Hubbry Logo
American tree sparrowAmerican tree sparrowMain
Open search
American tree sparrow
Community hub
American tree sparrow
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
American tree sparrow
American tree sparrow
American tree sparrow
View on Wikipedia
from Wikipedia

American tree sparrow
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Passerellidae
Genus: Spizelloides
Slager & Klicka, 2014
Species:
S. arborea
Binomial name
Spizelloides arborea
(Wilson, 1810)
Range map of Spizelloides arborea
  Breeding
  Migration
  Nonbreeding
Synonyms

Spizella monticola
Spizella arborea
Passerella arborea

American tree sparrow in Central Park

The American tree sparrow (Spizelloides arborea), also known as the winter sparrow,[2] is a medium-sized New World sparrow. It breeds in Alaska and Northern Canada and winters in Southern Canada and the Contiguous United States. It is the only member of the genus Spizelloides.

Taxonomy

[edit]

The American tree sparrow was originally placed in the genus Spizella. In 2014, it was moved to its own monotypic genus, Spizelloides, based on polyphyly in Spizella and multilocus molecular evidence suggesting the species was strongly divergent from other extant genera.[3][4]

Description

[edit]

The bird's measurements are as follows:[5]

  • Length: 5.5 in (14 cm)
  • Weight: 0.5–1.0 oz (13–28 g)
  • Wingspan: 9.4 in (24 cm)

Adults have a rusty cap and grey underparts with a small dark spot on the breast. They have a rusty back with lighter stripes, brown wings with white bars and a slim tail. Their face is grey with a rusty line through the eye. Their flanks are splashed with light brown. They are similar in appearance to the chipping sparrow.

Distribution and habitat

[edit]

Their breeding habitat is tundra or the northern limits of the boreal forest in Alaska and northern Canada. They nest on the ground. American tree sparrows migrate into southern Canada and the United States to spend the winter.

Diet and behavior

[edit]

These birds forage on the ground or in low bushes, often in flocks when not nesting. They mainly eat seeds and insects, but also eat some berries. They are commonly seen near feeders with dark-eyed juncos.

Nesting and breeding

[edit]

American Tree Sparrows typically nest on or near the ground. The nest is composed of fine grasses, feathers, mosses, twigs and strips of bark.[6]   

Despite laying one egg per day over a week, the hatching of the chicks is synchronized to within a few hours of each other. Because of this, all the chicks fledge and forage together.[7] Breeding pairs do not stay together after the season.[8]

Call

[edit]

This bird's song is a sweet high warble descending in pitch and becoming buzzy near the finish.

References

[edit]

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

American tree sparrow

View on Grokipedia
from Grokipedia
The American tree sparrow (Spizelloides arborea) is a small, plump, long-tailed bird in the family Passerellidae, characterized by its distinctive rusty-red cap, clear gray underparts with a dark central spot, bicolored bill (black above and yellow below), and white wing bars. It measures 5.5–6.5 inches (14–17 cm) in length, weighs 0.5–1.0 ounces (13–28 g), and has a wingspan of 9.4 inches (24 cm). Native to , this species breeds in open, scrubby habitats near or above the treeline across , northern , and the high , where it nests on the ground amid willows, alders, birches, and spruces. During the non-breeding season, American tree sparrows migrate southward to winter in weedy fields, marshes, roadsides, gardens, and backyards across southern and the , often forming flocks of dozens to hundreds that on the ground for seeds from grasses, sedges, ragweeds, and berries, supplemented by during breeding. These migrations occur relatively late in fall (–) and early in spring (–), primarily at night, with males typically wintering farther north than females and singing from perches as early as late winter to establish pairs before heading north. Breeding pairs construct cup-shaped nests on the ground or low in shrubs, lining them with ptarmigan feathers, , and grasses; females lay 4–6 pale blue eggs speckled with reddish-brown, incubating them for 11–13 days while males provide food. Chicks hatch altricial (helpless and sparsely down-covered) and after 8–10 days, becoming independent shortly thereafter, with both parents feeding them a diet rich in like beetles, flies, and moths to support rapid growth. The species exhibits strong fidelity to wintering sites but can live up to 10 years and 9 months in the wild, as recorded in a banded individual from . With an estimated global population of 26 million individuals (2019), the American tree sparrow is classified as of Least Concern by conservation assessments, though some regional winter populations show declines possibly linked to changes; it benefits from human-altered landscapes and readily visits bird feeders, co-occurring with like dark-eyed juncos.

