Curve-billed thrasher

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Curve-billed thrasher
Curve-billed Thrasher.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Mimidae
Genus: Toxostoma
Species:
T. curvirostre
Binomial name
Toxostoma curvirostre
(Swainson, 1827)
Curve-billed Thrasher range map.gif

The curve-billed thrasher (Toxostoma curvirostre) is a medium-sized mimid native to most of Mexico and to the deserts of southwestern United States. It is a non-migratory species, and throughout most of its range it is the most common desert thrasher. [2] Several subspecies have been classified since 1827, though there is no consensus on the number. Allopatric speciation is believed to have played a major role in the variations of the curve-billed. It is grey-brown overall with a slightly curved bill, and is similar in appearance to the related Bendire's thrasher. It generally resides in desert regions of the United States and Mexico, but can inhabit areas predominately populated by humans.

Contents

The demeanor of the curve-billed has been described as "shy and rather wild", but it allows humans to view it closely. [3] It is very aggressive in driving out potential threats, whether competitors for food or predators of its chicks. The curve-billed thrasher sometimes mimics several other species, though not to the extent of other mimids. It has a variety of distinctive songs, and this extensive repertoire of melodies has led it to be known as cuicacoche (songbird) in Mexico. [4]

Taxonomy and systematics

Atop a cholla cactus in Kingman, Arizona. Curve-billedThrasher-28APR2017.jpg
Atop a cholla cactus in Kingman, Arizona.

The species was first described as Toxostoma curvirostre by William John Swainson in 1827. Since then, six subspecies have been recognized, and have been divided into two branches. [5] Genetic research has indicated that the curve-billed thrasher is the sister species of a clade consisting of the ocellated thrasher, brown thrasher, long-billed thrasher, and Cozumel thrasher. [6] This contrasts with an earlier suggestion that curve-billed and ocellated thrashers are closest relatives. [6]

Subspecies

Eastern:

Western:

Description

Perched in a mesquite tree at the Desert Botanical Garden, Arizona Toxostoma curvirostre Cibomahto.jpg
Perched in a mesquite tree at the Desert Botanical Garden, Arizona

The curve-billed thrasher is immediately recognized as a thrasher by its long tail and short wings. [5] It is also recognized for its sickle-shaped bill, almost as long as its head width and brownish black in color. The body is compact with a large head, short wings and long tail. However, the tail is short relative to other thrasher species. [2] The chest is grayish brown with circular brown-gray spots. [5] The eyes are generally orange, shading to golden in adulthood. [2] Juveniles are lacking in pale tips, rectrices, abdominal feathers are unkempt and upper parts and chest are washed rufously. [5]

Variations are markedly different with each subspecies. The eastern subspecies has more distinct spots on its chest, more white along the tips and rectrices and obvious wing bars. T.c. palmeri has less spotting on chest and tips and less obvious wing bars. Other examples include T.c. curvirostre possessing longer wings and a tail than T.c. oberholseri; T.c. insularum is paler with more grey than T.c. palmeri and has more visible spotting on its breast. [5]

One study published in 2003 suggested that curve-billed speciation was due to climate, which could be explained by molt and feather wear. The same study suggested that the Sierra Madre Occidental acts as a barrier to initiate differentiation within the species. [9]

Measurements: [11]

Voice and song

The most distinctive voice of the curve-billed is an abrupt and brash whit-wheet, which sounds akin to a person whistling to get one's attention. [12] [13] It is usually uttered from high perches. [3] The songs are similar to that of the northern mockingbird but notes do not end as abruptly; its voice is regarded as more pleasant. [4] The curve-billed can utter songs consecutively two or three times, the length spanning from 2 to 15 seconds. [14] Some phrases are nasal and buzzy; its large vocabulary enables it to conjure successive songs that are usually different from one another. [14]

As a mimid it is capable of mimicking several species, including scissor-tailed flycatcher, northern cardinal, pyrrhuloxia and, in one instance, a black-headed grosbeak. [3] [15]

