Black-crowned night heron
The Black-crowned night heron, commonly shortened to just night heron in Eurasia, is a medium-sized heron found throughout a large part of the world, except in the coldest regions and Australasia. Adults are approximately 64 cm long and weigh 800 g and they have a black crown and back with the remainder of the body white or grey, red eyes, and short yellow legs. They have pale grey wings and white under parts, two or three long white plumes, erected in greeting and courtship displays, extend from the back of the head. The sexes are similar in appearance although the males are slightly larger, Black-crowned night herons do not fit the typical body form of the heron family. They are relatively stocky with shorter bills and necks than their more familiar cousins and their resting posture is normally somewhat hunched but when hunting they extend their necks and look more like other wading birds. Immature birds have dull grey-brown plumage on their heads and their underparts are paler and streaked with brown.
The young birds have orange eyes and duller yellowish-green legs and they are very noisy birds in their nesting colonies, with calls that are commonly transcribed as quok or woc. The breeding habitat is fresh and salt-water wetlands throughout much of the world, Black-crowned night herons nest in colonies on platforms of sticks in a group of trees, or on the ground in protected locations such as islands or reedbeds. Three to eight eggs are laid and this heron is migratory in the northernmost part of its range, but otherwise resident. The North American population winters in Mexico, the southern United States, Central America, and the West Indies, a colony of the herons has regularly summered at the National Zoo in Washington, D. C. for more than a century. These birds stand still at the edge and wait to ambush prey. They primarily eat small fish, frogs, aquatic insects, small mammals, during the day they rest in trees or bushes. N. n. hoactli is more gregarious outside the season than the nominate race. A thorough study performed by J.
Sitko and P. Heneberg in the Czech Republic in 1962–2013 suggested that the central European black-crowned night herons host 8 helminth species, the dominant species consisted of Neogryporhynchus cheilancristrotus, Contracaecum microcephalum and Opistorchis longissimus. The mean number of species recorded per host individual reached 1.41. Nycticorax means night raven and derives from the Ancient Greek nuktos night and korax and it refers to the largely nocturnal feeding habits and croaking crow-like call of this species. Black-crowned night heron on Animal Diversity Web Stiles, F. Gary, Skutch, a Guide to the Birds of Costa Rica. Herons and Egrets of the World, ISBN 978-0-679-45122-8. com Field Guide on Flickr Images and information of the black-crowned night heron from Portugal Black-crowned night-heron media
The striped skunk is a skunk of the genus Mephitis that is native to southern Canada, the United States and northern Mexico. It is currently listed as least concern by the IUCN on account of its wide range and it is a polygamous omnivore with few natural predators, save for birds of prey. The striped skunk has a history of association with humans, having been trapped and captively bred for its fur. It is one of the most recognizable of North Americas animals, the striped skunk is a stoutly-built, short-limbed animal with a small, conical head and a long, heavily furred tail. Adult males are 10% larger than females, with both sexes measuring between 52–77 cm in body length and usually weighing 1. 8–4.5 kg. The feet are plantigrade with bare soles, and are not as broad or flat as those of hog-nosed skunks, the forefeet are armed with five long, curved claws adapted for digging, while those on the hind feet are shorter and straighter. Some specimens have a patch on the chest, while others bear white stripes on the outer surface of the front limbs.
Brown or cream-colored mutations occasionally occur, like all skunks, the striped skunk possesses two highly developed scent glands, one on each side of the anus, containing about 15 milliliters of musk each. This oily, yellow-colored musk consists of a mixture of powerfully odorous thiols, if sprayed on the eyes, this compound can cause a temporary burning sensation. The English word skunk has two words of Algonquian and Iroquoian origin, specifically seganku and scangaresse. The Cree and Ojibwe word shee-gawk is the word for Chicago. Alternative English names for the striped skunk include common skunk, Hudsonian skunk, northern skunk, black-tailed skunk, the latter name was originally used by English settlers, who noted the animals similarity to the European polecat. This association likely resulted in the striped skunks subsequent unfavorable reputation as a poultry thief, the name Alaska sable was employed by furriers during the late 19th century. The earliest fossil attributable to Mephitis were found in the Broadwater site in Nebraska.
