on severely
burned plots, increasing to 15 pairs per 100 acres (15/40 ha) in the
second year. They were not observed on moderately burned or unburned
plots, or on 43-year-old burned plots [62].

In Alberta fire-originated forests dominated by quaking aspen, balsam
poplar (Populus balsamea), and lodgepole pine, mountain bluebirds were
present in 14-year-old stands but not present in stands that had been
clearcut, nor in 30-, 60-, or 80-year-old stands [66]. In Montana mountain
bluebirds increased from postfire year 2 to postfire year 4 in both
burned and burned and logged areas [24].

In California mountain bluebirds were observed in large numbers (15.2
pairs per 100 acres [15.2/40 ha]) in postfire years 5, 6, and 7 in mixed
coniferous forest. Woodpecker activity was decreasing by the time of
the study [10]. In the Sierra Nevada a severe fire occurred in a
Jeffrey pine (Pinus jeffreyi)-white fir community in 1960. Birds were
censused in 1968 and 1975. Mountain bluebird densities were highest on
burned plots with standing dead trees and openings in 1968. They were
still present on burned plots in 1975; these plots had developed dense
brushfields [11].

Later postfire communities may not be as attractive as early
successional stages; Raphael and others [47] noted a decreasing trend
for mountain bluebirds in burned habitat in the Sierra Nevada between
1966 and 1985. In Yellowstone National Park mountain bluebirds
densities 5 to 25 years after fire depend on the number of standing
snags. At 25 to 30 postfire years mountain bluebird numbers may begin
to decline depending on the rate of snag loss. From 30 to 50 postfire
years mountain bluebirds depart as canopy closure develops [63].

Based on data from Brawn and Balda [13], Hejl [26] hypothesized a
mountain bluebird population decrease in southwestern ponderosa pine
due to fire exclusion and consequent closure of forests.

More info for the terms: altricial, selection

Spring Migration: Mountain bluebirds and western bluebirds arrive in
south-central Washington at the same time of year (February to March) in
mixed flocks with approximately equal sex ratios [29]. Power [46]
however, reported that males usually arrive on Montana breeding grounds
first, from only few days to as many as 30 days before the females. The
median arrival date for males was April 8; for females, April 25 [46].
In southwestern Manitoba mountain bluebirds usually arrive in late March
[37]. In Zion National Park mountain bluebirds are summer residents
above 8,000 feet (2,438 m) elevation but move to lower elevations in
winter [8].

Nest Site Selection and Territory Defense: Mountain bluebird territory
type is Berger's type A: a large breeding area where courtship,
copulation, nesting, and food seeking occur. In south-central
Washington western bluebirds select and defend nest boxes soon after
arrival but mountain bluebirds continue to prospect. Mountain bluebirds
make nest box selection about 2 weeks after western bluebirds have
established territory but mountain bluebird nest-building activity peaks
1 week earlier than that of western bluebird [29]. Mountain bluebirds
and western bluebirds exhibit interspecific territoriality, as do
mountain bluebirds and eastern bluebirds in areas of sympatry [45].
Interspecific attempts at displacement of resident birds at nest boxes
are not usually successful [29]. In Montana pairs using nest boxes on
fenceposts or utility poles mostly stayed along the fence or utility
line and its immediate vicinity. The smallest territory was 100 yards
(91 m) wide. Some territories had no clear boundaries [46].

Clutch Size and Incubation: Typical mountain bluebird clutch size is
five or six eggs (range 3-8) [8,18,29]. Incubation, usually by the
female, lasts 13 to 14 days [18]. Some of Bent's [8] contributors
observed occasional incubation by the male.

Development of Young: Mountain bluebird hatchlings are altricial,
blind, and without feathers. Natal down appears on the second day.
Eyes begin to open by the fourth or fifth day. Mountain bluebird
nestlings are fed by both parents but usually only brooded by the
female. Mountain bluebirds fledge at about 22 to 23 days but are not
independent of parental feedings until 22 to 28 days after fledging
[18].

Double-Brooding: Mountain bluebirds often raise a second brood in the
same season [29].

