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Western Bluebird - BirdForum Opus

Revision as of 23:28, 6 March 2023 by Deliatodd-18346 (talk | contribs) (→‎External Links: Multiple GSearches combined)
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Male
Photo © by Garrett Lau
San Jose, California, USA, 2 April 2005
Sialia mexicana

Identification

Female
Photo © by CalvinFold
Pleasanton, California, USA, 9 May 2015

Length 16.5-19 cm (6.5-7 in), weight 24-31 g

  • A dark blue-and-orange bluebird
  • Appears round-shouldered when perched

Male:

  • Blue head, wings, and tail
  • Rusty orange-red back
  • In some birds the back is partially or wholly blue
  • Blue throat

Female:

  • Paler and duller
  • Rusty breast
  • Grayish throat and belly

Immature:

  • Speckle-breasted and -backed
  • Grayish
  • No red
  • Some blue in wings and tail

Similar species

Juvenile
Photo © by bobsofpa
Azalea Campground, Kings Canyon National Park, California, USA, 5 June 2007
  • Eastern Bluebird is slightly paler blue above, orange (never blue) on the throat, and does not have any orange on the back; some females can be very hard to distinguish.
  • Mountain Bluebird is much paler blue, and lacks orange tones, being pale blue (males) or greyish (females) below.

Distribution

West coastal states of central North America, from southern British Columbia south to northern Baja California, the four-corners states, and extending south through Mexico, east into western Texas, and north just into southern Wyoming.

A partial migrant, moving out of the colder parts of the range (British Columbia except for the Vancouver area, and areas east of the Cascades mountains and north of central Utah and Colorado) in winter, with birds arriving in lowland desert areas of Arizona and northern Mexico where they do not breed.

Taxonomy

Subspecies

This is a polytypic species consisting of six to eight subspecies depending on authority[1][2]:

  • S. m. occidentalis:
  • S. m. bairdi:
  • South-western USA to north-western Mexico (Sonora and Chihuahua).
  • S. m. anabelae (accepted by Clements[1], not by IOC[2]):
  • Mountains of northern Baja California (Sierra Juárez and San Pedro Mártir).
  • S. m. jacoti (accepted by IOC, not by Clements):
  • S. m. amabilis:
  • Sierra Madre Occidental of Mexico (southern Chihuahua to Zacatecas).
  • S. m. nelsoni (accepted by IOC, not by Clements):
  • Central Mexico. Very dark; mostly blue, with minimal orange.
  • S. m. mexicana:
  • Plateau of north-eastern Mexico (Coahuila to Nuevo León and Tamaulipas).
  • S. m. australis (accepted by Clements, not by IOC):
  • Southern plateau of Mexico (Jalisco to Morelos, Puebla and Veracruz).

Habitat

Open woodlands, riparian zones, agricultural areas. Deserts in winter.

Behaviour

Usually in pairs, but gathers in flocks in winter. Has favorite perches, from which it drops to the ground to pick up prey or captures flying insects mid-air, flycatcher-style.

Diet

The diet includes insects, worms, snails, and spiders, adding berries in season.

Breeding

Breeds in tree holes; often in nest boxes. Monogamous, but up to 45% of nests have young not fathered by the defending male.

Vocalisations

Common call is a wavering "kew." Song is variable with strings of various notes including "kew" calls.

Movements

Mainly partial diurnal migrant. Movements largely opportunistic; in mild winters may remain on breeding grounds.

References

  1. Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2019. The eBird/Clements Checklist of Birds of the World: v2019. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
  2. Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.1). doi : 10.14344/IOC.ML.10.1. Available at http://www.worldbirdnames.org/
  3. Guinan, J. A., P. A. Gowaty, and E. K. Eltzroth (2020). Western Bluebird (Sialia mexicana), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.wesblu.01
  4. Cornell Lab of Ornithology. 2019. All About Birds. Cornell Lab of Ornithology, Ithaca, New York. https://www.allaboutbirds.org Accessed on 5 May 2020

Recommended Citation

External Links

GSearch checked for 2020 platform.1

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