Similar species

Because its coloration is similar to Bendire's thrasher, the two birds are easily mistaken for one another. The bill of the curve-billed is all black, while that of Bendire's is paler down to the lower mandible, showing a dark grey with a basal area that does not feature a stark contrast. [16] The upper and lower mandibles of the curve-billed are curved, while the upper is curved and lower is essentially straight for the Bendires'. [16] [17] Although geographic variances for the curve-billed can make discerning breast patterns difficult, the curve-billed has a tendency to display larger and rounder spots overall on its breast, in contrast to the Bendires' smaller, more pronounced markings shaped like arrowheads. [16] However, curve-billed thrashers can also present this feature. [16] Bendires' typically have yellow eyes while curve-billed eyes are typically orange, but Bendires' can have variations that appear yellow-orange while some curve-billed eyes are red-orange, yellow-orange, or yellow. [16] [17] The curve-billed is heavier and is more likely to inhabit suburban regions; Bendires' are likely to avoid dense vegetation such as mesquite and prefers open grassland with scattered yucca or around hedgerows in agricultural areas. [2] [16] The song call of Bendire's is said to be more melodic and continuous with a chuck, while the curve-billed is known for its whit-wheet calls. [2]

Some of the aforementioned differences, such as streaks on the breast, bill shape and eye color are even more prominent in juveniles of the two species. [16] [17]

Habitat and distribution

On a saguaro, whose nearly open blooms will provide important food Toxostoma curvirostre Arizona.jpg
On a saguaro, whose nearly open blooms will provide important food

The curve-billed thrasher is commonly found throughout the southwestern United States from Arizona's Sonoran Desert across New Mexico to west Texas, southeastern Colorado and southwestern Kansas as well as most of Mexico from the Sonoran-Chihuahuan Deserts and south through the Mexican Plateau into Central Tamaulipas, inland to Oaxaca, and on the coast of Sonora to Nayarit. [2] [5] Vagrants have been found in bordering states of its range, as far north as North Dakota, Alberta and Manitoba and as far east as Florida. [5] Palmeri types have been spotted in Florida, while curvirostre have been found in Iowa on several occasions. [5] Other than previously noted exceptions, the curve-billed is essentially non-vagrant. [2]

In comparison with other desert thrashers, the curve-billed is not as particular with habitats and can be found from ground level up to 3,000 m (9,800 ft). [5] It generally resides where cholla and saguaro cacti, ocotillo, mesquites, palo verde, and creosote bushes are prevalent. [4] It can also be located along woodland edges, piñon, dry desert bushland and areas within its region where cacti are present. [2] If there is an adequate amount of desert vegetation near human habitation, along with feeders, the curve-billed can adapt within these environments. [2]

Behavior and ecology

The curve-billed thrasher can generally be found running rapidly from cover to cover or flying near ground level from bush to bush. [5] However, this bird is not shy about being in the open. [2] It is generally a forager on ground level but can be very aggressive in routing out potential competitors for food at feeders, such as the Inca dove and round-tailed ground squirrel. [4] [5]

Mating

One recorded case of courtship behavior involving curve-billed thrashers describes two males attacking each other vigorously and resorting to purring and hissings sounds when neither bird appeared to relent. The two males then puffed up their chests and strutted up and down in front of the female. They continued to alternate between purr and hiss and fighting one another until one triumphed. The victor flew towards the female and both chirped melodically before copulation. [4]

Breeding

Nest with eggs in a cactus, showing off the open cup construction Toxostoma curvirostre -Tuscon, Arizona, USA -eggs in nest-8.jpg
Nest with eggs in a cactus, showing off the open cup construction

The curve-billed breeding season begins in February and reaches an apex between March and May; however, new fledglings have been recorded as late as August. Dates vary within its range due to temperature and rainfall. [3] [5] Nests are generally built at conspicuous locations, the cholla being favored. [3] [5] Other potential nesting sites range from mesquite, prickly pear or yucca to the occasional oak and pine trees. [3] [5] The nest is generally a deep cup but can be flat with a depression for the eggs. [3] The outer layer consists of thorny twigs while the inner layer includes smooth sticks, roots, coarse and fine grasses, rootlets or hair. [3] [5]

Curve-billed thrasher chicks in a nest constructed between branches of cholla cactus. Curve-billedThrasherChicks.jpg
Curve-billed thrasher chicks in a nest constructed between branches of cholla cactus.

