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Townsend's warbler
Townsend's warbler
Townsend's warbler
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Townsend's warbler
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Parulidae
Genus: Setophaga
Species:
S. townsendi
Binomial name
Setophaga townsendi
(Townsend, 1837)
Range of S. townsendi
  Breeding range
  Year-round range
  Wintering range
Synonyms

Sylvia townsendi (protonym)
Dendroica townsendi

Townsend's warbler (Setophaga townsendi) is a small songbird of the New World warbler family.

Taxonomy

[edit]

Townsend's warbler was formally described in 1837 by the American naturalist John Kirk Townsend under the binomial name Sylvia townsendi.[2] The type locality is Fort Vancouver on the Columbia River in the state of Washington.[3] After the merger of the genera Dendroica and Setophaga,[4] Townsend's warbler is now placed in the genus Setophaga that was introduced by the English naturalist William Swainson in 1827.[5][6] The species is monotypic: no subspecies are recognised.[6]

Description

[edit]

Townsend's warbler has a yellow face with a black stripe across its cheeks extending into an ear patch, a thin pointed bill, two white wing bars, olive upperparts with black streaks on their backs and flanks, and a white belly.[7] Adult males have a black cap, black throat and yellow lower breast; females have a dark cap and a yellow throat. Immature birds are similar to females with a dark green cap and cheeks.[8]

Adult female showing lighter facial markings and yellow throat as opposed to the Male's black markings and black throat.
Standard Measurements[9][8]
length 4.5–5 in (110–130 mm)
weight 8.8 g (0.31 oz)
wingspan 8 in (200 mm)
wing 63.1–69.9 mm (2.48–2.75 in)
tail 47.1–54 mm (1.85–2.13 in)
culmen 9.9–10.8 mm (0.39–0.43 in)
tarsus 18.1–19 mm (0.71–0.75 in)

Life history

[edit]
In California, USA

Their breeding habitats are coniferous forests with large trees on the northwestern coast of North America.[7] Their nests are shallow cups built with grass and lined with moss.[10] These nests are usually placed atop a branch in a conifer. The female lays 4 to 5 brown-speckled white eggs.[10]

This bird is closely related to the hermit warbler, and the two species interbreed where their ranges overlap.[8]

Birds from Haida Gwaii migrate short distances further south on the Pacific coast. Other birds winter in Mexico, Central America, and the south-western United States.[7]

They forage actively in the higher branches, often gleaning insects from foliage and sometimes hovering or catching insects in flight.[11] They mainly eat insects and spiders and seeds. Outside of the nesting season, these birds forage in mixed flocks. In winter, they also eat berries and plant nectar,[10] and honeydew directly from the anus of scale insects.[12]

The song of the male bird is a buzzed zee-zee-zee-bzz-zee or weazy weazy weazy weazy twea,[10] somewhat similar to that of its eastern relative, the black-throated green warbler.[8] The call is a sharp tup.

This bird was named after the American ornithologist, John Kirk Townsend.[2] Although Townsend is also credited with first describing this bird, he used a name chosen by Thomas Nuttall, who was travelling with him, and so sidestepped the convention against naming a species after oneself.[7]

References

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

Townsend's warbler

View on Grokipedia
from Grokipedia
The Townsend's warbler (Setophaga townsendi) is a small, colorful native to western , renowned for its striking and high-elevation habits. Measuring 11–13 cm in length with a of 19–21 cm, males exhibit a bold black throat and crown, bright yellow breast and forehead, olive-green upperparts streaked with black, white wing bars, and yellowish-white underparts with dark streaks on the flanks. Females and immatures are similar but duller overall, with a predominantly yellow throat lacking the male's solid black patch. This species breeds in mature coniferous forests across the Pacific Northwest, from coastal and southward through Washington, , and into and the of , , and northwest , favoring tall, dense stands of , , hemlock, and with at least 70% canopy cover. During migration and winter, it ranges widely, with most individuals heading to the highlands of and , though some remain along the Pacific Coast from southern to in varied habitats like oak woodlands, forests, mangroves, and even urban backyards. Townsend's warblers are active , typically gleaning insects from the upper canopy or hovering to probe foliage, and they often join mixed-species flocks outside the breeding season; their diet consists primarily of caterpillars, beetles, spiders, and flies during breeding, shifting to include honeydew from scale insects, berries, , and seeds in winter. The species is currently assessed as Least Concern by the IUCN, with an estimated global population of 21 million mature individuals as of 2019, though populations are decreasing and it faces potential threats from habitat loss due to and in its breeding grounds. Named after naturalist John Kirk Townsend, who collected the first specimens in the , this warbler is a key indicator of health in its range.