Taxonomy

Nomenclature and history

The American tree sparrow, Spizelloides arborea, was first described by Scottish-American ornithologist Alexander Wilson in his seminal work American Ornithology, volume 2, published in 1810. Wilson assigned it the protonym Fringilla arborea, placing it within the broad genus Fringilla then used for many small passerines, with the specific epithet arborea derived from Latin meaning "tree-dwelling," reflecting its perceived arboreal habits despite its predominantly ground-based behavior. The description appeared on page 123, accompanied by an illustration in plate 16, figure 3, based on specimens observed in the northern United States during winter. In 1832, French-American ornithologist Charles Lucien Bonaparte established the genus Spizella for a group of New World sparrows, with the type species Fringilla pusilla (now Spizella pusilla), and soon included the American tree sparrow as Spizella arborea. This reclassification separated it from Old World finches and aligned it with morphologically similar North American emberizids, a placement that persisted for nearly two centuries based on shared plumage patterns and vocalizations. The common English name "American tree sparrow" originated with early European settlers in North America, who likened its appearance—particularly the rufous crown and streaked back—to the Eurasian tree sparrow (Passer montanus), a familiar species in Europe, though the American species nests in tundra shrubs rather than trees. A , S. a. ochracea, was described in 1882 by American ornithologist William Brewster from specimens collected in , distinguished by its paler overall plumage, more cinnamon-rufous crown, narrower black streaks on the mantle, and whitish outer edges on the rectrices compared to the nominate S. a. arborea. Genetic analyses in the early 21st century, including multilocus phylogenies, revealed that the American tree sparrow is not closely related to other Spizella species but instead forms a sister clade to the fox sparrow (Passerella iliaca), prompting its transfer to a monotypic genus Spizelloides in 2014. The new generic name Spizelloides combines Spizella with the Greek suffix -oides ("resembling"), acknowledging its superficial similarity to other Spizella sparrows while highlighting its distinct evolutionary lineage within the family Passerellidae.

Classification

The American tree sparrow (Spizelloides arborea) belongs to the kingdom Animalia, phylum Chordata, class Aves, order Passeriformes, Passerellidae, Spizelloides, and species arborea . This placement reflects its status as a , characterized by adaptations for ground-foraging and seed-eating in temperate and environments . Historically, the species was classified in the genus Spizella alongside other North American sparrows such as the (Spizella passerina) . However, in 2015, the (now the ) reclassified it into its own monotypic genus Spizelloides based on molecular phylogenetic analyses . This change was driven by evidence from mitochondrial and nuclear DNA studies indicating that S. arborea is not closely related to other Spizella species but instead forms a sister clade to the fox sparrow (Passerella iliaca) . Phylogenetically, Spizelloides arborea diverged from the Passerella lineage approximately 4–5 million years ago, with genetic markers supporting its basal position within the Passerellidae radiation of . This reclassification underscores the role of genomic data in refining avian taxonomy, distinguishing Spizelloides by its unique combination of morphological traits and genetic affinities . Two are currently recognized: the nominate S. a. arborea and S. a. ochracea (Brewster, 1882), though minor geographic variation in exists across its breeding range .

