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Bluebird

Bluebirds are a North American genus (Sialia) of three medium-sized thrush species in the family Turdidae, characterized by their striking blue plumage, particularly in males, and primarily insectivorous or omnivorous diets.^[1] These passerine birds, including the eastern bluebird (S. sialis), western bluebird (S. mexicana), and mountain bluebird (S. currucoides), are secondary cavity nesters that readily adapt to human-modified landscapes through the use of artificial nest boxes.^[2] Known for their melodic calls and vibrant colors, bluebirds symbolize hope and happiness in various cultural traditions, and their populations have rebounded significantly due to conservation efforts.^[3] The eastern bluebird (Sialia sialis), the most widespread species, inhabits open woodlands, farmlands, orchards, and suburban areas across eastern North America, from southern Canada to Central America.^[4] Males display brilliant royal blue upperparts with a rusty red-brown breast and white underparts, while females are duller with grayish-blue tones; both sexes measure about 16–21 cm in length and weigh 27–34 g.^[5] These birds forage by perching and dropping to the ground for insects like beetles and grasshoppers, supplemented by wild fruits and berries, especially in winter.^[5] Breeding occurs in cavities from March to July, with clutches of 3–7 eggs incubated primarily by the female; their population, estimated at 23 million mature individuals (as of 2019), has increased thanks to nest box programs combating historical declines from habitat loss and competition with invasive species like house sparrows.^[3]^[6] The western bluebird (Sialia mexicana) occupies open woodlands, forest edges, and oak savannas in the western United States and Mexico, with a breeding population of approximately 7.1 million mature individuals (as of 2019).^[7]^[8] Slightly smaller than the eastern species at 16.5–19 cm and 24–31 g, males feature deep blue upperparts, a cinnamon-red breast, and gray belly, whereas females are grayer overall.^[9] They consume a mix of insects, such as flies and caterpillars, and berries, often hunting by flycatching from perches; breeding involves 1–3 broods per year in natural or artificial cavities, with eggs numbering 3–6.^[10] Like their eastern counterparts, western bluebirds have benefited from conservation, maintaining stable or increasing trends in suitable habitats.^[11] The mountain bluebird (Sialia currucoides), the state bird of Idaho and Nevada, thrives in open montane meadows, grasslands, and aspen groves across the Rocky Mountains and Great Basin, migrating to lower elevations in winter.^[12] This species is the most aerial of the bluebirds, with males exhibiting uniform sky-blue plumage and females showing gray-brown tones with blue wings and tail; they span 15.5–18 cm and weigh 24–37 g.^[13] Their diet emphasizes flying insects like grasshoppers and spiders, captured mid-air, alongside berries and small vertebrates; they nest in tree cavities or cliffs, laying 4–8 eggs per clutch from April to August.^[14] With a population of approximately 6 million mature individuals (as of 2016) and a stable to increasing trend, mountain bluebirds face threats from habitat fragmentation but are resilient in expansive western landscapes.^[15]^[16]

Taxonomy and classification

Etymology and naming

The name "bluebird" is a compound word derived from Old English "blāw," meaning blue, and "brid," referring to a young bird or nestling, first appearing in English in the late 17th century to describe North American thrushes with striking blue plumage.^[17] Early European settlers in North America, upon encountering these birds, initially dubbed them "blue robins" due to their size, rusty breast, and cheerful demeanor reminiscent of the familiar European robin (Erithacus rubecula), but the name evolved to "bluebird" to emphasize their vibrant azure upperparts.^[18]^[19] In scientific nomenclature, the bluebirds were formally classified by Swedish naturalist Carl Linnaeus in the 10th edition of Systema Naturae in 1758, under the binomial Motacilla sialis for the eastern bluebird. The genus Sialia—derived from the Greek sialis, denoting a type of bird—was introduced by English ornithologist William Swainson in 1827, with S. sialis as the type species; the western bluebird (Sialia mexicana Swainson, 1827) and mountain bluebird (Sialia currucoides (Bechstein, 1798)) received similar binomials. This genus name reflects their placement within the thrush family Turdidae, underscoring their thrush-like characteristics.^[20]^[21]^[22]^[23] Among North American indigenous peoples, bluebirds held cultural significance and were referred to by names that often evoked their color or symbolic role, later translated into English as "bluebird." For instance, the Navajo term "Doli" directly means bluebird, while the Hopi name "Chosovi" also translates to bluebird, reflecting the bird's association with spring renewal and good fortune in these traditions.^[24]^[25]

Phylogenetic relationships

Bluebirds of the genus Sialia are classified within the family Turdidae (thrushes) and subfamily Turdinae, a placement supported by molecular phylogenetic studies employing DNA sequencing.^[26] Mitochondrial DNA analyses from the 1990s and 2000s, including sequences of the cytochrome b and ND2 genes, have confirmed Sialia as occupying a basal position within Turdinae relative to other thrushes, with divergence from the remaining subfamily estimated at approximately 11 million years ago during the mid-to-late Miocene.^[26] This basal placement positions Sialia as part of a clade with genera such as Myadestes (solitaires) and Neocossyphus, sister to a diverse clade of other Turdinae genera, reflecting an early dispersal to the New World.^[26] Bluebirds show affinities with other thrushes in Turdinae, including New World genera like Turdus (robins) and Catharus (e.g., veeries), which form part of the monophyletic New World radiation nested within the subfamily.^[26] Fossil evidence links Sialia to ancestral thrush forms in North America, with Turdidae records from the Miocene suggesting the family's presence on the continent around 15 million years ago, while genus-specific fossils date to the Pleistocene.^[21]^[27]