Phylogenetic analyses of the cytochrome b gene and microsatellite data in 2012 indicated that there are four phylogroups of striped skunk. The first emerged from the Texas-Mexico region during the Rancholabrean before the Illinoian glaciation, the second, still originating in the Texas-Mexico region, expanded westwards to the Rocky Mountains during the Illinoian glacial period. Two subsequent subclades were formed during the Sangamonian interglacial on either side of the Sierra Nevada, a similar, but less significant, secondary contact occurred when the same subclade intermingled with members of the eastern phylogroup east of the Mississippi river. The mating season occurs between mid-February to mid-April, though it is delayed at higher latitudes
Land that is more severely contaminated and has high concentrations of hazardous waste or pollution, such as a Superfund site, does not fall under the brownfield classification. After clean up, such an area can become a community park or business development, the term brownfields first came into use on June 28,1992, at a U. S. congressional field hearing hosted by the Northeast Midwest Congressional Coalition. Also in 1992, the first detailed analysis of the issue was convened by the Cuyahoga County Planning Commission. The United States Environmental Protection Agency selected Cuyahoga County as its first brownfield pilot project in September 1993, the term applies more generally to previously used land or to sections of industrial or commercial facilities that are to be upgraded. Brownfield land is an area of previously used or built upon, as opposed to greenfield land. Land that is severely contaminated and has high concentrations of hazardous waste or pollution, such as a Superfund site.
Mothballed brownfields are properties that the owners are not willing to transfer or put to productive reuse, Brownfield status is a legal designation which places restrictions, conditions or incentives on redevelopment and use on the site. In the United Kingdom, the term brownfield has a meaning roughly equivalent to the American usage described above, i. e. vacant or derelict land or property. In terms of British Town and Country Planning, the meaning of brownfield is more complex, small brownfields may be found in older residential neighborhoods, as for example dry cleaning establishments or gas stations produced high levels of subsurface contaminants. Typical contaminants found on contaminated brownfield land include hydrocarbon spillages, pesticides, heavy metals such as lead, tributyl tins, old maps may assist in identifying areas to be tested. The primary issue facing all nations involved in attracting and sustaining new uses to brownfield sites is that industries are globally oriented and this directly affects brownfield reuse, such as limiting the effective economic life of the use on the revitalized sites.
United States estimates suggest there are over 500,000 brownfield sites contaminated at levels below the Superfund caliber in the country, the Clinton-Gore administration and US EPA launched a series of brownfield policies and programs in 1993 to tackle this problem. Canada has an estimated 200,000 contaminated sites across the nation, the provincial governments have primary responsibility for brownfields. The provinces´ legal mechanisms for managing risk are limited, as there are no tools such as No Further Action letters to property owners finality and certainty in the cleanup. Yet, Canada has cleaned up sites and attracted investment to contaminated lands such as the Moncton rail yards, a strip of the Texaco lands in Mississauga is slated to be part of the Waterfront Trail. However, Imperial Oil has no plans to sell the 75-acre property which has been vacant since the 1980s.9 billion. The report listed significant sites called the Big Five with a liability of $1.8 billion, Faro mine, Colomac Mine, Giant Mine, Cape Dyer-DEW line, the Port Hope, Ontario site has a liability of $1 billion.
By 2010 it was projected that it would cost well over a billion dollars for the remediation project
The northern mockingbird is the only mockingbird commonly found in North America. This bird is mainly a permanent resident, but northern birds may move south during harsh weather and this species has rarely been observed in Europe. This species was first described by Linnaeus in his Systema Naturæ in 1758 as Turdus polyglottos, the northern mockingbird is known for its mimicking ability, as reflected by the meaning of its scientific name, many-tongued mimic. The northern mockingbird has gray to brown upper feathers and a paler belly and its tail and wings have white patches which are visible in flight. The northern mockingbird is an omnivore and it eats both insects and fruits. It is often found in areas and forest edges but forages in grassy land. The northern mockingbird breeds in southeastern Canada, the United States, northern Mexico, the Bahamas, the Cayman Islands and it is replaced further south by its closest living relative, the tropical mockingbird. The Socorro mockingbird, a species, is closely related.
The northern mockingbird is listed as of Least Concern according to the International Union for Conservation of Nature, the northern mockingbird is known for its intelligence and has been noted in North American culture. A2009 study showed that the bird was able to recognize individual humans, birds recognize their breeding spots and return to areas in which they had greatest success in previous years. Urban birds are likely to demonstrate this behavior. Finally, the mockingbird has influenced United States culture in multiple ways, the bird is a state bird of five different states, has been used in book titles, and has been used in popular songs and lullabies among other appearances in U. S. culture. Swedish zoologist Carl Linnaeus first described species in his Systema Naturae in 1758 as Turdus polyglottos. The northern mockingbird is considered to be conspecific with the tropical mockingbird and this species is categorized as the northern mockingbird as the closest living relative to M. gilvus.