Description

Measurements and morphology

The American tree sparrow (Spizelloides arborea) is a small bird, measuring approximately 14–17 cm in length from bill to tail tip. Its body mass ranges from 13–28 g, with an average around 20 g, reflecting adaptations for efficient in environments where daily demands are high. The wingspan spans 21–25 cm, enabling agile flight during migration and short bursts over snowy ground cover. Morphologically, the species exhibits a compact, plump body form with a rounded head and a relatively long, slender tail that aids in balance while hopping on the ground or perching in low shrubs. The bill is small and conical, typical of granivorous sparrows, suited for cracking seeds and probing leaf litter, with subtle absent in overall size. Wings are moderately broad, facilitating sustained flight over open , while the legs and feet are sturdy and pale, adapted for scratching through to access food sources.
MeasurementRangeAverageSource
Length14–17 cm15 cmAudubon Field Guide
Mass13–28 g20 gCornell Lab of Ornithology
Wingspan21–25 cm24 cm
Subspecies show minor morphological variation, with the nominate S. a. arborea being slightly smaller and darker overall compared to the paler, marginally larger western S. a. ochracea, though these differences are subtle and primarily influence rather than structural dimensions.

Plumage

The adult American tree sparrow displays a plumage pattern dominated by reddish-brown and gray tones, with a distinctive rusty red cap and a matching rusty eyeline that accentuates the pale gray face. The bill is bicolored, featuring a black upper mandible and a yellow lower mandible, providing a clear field mark. The breast is smooth and unstreaked, ranging from gray to buff with a characteristic dark central spot, while the flanks and undertail coverts show subtle rufous tones. The back and scapulars are streaked with brown, contrasting the paler nape, and the wings include two prominent white wingbars that aid in identification. The tail is long, dark, and slightly notched with square tips, completing the overall plump, ground-foraging appearance. Both sexes exhibit nearly identical plumage, showing no significant sexual dimorphism in coloration or pattern. Juveniles, however, possess a heavily streaked plumage across the underparts and body, which is duller and less contrasted than in adults; this juvenile phase is rarely observed outside the Arctic breeding grounds due to rapid post-fledging molt. There are no marked seasonal variations in adult plumage, as the species undergoes a complete prebasic molt in late summer but retains its core color scheme year-round. These features collectively distinguish the American tree sparrow from similar species like the chipping sparrow, which lacks the rusty cap and central breast spot.

Distribution and migration

Breeding range

The American tree sparrow (Spizelloides arborea) breeds across the far northern regions of , primarily in and throughout , including the Yukon Territory, , northern Manitoba, northern Ontario, northern Quebec, and . This distribution encompasses areas from the Arctic tundra north of the treeline to the transitional zones near the northern forest edge. Within this breeding range, the species favors open, scrubby habitats at or above the treeline, such as and thickets, alder shrublands, and stunted spruce areas, often in proximity to lakes or bogs. These sites provide low vegetation for nesting on or near the ground, typically in grass clumps, hummocks, or beneath shrubs, supporting the species' ground-foraging behavior despite its name. Nests are rarely placed higher than 1.2 meters above ground, emphasizing the preference for undisturbed, low-shrub environments.

Non-breeding range

The American tree sparrow (Spizelloides arborea) occupies a broad non-breeding range across southern and the during winter, typically from late fall to early spring. This range extends from the Atlantic seaboard westward to the Pacific coast, encompassing provinces such as , , and in Canada, and states including , , , New York, , and Washington in the United States. Populations are most abundant in the central and eastern portions of this area, where they form flocks in open, snow-covered landscapes. The southern extent of the non-breeding range generally reaches latitudes around 35°N to 40°N, including northern parts of states like , , , , and , though birds are less common and more irregular farther south. For instance, in , they are widespread throughout the state but concentrated in the northern and western sections, while in , they winter primarily in the northern regions with only occasional vagrants reaching . Recent observations indicate declines in southern winter populations, possibly linked to , with vagrants becoming scarcer in states like . Females tend to winter slightly farther south than males on average, contributing to subtle variations in distribution. This southward migration avoids the harsh Arctic conditions of their breeding grounds, with birds arriving relatively late in fall—often after the first heavy snows—and departing early in spring. Throughout this non-breeding distribution, the species shows adaptability to human-modified environments, frequently appearing in suburban backyards and at feeders, which has facilitated observations and monitoring across its wintering areas. While the overall range remains stable, local abundances can fluctuate with weather patterns, such as colder temperatures driving birds farther south in severe winters.