Taxonomy

Etymology and discovery

The Townsend's warbler (Setophaga townsendi) receives its common and specific names in honor of John Kirk Townsend (1809–1851), an American naturalist and collector who first documented the species during an overland expedition to the . Townsend, then in his mid-20s, joined botanist on a journey organized by fur trader Nathaniel Wyeth, departing in 1834 to explore the and reach the . During the expedition, Townsend collected numerous bird specimens, including the type series of the —a male obtained in the coniferous forests near at the mouth of the in present-day Washington. This marked one of several avian discoveries by Townsend in the region, highlighting the of the area's coastal habitats, though the proved challenging to observe due to its high in tree canopies. The species was formally described in 1837 by Nuttall, Townsend's expedition companion, in the Journal of the Academy of Natural Sciences of (volume 7, page 191), under the binomial Sylvia townsendi. The specific epithet townsendi directly commemorates Townsend's contributions to , a practice common in 19th-century for recognizing collectors and explorers. Originally placed in the warbler genus Sylvia (a Linnaean name for Old World sylviid warblers), the species was later reclassified into Dendroica and, following molecular phylogenetic studies, into the expanded genus Setophaga in 2011, reflecting its close relation to other wood warblers.

Classification and phylogeny

The Townsend's warbler (Setophaga townsendi) belongs to the kingdom Animalia, phylum Chordata, class Aves, order Passeriformes, family Parulidae (New World warblers), genus Setophaga, and species S. townsendi. The species was originally described in 1837 under the basionym Sylvia townsendi by Thomas Nuttall, attributing authorship to John Kirk Townsend, based on specimens collected by Townsend during his 1834 overland expedition to the Pacific Northwest. It was later reclassified as Dendroica townsendi in the 19th and 20th centuries, reflecting traditional groupings within the Parulidae based on plumage and morphology. Phylogenetic studies using multilocus DNA sequences (mitochondrial and nuclear loci across nearly all Parulidae ) have revealed that many traditional genera, including Dendroica, are not monophyletic. Instead, Dendroica form a well-supported with those previously assigned to , Parula, and Wilsonia, leading to a revised classification that merges them into a single expanded genus comprising 34 . This reorganization, proposed in 2010, aligns generic boundaries with major evolutionary radiations within the core Parulidae , which originated approximately 15–20 million years ago in the . Within , S. townsendi is positioned in a of black-and-white or yellow-throated species that includes close relatives such as the hermit warbler (S. occidentalis) and the (S. virens). Hybridization between S. townsendi and S. occidentalis in hybrid zones along the further supports their close phylogenetic relationship, with molecular markers confirming shared ancestry and . Subsequent genomic studies have reinforced this phylogeny, showing no major revisions to the generic placement of S. townsendi as of 2021.

Description

Plumage and coloration

The Townsend's exhibits a striking characterized by bold contrasts of , , olive-green, , which aids in its identification among North American wood warblers. males in breeding display a crown and throat, accented by bright supraloral and malar regions that form a conspicuous below the eye and surround a auricular patch. The upperparts are olive-green with streaks on the back and scapulars, while the underparts feature a and belly with prominent streaks on the flanks. The wings are grayish with two thick white wingbars, and the is blackish with white spots on the outer rectrices, contributing to its distinctive when foraging in canopies. Adult females possess similar overall patterns but with more subdued coloration, lacking the extensive black on the crown, throat, and auriculars; instead, the throat is mostly yellow, and the head shows olive streaking rather than solid black. The back remains olive-green with blackish streaks, the breast and belly are yellow with fainter black flank streaks, and the wings and tail mirror the male's with white wingbars and outer tail spots. This dimorphism helps distinguish sexes during the breeding season, though overlap in markings can occur. Juveniles and immatures resemble adult females closely, with yellow throats, olive-streaked crowns, and reduced black markings on the face and underparts, transitioning to adult-like through preformative and second-cycle molts. The species undergoes a complete post-breeding molt into basic , with minimal seasonal variation in coloration between breeding and non-breeding periods, maintaining the core yellow-and-black facial pattern year-round. Diagnostic features include the yellow lower eye-crescent contrasting against the dark auriculars and the notched tail shape, which set it apart from similar warblers like the hermit warbler.

