An extremely small (4 inches) songbird, the male Ruby-crowned Kinglet is most easily identified by its small size, olive-green body, white eye-rings, black wings with white wing bars, and solid red crown. Female Ruby-crowned Kinglets are similar, but lack the male’s red crown. Both sexes may be separated from the related Golden-crowned Kinglet (Regulus satrapa) by that species’ pale face, black eye-stripe, and yellow on the head. The Ruby-crowned Kinglet breeds across Alaska, Canada, and the northern tier of the United States. In the west, this species’ range extends south at higher elevations as far as southern Arizona. In winter, most populations migrate south to the southern half of the U.S., along the Pacific coast from British Columbia to California, and in Mexico, although some populations breeding in the mountain west simply winter at lower altitudes nearby. Ruby-crowned Kinglets breed in northern and high-mountain evergreen forests. In winter, this species may be found in a variety of forest habitats from temperate deciduous woodland to open tropical forest. Ruby-crowned Kinglets primarily eat small insects and spiders, but will also eat fruit and seeds during the winter or when invertebrates are not available. In appropriate habitat, Ruby-crowned Kinglets may be observed flitting through the forest canopy while plucking small invertebrates from leaves or evergreen needles. Birdwatchers may also listen for this species’ song, a series of high chirps followed by a jumble of notes and a trill. Ruby-crowned Kinglets are primarily active during the day.
- Swanson, David L., J. L. Ingold and G. E. Wallace. 2008. Ruby-crowned Kinglet (Regulus calendula), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/119
- Peterson, Roger Tory. Birds of Eastern and Central North America. Boston: Houghton Mifflin, 1980. Print.
- eBird Range Map - Ruby-crowned Kinglet. eBird. Cornell Lab of Ornithology, N.d. Web. 20 July 2012. http://ebird.org/ebird/map/ruckin.
- Regulus calendula. Xeno-canto. Xeno-canto Foundation, n.d. Web. 20 July 2012. http://xeno-canto.org/browse.php?query=Regulus+calendula.
- Ruby-crowned Kinglet (Regulus calendula). The Internet Bird Collection. Lynx Edicions, n.d. Web. 20 July 2012. http://ibc.lynxeds.com/species/ruby-crowned-kinglet-regulus-calendula.
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Breeding
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: BREEDING: Labrador east through Quebec, northern Manitoba, and northwestern Canada to Alaska, south to northern New England, northern Great Lakes region, Manitoba, Saskatchewan, New Mexico, Arizona, southern California. NON-BREEDING: Pacific states, British Columbia, and southern U.S. south through Mexico to Guatemala, also western Cuba and Bahamas.
Length: 11 cm
Weight: 7 grams
Comments: Nests in coniferous forests and woodlands. In migration and winter it also inhabits deciduous woodlands, shrubs and thickets and may be found in old fields, gardens, yards and parks. BREEDING: Nests in coniferous trees (usually spruce), 1-30 m above ground. Nest usually hangs from stem or twig fork, occasionally it saddles a branch.
Habitat and Ecology
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
Migrates to lower latitudes or elevations for winter.
Comments: Primarily insects and other small invertebrates (e.g., wasps, ants, beetles, moths, spiders and pseudoscorpions). Eats some berries and seeds; drinks sap. Forages at branch tips in trees and often in shrubs; may hover while foraging; captures aerial prey and plucks insects from coniferous or deciduous foliage (Keast and Saunders 1991).
Population declines occur after exceptionally cold winters. Seen in scattered groups in association with golden-crownd kinglets, nuthatches, chickadees, etc.
Life History and Behavior
Lifespan, longevity, and ageing
Clutch size 5-11 (usually 7-8). Incubation about 12 days, by female (Terres 1980). Altricial, downy nestlings tended by both parents. Young first fly at about 12 days.