Both sexes build the nest; the building periods can be as brief as three days to as long as four weeks. [3] Egg count differs by location; the number has been as low as two and as high as five. [5] Egg color varies; they can appear bluish green to pale yellowish blue, spotted abundantly in reddish brown. [5] Both sexes incubate but the female is mainly responsible as well as being the sole provider of brooding. [3] Curve-billed parents defend their nests fervently against other species; snakes are the most frequent predators of eggs and nestlings. Curved-billed Thrashers are rarely victims of nest parasitism by cowbirds. [3] [5] In situations where food is scarce, parents feed older fledglings first. [3] The fledging period ranges from 11 to 18 days. [5]

Feeding

The curve-billed thrasher is an omnivore. Its diet includes invertebrates such as beetles, moths, butterflies, arachnids, and snails. [3] [5] It also eats vegetable matter, and fruits from cacti, prickly pear, hackberries, and anacua, among other plants. The curve-billed has also been spotted eating dog food, and will feed it to their chicks. [3] They are ground feeders, and not well adapting to climbing on branches. Thrashers will take surface prey, but will also dig holes more than 2 inches (5.1 cm) deep to search for food. Curve-billeds will also sip nectar from saguaro blossoms and eat insects trapped within, serving as pollinators in the process. They also have great love for the resulting saguaro fruits, which is an important source of water in dry months. [18] :168-187

Threats

Predators, which mainly focus on young birds, include snakes, coyotes, and roadrunners. This may account for very low brood success in the species, as only 20% of nests are successful in a year. [18] :183-185

Curve-billed thrashers share a very similar range to the cactus wren, as well as a favorite species to nest in: the jumping cholla. Because of this, interspecific conflict is frequent. Fights over food are rare, but fights to protect fledglings are heated. They will vigorously work to destroy each other's nests, although typically only roosting nests, not breeding nests, are destroyed. Despite this, nests of curve-billeds and cactus wrens may still be concurrently and successfully raised even feet away from each other. Anderson & Anderson noted a minimum nest distance of a highly unusual 15 centimetres (neither nest was destroyed by the either throughout the entire season), although average interspecies nest distances were well over thirty metres. Nest destruction is almost always unsuccessful, and less intense, during breeding times, as both species adamantly defend their own nests. Once breeding season wanes, and fledglings emerge, competition becomes more fierce. [18] :168-187

Status

Although its populations is declining, the curve-billed thrasher is rated as a species of least concern by the International Union for Conservation of Nature. [1]

Related Research Articles

<span class="mw-page-title-main">Mimid</span> Family of birds

The mimids are the New World family of passerine birds, Mimidae, that includes thrashers, mockingbirds, tremblers, and the New World catbirds. As their name suggests, these birds are notable for their vocalization, especially some species' remarkable ability to mimic a wide variety of birds and other sounds heard outdoors. They are commonly referred to as mimic thrushes but are not, in fact, thrushes.

<span class="mw-page-title-main">Gray catbird</span> Species of bird

The gray catbird, also spelled grey catbird, is a medium-sized North American and Central American perching bird of the mimid family. It is the only member of the "catbird" genus Dumetella. Like the black catbird, it is among the basal lineages of the Mimidae, probably a closer relative of the Caribbean thrasher and trembler assemblage than of the mockingbirds and Toxostoma thrashers. In some areas it is known as the slate-colored mockingbird.

<span class="mw-page-title-main">Bendire's thrasher</span> Species of bird

Bendire's thrasher is a medium-sized species of thrasher native to the southwestern United States and northwestern Mexico. It is 23–28 centimetres (9.1–11.0 in) long, with a long tail and a medium-sized bill. Coloration is grayish-brown on its upperparts with paler, faintly dark streaked underparts. The base of the lower bill is often pale, the eyes are bright yellow, and the tips of the tail are white-tipped.