Size and morphology

The Townsend's warbler (Setophaga townsendi) is a small to medium-sized , measuring approximately 11–13 cm in total length and weighing 7–10 g on average. Its wingspan ranges from 19–21 cm, contributing to a compact yet agile silhouette suited for in dense coniferous foliage. Compared to other passerines, it is larger than a but smaller than a , with a slender body build that facilitates movement through treetops. Morphologically, the species features a short, fine, pointed bill adapted for from needles and leaves, typical of wood warblers in the genus . The wings are rounded for maneuverability in flight, while the tail is moderately long, notched, and square-tipped, aiding in balance during hovering or quick turns while foraging. Legs and feet are slender and dark, supporting a primarily arboreal with occasional ground visits. There is slight in size, with males averaging longer wings, tails, and tarsi than females, though bill length shows no significant difference between sexes; male mass is marginally higher. Overall, these traits reflect adaptations for a life in the upper canopy of mature forests.

Distribution and habitat

Breeding range

The Townsend's warbler (Setophaga townsendi) breeds across western , primarily in coniferous forests ranging from east-central southward through the Yukon Territory, , and Washington to the mountains of western , , western Montana, and northwestern . This distribution encompasses both coastal and interior regions, with breeding occurring from in the northern portions of the range to subalpine elevations in the south. Within this range, the species favors mature and old-growth coniferous forests, including fir-dominated stands in the , spruce-hemlock woodlands along the coast, and montane spruce-fir (Picea-Abies) forests in inland areas. It is less common in logged or immature forests, preferring habitats with tall trees and dense canopies for nesting and foraging high in the treetops. Mixed coniferous-deciduous woodlands are occasionally used, particularly at higher elevations or in transitional zones. Breeding density varies regionally, with higher concentrations in coastal and the of , where suitable old-growth is abundant, compared to more fragmented inland montane areas. The species' range overlaps with that of the closely related hermit warbler (Setophaga occidentalis) in parts of Washington and , leading to occasional hybridization in shared habitats.

Non-breeding range and migration

The Townsend's warbler (Setophaga townsendi) is a medium- to long-distance Neotropical migrant, undertaking annual journeys between its breeding grounds in coniferous forests of Alaska, western Canada, and the Pacific Northwest of the United States and its wintering areas farther south. Fall migration typically commences in late summer or early fall, with birds departing breeding sites in Washington state around September and continuing southward over an extended period. Spring migration is similarly protracted, spanning several weeks; the first individuals appear in California by mid-April, with peak passage occurring from late April to mid-May, and most migrants reaching north of the U.S.-Mexico border by the end of the first week of May. Males generally arrive on breeding territories later, in late May. Migration routes follow a primarily coastal and montane corridor along the Pacific slope, utilizing coniferous mountain forests and streamside riparian zones in lowlands during passage. In the southwestern United States, migrants occur at a wide range of elevations but are most abundant in montane habitats. Birds from interior breeding populations, such as those in Idaho, Montana, and Wyoming, tend to travel longer distances to reach wintering sites, while coastal breeders from British Columbia often undertake shorter migrations along the Pacific seaboard. This pattern reflects adaptations to favorable stopover sites rich in arthropod prey, though the species exploits diverse habitats during transit, including mixed woodlands. The non-breeding range encompasses two primary regions during the northern winter (roughly October to April): a coastal strip from southwestern southward along the to northern , , and the highlands of southern extending into as far as . In the coastal zone, particularly , , and Washington, wintering birds—often from nearby breeding populations—occupy oak woodlands, conifer stands, and even suburban backyards with suitable vegetation. Farther south in the Mexican and Central American highlands, the species is a common to abundant winter resident in montane pine-oak-alder forests, where it forages in the canopy and midstory; in some locales, it ranks among the most frequently encountered warblers. Small numbers occasionally overwinter north of typical coastal limits, such as on .