Physical description

Plumage and coloration

Bluebirds in the genus Sialia exhibit striking sexual dimorphism in their plumage, with males displaying vibrant blue upperparts produced by structural coloration rather than pigments. This blue hue results from the scattering of light by the spongy keratin matrix and air-filled barbules in the feathers of the head, back, wings, rump, and tail, creating a non-iridescent effect that appears vivid under direct light. In contrast, the males' breasts and throats feature rusty-brown or chestnut coloration derived from melanin pigments, while the underbelly and undertail coverts are white, providing a sharp demarcation that enhances their overall visual appeal.^[28]^[29] Females possess a duller version of this plumage pattern, with grayish-blue upperparts that lack the intensity of the males' structural blue, along with a more subdued cinnamon or grayish breast and white underparts. This muted coloration aids in camouflage during nesting activities. Across species like the Eastern (S. sialis), Western (S. mexicana), and Mountain (S. currucoides) bluebirds, female plumage varies slightly—grayer in Mountain Bluebirds and somewhat browner in Western—but consistently shows reduced saturation compared to males.^[28]^[30] Juveniles of both sexes initially sport a thrush-like plumage with grayish-brown upperparts, heavily spotted or streaked breasts, and minimal blue tones, which helps them blend into their surroundings. These spots, reminiscent of other thrushes in the family Turdidae, gradually fade as the birds undergo their first preformative molt shortly after fledging. By late summer, juveniles begin acquiring more adult-like feathers, with males developing brighter blue elements earlier than females.^[28]^[30]^[31] Adult bluebirds undergo a complete post-breeding (prebasic) molt in late summer, replacing all body feathers and some flight feathers to refresh their plumage for the non-breeding season. This molt typically occurs from July to October, depending on latitude and species, resulting in crisp, vibrant colors at the start of fall. However, by winter, feather wear from exposure leads to slight fading and dulling of the structural blue, particularly in the upperparts; bluebirds lack a prealternate molt, and vibrancy is renewed by the next annual prebasic molt.^[32]^[33]^[28]

Size and morphology

Bluebirds of the genus Sialia are small thrushes measuring 16–21 cm in length, with wingspans of 28–35 cm and weights ranging from 25–35 g across the three North American species.^[28]^[29]^[34] The Eastern Bluebird (S. sialis) is slightly larger than the Mountain Bluebird (S. currucoides), with lengths up to 21 cm and weights averaging 28–32 g, while the Western Bluebird (S. mexicana) tends toward the smaller end of the spectrum at 16–19 cm and 24–31 g.^[28]^[34]^[29] These birds exhibit key morphological adaptations suited to their lifestyle, including short, straight bills that facilitate probing for insects on the ground or in vegetation.^[28]^[29]^[34] Their wings are rounded to elliptical in shape, enabling agile, maneuverable flight for pursuits from perches.^[35] Strong, fairly short legs support upright perching on wires, branches, or fence posts, aiding in their flycatching behavior.^[28]^[29] Sexual dimorphism in size is minimal, though males are marginally larger than females in wing length and overall mass in some populations.^[32] Species differ in build as well: the Western Bluebird has a stockier, more compact form, while the Mountain Bluebird appears slimmer and lankier with proportionately longer wings.^[29]^[34] The Eastern Bluebird presents an intermediate plump body with a large, rounded head.^[28]

Distribution and habitat

Geographic range

Bluebirds, comprising three primary species in North America—the Eastern Bluebird (Sialia sialis), Western Bluebird (S. mexicana), and Mountain Bluebird (S. currucoides)—exhibit distinct yet overlapping geographic distributions shaped by historical and contemporary environmental factors. The Eastern Bluebird breeds across a broad expanse east of the Rocky Mountains, from southeastern Canada (including southern Ontario and Quebec) southward through the eastern and central United States to central Mexico, with year-round residency in the southern portions of its range, such as the southeastern U.S. states.^[4]^[36] The Western Bluebird occupies western regions, breeding along the Pacific Coast from southern British Columbia and southwestern Alberta in Canada, extending south through the western United States (including California, Oregon, and the interior mountains) to northern Baja California and the Central Volcanic Belt in Mexico.^[37]^[38] In contrast, the Mountain Bluebird favors higher elevations, breeding from Alaska and the Yukon Territory in Canada across the Rocky Mountains and intermountain west, through the northern Great Plains to central Mexico, with a focus on montane areas in states like Colorado, Wyoming, and Montana.^[39]^[13] Historically, these species underwent significant range expansions following the Pleistocene glaciation, as retreating ice sheets around 10,000–8,000 years ago allowed recolonization of northern latitudes from southern refugia. Fossil evidence confirms the Eastern Bluebird's presence in the upper Midwest by 8,000–10,000 years ago, marking post-glacial northward migration into previously glaciated territories. Similarly, the Mountain Bluebird's distribution models indicate restriction to southern refugia during the Last Glacial Maximum approximately 21,000 years ago, followed by rapid northward expansion as habitats opened in the Rocky Mountains and Great Plains. The Western Bluebird likely followed comparable patterns along coastal and montane corridors in the west, though specific fossil records are less documented for this species.^[40]^[41] In more recent centuries, bluebird ranges have experienced contractions primarily due to habitat loss from agricultural expansion, urbanization, and deforestation, which peaked in the early 20th century and led to population declines of up to 90% in some areas for the Eastern Bluebird. These pressures reduced suitable open woodlands and edge habitats across the Midwest and eastern ranges, though conservation efforts like nest box programs have facilitated recoveries and stabilized distributions since the mid-20th century. Western and Mountain Bluebirds faced analogous threats in western rangelands and montane forests, contributing to localized range retreats, particularly in fragmented landscapes.^[3]^[42] Overlap zones occur where ranges converge, notably in the Great Plains, where the Eastern and Mountain Bluebirds interbreed in hybrid zones, producing mixed offspring documented in areas like Nebraska and the northern prairies; such hybridization remains rare but highlights dynamic boundaries influenced by climate and habitat shifts. Migration patterns briefly link to these breeding ranges, with northern populations of all three species wintering southward within or beyond their core distributions.^[30]^[43]