There are three recognized subspecies for the northern mockingbird, there have been proposed races from the Bahamas and Haiti placed under the orpheus section. M. p. polyglottos, generally found in the portion of North America ranging from Nova Scotia to Nebraska, to as far south as Texas. M. p. leucopterus Western Mockingbird, generally found in the portion of North America ranging from NW Nebraska and Western Texas to the Pacific Coast, and south to Mexico. Larger than M. p. polyglottos and has a shorter tail, upperparts are more buff and paler
Eschscholzia californica is a species of flowering plant in the Papaveraceae family, native to the United States and Mexico. It is a plant and it is used medicinally and in cooking. It is a perennial or annual plant growing to 5–60 in tall with alternately branching glaucous blue-green foliage, the leaves are alternately divided into round, lobed segments. The petals close at night and open again the following morning, the fruit is a slender, dehiscent capsule 3 to 9 cm long, which splits in two to release numerous small black or dark brown seeds. It survives mild winters in its range, dying completely in colder climates. Its native habitat includes California and extends to Oregon, Nevada, New Mexico, the Antelope Valley California Poppy Reserve is located in northern Los Angeles County. At the peak of the season, orange flowers seem to cover all 1,745 acres of the reserve. Other prominent locations of California poppy meadows are in Bear Valley, California poppy is highly variable, with over 90 synonyms.
Some botanists accept two subspecies — one with four varieties — though others do not recognize them as distinct, native to California, Baja California, and Oregon, widely planted as an ornamental, and an invasive elsewhere. Californica var. californica, which is found along the coast from the San Francisco Peninsula north and they are perennial and somewhat prostrate, with yellow flowers. Californica var. maritima Jeps. which is found along the coast from Monterey south to San Miguel Island and they are perennial, long-lived, short in stature, and have extremely prostrate growth and yellow flowers. Californica var. crocea Jeps. which grows in inland regions. They are perennial and have orange flowers, californica var. peninsularis Munz, which is an annual or facultative annual growing in arid inland environments. Clark, the Mexican Gold Poppy, which is found in the Sonoran Desert, some authorities refer to it as E. Mexicana. California poppy leaves were used medicinally by Native Americans and the pollen was used cosmetically, the plant is used as an herbal remedy, an aqueous extract of the plant has sedative and anxiolytic actions.
The extract induced peripheral analgesic effects in mice but did not possess antidepressant, E. californica is drought-tolerant, self-seeding, and easy to cultivate. It is best grown as an annual in full sun and sandy, well-drained, horticulturalists have produced numerous cultivars with a range of colors and blossom and stem forms. These typically do not breed true on reseeding, seeds are often sold as mixtures
The Muscovy duck is a large duck native to Mexico and South America. Feral Muscovy ducks are found in New Zealand and they are large ducks, with the males about 76 cm long, and weighing up to 7 kg. Females are considerably smaller, and only grow to 3 kg, the bird is predominantly black and white, with the back feathers being iridescent and glossy in males, while the females are more drab. The amount of white on the neck and head is variable, as well as the bill and they may have white patches or bars on the wings, which become more noticeable during flight. Both sexes have pink or red wattles around the bill, those of the male being larger, although the Muscovy duck is a tropical bird, it adapts well to cooler climates, thriving in weather as cold as −12 °C and able to survive even colder conditions. In general, Barbary duck is the used for C. moschata in a culinary context. The domestic breed, Cairina moschata domestica, is known in Spanish as the pato criollo. They have been bred since pre-Columbian times by Native Americans and are heavier and their plumage color is more variable.
Other names for the breed in Spanish are pato casero. All Muscovy ducks have long claws on their feet and a flat tail. In the domestic drake, length is about 86 cm and weight is 4. 6–6.8 kg, while the hen is much smaller. Large domesticated males often weigh up to 8 kg, and large domesticated females up to 5 kg, the true wild Muscovy duck, from which all domesticated Muscovys originated, is blackish, with large white wing patches. Length can range from 66 to 84 cm, wingspan from 137 to 152 cm, on the head, the wild male has short crest on the nape. The bill is black with a speckling of pale pink, a blackish or dark red knob can be seen at the bill base, and the bare skin of the face is similar to that in color. The legs and webbed feet are blackish, the wild female is similar in plumage, but is much smaller, and she has feathered face and lacks the prominent knob. The juvenile is overall, with little or no white on the upperwing. Domesticated birds may look similar, most are brown or black mixed with white.
