Western Bluebird
Encyclopedia
The Western Bluebird is a small thrush
, approximately 15 cm (5.9 in) to 18 cm (7.1 in) in length.
Adult males are bright blue on top and on the throat with an orange breast and sides, a brownish patch on back, and a gray belly and undertail coverts. Adult females have a duller blue body, wings, and tail than the male, a gray throat, dull orange breast, and a gray belly and undertail coverts. Immature Western Bluebirds have duller colors than the adults, they also have spots on their chest and back.
They are sometimes confused with other bluebirds, however they can be distinguished without difficulty. The Western Bluebird has a blue (male) or gray (female) throat, the Eastern Bluebird
has an orange throat, and the Mountain Bluebird
lacks orange color anywhere on its body.
areas. The year round range includes California
, southern Rocky Mountains
, Arizona
, and New Mexico
in the U.S., and as far south as the states of Oaxaca
and Veracruz
in Mexico
. The summer breeding range extends as far north as the Pacific Northwest
, British Columbia
, and Montana
. Northern birds can migrate
to the southern parts of the range; southern birds are often permanent residents.
They nest in cavities or in nest box
es, competing with Tree Swallow
s, House Sparrow
s, and European Starling
s for natural nesting locations. Because of the high level of competition, House sparrows often attack Western Bluebirds for their nests. The attacks are made both in groups or alone.
Western Bluebirds have been found to enjoy more success with nest boxes than in natural cavities. They started egg laying earlier, had higher nesting success, lower predation rates, and fledged more young in boxes than in cavities but they did not have larger clutches of eggs.
The eggs are commonly 2-8 which average 20.8 x 16.2mm. Eggs are oval shape with a smooth and glossy shell. They are pale blue to bluish white and sometimes white in color. Nestlings remain in a nest about 19-22 days before fledging.
According to genetic studies, 45% of Western Bluebirds' nests carried young that were not offspring of the male partner. In addition, Western Bluebirds will help their parents raise a new brood after their own nest fails. Western Bluebirds are also helped by other birds belonging to a different species altogether.
These birds wait on a perch and fly down to catch insects, sometimes catching them in midair. They mainly eat insect
s and berries.
Thrush (bird)
The thrushes, family Turdidae, are a group of passerine birds that occur worldwide.-Characteristics:Thrushes are plump, soft-plumaged, small to medium-sized birds, inhabiting wooded areas, and often feed on the ground or eat small fruit. The smallest thrush may be the Forest Rock-thrush, at and...
, approximately 15 cm (5.9 in) to 18 cm (7.1 in) in length.
Adult males are bright blue on top and on the throat with an orange breast and sides, a brownish patch on back, and a gray belly and undertail coverts. Adult females have a duller blue body, wings, and tail than the male, a gray throat, dull orange breast, and a gray belly and undertail coverts. Immature Western Bluebirds have duller colors than the adults, they also have spots on their chest and back.
They are sometimes confused with other bluebirds, however they can be distinguished without difficulty. The Western Bluebird has a blue (male) or gray (female) throat, the Eastern Bluebird
Eastern Bluebird
The Eastern Bluebird, Sialia sialis, is a small thrush found in open woodlands, farmlands and orchards, and most recently can be spotted in suburban areas. It is the state bird of Missouri and New York....
has an orange throat, and the Mountain Bluebird
Mountain Bluebird
The Mountain Bluebird is a medium-sized bird weighing about 2-5 ounces, with a length from 15–20 cm . They have light underbellies and black eyes. Adult males have thin bills are bright turquoise-blue and somewhat lighter beneath. Adult females have duller blue wings and tail, grey breast,...
lacks orange color anywhere on its body.
Nesting
Nesting habitat
Western Bluebird breeding habitat is semi-open country, excluding desertDesert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
areas. The year round range includes California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, southern Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
, Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, and New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
in the U.S., and as far south as the states of Oaxaca
Oaxaca
Oaxaca , , officially Estado Libre y Soberano de Oaxaca is one of the 31 states which, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided into 571 municipalities; of which 418 are governed by the system of customs and traditions...
and Veracruz
Veracruz
Veracruz, formally Veracruz de Ignacio de la Llave officially Estado Libre y Soberano de Veracruz de Ignacio de la Llave , is one of the 31 states that, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided in 212 municipalities and its capital city is...
in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. The summer breeding range extends as far north as the Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
, British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, and Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
. Northern birds can migrate
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
to the southern parts of the range; southern birds are often permanent residents.
They nest in cavities or in nest box
Nest box
A nest box, also spelled nestbox is a man-made box provided for animals to nest in. Nest boxes are most frequently utilized for wild and domesticated birds, in which case they are also called birdhouses, but some mammalian species may also use them. Birdhouses are the most common types of nest...
es, competing with Tree Swallow
Tree Swallow
The Tree Swallow, Tachycineta bicolor, is a migratory passerine bird that breeds in North America and winters in Mexico, Central America and the Caribbean. It is a very rare vagrant to western Europe....
s, House Sparrow
House Sparrow
The House Sparrow is a bird of the sparrow family Passeridae, found in most parts of the world. One of about 25 species in the genus Passer, the House Sparrow occurs naturally in most of Europe, the Mediterranean region, and much of Asia...
s, and European Starling
European Starling
The Common Starling , also known as the European Starling or just Starling, is a passerine bird in the family Sturnidae.This species of starling is native to most of temperate Europe and western Asia...
s for natural nesting locations. Because of the high level of competition, House sparrows often attack Western Bluebirds for their nests. The attacks are made both in groups or alone.
Nest type and habitat comparison
In restored forests Western Bluebirds have a higher probability of successfully fledging young than in untreated forests, but they are at greater risk of parasitic infestations. The effects on post-fledging survival are unknown.Western Bluebirds have been found to enjoy more success with nest boxes than in natural cavities. They started egg laying earlier, had higher nesting success, lower predation rates, and fledged more young in boxes than in cavities but they did not have larger clutches of eggs.
The eggs are commonly 2-8 which average 20.8 x 16.2mm. Eggs are oval shape with a smooth and glossy shell. They are pale blue to bluish white and sometimes white in color. Nestlings remain in a nest about 19-22 days before fledging.
Rearing of young
These birds wait on a perch and fly down to catch insects, sometimes catching them in midair. They mainly eat insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s and berries.
Similar species
- Eastern BluebirdEastern BluebirdThe Eastern Bluebird, Sialia sialis, is a small thrush found in open woodlands, farmlands and orchards, and most recently can be spotted in suburban areas. It is the state bird of Missouri and New York....
(Sialia sialis) - Mountain BluebirdMountain BluebirdThe Mountain Bluebird is a medium-sized bird weighing about 2-5 ounces, with a length from 15–20 cm . They have light underbellies and black eyes. Adult males have thin bills are bright turquoise-blue and somewhat lighter beneath. Adult females have duller blue wings and tail, grey breast,...
(Sialia currucoides)
External links
- Western Bluebird page at Cornell
- Western Bluebird Species Information from Bluebird Information and Awareness
- Western Bluebird videos, photos & sounds on the Internet Bird Collection
- Western Bluebird Information at USGS Patuxent Bird Identification Infocenter
- Western Bluebird slow motion hovering video