Habitat preferences

Bluebirds of the genus Sialia exhibit a strong preference for semi-open habitats that balance access to nesting cavities and foraging opportunities, including open woodlands, farmlands, and forest edges characterized by scattered trees such as snags or dead pines and oaks that provide perches and natural cavities for nesting.^[42]^[10] These environments typically feature sparse understory vegetation and low ground cover, which facilitate ground-level insect hunting from elevated perches, while the species actively avoid dense, closed-canopy forests that limit visibility and prey access.^[42]^[44] The Western Bluebird (Sialia mexicana) shows a particular affinity for woodland edges and oak savannas, often in more forested settings than its congeners, but still requires open patches for hunting.^[10] Altitudinal preferences vary by species, reflecting adaptations to regional climates and vegetation zones. The Eastern Bluebird (Sialia sialis) primarily occupies lowlands from sea level to 2,700 m (approximately 8,860 ft), thriving in meadow-edge habitats and savannas.^[45]^[6] In contrast, the Mountain Bluebird (Sialia currucoides) favors higher elevations, breeding in open montane meadows and sagebrush deserts up to 3,500 m (11,500 ft) in the Rockies and Sierra Nevada, where short grasses and scattered conifers dominate.^[14]^[46] The Western Bluebird overlaps with both but extends into mid-elevation ponderosa pine forests and chaparral, generally from near sea level to 2,500 m (8,200 ft).^[10] At the microhabitat scale, bluebirds select sites near insect-rich grasslands and open fields that support abundant prey like beetles and grasshoppers, often within proximity to water sources such as ponds or streams that enhance local insect diversity and provide drinking opportunities.^[44]^[47] These birds have demonstrated notable adaptability to human-modified landscapes, readily utilizing orchards, vineyards, and suburban edges with nest boxes or remnant snags, where they contribute to pest control by preying on crop-damaging insects.^[48]^[49] Such flexibility has supported population recovery in agricultural regions, provided suitable perches and cavities are maintained.^[44]

Behavior and ecology

Foraging and diet

Bluebirds of the genus Sialia, including the eastern (S. sialis), western (S. mexicana), and mountain (S. currucoides) species, maintain a primarily insectivorous diet, with insects comprising the majority of their food intake during the breeding season.^[50] Common prey items include beetles, grasshoppers, crickets, caterpillars, insect larvae, cicadas, and spiders, which provide essential proteins for reproduction and growth.^[51] In the breeding period, insects can account for 68-90% of the diet, as observed in studies of eastern bluebirds where arthropods comprise about 68% overall but up to 90% in nestling provisioning.^[52]^[53] To obtain food, bluebirds employ a variety of foraging techniques centered around perch-hunting. They typically scan for prey from low perches (0.5-15 m above ground) in open habitats, then perform sallying flights—short aerial pursuits up to 15-20 m—to capture insects in mid-air (hawking) or drop to the ground for gleaning.^[50] Hovering briefly over vegetation or soil allows them to pluck items without landing, enhancing efficiency in grassy or shrubby areas.^[44] Adults consume approximately 12-15% of their body weight in food daily, equivalent to about 4 grams for a typical 30-gram bird, supporting high metabolic demands.^[54] Seasonal dietary shifts occur as insect abundance declines in fall and winter, with fruits making up an increasing proportion—up to 30-50% in non-breeding periods for eastern and western bluebirds.^[52] Preferred fruits include persistent berries such as those from sumac, serviceberry, black cherry, elderberry, and mistletoe, which provide vital energy when arthropods are scarce.^[38] Juveniles, post-fledging, learn these foraging skills through observation and continued provisioning by parents for 2-3 weeks, gradually transitioning to independent hunting.^[42]

Migration patterns

Bluebirds exhibit partial migration patterns, where northern populations undertake seasonal movements southward while southern populations remain largely sedentary. For instance, Eastern Bluebirds (Sialia sialis) breeding in Canada and the northern United States migrate in fall to the U.S. Gulf Coast and southern states, covering distances of 500–2,000 km or more in small flocks typically numbering 5–50 individuals.^[55]^[44]^[56] Southern populations of Eastern Bluebirds, particularly those in the southeastern U.S., are mostly year-round residents, though some may engage in limited local movements during harsh winters.^[55]^[57] Migration timing varies by species and region but generally aligns with seasonal changes in food availability and weather. Fall migration for Eastern Bluebirds occurs from September to November, with spring return flights taking place between March and May; birds arrive early in spring and depart late in fall from northern breeding areas.^[55]^[44] Western Bluebirds (Sialia mexicana) follow a similar schedule in their northern ranges, arriving early in spring and lingering into late fall, while remaining permanent residents farther south.^[11] The Mountain Bluebird (Sialia currucoides), the most migratory of the three North American species, breeds at high elevations in alpine and subalpine zones but undergoes longer altitudinal migrations in winter, descending to lower valleys, open grasslands, and pinyon-juniper woodlands, with fall movements starting relatively late and spring returns occurring early.^[15]^[12] Bluebirds rely on a combination of navigational cues during migration, including Earth's magnetic fields for orientation, visual landmarks such as rivers and mountain ranges for route guidance, and weather fronts to time departures and optimize flight conditions.^[58]^[59] These short- to medium-distance migrants also exhibit irruptive movements, where flocks may shift irregularly southward in response to regional food shortages, such as reduced insect or berry availability during prolonged cold snaps.^[55]^[15] Winter range variability in species like the Mountain Bluebird is particularly influenced by such food-driven irruptions, leading to annual fluctuations in distribution.^[15]