Behavior and ecology

Foraging and diet

Townsend's warblers primarily in the upper canopy of coniferous forests, where they glean and other small prey from , twigs, and buds. They often hover briefly to pluck items from foliage or extend their reach, and occasionally pursue flying in short aerial sallies known as hawking. Outside the breeding season, they frequently join mixed-species flocks with other warblers and small to enhance efficiency, but during nesting, pairs independently or with their mate. The diet consists mainly of arthropods, particularly during the breeding season, when adults consume a variety of including caterpillars (especially spruce budworms), , bees, moths, beetles, weevils, true bugs such as stinkbugs, and leafhoppers. Spiders supplement the insect prey, while small amounts of and provide additional nutrition. When feeding nestlings, parents descend to lower strata to capture suitable soft-bodied and larvae. During migration, Townsend's warblers incorporate floral into their diet, probing flowers for energy-rich rewards to fuel long flights. On wintering grounds in and , they shift toward sweeter resources, feeding extensively on honeydew—the sugary excretions produced by scale on oak trees—as well as berries. In human-altered habitats, they opportunistically visit feeders for mealworms, , and . This dietary flexibility supports their survival across diverse seasonal environments.

Social behavior and vocalizations

Townsend's warblers exhibit territorial behavior during the breeding season, with males arriving on breeding grounds earlier than females to establish through persistent singing and prolonged aggressive encounters with rival males that can last for days until boundaries are defined. Both sexes actively defend these by chasing intruders, including other warblers and sparrows, particularly around nesting and foraging areas after young hatch. In regions of with hermit warblers, Townsend's warblers demonstrate interspecific aggression, displacing the latter in narrow hybrid zones and contributing to ongoing range shifts. The is primarily monogamous, with pairs forming rapidly after territory establishment; however, extra-pair copulations occur, as evidenced by observations of up to three additional males associating with paired females. Both parents participate in feeding and caring for the young, fostering biparental investment in offspring survival. Outside the breeding season, social structure shifts, with individuals often joining mixed-species foraging flocks alongside other warblers and small passerines, except during nesting when they remain solitary or paired. In wintering grounds, particularly in and , Townsend's warblers defend individual territories around trees producing honeydew from scale insects, aggressively excluding conspecifics and other from these resource-rich patches. Vocalizations play a central role in social and reproductive interactions. Males produce two primary song types: Type I, consisting of a series of clear, whistled notes at the same pitch—often interspersed with buzzy elements—followed by one to three higher-pitched buzzy notes, used mainly for mate attraction and general territory advertisement; and Type II, a variant more commonly employed during aggressive territorial disputes with intruding males. These songs are typically described as buzzy and rising, featuring two phrases where the first (e.g., "weazy weazy weazy") is repeated three or four times and the second (e.g., "twea" or "dee-de de") once or twice, delivered from high perches in coniferous forests. Calls include a soft chip note produced by both sexes for contact and mild alarm, as well as a rapid twittering or fluttering series associated with ; males emit this during fights with rivals, while females use it when disturbed at the nest. Additional call variations encompass buzzes, chirps, and whistles, often with flat, rising, or undulating patterns, serving functions in flock coordination during migration and winter .