Molecular Biology and Genetics
Barcode data: Regulus calendula
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Regulus calendula
Public Records: 37
Specimens with Barcodes: 38
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N5B - Secure
Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
IUCN Red List Assessment
Red List Category
Red List Criteria
The ruby-crowned kinglet (Regulus calendula) is a very small passerine bird found throughout North America. It is a member of the kinglet family. The bird has olive-green plumage with two white wing bars and a white eye-ring. Males have a red crown patch, which is usually concealed. The sexes are identical (apart from the crown), and juveniles are similar in plumage to adults. It is one of the smallest songbirds in North America. The ruby-crowned kinglet is not closely related to other kinglets, and is put in its own subgenus, Corthylio. Three subspecies are currently recognized.
The kinglet is migratory, and its range extends from northwest Canada and Alaska south to Mexico. Its breeding habitat is spruce-fir forests in the northern, mountainous, United States and Canada. The ruby-crowned kinglet builds a cup-shaped nest, which may be pensile or placed on a tree branch and is often hidden. It lays up to 12 eggs, and has the largest clutch of any North American passerine for its size. It is mainly insectivorous, but also eats fruits and seeds.
The ruby-crowned kinglet is a very small bird, being 9 to 11 cm (3.5 to 4.3 in) long, having a wingspan of 16 to 18 cm (6.3 to 7.1 in), and weighing 5 to 10 g (0.2 to 0.4 oz). It has gray-green upperparts and olive-buff underparts. It has two white wingbars and a broken white eye ring. The wingbar on the greater secondary coverts (closer to the wing-tip) is wider, and is next to a dark band. The kinglet has a relatively plain face and head, although the male has a scarlet-red crown patch, which is usually concealed by the surrounding feathers. The crown patch is rarely orange, yellow, or not present. Females are identical to males (except for the crown). Immature birds are similar to adult females, since young males lack a crown patch. The kinglet usually moves along branches or through foliage with short hops, and flies with bursts of rapid wing beats. It is constantly active, and is easily recognized by its characteristic wing-flicking. Its flight has been described as "swift, jerky, and erratic".
Compared to the related golden-crowned kinglet, the ruby-crowned kinglet is slightly larger, more elongated, and has greener plumage. The bird can be mistaken for the Hutton's Vireo, which also displays wing-flicking, though less frequently than the kinglet. It can also be mistaken for the Dwarf Vireo in Mexico. However, both of the vireos are larger, have stouter bills and legs, and lack the kinglet's black bar on the wings.
The ruby-crowned kinglet's vocalizations are remarkably loud and complex for its size. Its song can be divided into three main parts: a series of high pitched notes (zee-zee-zee or tee-tee-tee), two to five low trills (turr or tu), and a repeated three note "galloping" phrase (tee-da-leet, tee-da-leet). However, there is variation in the songs of a given individual, and they often contain only one or two of the three parts. The third part is only sung by male birds; an abbreviated version is heard from the females. Other vocalizations of the ruby-crowned kinglet include alarm calls, simple contact calls, and begging calls produced by chicks.
The kinglets are a small group of birds sometimes included in the Old World warblers, but frequently given family status, especially as recent research showed that, despite superficial similarities, the crests are taxonomically remote from the warblers. The names of the family, Regulidae, and its only genus, Regulus, are derived from the Latin regulus, a diminutive of rex, "a king", and refer to the characteristic orange or yellow crests of adult kinglets. The ruby-crowned kinglet was first described in 1766, in the 12th edition of Carl Linnaeus's Systema Naturae. Its species name means "by the month", and is shared with a genus of flower.
As a result of its larger size, strongly red (rather than orange or yellow) crest and lack of black crown stripes, as well as its distinctive vocalisations, the ruby-crowned kinglet is sometimes considered different enough from the Old World kinglets and the other American species, the Golden-crowned Kinglet, to be sometimes assigned to a separate genus, Corthylio.
Up to five subspecies have been recognized, but "cineraceus", breeding in montane western North America, and "arizonensis", breeding in Arizona, are considered to be clinal variants of the nominate subspecies. The form grinnellii, breeding from southeast Alaska to British Columbia differs significantly from nominate calendula, and so is considered to be represent a valid subspecies: it is smaller and shorter-winged, its upperparts are darker and greener, its underparts are buffy rather than grayish olive, and the vent is tinged yellow rather than dull whitish olive. The subspecies obscurus, from Guadalupe Island, off Baja California, is considered endangered, and may already be extinct.