Fall Migration: In Manitoba mountain bluebirds usually stay through
late October [37]. In Montana large flocks of mountain bluebirds gather
from October to November. These flocks usually stay together during
seasonal movements and over the winter [46].

In Wyoming, Finzel recorded 6-7 bluebirds/16.2 ha (Bureau of Land Management, no date).

Maximum longevity: 9 years (wild)

Clutch size 4-8 (usually 5-6). Sometimes 2 broods per year. Both sexes, primarily female, incubate about 13-14 days (Harrison 1978). Altricial young tended by both parents (may be assisted by young of first brood).

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 5 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

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Barcode of Life Data Systems (BOLDS) Stats
Public Records: 5
Specimens with Barcodes: 5
Species With Barcodes: 1

Atwood [4] compiled state status lists for small western landbirds; of
the western states, mountain bluebird was only listed by Colorado, and
its status was "undetermined."

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
• 2004
  Least Concern

Canada

Rounded National Status Rank: N5B - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

More info for the terms: cover, natural, prescribed fire, snag, tree

Savannas and open stands of mature pine are natural mountain bluebird
habitats that require recurrent fire for maintenance. Prescribed fire
is usually beneficial to mountain bluebirds, especially if it controls
shrubs and understory trees [45]. Mountain bluebird densities 5 to 25
postfire years depend on the number of standing snags with nest cavities
[63]. In Wyoming, mountain big sagebrush (Artemisia tridentata var.
vaseyana) communities, bordered by Douglas-fir and quaking aspen stands,
were burned with both spring and fall prescribed fires (not on the same
plots). Mountain bluebirds were present as nonbreeders at higher
densities on the burned plots than on unburned plots (both treatments)
[41]. In Nevada pinyon-juniper woodlands burned with prescribed fire
for 3 consecutive years, mountain bluebird populations were the same on
burned and unburned plots in the first postfire year, but were higher on
burned plots in the second year. Nest cavities were lost to the fire
the first year, but by the second season cavity numbers were increasing
[38].

Some bird species are eliminated from burned areas, but other species
are attracted to them, creating a similar amount of species diversity
[17]. Prescribed fire in Wind Cave National Park, South Dakota,
temporarily improved foraging habitat for mountain bluebirds by reducing
surface cover. There was little change in overall tree and snag density
on these sites [12]. Burned areas less than 5 years old, particularly
those that had severely burned, are highly valuable for many cavity
nesting species including mountain bluebirds [62]. For enhancement of
wildlife habitat it is strongly recommended that severely burned areas
be allowed to develop naturally rather than be subject to salvage
logging. When salvage is considered essential (for sanitary reasons or
as a firebreak), it is recommended that a substantial area be left uncut
rather than thinning the entire burn [32].

More info for the terms: competition, cover, density, natural

Population Status and Trends: In the early 1900's the range of mountain
bluebird expanded east into the Great Plains [45]. Herlugson [28]
suggested that in this century, mountain bluebird has replaced western
bluebird as the predominant bluebird in the Northwest. Changes in
relative abundance of mountain bluebird and western bluebird in areas of
sympatry are probably caused by changes in the openness of the
landscape. Grazing reduces herb density and may benefit mountain
bluebird at the expense of western bluebird. Mountain bluebird probably
benefits more from logging than either eastern or western bluebird [45].
In Arizona Szaro [58] recorded the replacement of western bluebird by
mountain bluebird following clearcutting in ponderosa pine forests.
Sharp [54] indicated that mountain bluebird populations increased in
juniper woodlands in Oregon between 1899 and 1983. Johnson [34]
reported an increasing trend for mountain bluebird in Nevada between
1939 and 1973. DeSante and George [16], however, listed mountain
bluebirds as decreasing in Alberta and Nevada in the last 100 years. In
northern Idaho populations of secondary cavity nesters including
mountain bluebird have been declining since the early 1970's as
suitable breeding areas are lost to agricultural expansion [67]. Hejl
[26] hypothesized that species associated with burns and/or snags, such
as mountain bluebird, are less abundant than they were 100 years ago;
nest site availability is a limiting factor in mountain bluebird
productivity [29].