Reproduction

Breeding biology

Townsend's warblers breed primarily in coniferous forests across their range in western , with the breeding season varying by latitude. In southern portions of the range, such as the , males arrive on breeding grounds in late May and establish territories through persistent singing, with egg-laying commencing by late June. Further north, in , birds arrive as early as late , allowing for an extended breeding period that extends into early July. Typically, pairs produce a single brood per season, though renesting may occur following nest failure. Courtship involves males advertising territories with high-pitched songs and displays to attract . Once paired, males follow closely during nest-building and egg-laying, occasionally performing a display by lowering the head and flaring the wings and tail feathers. Territories are defended aggressively against same-sex conspecifics, with males sometimes engaging in physical confrontations prior to arrival. Nests are constructed primarily by the , forming a shallow cup of grass, , bark strips, and twigs, lined with feathers and hair, and placed 2–18 meters above ground on horizontal branches of coniferous trees, preferably in mature or old-growth stands. Clutch sizes generally range from 3 to 5 eggs in southern populations, though northern boreal forest nests often contain 5–7 eggs, with a modal size of 6. Eggs are white with brown speckles and are laid daily until the clutch is complete. Incubation, performed by the female, lasts about 12 days (range 11–14 days), during which she is fed by the male. is typically synchronous, with all young emerging within one day, though it may extend to the next in some cases. Nestlings are altricial and remain in the nest for 8–10 days before fledging, during which both parents provision them with . Fledglings continue to be fed by both adults for several weeks post-fledging. Nest success varies with habitat quality; in Alaskan boreal forests, about 54% of nests succeed, with predation accounting for most failures, and success higher in larger trees and taller nests with sparser .

Nesting and parental care

Townsend's warblers construct nests in mature forests, typically placing them on horizontal branches of or trees at an average height of 36 feet (11 meters), though heights range from 7 to 60 feet (2 to 18 meters). The primarily builds the bulky, shallow cup-shaped nest, which measures about 4 inches (10 cm) across and 3 inches (7.6 cm) tall externally, with an interior cup of 2.4 inches (6 cm) across and 1.5 inches (3.8 cm) deep; it is composed of bark strips, needles, twigs, plant fibers, grass, lichens, and or cocoons, and lined with fine grasses, , feathers, and hair. Nests are often situated in areas with high densities of large trees for support and smaller spruces for concealment from predators, with 97% of observed nests in . Clutch sizes typically range from 3 to 5 eggs, though up to 7 have been recorded; the eggs are white with brown speckles and measure approximately 0.7 inches (1.7 cm) in length and 0.5 inches (1.3 cm) in width. Incubation lasts 11 to 14 days and is performed by the female. Nestlings are altricial, hatching helpless with sparse down after the . Both parents feed the young exclusively , making frequent provisioning trips without regurgitation, throughout the 9- to 11-day nestling period. The young fledge 8 to 10 days after hatching but remain dependent on for several weeks post-fledging, with adults continuing to and deliver food to support growth and survival.

Conservation

Population status

The Townsend's warbler () maintains a large global breeding population estimated at 21 million mature individuals (as of ). This species is rated as of low conservation concern, with a Continental Concern Score of 12 out of 20 according to Partners in Flight assessments. Population trends indicate overall stability or slight declines across much of its range. Data from the North American Breeding Bird Survey show roughly stable or slightly declining numbers between 1968 and 2015, while more recent estimates suggest a 7% decline over the decade prior to . Regionally, trends vary: in , populations exhibit a significantly positive trajectory based on 1993–2015 data, whereas Canadian surveys from 1970 indicate a 41% national decline with regional variations from little overall change to large decreases (as of ). In the , short-term trends show a modest increase of about 2.3% as of 2023. The International Union for Conservation of Nature (IUCN) classifies the Townsend's warbler as Least Concern (as of the 2021 assessment, unchanged as of 2025), reflecting its widespread distribution and lack of immediate extinction risk. Despite this status, ongoing monitoring is essential due to potential vulnerabilities in breeding habitats from and fragmentation, though the species' abundance mitigates broader threats.