Migration

The American tree sparrow (Spizelloides arborea) is a short-distance migrant, breeding in the and regions of and wintering in more temperate areas farther south. Its migration connects remote northern breeding grounds near the treeline in and to wintering habitats across southern and the northern and . This movement typically spans distances of 1,500 to 3,000 miles, occurring primarily at night to avoid daytime predators and thermal updrafts. Fall migration begins in late summer or early fall, with departing breeding areas in or September and arriving at wintering sites from October through November, sometimes extending into December in southern regions. Spring migration starts earlier, with northward movement initiating in the southern portions of the winter range as early as late , peaking between 30 March and 8 April in the Mississippi Valley, and continuing into late April or early May in northern wintering areas; reach breeding grounds by May. Females tend to winter farther south than males, potentially influencing the staggered timing of their departures. Weather conditions, particularly clear nights, play a key role in driving spring progression, facilitating nocturnal flights. During both seasons, American tree sparrows travel in flocks, foraging in weedy fields, marshes, and open woodlands by day to fuel their journeys. As spring migration advances, these flocks begin to dissolve, with birds pairing up en route to breeding sites. The follows broad overland routes across the , with no pronounced coastal or interior bias, though peaks in abundance reflect mid-continental corridors like the Mississippi Valley.

Habitat

Breeding habitat

The American tree sparrow (Spizelloides arborea) breeds across vast northern regions of , primarily near the treeline in and , spanning approximately 250 million acres of remote, landscapes. These areas mark the transition from boreal forest to open , where the bird exploits edge habitats for nesting and . Preferred breeding sites feature scrubby, low-lying vegetation, including scattered thickets of , , , and stunted , interspersed with open . The species favors scrub and thickets for cover, often selecting territories with nearby water sources and small trees or shrubs that serve as singing perches for males. In some cases, breeding occurs in forest openings dominated by dwarfed conifers or expansive with taller shrubs, providing a mix of concealment and access to insect-rich ground cover. These habitats remain relatively undisturbed due to their inaccessibility, supporting the sparrow's ground-based lifestyle during the short summer season, though is predicted to reduce suitable breeding habitat through shifts in vegetation and treeline advancement. Nests are constructed on or near the ground, typically in grass tussocks, mossy hummocks, or beneath low shrubs, which offer protection from predators and harsh weather. Rarely, nests may be placed up to 4 feet (1.2 meters) above ground in the limbs of or , adapting to slightly more structured vegetation in transitional zones. This selection of microhabitats ensures proximity to foraging areas abundant in seeds, , and berries, essential for the breeding pair's energy demands.

Winter habitat

During winter, the American tree sparrow occupies open and semi-open landscapes across southern Canada and the , adapting readily to both natural and human-modified environments. This non-breeding range spans from the Midwest and —where densities are highest—eastward through the Northeast, excluding extreme southern and western fringes of the contiguous U.S. Preferred winter habitats consist of weedy fields, marshes, hedgerows, shrubby edges, and borders, where sparse provides ample opportunities amid cover. These birds also thrive in disturbed areas such as open forests, gardens, and residential backyards equipped with seed feeders, demonstrating flexibility in utilizing human-altered spaces for shelter and food. Such adaptability allows them to persist in regions with intensified or development, though loss from farming and poses ongoing threats to weedy and shrubby patches. In these winter settings, American tree sparrows form small flocks to forage primarily on the ground, scratching through for from grasses, sedges, ragweeds, and goldenrods, or hopping onto bent weeds and flapping wings to dislodge hidden caches. They occasionally consume berries or millet from feeders and even continue feeding during blizzards, while obtaining water by eating . For roosting, they seek communal shelter under snowdrifts, in dense , thickets, or haystacks, which provides insulation against cold; dominance hierarchies may emerge within flocks to access prime spots. This behavior underscores their hardiness in harsh, snow-dominated conditions.