Distribution and habitat
Their breeding habitat is coniferous forests across Canada, Alaska, northern New England and the western United States. They nest in a well-concealed hanging cup suspended from a conifer branch and may lay as many as twelve eggs in a clutch.
The recent counting indicates that the ruby-crowned kinglet population is on the rise. This is mainly due to discovery of less disturbed territory farther north. This allows more successful breeding.
Ruby-crowned kinglets forage actively in trees or shrubs, mainly eating small insects and spiders, some berries and tree sap. They may hover over a branch while feeding and sometimes fly out to catch insects in flight. The red crest is raised when agitated or in display. Often, they perform a "broken-wing" act to draw predators away from their nest, which they will defend fearlessly, mobbing the intruder which may be a cat, squirrel, or human.
- BirdLife International (2012). "Regulus calendula". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- "Ruby-crowned Kinglet". Cornell Lab of Ornithology Bird Guide. Cornell Lab of Ornithology. 1994. Retrieved 2 November 2010.
- Knight, Ora Willis (1908). The birds of Maine. Bangor: C. H. Glass & co. pp. 616–619. ISBN 1-145-46819-5. Retrieved 1 November 2010.
- Ingold, J L; Wallace, G E (28 July 2008). "Ruby-crowned Kinglet: Distinguishing Characteristics". The Birds of North America Online. Cornell Lab of Ornithology. Retrieved 3 November 2010.
- Dunne, Peter (2006). Pete Dunne's essential field guide companion. New York: Houghton Mifflin Harcourt. p. 487. ISBN 0-618-23648-1. Retrieved 3 November 2010.
- Sibley, David Allen (2000). The Sibley Guide to Birds. New York: Alfred A. Knopf. p. 394. ISBN 0-679-45122-6.
- Borror, Donald J (1984). Songs of Eastern Birds. Don Mills: Dover Publications. pp. 44–45. ISBN 0-486-99912-2. Retrieved 3 November 2010.
- Ingold, J L; Wallace, G E (28 July 2008). "Ruby-crowned Kinglet: Sounds". The Birds of North America Online. Cornell Lab of Ornithology. Retrieved 3 November 2010.
- Monroe, Burt L. (February 1992). "The new DNA-DNA avian classification: What's it all about?". British Birds 85 (2): 53–61.
- Barker, F Keith; Barrowclough, George F; Groth, Jeff G (2002). "A phylogenetic hypothesis for passerine birds: taxonomic and biogeographic implications of an analysis of nuclear DNA sequence data". Proceedings of the Royal Society of London B 269 (1488): 295–308. doi:10.1098/rspb.2001.1883. PMC 1690884. PMID 11839199.
- Spicer, Greg S; Dunipace, Leslie (2004). "Molecular phylogeny of songbirds (Passerifor-mes) inferred from mitochondrial 16S ribosomal RNA gene sequences". Molecular Phylogenetics and Evolution 30: 325–335. doi:10.1016/S1055-7903(03)00193-3. PMID 14715224.
- Brookes, Ian (editor-in-chief) (2006). The Chambers Dictionary, ninth edition. Edinburgh: Chambers. pp. 223, 735, 1277. ISBN 0-550-10185-3.
- (Latin) Linnaeus, Carolus (1766). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. Holmiae. (Laurentii Salvii). p. 338.
- "Plant Guide: Calendula". Gardener's Path. 2003. Retrieved 3 November 2010.
- Martens, Jochen; Päckert, Martin "Family Regulidae (Kinglets & Firecrests)" pp. 330–349 in Del Hoyo, Josep; Elliott, Andrew; Christie David A (eds) (2006). Handbook of the Birds of the World: Old World Flycatchers to Old World Warblers v. 11. Barcelona: Lynx Edicions. ISBN 84-96553-06-X.
- pp. 375-76 in Pyle, Peter (1997). Identification Guide to North American Birds Part 1. Bolinas, California: Slate Creek Press. ISBN 0-9618940-2-4.
Names and Taxonomy
Comments: Formerly in family Muscicapidae; returned to Regulidae by AOU (1997). See Banks and Browning (1995) for brief comments on generic nomenclature.