Other colors such as lavender or all-white are seen, both sexes have a nude black-and-red or all-red face, the drake has pronounced caruncles at the base of the bill and a low erectile crest of feathers
Washingtonia filifera, known as desert fan palm, California fan palm or California palm, is a flowering plant in the palm family, and native to the southwestern U. S. and Baja California. Growing to 15–20 m tall by 3–6 m broad, it is a monocot with a tree-like growth habit. It has a columnar trunk and waxy fan-shaped leaves. Other common names include California fan palm and petticoat palm, the specific epithet filifera means thread-bearing. Washingtonia filifera is the only native to the Western United States. Primary populations are found in riparian habitats at spring-fed and stream-fed oases in the Colorado Desert. It is a species in the warm springs near Death Valley. It is naturalized in the Southeast, Hawaii, the U. S. Virgin Islands. Washingtonia filifera grows to 18 metres in height in ideal conditions, the California Fan Palm Tree is known as the Desert Fan Palm, American Cotton Palm and Arizona Fan Palm. The fronds are up to 3. 5–4 metres long, made up of a petiole up to 2 metres long, bearing a fan of leaflets 1. 5–2 metres long.
They have long white fibers and the petioles are pure green with yellow edges and filifera-filaments. The trunk is gray and tan and the leaves are gray green, when the fronds die they remain attached and drop down to cloak the trunk in a wide skirt. The shelter that the skirt creates provides a microhabitat for many small birds, if there is any red color present on petioles or trunk it is not a pure filifera but a fila-busta hybrid. Washingtonia filifera can live from 80 to 250 years or more, Desert fan palms provide habitat for the giant palm boring beetle, western yellow bat, hooded oriole and many other bird species. Hooded orioles rely on the trees for food and places to build nests, numerous insect species visit the hanging inflorescences that appear in late spring. The palm boring beetle Dinapate wrightii can chew through the trunks of this as well as other palms, eventually a continued infestation of beetles can kill various genera and species of palms. The recent discovery of the red palm weevil in Southern California may pose a threat to many palms, however, it seems that this species is resistant to the red palm weevil through a mechanism based on antibiosis.
Currently the desert fan palm is experiencing a population and range expansion, natural oases are mainly restricted to areas downstream from the source of hot springs, though water is not always visible at the surface
Great blue heron
It is a rare vagrant to coastal Spain, the Azores, and areas of far southern Europe. An all-white population found only in the Caribbean and Florida was once treated as a separate species, the great blue heron was one of the many species originally described by Carl Linnaeus in his 18th-century work, Systema Naturae. The scientific name comes from Latin ardea, and Ancient Greek erodios and it forms a superspecies with this and with the cocoi heron from South America, which differs in having more extensive black on the head, and a white breast and neck. It has head-to-tail length of 91–137 cm, a wingspan of 167–201 cm, a height of 115–138 cm, in British Columbia, adult males averaged 2.48 kg and adult females 2.11 kg. The feathers on the neck are long and plume-like, it has plumes on the lower back at the start of the breeding season. The bill is yellowish, becoming orange briefly at the start of the breeding season. Immature birds are duller in color, with a dull blackish-gray crown, and the pattern is only weakly defined, they have no plumes.
Among standard measurements, the chord is 43–49.2 cm, the tail is 15. 2–19.5 cm, the culmen is 12. 3–15.2 cm. The herons stride is around 22 cm, almost in a straight line, two of the three front toes are generally closer together. In a track, the front toes, as well as the back, the subspecies differ only slightly in size and plumage tone, with the exception of subspecies A. h. occidentalis, which has a distinct white morph, known as the great white heron. It is found only in south Florida and some parts of the Caribbean, the great white heron differs from other great blues in bill morphology, head plume length, and in having a total lack of pigment in its plumage. It averages somewhat larger than the sympatric race A. h. wardi and may be the largest race in the species. In a survey of A. h. occidentalis in Florida, males were found to average 3.02 kg and females average 2.57 kg and this is mainly found near salt water, and was long thought to be a separate species. Birds intermediate between the normal morph and the white morph are known as Würdemanns heron, these birds resemble a normal great blue with a white head.