Behavior and foraging

Social behavior

The American tree sparrow exhibits distinct social patterns that vary by season. During the breeding season, pairs are generally solitary and territorial, with males actively defending nesting areas through persistent and chasing intruders of the same . Each male typically uses a single song type for territorial proclamation and mate attraction, while females occasionally participate in defense by chasing rivals. Pairs form monogamous bonds in mid-June, lasting only through the breeding period, with males displaying behaviors such as wing-spreading and darting flights to court females, who respond with specific "wehy" calls. Both parents cooperate in feeding fledglings for 2-3 weeks after leaving the nest, but territories encompass small areas (0.0038-0.005 km²) centered on singing perches, water sources, and nest sites. Post-breeding, in late summer, family groups join larger flocks as juveniles become independent, marking a shift from solitary pair dynamics to communal foraging. These flocks persist through migration and winter, where American tree sparrows forage gregariously in small to large groups, often associating with other species like dark-eyed juncos at backyard feeders or weedy fields. Winter flocks do not defend territories but establish linear dominance hierarchies, influencing access to food resources through aggressive interactions such as supplantations and peck orders, as observed in captive and wild studies. Dominant individuals, often adults, secure preferred foraging spots, while subordinates wait or avoid conflicts, promoting social stability within flocks. This flocking behavior aids in predator detection and efficient seed harvesting, with birds sometimes sheltering communally under snow during harsh conditions.

Diet and feeding

The American tree sparrow's diet varies significantly between seasons, reflecting changes in food availability and reproductive needs. During the non-breeding season, particularly winter, its diet consists primarily of from grasses, sedges, weeds such as , , and , along with occasional berries, catkins, and small amounts of or their eggs and larvae. In this period, plant matter accounts for approximately 98% of its intake, with animal matter making up just 2%, including weevils, beetles, caterpillars, and spiders. These sparrows also consume millet and other from backyard feeders when available. In contrast, during the breeding season in summer, the diet shifts to predominantly animal matter, with such as beetles, flies, leafhoppers, wasps, moths, and caterpillars comprising the majority of consumption, supplemented by spiders, snails, and some seeds from , , blueberries, or cranberries. This insect-rich diet is essential for providing protein to growing , who are fed nearly 100% animal matter by their parents; adults may consume more seeds later in the season as breeding concludes. The transition to insects begins in spring around April or May, peaking in June and July. Foraging behavior is adapted to these dietary shifts. In winter, American tree sparrows typically forage in small flocks or in low , scratching at the or snow to uncover , hopping along weeds and branches, or beating seedheads with their wings to dislodge grains. They are notably resilient, continuing to feed during blizzards by probing through snow cover. During summer, they glean , , and berries from weeds and bushes, occasionally pursuing flying prey in short aerial darts. Parents deliver to nestlings at rates of up to 16 times per hour, totaling around 275 feedings per day per chick. Overall, these sparrows require about 30% of their body weight in and a similar amount in daily to maintain energy levels.

Reproduction

Breeding season and courtship

The American tree sparrow (Spizelloides arborea) breeds primarily in the summer months, with the season typically spanning from late May to early in its northern range across and . Pairs form shortly after the birds arrive on the breeding grounds, often around mid-June, as flocks dissolve during the latter stages of spring migration. This monogamous pairing usually lasts only for the duration of the breeding season, with birds raising a single brood per year. Courtship begins with males establishing and defending territories through persistent from perches in small trees or shrubs within the breeding habitat. Each male typically employs a single song type, consisting of high, thin whistles that last 1–2 seconds and are widely shared among individuals in the population, serving to attract females and deter rivals. Females may respond to a singing male with an excited "wehy" call, signaling interest and potentially initiating pair formation. Once a pair forms, displays involve the performing aerial maneuvers, such as spreading his wings, fluttering, and darting to the ground in front of the before returning to a , often repeating this sequence to reinforce the bond. also actively chase away intruding conspecifics to protect the , ensuring exclusive access to resources for nesting and . These behaviors can occur opportunistically during other activities, such as feeding or early nest construction, and may continue up to the day before egg-laying begins.