Reproduction and life cycle

Breeding biology

Bluebirds in the genus Sialia, including the eastern bluebird (S. sialis), western bluebird (S. mexicana), and mountain bluebird (S. currucoides), typically form socially monogamous pairs for the duration of a breeding season, with pair bonds often persisting across multiple years.^[42]^[10]^[14] Males initiate courtship by selecting potential nest sites and performing displays to attract females, including perching near cavities while singing melodious perch songs and engaging in wing-fluttering or wing-waving behaviors to showcase plumage and demonstrate vitality.^[42]^[60] These displays help establish pair bonds, after which the female inspects sites and begins nest construction. Once paired, females lay clutches of 2–8 pale blue eggs (depending on species: 2–7 for eastern, 2–8 for western, 4–8 for mountain), one per day, with incubation lasting 12–17 days and handled exclusively by the female, who covers the eggs when leaving the nest to maintain warmth.^[61]^[42]^[10]^[14] Both eastern and western bluebirds exhibit significant levels of extra-pair mating, resulting in sperm competition. Genetic studies using DNA fingerprinting have revealed extra-pair paternity rates of approximately 20–25% of offspring in eastern bluebird broods and 19–20% in western bluebird broods, where offspring are sired by neighboring males, often during the female's fertile period.^[62]^[10] These rates underscore the prevalence of alternative reproductive tactics, with males engaging in mate-guarding and frequent copulations to counter competition.^[63] Extra-pair paternity also occurs in mountain bluebirds, though specific rates are less documented.^[14] Reproductive physiology in bluebirds is triggered by environmental cues, particularly increasing day length in spring, which stimulates hypothalamic-pituitary-gonadal axis activity and elevates plasma testosterone levels in males.^[64] This hormonal surge promotes territorial defense behaviors, such as aggressive displays and singing to deter rivals, thereby securing breeding resources and enhancing mating opportunities.^[65] In females, photoperiodic changes induce ovarian development and yolk deposition, preparing for egg production, though testosterone levels remain lower to support incubation roles.^[64]

Nesting and parental care

Bluebirds are secondary cavity nesters, relying on natural tree holes excavated by woodpeckers or human-provided nest boxes for breeding. In eastern bluebirds, the female constructs the nest almost entirely on her own, forming a cup-shaped structure approximately 1–4 inches deep from woven fine grasses, pine needles, or strips of bark, and lining the interior with softer materials such as feathers, horsehair, or plant down for insulation and comfort. Nest building typically requires 4–6 days, though it can extend to 2 weeks in some cases, with the male occasionally contributing materials or actively defending the site from intruders.^[66]^[42]^[67] Western and mountain bluebirds follow similar patterns, with females building nests from grasses, pine needles, moss, and fur, often taking several days to over a week; mountain bluebirds may nest in lower cavities (up to 3 feet high) in open areas.^[10]^[14] Following egg-laying, the female assumes primary responsibility for incubation, which lasts 12–17 days on average (ranging from 11–19 days depending on environmental conditions and species), during which she rarely leaves the eggs unattended. The male supports her by foraging and delivering food, primarily insects, directly to the incubating female at the nest entrance. This biparental division of labor ensures the eggs maintain optimal temperature and humidity. Once the altricial nestlings hatch, both parents shift to intensive chick-rearing, with the pair making frequent trips to supply the brood with high-protein invertebrates such as beetles, caterpillars, and grasshoppers; the female often broods the young initially to regulate their body temperature while the male handles more of the early feeding.^[44]^[42]^[68] Nestlings develop rapidly under this care, growing feathers and gaining mobility over 16–21 days before fledging, at which point they are nearly adult-sized but remain dependent on parental provisioning for several weeks post-fledging. Eastern and western bluebirds typically produce 1–3 broods per year during the breeding season from April to August, while mountain bluebirds produce 1–2 broods; pairs often reuse the same nest structure after minor refurbishment, which allows for efficient reproduction in favorable conditions. However, in larger clutches (up to 7–8 eggs), intense sibling competition for limited food resources can result in elevated mortality, particularly among smaller or later-hatched chicks, as dominant individuals secure more parental deliveries and exhibit aggressive behaviors like pecking or displacement.^[69]^[42]^[10]^[14]^[70]

Conservation status

Population trends

The Eastern Bluebird (Sialia sialis) experienced a severe population decline of approximately 90% from the 1920s to the 1970s, primarily due to pesticide use and habitat changes, reaching critically low levels by the mid-20th century.^[71]^[42] Through widespread nest box programs initiated in the late 1960s, populations recovered significantly, with the North American Breeding Bird Survey (BBS) documenting an overall increase of more than 2% annually from 1966 to 2019.^[42]^[72] Current estimates place the global breeding population at 20–23 million individuals, indicating stability in the 2020s across much of its range in eastern North America.^[3]^[42] In contrast, the Western Bluebird (Sialia mexicana) has maintained relatively stable populations throughout the late 20th and early 21st centuries, with BBS data showing minimal long-term declines and localized increases in some regions since the 1970s.^[8] Estimates suggest a global breeding population of approximately 7 million individuals, concentrated in western North America.^[8] The Mountain Bluebird (Sialia currucoides) has shown overall increasing trends in population according to BirdLife International assessments, though regional declines have been noted in areas like the southern Rockies and New Mexico; estimates place the global breeding population at approximately 5.6 million individuals as of the 2020s.^[16]^[15] Population monitoring through the annual Christmas Bird Count (CBC) and BBS reveals short-term fluctuations in bluebird numbers, often linked to weather variability; for instance, severe winters or late spring storms have caused regional declines of 10–90% in subsequent breeding seasons, as observed in multiple studies from the 1970s onward.^[72]^[73] These datasets, spanning decades, highlight how extreme weather events can temporarily reduce abundances by 10–20% in affected areas before recovery in milder years.^[72] Demographic factors contribute to these dynamics, with adult annual survival rates typically ranging from 50% to 60% and juvenile survival from fledging to the following year around 30% to 40%, based on long-term banding studies.^[74] In optimal habitats like open woodlands, populations exhibit density-dependent regulation, where higher densities lead to reduced reproductive success and survival, helping maintain equilibrium.^[74]