The theory that great white herons may be a species from great blue heron has again been given some support by David Sibley. The great white heron could be confused with great egret, but is larger, the reddish egret and little blue heron could be mistaken for the great blue heron, but are much smaller, and lack white on the head and yellow in the bill. In the southern reaches of its range, the great blue sometimes overlaps in range with the closely related, the cocoi is distinguished by a striking white neck and solid black crown, but the duller juveniles are more easily confused. More superficially similar is the slightly smaller grey heron, which may sometimes vagrate to the coasts of North America
Western fence lizard
The western fence lizard is a common lizard of Arizona, Idaho, Oregon, Washington, Northern Mexico, and the surrounding area. As the ventral abdomen of an adult is characteristically blue, it is known as the blue-belly. It is a member of the genus Sceloporus, taxonomy for the western fence lizard has been under much debate. S. occidentalis belongs in the order Squamata and the suborder Iguania, the family in which it belongs is still under scrutiny. Most literature, still place the phrynosomatids in Iguanidae, recent work in molecular systematics has suggested there are four clades and 11 genetically separable populations, and the subspecies will probably have to be redefined. Western fence lizards measure 5. 7-8.9 cm and a length of about 21 cm. They are brown to black in color and have black stripes on their backs, the ventral sides of the limbs are yellow. These lizards have patches on their throats. This bright coloration is faint or absent in females and juveniles. In some populations the males display iridescent, bright blue spots on the dorsal surface.
The scales of S. occidentalis are sharply keeled, and between the interparietal and rear of thighs, there are 35-57 scales, many other lizards have similar bright-blue coloring. The eastern fence lizard, S. undulatus, instead of having one large patch on its throat, has two small patches, the sagebrush lizard, S. graciosus, lacks yellow limbs and has smaller dorsal scales. S. occidentalis resembles the side-blotched lizard, Uta stansburiana, the axilla of U. stansburiana usually has a black spot behind it and it has a complete gular fold. There is a population in the Northwestern Tualitin Valley. The western fence lizard occupies a variety of habitats and it is found in grassland, broken chaparral, woodland, coniferous forest, and farmland, and occupies elevations from sea level to 10,800 ft. They generally avoid the desert and are often found near water. As of now, the fence lizard is listed as unprotected. They protect themselves by employing their fast reflexes, which are common in other lizards including biting
The desert cottontail, known as Audubons cottontail, is a New World cottontail rabbit, and a member of the family Leporidae. The desert cottontail is found throughout the western United States from eastern Montana to western Texas, westwards its range extends to central Nevada and southern California and Baja California. It is found at heights of up to 2,000 m and it is particularly associated with the dry near-desert grasslands of the American southwest, though it is found in less arid habitats such as pinyon-juniper forest. The desert cottontail is quite similar in appearance to the European rabbit and it is social among its peers, often gathering in small groups to feed. The desert cottontail uses burrows made by rodents rather than making its own, like all cottontail rabbits, the desert cottontail has a rounded tail with white fur on the underside which is visible as it runs away. It is a light grayish-brown in color, with almost white fur on the belly, adults are 33 to 43 cm long and weigh up to 1.5 kg.
The ears are 8 to 10 cm long, and the feet are large. There is little sexual dimorphism, but females tend to be larger than the males, the desert cottontail is not usually active in the middle of the day, but it can be seen in the early morning or late afternoon. It mainly eats grass, but will eat other plants, vegetables. It rarely needs to drink, getting its water mostly from the plants it eats or from dew, like most lagomorphs, it is coprophagic, re-ingesting and chewing its own feces, this allows more nutrition to be extracted. Southwestern Native Americans hunted them for meat but used their fur, the cottontails normal anti-predator behavior is to run away in evasive zigzags, it can reach speeds of over 30 km/h. The young are born in a burrow or above ground, but they are helpless when born. Where climate and food supply permit, females can produce several litters a year, unlike the European rabbit, they do not form social burrow systems, but compared with some other leporids, they are extremely tolerant of other individuals in their vicinity.