Nesting and eggs

The American tree sparrow constructs its nest on or near the ground, typically in concealed locations such as grass tussocks at the base of shrubs, mossy hummocks on , or depressions among and thickets. Occasionally, nests are placed up to 4 feet above ground in low shrubs like dwarf or . The female builds the nest alone over approximately 7 days, while the male remains nearby but does not assist. Nest structure consists of an open cup with three layers: an outer shell of coarse grasses, moss, lichens, bark shreds, and twigs (20–40 mm thick); an inner coat of finer grasses (about 10 mm thick); and a soft lining of feathers, most commonly ptarmigan feathers (29–152 per nest), though occasionally including duck or other bird feathers or animal hairs. Average nest dimensions are 130 mm in exterior diameter, 50 mm in interior diameter, 54 mm deep, and weighing 15.6 g. Following completion, there is often a rest period of several days before egg-laying begins, during which the birds visit the site infrequently. The female lays one per day, typically in the early morning between 6:00 and 7:30 a.m., with sizes ranging from 3 to 6 eggs, though 4–5 is most common (mean of 4.6–5 eggs reported in studies from and ). Eggs are pale blue to greenish-blue, marked with reddish-brown flecks or spots often concentrated at the larger end, measuring on average 19.1 mm long, 14.2 mm wide, and weighing 2.12 g. Incubation begins with the penultimate or last egg and is performed solely by the female, lasting 10–14 days until . The typically raises only one brood per breeding season due to the brief summer, though pairs may attempt to renest if the first attempt fails.

Incubation and parental care

The female American tree sparrow incubates alone for 11–13 days, during which the male frequently visits the nest but does not participate in incubation. Incubating females exhibit a diurnal of attentiveness, with 25–56 on-bout periods per day, each lasting 12.1–29.7 minutes on average, and inattentive periods averaging 6.7–9.4 minutes; longer on-bouts occur before and after night rest, while shorter ones prevail midday. Females also sleep on the nest during egg-laying and increase nest visits as incubation progresses. Upon , which occurs asynchronously over 1–2 days, the altricial young weigh about 1.6 g and measure 33 mm in length; the initially broods them while both parents feed the nestlings primarily at rates starting at 3–4 times per hour and rising to about 16 times per hour by later stages, with males assuming a larger share as brooding decreases. Nestlings grow rapidly, reaching 16.7 g and 75 mm by day 9, with eyes opening around day 5 and basic behaviors like calls emerging shortly after; the continues brooding for the first few days before focusing on feeding. The nestling period lasts 8–10 days on average, after which young fledge, though full flight capability develops around day 14; both parents continue provisioning the fledglings for 1–3 additional weeks, until the young reach about 22 days old and become independent. Pairs typically raise only one brood per breeding season.

Vocalizations

Songs

The American tree sparrow (Spizelloides arborea) produces songs primarily during the breeding season in its northern and subarctic habitats, though singing begins as early as late winter; males deliver them from elevated perches to establish territories and attract mates. Only males sing, and each individual typically possesses a single type that is widely shared among populations, facilitating conspecific recognition in sparse breeding environments. This uniformity contrasts with more variable repertoires in temperate sparrows and may reflect adaptations to low-density breeding sites north of the treeline. Songs consist of a series of high-pitched, sweet-toned whistled notes, often lasting 1 to 2 seconds and generally descending slightly in pitch overall. They typically begin with clearer, musical phrases followed by more complex, jumbled warbles or trills, creating a distinctive of thin, ethereal whistles that carry effectively over open . Research on song recognition indicates that key acoustic features, such as and syllable structure, help distinguish these songs from sympatric like Savannah sparrows, supporting the sound environment hypothesis where overlapping heterospecific signals shape conspecific cues. In territorial contexts, males sing persistently and dusk, with playback experiments showing heightened responses to local variants, underscoring the role of shared types in maintaining bonds and deterring intruders. While wintering individuals in southern regions rarely vocalize beyond calls, the breeding remains a critical signal for in remote habitats.