Threats and protection efforts

Bluebirds face several primary threats that have contributed to population declines, particularly for species like the Eastern Bluebird (Sialia sialis). Habitat fragmentation due to agricultural expansion has drastically reduced suitable open woodlands and grasslands, converting vast areas into monoculture croplands and eliminating critical nesting and foraging sites.^[52] Competition from invasive species, such as House Sparrows (Passer domesticus), exacerbates this by aggressively usurping nesting cavities, often leading to the eviction or destruction of bluebird nests.^[75] Additionally, pesticide use has diminished insect prey populations, indirectly affecting bluebird nutrition and reproductive success, with some reports indicating direct toxicity from consuming contaminated insects.^[76] Protection efforts have focused on mitigating these threats through targeted conservation initiatives. The North American Bluebird Society, founded in 1978, has promoted the widespread installation and monitoring of nest boxes, with millions deployed across North America to provide artificial cavities in fragmented landscapes.^[77] Bluebirds are protected under the Migratory Bird Treaty Act of 1918, which prohibits their take, possession, or disturbance without permits, offering legal safeguards against habitat destruction and poaching.^[78] Reintroduction programs in areas with high habitat fragmentation, such as southeastern Florida, have successfully bolstered local populations by supplementing nest sites and monitoring breeding success.^[79] These efforts have yielded notable success, including a three-fold increase in Eastern Bluebird populations from 1980 to 2004, attributed to nest box programs and reduced pesticide impacts, with continued recovery observed through 2020.^[80] Overall population trends reflect this recovery, underscoring the effectiveness of human interventions in countering historical declines.^[42]

Cultural significance

Symbolism in folklore

In Native American lore, bluebirds often embody themes of renewal, joy, and spiritual communication across diverse tribes. Among the Iroquois, the bird's melodic song is said to dispel the malevolent demigod Tawiscaron, who represents winter's harshness, thereby heralding the return of spring and symbolizing happiness and seasonal rejuvenation.^[81] Similarly, the Iroquois and Navajo regarded bluebirds as auspicious omens of fertility and prosperity, their vibrant plumage evoking the promise of bountiful growth and new beginnings.^[82] Hopi traditions link bluebirds to fertility through clan narratives and ceremonial contexts. The Bluebird Clan features prominently in Songoopovi oral histories, where stories depict the clan's role in safeguarding pregnancy and childbirth, as in the tale of a group protecting a pregnant woman until her child is born, underscoring the bird's association with life's generative forces during kachina dances that invoke agricultural abundance.^[83] European settlers in North America viewed the bird as a harbinger of good fortune and shifting weather patterns that signal warmer seasons. In 19th-century American tales, sightings of bluebirds were frequently interpreted as portents of favorable conditions for farming, linking their arrival to expectations of prosperous harvests and communal well-being, as reflected in naturalist writings like John Burroughs' 1871 essay "The Bluebird," which celebrates the bird's emergence as a joyful precursor to spring's productivity.^[84] In contemporary interpretations rooted in Cherokee storytelling, bluebirds serve as emblems of hope and resilience, exemplified in legends where the bird acquires its striking blue hue by bathing in a sacred lake at dawn, carrying the light of renewal to overcome adversity and inspire endurance among the people.^[85]^[86]

Representation in arts and media

Bluebirds have appeared prominently in American literature, often symbolizing the unspoiled essence of nature. In his journals from the 1850s, Henry David Thoreau frequently referenced the eastern bluebird, famously noting on April 3, 1852, that "the bluebird carries the sky on his back," evoking the bird's vibrant plumage as a bridge between earth and the heavens, emblematic of wild purity. This transcendentalist portrayal underscored the bluebird's role as a harbinger of spring and a emblem of natural harmony in Thoreau's observations of Concord's landscapes. Additionally, Maurice Maeterlinck's 1909 play The Blue Bird, adapted into various children's fables and stories in the early 20th century, popularized the "bluebird of happiness" motif, where the elusive bird represents hope and fulfillment sought by child protagonists on a fantastical quest.^[87] In music, bluebirds have inspired compositions evoking themes of freedom and melancholy across genres. The 1967 rock song "Bluebird" by Buffalo Springfield, written by Stephen Stills and featured on their album Buffalo Springfield Again, uses the bird as a metaphor for fleeting joy and emotional depth, with lyrics describing its laughter amid inner turmoil. Similarly, Paul McCartney's "Bluebird" from Wings' 1973 album Band on the Run portrays the bird as a symbol of liberated love, with acoustic bossa nova rhythms accompanying lines about flying through doors at night. Earlier, 19th-century American folk traditions incorporated bluebirds into ballads and tunes, such as John Burroughs' 1875 poem "The Bluebird" celebrating the bird's arrival as a joyful sign of renewal in rural life.^[88] Bluebirds hold a notable place in visual arts and popular media, often depicted as cheerful emblems of the American countryside. John James Audubon's 1827 engraving of the eastern bluebird in The Birds of America (Plate 113) showcased the species in dynamic poses amid apple blossoms, influencing ornithological illustrations and wildlife art for generations. The bird's cultural prominence grew with its designation as the state bird of Missouri in 1927 and New York in 1970, leading to widespread imagery on state seals, stamps, and public murals symbolizing happiness and resilience.^[89]^[90] In film, bluebirds appear as whimsical forest companions in Disney's 1942 animated feature Bambi, where they flutter around the young deer in spring scenes, enhancing the film's portrayal of woodland serenity and innocence.^[91]