The lifespan of a cottontail averages about two years, depending on the location, unfortunately for the cottontail, almost every living carnivorous creature larger or faster than the Lagomorph is its predator. Cottontail lagomorphs borrow burrows that have been vacated by other animals and she is defenseless against any and all that would get close enough to eat her or her young. Though cottontails are very sexually active creatures, and mated pairs have several offspring many times in all seasons and those that do manage to avoid being eaten, grow very quickly and are considered full grown adults at three months. It can only use its nose to move and adjust the position of the food that it directly in front of its front paws on the ground. The cottontail rabbit will turn the food with its nose to find the cleanest part of the vegetation to begin its meal, the only time a cottontail uses its front paws to enable eating is when vegetation is above its head on a living plant
Union Pacific Railroad
The Union Pacific Railroad is a freight hauling railroad that operates 8,500 locomotives over 32,100 route-miles in 23 states west of Chicago and New Orleans, Louisiana. The Union Pacific Railroad network is the largest in the United States and it is one of the worlds largest transportation companies. Union Pacific Railroad is the operating company of Union Pacific Corporation. Union Pacific Corporations main competitor is the BNSF Railway, the second largest freight railroad. Together, the two railroads have a duopoly on all freight rail lines in the U. S. The original company was incorporated on July 1,1862, under an act of Congress entitled Pacific Railroad Act of 1862. The act was approved by President Abraham Lincoln, and it provided for the construction of railroads from the Missouri River to the Pacific as a war measure for the preservation of the Union. It was constructed westward from Council Bluffs, Iowa to meet the Central Pacific Railroad line, the line was constructed primarily by Irish labor who had learned their craft during the recent Civil War.
The two lines were joined together at Promontory Summit, Utah,53 miles west of Ogden on May 10,1869, hence creating the first transcontinental railroad in North America. Under the guidance of its dominant stockholder Dr. Thomas Clark Durant, the namesake of the city of Durant, the first rails were laid in Omaha. It built or purchased local lines that gave it access to Denver, Colorado, to Portland, Oregon and it owned narrow gauge trackage into the heart of the Colorado Rockies and a standard gauge line south from Denver across New Mexico into Texas. UP was entangled in the Crédit Mobilier scandal, exposed in 1872 and its independent construction company the Crédit Mobilier had bribed congressmen. The UP itself was not guilty but it did get bad publicity, the financial crisis of 1873 led to financial troubles but not bankruptcy. The company was reorganized as the Union Pacific Railway on January 24,1880, the new company declared bankruptcy during the Panic of 1893. When it emerged in 1897 it reverted to the original name, the corporate headquarters of the Union Pacific Corporation were located in New York City from its initial founding in the 1860s until Drew Lewis became CEO in the mid-1980s.
He relocated it to Bethlehem, the headquarters was shifted to Dallas, before relocating to Omaha to join the operating headquarters. From the ICC annual reports, except 1979 is from Moodys, on December 31,1925 UP-OSL-OWRN-LA&SL-StJ&GI operated 9,834 route-miles and 15,265 track-miles. At the end of 1980, Union Pacific operated 9,266 route-miles and 15,647 miles of track, Moodys shows 220,697 million revenue ton-miles in 1993 on the expanded system
The western bluebird is a small thrush, about 15 to 18 cm in length. Adult males are blue on top and on the throat with an orange breast and sides, a brownish patch on back. Adult females have a blue body and tail than the male, a gray throat, a dull orange breast. Immature western bluebirds have duller colors than the adults, they have spots on their chest and these color patterns help play a part in the mating ritual, when males compete for breeding rights to females. They are sometimes confused with other bluebirds, but they can be distinguished without difficulty, the western bluebird has a blue or gray throat, the eastern bluebird has an orange throat, and the mountain bluebird lacks orange color anywhere on its body. It has a build, and a thin straight beak with a fairly short tail. Its posture consists of perching upright on wire fences and high perches, the western bluebird pounces on the ground when looking for food, such as worms and berries. It flies to catch prey, like insects, when available.
The western bluebird consumes water from streams and commonly used bird baths. The year-round range includes California, the southern Rocky Mountains and New Mexico in the United States, the summer breeding range extends as far north as the Pacific Northwest, British Columbia, and Montana. Northern birds can migrate to the parts of the range. They nest in cavities or in nest boxes, competing with tree swallows, house sparrows, because of the high level of competition, house sparrows often attack western bluebirds for their nests. The attacks are both in groups or alone. Attacks by starlings can be reduced if the nesting box opening is kept to 1.5 in diameter to avoid takeover. Nest boxes come into effect when the species is limited and dying out due to the predators, raccoons, possums. Ants, bees and wasps can crawl into the nesting boxes, Western bluebirds are among the birds that nest in, or holes in trees, or nest boxes. Their s are too weak and small to dig out their own holes, 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 and they have been found to enjoy more success with nest boxes than in natural cavities