Calls

The American tree sparrow (Spizelloides arborea) produces a range of high-pitched, metallic calls that facilitate communication within flocks, signaling alarm, and coordinating movement, particularly during its winter range in . These calls are typically short and variable, serving functions year-round but becoming more frequent in non-breeding seasons when birds form loose flocks. A prominent call is a sharp tink or chink, often delivered in rapid series, which is given especially during flight or in response to potential threats. This alarm or contact call helps maintain group cohesion and alert others to danger. Another common vocalization is a softer, more musical tseet or tsip, used primarily for keeping in touch with flock members while or resting. In winter feeding contexts, birds emit a distinctive silvery tsee-ler, characterized by a falling or pattern that aids in locating food sources amid cover. Flight calls during migration are typically brief and high-pitched, resembling a tseep or seep, which allows for identification in nocturnal or low-visibility conditions. These calls vary slightly by context but generally exhibit a chip-like quality, with individuals producing them at rates up to 1.62 calls per minute in flock settings. Overall, the calls' simplicity and repeatability support efficient social interactions in dynamic environments like shrubby edges and open woodlands.

Conservation status

The global breeding population of the American tree sparrow (Spizelloides arborea) is estimated at 26 million individuals, primarily distributed across northern . This figure is derived from the Partners in Flight Population Estimates Database, version 3.0 (2019), which integrates data from the North American Breeding Bird Survey (BBS) and other monitoring programs to account for breeding ranges in , , and the . Population trends indicate a significant decline, with BBS data showing a 53% reduction in abundance from 1970 to 2014 across the species' breeding range. This equates to an average annual decline of approximately 1.8%, placing the American tree sparrow among common North American landbirds experiencing steep decreases. Analyses, including Christmas Bird Count (CBC) data through 2015, confirm ongoing decreases since 1970, particularly in eastern and central North America, though the species remains abundant in remote northern breeding areas. Recent eBird analyses through 2023 confirm continued declines in relative abundance across much of the winter range, though breeding populations in remote northern areas remain stable. The causes of these declines are not entirely clear but are likely linked to habitat alterations, such as the loss of weedy fields and shrubby edges in wintering grounds due to agricultural intensification and , as well as maturation reducing suitable breeding sites in the boreal zone. eBird Status and Trends reports from 2011 to 2021 further illustrate regional variations, with significant declines in relative abundance across much of the winter range (e.g., Midwest and Northeast U.S.), though some northern areas show stable or less pronounced changes. Despite these trends, the overall supports a Least Concern under IUCN criteria.

Threats and protection

The American tree sparrow (Spizelloides arborea) faces several environmental threats, primarily driven by habitat alteration and . Habitat loss and fragmentation, particularly from intensified in the Midwest and , have contributed to a of approximately 50% over the past 50 years. In breeding areas of and , large-scale development and mining activities pose risks, with local populations showing elevated levels in gold-mining regions of the . may shift suitable habitats northward and alter weather patterns, potentially impacting breeding and wintering areas. On wintering grounds across the continental , suburban practices such as clearing underbrush, removing weeds, and mowing lawns reduce food availability in weedy fields and shrubby edges. Despite these pressures, the species maintains a global breeding population of about 26 million mature individuals and is classified as Least Concern on the , owing to its large range of 8.26 million km² and the decline rate (1.8% annually from 1970 to 2014) not meeting thresholds for higher risk categories. However, it is flagged as a "Common Bird in Steep Decline" by Partners in Flight due to long-term trends, with regional variations showing decreases in southern wintering areas and slight increases in the north. Predation by hawks, , and mammals like weasels and foxes occurs but does not significantly impact overall numbers. Protection efforts focus on legal safeguards and habitat support. The species is protected under the U.S. Migratory Bird Treaty Act, which prohibits hunting and trade, though it holds no special status under the Endangered Species Act or CITES. Systematic monitoring through programs like the North American Christmas Bird Count tracks population trends and informs conservation. Nesting habitats remain largely remote and undisturbed, with much of the range covered by protected sites. In winter, supplemental feeding at backyard stations helps offset food shortages in altered landscapes, while recommendations for bird-friendly yards—preserving native shrubs and seeds—aid local resilience. Organizations like Audubon and Mass Audubon promote habitat maintenance and public education to mitigate declines, emphasizing the species' adaptability to human-modified environments.