References

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Bluebirds (Genus Sialia) - iNaturalist
The bluebirds are a group of medium-sized, mostly insectivorous or omnivorous bird in the order of Passerines in the genus Sialia of the thrush family.Missing: facts | Show results with:facts
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Eastern Bluebird - American Bird Conservancy
Scientific Name: Sialia sialis · Population: 20 million · Trend: Increasing · Habitat: Open habitat near trees, such as savannas, forest clearings, pasture, parks, ...Eastern Bluebird · At A Glance · Secondary NestersMissing: facts | Show results with:facts
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Sialia sialis (eastern bluebird) | INFORMATION | Animal Diversity Web
Eastern bluebirds are small birds with short, slender beaks and short legs. They are brightly colored, with a blue upper body, red breast, and white abdomen.
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Eastern Bluebird Overview, All About Birds, Cornell Lab of Ornithology
Eastern Bluebirds eat mostly insects, wild fruit and berries. Occasionally, Eastern Bluebirds have also been observed capturing and eating larger prey items ...Missing: genus | Show results with:genus
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Western Bluebird - Pajarito Environmental Education Center
The total western bluebird breeding population is 6.7 million with 67% of the birds in the U.S., 52% in Mexico, and 1% breeding in Canada.
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Sialia mexicana (western bluebird) - Animal Diversity Web
Western bluebirds are small thrushes ranging in length from 16.5 to 19 cm and weighing from 24 to 31 g. Male and female adult western bluebirds differ in their ...
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Western Bluebird Life History - All About Birds
Western Bluebirds live in open woodlands and at the edges of woods. They are much less frequently seen in large meadows than either Eastern Bluebirds or ...
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Western Bluebird | Audubon Field Guide
Population. 7.100.000 ; Size. About the size of a Robin, About the size of a Sparrow ; Color. Blue, Gray, Orange ; Wing Shape. Rounded ; Tail Shape. Notched, Square ...
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Mountain Bluebird - American Bird Conservancy
The Mountain Bluebird is a small, sky-blue thrush, about two-thirds the size of a robin, that breeds in open areas and winters on plains and grasslands. It is ...
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Sialia currucoides (mountain bluebird) - Animal Diversity Web
They are relatively large, ranging from 15.5 to 18 cm in length, and 24 to 37 g in mass. They are sexually dimorphic, with adult males displaying brilliant ...Physical Description · Reproduction · Predation
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Mountain Bluebird Life History - All About Birds
Mountain Bluebirds live in open areas, eat insects, nest in cavities, and have 1-2 broods with 4-8 eggs. They flycatch and form flocks.
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Mountain Bluebird | Audubon Field Guide
The powder-blue male Mountain Bluebird is among the most beautiful birds of the West. Living in more open terrain than the other two bluebirds.
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Bluebird - Etymology, Origin & Meaning
"feathered, warm-blooded vertebrate animal of the class Aves," Old English bird, a rare collateral form of bridd, originally meaning "young bird, nestling" ( ...
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The early settlers in Plymouth Colony welcomed this friendly, cheerful songster, which reminded them of their beloved English robin redbreast, and they named ...
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Jul 28, 2010 · European settlers called them “blue robins,” because the birds' size and rusty breast reminded them of English robins. Comparatively scarce ...
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Bluebirds, family Turdidae, belong to the genus Sialia, from the Greek meaning “a kind of bird.” Not a very helpful description.
[18]
Scientific & Common Names, Subspecies Bluebirds - Sialis.org
“Sialia” comes from the Greek word sialis which simply means “a bird,” according to bluebirder Fred Loane. Swainson described the genus Sialia in 1827.Missing: facts | Show results with:facts
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75 Traditional Navajo Indian Names and Meanings - FamilyEducation
Oct 7, 2022 · Popular names include Tallulah, which means leaping water, Chenoa, which means white dove, and Enola, which means magnolia.<|control11|><|separator|>
[20]
(PDF) A molecular phylogenetic analysis of the “true thrushes” (Aves
Aug 7, 2025 · We identify an exclusively New World clade that includes a monophyletic Catharus, Hylocichla, Cichlopsis, Entomodestes, Ridgwayia, and Ixoreus.
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Phylogenomics and biogeography of the world's thrushes (Aves ...
Jan 22, 2020 · The study found a monophyletic African radiation, a single dispersal to the Americas, and a crown age of 9.3 million years for thrushes.
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Systematics - Western Bluebird - Sialia mexicana - Birds of the World
Fossils. Fossil remains attributed to S. mexicana dating from the Pleistocene found at Carpinteria, CA, and of Sialia sp. at Rancho La Brea ...
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Eastern Bluebird Identification - All About Birds
The Eastern Bluebird is a small thrush with a big, rounded head, large eye, plump body, and alert posture. The wings are long, but the tail and legs are fairly ...
[24]
Western Bluebird Identification - All About Birds
Small stocky thrush with a thin bill and short tail. Usually ... Juveniles look like females, but have spotting on the back and streaking on the breast.Mountain Bluebird · Western Bluebird · Western Bluebird Range Map · Photo GalleryMissing: spotted | Show results with:spotted
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How to identify bluebirds - BirdWatching Magazine
Jun 28, 2024 · As with most songbirds, these bluebirds begin to molt out of juvenile plumage within a couple of months after leaving the nest, so there is ...
[26]
Determine the Gender of Young Bluebirds Through their Plumage
Young male and female bluebirds have a distinctive plumage during their juvenile phase, which they typically retain for just a few months before transitioning ...
[27]
Plumages, Molts, and Structure - Eastern Bluebird - Sialia sialis
Eastern Bluebirds are also sexually dimorphic in the feather structures that proximately control coloration as opposed to blue pigmentation (Shawkey et al. 2005) ...Missing: structural | Show results with:structural
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Effects of age and weather during moult on Mountain Bluebird ...
Feb 18, 2021 · In this study, we examined variation in structural colour expression in relation to age as well as rainfall and temperature during post-breeding ...
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Mountain Bluebird Identification - All About Birds
Male Mountain Bluebirds are sky-blue, a bit darker on wings and tail and a bit paler below, with white under the tail. Females are mostly gray-brown with tinges ...Eastern Bluebird · Mountain Bluebird · Mountain Bluebird Range Map