Nest-site Competition: Interspecific competition for nest cavities has
probably contributed to the decline of some mountain bluebird
populations in this century. Primary competitors include northern
flicker (Cloaptes auratus), swallows, and, since their introduction from
Europe, house sparrows and European starlings (Sturnus vulgaris)
[18,29]. Competition with European starlings for nest sites has
probably contributed to mountain bluebird population decline in Utah
[25]. Nest boxes in south-central Washington are used by other species
including violet-green swallows (Tachycinera thalassina), deer mice, and
yellow-pine chipmunks (Tamias amoenus) [29]. Other nest-site
competitors include eastern and western bluebirds in areas of sympatry,
particularly in the Great Plains grasslands where eastern and mountain
bluebirds have expanded their ranges [45].

Management Recommendations: Mountain bluebirds prefer open habitats;
throughout their range they are always more abundant in recent clearcuts
than in uncut forest [27]. In northern Utah mountain bluebirds were
visitors on quaking aspen study sites prior to timber harvest but
returned as breeders to clearcut areas. Apparently, clearcutting small
patches provides more open habitat adjacent to uncut forest; this
improves foraging habitat for mountain bluebirds while retaining
sufficient numbers of cavities for nesting [15]. Also in Utah mountain
bluebirds were only observed in a 17-year-old clearcut that had been
bulldozed and broadcast burned after harvest. At the time of the census
the stand consisted of lodgepole pine about 6 to 15 feet (1.8-4.6 m)
tall with a moderately dense, forb-dominated ground cover. Mountain
bluebirds were not observed in a 37-year-old clearcut, mature forest,
stagnated forest, wet meadow, or dry meadow [5]. An unpublished report
described by Astroth and Frischknecht [3] indicated that mountain
bluebirds declined immediately after removal of pinyon (Pinus
spp.)-juniper woodlands (for range improvement) but returned to
pretreatment levels in 1 year. Szaro and Balda [59] suggested that for
northern Arizona ponderosa pine communities, removal of one-sixth to
two-thirds of available foliage either in strips or by thinning is not
detrimental to breeding bird communities in terms of species richness,
density, or diversity. The species present in disturbed communities
are, however, different from those of undisturbed communities.

Any management plan should consider the importance of snags for wildlife
[39]. Hutto [32] emphasized the importance of snags for cavity nesters.
It is generally recommended that all natural snags be left during timber
harvest operations unless they pose immediate safety hazards [32,45,52].
Mature and decadent living trees should be left as well to provide snags
in the future [45]. Salvage cutting of burned forest is detrimental to
cavity nesting species, particularly woodpeckers and secondary cavity
nesters such as mountain bluebirds [32]. McClelland and others [40]
recommend leaving old-growth components within harvested areas. For
example for every 1,000 acres (405 ha) management unit, they recommended
leaving 50 to 100 acres (20-40.5 ha) uncut (old growth) for wildlife
feeding areas; on the remaining acreage logs, snags, and cull trees
should be left. Firewood cutting should be limited to snags less than
15 inches (38 cm) d.b.h. [40].

Nest Box Programs: Nest boxes resulted in a substantial increase in
breeding mountain bluebird densities in northern Idaho study plots [67].
In south-central Washington nest box placements have also resulted in
breeding density increases. Nest box fidelity is fairly high,
particularly among successful breeders (68.2%). Unsuccessful breeders
(5 individuals in this study) had a lower rate of nest box fidelity:
two used the same box, one changed territory but not box type, and two
changed territory and box type [30]. Nest boxes for mountain bluebirds
in southwestern ponderosa pine forests should be placed along forest
edges or in grassy glades within open forests. Mountain bluebirds use
large nest boxes with 3-inch (7.6 cm) holes if no other sites are
available [21].

REFERENCES :
NO-ENTRY

Restoration Potential: See Mitchell (1988) for specifications for the construction and placement of nest boxes.