References

  1. https://www.audubon.org/field-guide/bird/american-tree-sparrow
  2. https://www.allaboutbirds.org/guide/American_Tree_Sparrow/id
  3. https://www.allaboutbirds.org/guide/American_Tree_Sparrow/lifehistory
  4. https://www.allaboutbirds.org/guide/American_Tree_Sparrow/overview
  5. https://avibase.bsc-eoc.org/species.jsp?avibaseid=2A86F9C93636CDA3
  6. https://birdsoftheworld.org/bow/species/amtspa/cur/systematics
  7. https://birdsoftheworld.org/bow/species/amtspa/cur/introduction
  8. https://mapress.com/zootaxa/2014/f/z03821p400f.pdf
  9. https://www.eastsideaudubon.org/corvid-crier/2019/8/28/american-tree-sparrow
  10. https://checklist.americanornithology.org/taxa/
  11. https://academic.oup.com/auk/article/132/3/748/5149071
  12. https://doi.org/10.1111/ibi.12068
  13. https://doi.org/10.1093/auk/131.2.278
  14. https://www.nationalgeographic.com/animals/birds/facts/american-tree-sparrow
  15. https://animaldiversity.org/accounts/Spizella_arborea/
  16. https://www.allaboutbirds.org/guide/American_Tree_Sparrow/maps-range
  17. https://mdc.mo.gov/discover-nature/field-guide/american-tree-sparrow
  18. https://ncbirds.carolinabirdclub.org/view.php?species_id=501
  19. https://northernwoodlands.org/outside_story/article/american-tree-sparrows
  20. https://birdsoftheworld.org/bow/species/amtspa/cur/movement
  21. https://journal.afonet.org/vol96/iss3/art1/
  22. https://birdsoftheworld.org/bow/species/amtspa/cur/habitat
  23. https://stateofthebirds.nhaudubon.org/bird_database/american-tree-sparrow/
  24. https://doi.org/10.2173/bow.amtspa.01
  25. https://biokids.umich.edu/critters/Spizella_arborea/
  26. https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=4214&context=wilson_bulletin
  27. https://birdsoftheworld.org/bow/species/amtspa/cur/breeding
  28. https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=1565&context=bird_banding
  29. https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=18559&context=auk
  30. https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=1593&context=bird_banding
  31. https://nhpbs.org/wild/americantreesparrow.asp
  32. https://birdsoftheworld.org/bow/species/amtspa/cur/sounds
  33. https://www.allaboutbirds.org/guide/American_Tree_Sparrow/sounds
  34. https://brill.com/view/journals/beh/123/3-4/article-p314_7.xml
  35. https://www.fs.usda.gov/rm/pubs/rmrs_p016/rmrs_p016_151_159.pdf
  36. https://soar.wichita.edu/bitstreams/db002720-f151-46ec-b950-092935df9f30/download
  37. https://pif.birdconservancy.org/wp-content/uploads/2021/03/PopEsts_ContGlobal_3-01-19.xlsx
  38. https://partnersinflight.org/wp-content/uploads/2016/08/pif-continental-plan-final-spread-double-spread.pdf
  39. https://wildlife-species.canada.ca/bird-status/oiseau-bird-eng.aspx?sY=2019&sL=e&sM=a&sB=ATSP
  40. https://ebird.org/science/status-and-trends/amtspa/trends-map
  41. https://birdsoftheworld.org/bow/species/amtspa/cur/demography
  42. https://datazone.birdlife.org/species/factsheet/american-tree-sparrow-passerella-arborea
  43. https://www.birdweb.org/birdweb/bird/american_tree_sparrow
  44. https://www.massaudubon.org/nature-wildlife/birds/tree-sparrows
Add your contribution
Related Hubs
User Avatar
No comments yet.