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[PDF] Birds and their Wing Shapes - Cornell Lab of Ornithology
There are four general wing shapes that are common in birds: Passive soaring, active soaring, elliptical wings, and high-speed wings. Passive soaring wings have ...Missing: agile | Show results with:agile
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Distribution - Eastern Bluebird - Sialia sialis - Birds of the World
See Fig. 9. During mild winters, species may remain sporadically north to S. Dakota, Minnesota, s. Ontario, Quebec, and New England states (eBird data). Winters ...
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Distribution - Western Bluebird - Sialia mexicana - Birds of the World
Breeds in w. North America from s. British Columbia and sw. Alberta south to n. Baja California and the Central Volcanic Belt of Mexico, but largely absent from ...
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Sialia mexicana - Forest Service - USDA
The breeding range of western bluebird extends from southern British Columbia, western and south-central Montana south through the mountains to northern Baja ...
[34]
Distribution - Mountain Bluebird - Sialia currucoides
Alberta: Appears to breed primarily in the lower two-thirds of the province, south of approximately Fort McMurray in the east and the Peace River region around ...Distribution · Introduction · Breeding Range
[35]
How the Peterson nest box saved the Eastern bluebird - MinnPost
Oct 20, 2025 · Fossil evidence dates the birds' presence in the upper Midwest at 8,000 to 10,000 years ago, around the end of the last glacial period. The ...
[36]
Neutral markers reveal complex population structure across the ...
Jul 7, 2024 · Like many species, mountain bluebirds were displaced from their northern range by the ice sheets during the last glacial maximum. Our species ...
[37]
Eastern Bluebird Life History - All About Birds
Eastern Bluebirds live in open country around trees, but with little understory and sparse ground cover. Original habitats probably included open, frequently ...
[38]
Eastern x Mountain Bluebird (hybrid) - Birds of Nebraska – Online
Feb 16, 2021 · Two broods were produced by a pair comprised of a male hybrid Eastern X Mountain Bluebird and a female Mountain Bluebird in Dawes Co in 1985.Missing: zones | Show results with:zones
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Eastern Bluebird | Audubon Field Guide
This is the most widespread of the three bluebirds. Although it is mostly 'eastern' in our area, the total range of the Eastern Bluebird extends south to ...
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Eastern bluebird - NC State
Limited to elevation range: less than 4000 ft. ... Test of nest box preferences of eastern bluebirds, SIALIA SIALIS, and tree swallows, TACHYCINETA BICOLOR.<|separator|>
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Eastern Bluebird Sialia Sialis Species Factsheet | BirdLife DataZone
Elevation. 700 - 2,700 m. Occasional elevation limits. -. Generation length. 2.2 years. Species type. Landbird. Habitat classification. Habitat (level 1) ...
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Mountain Bluebird | Ask A Biologist
Jul 13, 2017 · Breeds in higher elevation coniferous forest edge with meadows or pastures. Typically seen sitting on low fence wire, posts or the ground, ...
[43]
[PDF] Predicting Nest Success from Habitat Features in Aspen Forests of ...
Proximity to standing water. Distance to water influenced nest success of small migrants and residents and secondary cavity nesters. Nest success decreased ...
[44]
At Orchards and Vineyards, Birds Are Outperforming Pesticides
Jun 25, 2021 · Birds including American Kestrels, Barn Owls, and Western Bluebirds are better than chemicals at reducing pest damage.<|separator|>
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Grazing Part 1: How this farming technique may benefit declining ...
Mar 20, 2024 · Eastern bluebirds are common farm birds if they can find natural tree cavities or bird houses to nest nearby. This male is holding his insect ...
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Diet and Foraging - Eastern Bluebird - Sialia sialis - Birds of the World
During the breeding season, ground arthropods. In late summer and into winter, add small fleshy fruits to their mostly insect diet.
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Can diet composition estimates using stable isotope analysis ... - NIH
Oct 14, 2021 · We found that bluebirds fed their young 5 main types of prey: beetles, cicadas, grasshoppers, insect larvae, and spiders.
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Managing Habitat for Eastern Bluebirds
### Summary of Eastern Bluebird Diet, Fruit Reliance, Seasonal Shifts, and Foraging Methods
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[PDF] Weights of Some Small Birds in Central New York
Taber (193g) concluded that the average daily food consumption was 15 or 16 percent of a bird's weight. This being the case, something in addition is needed to.
[50]
Bluebird Migration - Sialis.org: Info on Bluebirds & Other Small ...
The birds that did not migrate may have died due to long periods of cold temperatures and lack of food. Western bluebird in flight, photo by David Brown. In ...Missing: irruptive shortages
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Movements and Migration - Eastern Bluebird - Sialia sialis
Migration is associated with weather and/or food availability. Known as a “partial migrant” -- some individuals within populations migrate and some take up ...Movements And Migration · Migration Overview · Timing And Routes Of...
[52]
The Basics: How Birds Navigate When They Migrate
Apr 1, 2008 · A second theory suggests that birds use the earth's magnetic field to obtain at least a partial map of its position. The earth's magnetic field ...Missing: bluebird | Show results with:bluebird
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How Migrating Birds Use Quantum Effects to Navigate
Apr 1, 2022 · But unlike humans, birds also detect the magnetic field generated by Earth's molten core and use it to determine their position and direction.Missing: bluebird landmarks
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General Information on the Eastern Bluebird (Sialias sialia) |
Dec 30, 2014 · To attract a female, the male perches outside of the nest cavity and makes displays such as wing flapping or tail raising. The pair bonds are ...
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Attracting Bluebirds to Your Property | MU Extension
The female will lay one egg a day for four to six days and then incubate the pale blue eggs for 12 to 14 days. Incubation begins with the last egg laid so that ...Missing: period | Show results with:period
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[PDF] Specialized Extrapair Mating Display in Western Bluebirds - Digital ...
Specialized Extrapair Mating Display in Western Bluebirds. Janis L. Dickinson ... Extra-group courtship displays and other reproductive tactics of ...
[57]
Extrapair Copulations in Western Bluebirds (Sialia mexicana) - jstor
In western bluebirds (Sialia mexicana), a species with 20% extrapair paterni- ty, two to four observers monitored extrapair copulations (EPCs) occurring on the ...
[58]
[PDF] Extrapair Paternity and Intraspecific Brood Parasitism in Eastern ...