<span class="mw-page-title-main">Mexican violetear</span> Species of bird

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<span class="mw-page-title-main">LeConte's thrasher</span> Species of bird

LeConte's thrasher is a pale bird found in the southwestern United States and northwestern Mexico. It prefers to live in deserts with very little vegetation, where it blends in with the sandy soils. LeConte's thrashers are nonmigratory birds that reside in the same territory annually. Although the species has been decreasing in certain areas of its range, in particular California, it still is abundant enough to not be considered for vulnerable status.

<span class="mw-page-title-main">Crissal thrasher</span> Species of bird

The crissal thrasher is a large thrasher found in the Southwestern United States to central Mexico.

<span class="mw-page-title-main">Canyon wren</span> Species of bird

The canyon wren is a small North American songbird of the wren family Troglodytidae. It is resident throughout its range and is generally found in arid, rocky cliffs, outcrops, and canyons. It is a small bird that is hard to see on its rocky habitat; however, it can be heard throughout the canyons by its distinctive, loud song. It is currently in a monotypic taxon and is the only species in the genus Catherpes.

<span class="mw-page-title-main">California thrasher</span> Species of passerine bird found in chaparral habitats

The California thrasher is a large member of family Mimidae found primarily in chaparral habitat in California and Baja California. It is the only species of Toxostoma throughout most of its range.

<span class="mw-page-title-main">Long-billed thrasher</span> Species of bird

The long-billed thrasher is a medium-sized resident songbird of South Texas and eastern Mexico. It bears a strong resemblance to its close relative the brown thrasher in appearance, calls, and various other behaviors; however, the two species do not overlap in range except in the winter when the brown thrasher will temporarily reside in the northern range of the long-billed.

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The black catbird is a songbird species in the monotypic genus Melanoptila, part of the family Mimidae. At 19–20.5 cm (7.5–8.1 in) in length and 31.6–42 g (1.11–1.48 oz) in mass, it is the smallest of the mimids. Sexes appear similar, with glossy black plumage, black legs and bill, and dark brownish eyes. The species is endemic to the Yucatán Peninsula, and is found as far south as Campeche, northern Guatemala and northern Belize. Although there are historical records from Honduras and the US state of Texas, the species is not now known to occur in either location. It is found at low elevations in semi-arid to humid habitats ranging from shrubland and abandoned farmland to woodland with thick understory, and is primarily sedentary.

<i>Toxostoma</i> Genus of birds

Toxostoma is a genus of bird in the family Mimidae. This genus contains most of the birds called thrashers, and accordingly members of this genus are sometimes referred to as the "typical thrashers".

<span class="mw-page-title-main">Cactus wren</span> Desert bird, United States and Mexico

The cactus wren is a species of wren that is endemic to the deserts of the southwestern United States and northern and central Mexico. It is the state bird of Arizona, and the largest wren in the United States. Its plumage is brown, with black and white spots as markings. It has a distinctive white eyebrow that sweeps to the nape of the neck. The chest is white, whereas the underparts are cinnamon-buff colored. Both sexes appear similar. The tail, as well as flight feathers, are barred in black and white. Their song is a loud raspy chirrup; akin in the description of some ornithologists to the sound of a car engine that will not start. It is well-adapted to its native desert environment, and the birds can meet their water needs from their diet which consists chiefly of insects, but also of some plant matter. The cactus wren is a poor flier and generally forages for food on the ground. Ornithologists generally recognize seven subspecies, with the exact taxonomy under dispute.