Threats and management

The primary threats to Townsend's warbler (Setophaga townsendi) stem from habitat loss and degradation, particularly in its breeding range of mature coniferous forests in western . Clear-cut logging and even-aged forest management practices fragment these habitats, reducing suitable nesting sites and increasing vulnerability to predation and . In , a 41% population decline has been observed since the early 1970s, attributed largely to the loss of older forests. On wintering grounds in and , conversion of tropical forests to agriculture and pastures poses additional risks by diminishing foraging areas. Introduced species also threaten local populations, such as the on , which preys on nests in coniferous habitats. exacerbates these pressures, with models predicting substantial contraction of the species' breeding range due to warming temperatures and altered forest conditions, potentially shifting suitable habitats upslope or northward. Overall, while global populations are estimated at 21 million mature individuals and considered decreasing (7% decline over the decade prior to 2019), regional declines highlight the need for targeted interventions. Management efforts focus on sustainable forestry practices to maintain mature conifer stands, which are critical for breeding. Recommendations include retaining large-diameter trees (e.g., grand fir, Douglas-fir, or with at least 15 cm ) and dense foliage for nest concealment, alongside high overstory retention (e.g., 320 stems/ha) to avoid clear-cutting. Landscape-level strategies emphasize extended rotations and preserving old-growth forests within the natural range of variability to support population resilience. Many breeding sites are protected in national parks and refuges, contributing to the ' secure status (G5 globally). Ongoing monitoring through programs like the North American Breeding Bird Survey tracks trends and informs , though further research on wintering habitat vulnerability and climate impacts is recommended. The is classified as Least Concern by IUCN and secure in and the U.S., with no recovery plans currently in place.

References

  1. https://www.allaboutbirds.org/guide/Townsends_Warbler/overview
  2. https://birdsoftheworld.org/bow/species/towwar/cur/introduction
  3. https://www.audubon.org/field-guide/bird/townsends-warbler
  4. https://www.allaboutbirds.org/guide/Townsends_Warbler/id
  5. https://datazone.birdlife.org/species/factsheet/townsends-warbler-setophaga-townsendi
  6. https://abcbirds.org/bird/townsends-warbler/
  7. https://www.confluenceproject.org/library-post/birding-along-the-columbia-river-1834-37/
  8. https://avibase.bsc-eoc.org/species.jsp?avibaseid=F6C6C3F7E27ED557
  9. https://birdnamesforbirds.wordpress.com/historical-profiles/profiles-a-z/townsend-john-kirk/
  10. https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=111978
  11. https://doi.org/10.1016/j.ympev.2010.07.018
  12. https://birdweb.org/Birdweb/bird/townsends_warbler
  13. https://fieldguide.mt.gov/speciesDetail.aspx?elcode=ABPBX03080
  14. https://birdsoftheworld.org/bow/species/towwar/cur/identification
  15. https://birdsoftheworld.org/bow/species/towwar/cur/appearance
  16. https://birdsoftheworld.org/bow/species/towwar/cur/distribution
  17. https://www.allaboutbirds.org/guide/Townsends_Warbler/lifehistory
  18. https://wildlife-species.canada.ca/bird-status/oiseau-bird-eng.aspx?sY=2019&sL=e&sB=TOWA&sM=p1
  19. https://www.allaboutbirds.org/guide/Townsends_Warbler/maps-range
  20. https://birdsoftheworld.org/bow/species/towwar/cur/movement
  21. https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.105911/Setophaga_townsendi
  22. https://birdsoftheworld.org/bow/species/towwar/cur/sounds
  23. https://www.allaboutbirds.org/guide/Townsends_Warbler/sounds
  24. https://www.conservationgateway.org/ConservationByGeography/NorthAmerica/UnitedStates/alaska/seak/era/cfm/Documents/7.6_TownsendsWarbler.pdf
  25. https://birdsoftheworld.org/bow/species/towwar/cur/behavior
  26. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=2115
  27. https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=13292&context=condor
  28. https://birdsoftheworld.org/bow/species/towwar/cur/breeding
  29. https://www.researchgate.net/publication/259953002_The_Relative_Importance_of_Nesting_and_Foraging_Sites_in_Selection_of_Breeding_Territories_by_Townsend%27s_Warblers
  30. https://accs.uaa.alaska.edu/wp-content/uploads/setophaga_townsendi.pdf
  31. https://mtnhp.org/rankreports/Rank_Report_Townsends_Warbler_20250130.pdf
  32. https://friresearch.ca/publications/townsends-warbler-forestry-fact-sheet
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