females' fertile periods. Eastern Bluebirds (Sialia sialis) are secondary cavity nesters, which readily breed in nest boxes. They are socially monogamous, with ...Missing: courtship | Show results with:courtship
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Eastern Bluebirds and Tree Swallows; Bird Hormones - Web – A Colby
Jun 5, 2011 · With increasing daylength, birds start to produce hormones: mainly testosterone in males and estradiol (an estrogen) in females. These hormones ...Missing: triggers | Show results with:triggers
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Testosterone in Females: Mediator of Adaptive Traits, Constraint on ...
In male birds, plasma testosterone (T) varies seasonally and among species according to mating system. When elevated experimentally, it is known to enhance some ...
[61]
First Egg: How Long Does it Take? - Sialis.org: Info on Bluebirds ...
Nest construction: 3-4 days up to 2 weeks. Only the female builds the nest, which is fairly complex. Egg laying: Usually 1-2 days after nest construction.Missing: care | Show results with:care
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[PDF] The Eastern Bluebird - University of Maryland Extension
The normal amount of time from hatching to fledg- ing for a young Bluebird is 17 to 18 days. 3. Page 4. Issued in furtherance of Cooperative Extension work ...Missing: clutch incubation period<|separator|>
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Bluebird Parental Care of Hatchlings, Nestlings, and Fledglings
Both parents care for young, feeding them protein-rich insects. The female broods initially, and both feed. After fledging, parents care for about three weeks.
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How Many Broods Will Bluebirds Have a Year? - Sialis.org
Eastern Bluebirds may have 3 or 4 broods, Western may only have 2 or maybe 3. Other species of cavity nesters are different. For example, Tree Swallows and ...Missing: construction | Show results with:construction<|separator|>
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Maternal Androgens Increase Sibling Aggression, Dominance, and ...
Mothers can favour certain young by conferring on them competitive advantages such as a leading position in the birth sequence, more resources or hormones.<|control11|><|separator|>
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Bringing back the eastern bluebird - Chesapeake Bay Program
Oct 1, 2019 · By 1970, the bird's numbers were down by 92% across the country. A miraculous comeback. In the late 1960s, public outcry over the bird's future ...
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Recent population trends of the eastern bluebird
North American Breeding Bird Survey data for the period 1966-1987 indicate that Eastern Bluebird (Sialia sialis) populations declined during the 1970s, ...<|control11|><|separator|>
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Recent population trends of the eastern bluebird - USGS.gov
Eastern Bluebird (Sialia sialis) populations declined during the 1970s, primarily in association with either severe winters or severe spring storms.Missing: estimate 2020s<|control11|><|separator|>
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Local bird lovers help western bluebird population soar
May 2, 2023 · According to the bird conservation organization Partners In Flight, the total western bluebird population is estimated to be at 7.1 million.
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[PDF] Recent Population Trends of the Eastern Bluebird
Jun 1, 1990 · correlation between cold winters and subsequent declines in Eastern Blue- bird populations. However, bird distribution in winter can vary in as-.
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Demography and Populations - Eastern Bluebird - Sialia sialis
In a study of adult and first year survival rates of Eastern Bluebirds in two piedmont locations (Athens, GA and Clemson, SC), 2001-2004 (PAG, P. Lang) ...
[72]
[PDF] wildlife in connecticut - CT.gov
Competition for nesting cavities from introduced European starlings and house sparrows, the loss of open field habitats, pesticide use, and severe weather ...Missing: threats | Show results with:threats
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Conservation and Management - Eastern Bluebird - Sialia sialis
Some anecdotal reports suggest that direct ingestion of pesticide-loaded insects have caused death of adult bluebirds. Endocrine Disruption From Pesticides.
[74]
NABS History – North American Bluebird Society
The date of incorporation was March 20, 1978 (Sialia 1:33-34). ... In order to make nest boxes readily available to bluebirders, NABS has used a number of ...
[75]
List of Birds Protected by the Migratory Bird Treaty Act (2023)
Apr 26, 2020 · The list is based on international treaties, found in CFR Title 50 Part 10.13, and includes families like Ducks, Flamingos, and Doves.
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Eastern Bluebird: Species Profile - National Park Service
Mar 17, 2025 · Population levels declined to about 30 breeding individuals and bluebirds remained at risk of extirpation in the park.
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What to know about Bluebirds - Wild Birds Unlimited
According to the statistics from the Breeding Bird Survey, survey-wide estimates of the Eastern Bluebird population show an increase of 2.4% per year for each ...
[78]
Native American Bluebird Mythology
Bluebird is a symbol of spring in many tribes. In Iroquois mythology, it is the singing of the bluebird that drives off the destructive demigod Tawiscaron.Missing: lore | Show results with:lore
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https://www.nps.gov/ever/learn/nature/bluebird.htm
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A Modern Kiva Mural - Traditional Fine Arts Organization
This is from the Songoopovi story about how the Bluebird Clan took a pregnant woman from her village and kept her until she gave birth. They baptized the child ...<|control11|><|separator|>
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The Bluebird by John Burroughs - 10,000 Birds
Mar 7, 2011 · “The Bluebird” is about more then just the bluebird. For Burroughs the return of the bluebird was one of the first signs of impending spring, and, as such, a ...
[82]
How the Bluebird and Coyote Got Their Color - Sialis.org
Bluebird got blue by bathing in a magic lake and singing a song. Coyote, wanting to be blue, did the same, but his pride led to him being covered in dirt.<|separator|>
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Tell Me a Story: Bluebird and Coyote (a Cherokee Indian tale)
May 7, 2012 · Bluebird lived near a wide, beautiful lake, a lake that was the most beautiful color of blue anyone had ever seen.Missing: Iroquois Hopi
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The Project Gutenberg eBook of Bird Stories from Burroughs, by ...
BIRD STORIES FROM BURROUGHS. SKETCHES OF BIRD LIFE TAKEN FROM THE WORKS OF. JOHN BURROUGHS. WITH ILLUSTRATIONS BY LOUIS AGASSIZ FUERTES.
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State Bird of Missouri | Eastern Bluebird
Missouri designated the lovely eastern bluebird (Sialia sialis) as the official state bird in 1927. The eastern bluebird is also the state bird of New York.
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New York State Bird | Eastern Bluebird
One of the first birds to return north each spring, the lovely eastern bluebird (Sialia sialis) was designated the official state bird of New York in 1970; ...