<span class="mw-page-title-main">Brown thrasher</span> Species of bird

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References

  1. 1 2 BirdLife International (2018). "Toxostoma curvirostre". IUCN Red List of Threatened Species . 2018: e.T22711115A132093983. doi: 10.2305/IUCN.UK.2018-2.RLTS.T22711115A132093983.en . Retrieved 12 November 2021.
  2. 1 2 3 4 5 6 7 8 9 10 Dunne, Pete (2006). Pete Dunne's Essential Field Guide Companion: A Comprehensive Resource for Identifying North American Birds. Houghton Mifflin Harcourt. p. 512. ISBN   978-0-300-09059-8.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 "Toxostoma curvirostre". Texas A&M AgriLifeExtension. Texas A&M University. 2000. Retrieved 15 May 2014.
  4. 1 2 3 4 5 Davis, Barbara L. (1997). A Field Guide to Birds of the Desert Southwest. Taylor Trade Publishing. pp. 228–29. ISBN   978-0-88415-278-1.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Brewer, David (2001). Wrens, Dippers, and Thrashers. Yale University Press. p. 115. ISBN   978-0-300-09059-8.
  6. 1 2 Lovette, I. J.; Arbogast, B. S.; Curry, R. L.; Zink, R. M.; Botero, C. A.; Sullivan, J. P.; Talaba, A. L.; Harris, R. B.; Rubenstein, D. R.; Ricklefs, R. E.; Bermingham, E. (2012). "Phylogenetic relationships of the mockingbirds and thrashers (Aves: Mimidae)" (PDF). Molecular Phylogenetics and Evolution. 63 (2): 219–229. doi:10.1016/j.ympev.2011.07.009. PMID   21867766. Archived from the original (PDF) on 2012-07-12.
  7. 1 2 3 4 5 6 7 "Curve-billed Thrasher(Toxostoma curvirostre)". Internet Bird Collection. Retrieved 9 May 2014.
  8. ↑ "Curve-billed Thrasher (Toxostoma curvirostre) (Swainson, 1827)". AviBase: The World Bird Database. Retrieved 9 May 2014.
  9. 1 2 Rojas-Soto, O. R. (2003). "Geographic Variation of the Curve-Billed Thrasher (Toxostoma Curvirostre) Complex". The Auk. 120 (2): 311. doi:10.1642/0004-8038(2003)120[0311:GVOTCT]2.0.CO;2. S2CID   85706382.
  10. ↑ "AOU Committee on Classification and Nomenclature (North & Middle America): Votes on Proposals 2009-D". American Ornithologists' Union. 2009. Retrieved 9 May 2014.
  11. ↑ "Curve-billed Thrasher Identification, All About Birds, Cornell Lab of Ornithology". www.allaboutbirds.org. Retrieved 2020-09-29.
  12. ↑ Rylander, Kent (2002). The Behavior of Texas Birds. University of Texas Press. p. 294. ISBN   978-0-292-77120-8.
  13. ↑ Peterson, Roger Tory (1999). A Field Guide to Mexican Birds: Mexico, Guatemala, Belize, El Salvador . Houghton Mifflin Harcourt. p.  180. ISBN   978-0-395-97514-5.
  14. 1 2 Borror, Donald J. (1984). Songs of Western Birds. Dover Publications. p. 36. ISBN   978-0-486-99913-5.
  15. ↑ Johnson, Roy R.; Haight, Lois T. (2010). "Occasional mimicry and night-time singing by the Western Curve-billed Thrasher (Toxostoma curvirostre palmeri).". The Wilson Journal of Ornithology. Wilson Ornithological Society. Archived from the original on 15 May 2014. Retrieved 10 May 2014.
  16. 1 2 3 4 5 6 7 Peterson, Robert Tory (1999). Advanced Birding. Houghton Mifflin Harcourt. pp. 220–21, 223. ISBN   978-0-395-97500-8.
  17. 1 2 3 Zimmer, Kevin J. (2000). Birding in the American West: A Handbook. Cornell University Press. pp. 236, 238–39. ISBN   978-0-8014-8328-8.
  18. 1 2 3 Anderson, Anders H.; Anderson, Anne (1972). The Cactus Wren. Tucson: University of Arizona Press. ISBN   0816503990. OCLC   578051.
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