Western Scrub-jay

__NOTOC__Taxobox
name = Western Scrub-Jay
status = LC
status_system= iucn3.1
status_ref = [IUCN2006|assessors=BirdLife International|year=2004|id=51095|title=Aphelocoma californica|downloaded=12 May 2006 Database entry includes justification for why this species is of least concern]


image_width = 250px
image_caption = A Western Scrub-Jay of the "California" population: "Aphelocoma californica californica"
regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Passeriformes
familia = Corvidae
genus = "Aphelocoma"
species = "A. californica"
binomial = "Aphelocoma californica"
binomial_authority = (Vigors, 1839)
subdivision_ranks = Subspecies
subdivision = 14 (7+7) - see text

The Western Scrub-Jay ("Aphelocoma californica"ref label|etymology|A|A),also known as California Jay or Long-tailed Jay (and see below) is a species of scrub-jay native to western North America, ranging from southern Washington to central Texas and central Mexico. In recent years, it has expanded its range into the Puget Sound region of Washington. The Santa Cruz or Island Scrub-Jay ("Aphelocoma insularis"), found only on Santa Cruz Island, and the Florida Scrub-Jay ("Aphelocoma coerulescens"), a Floridan endemic, are its closest relatives.Curry, Robert L.; Peterson, A. Townsend & Langen, T.A. (2002): Western Scrub-Jay ("Aphelocoma californica"). "In:" Poole, A. & Gill, F. (eds.): "The Birds of North America" 712. Academy of Natural Sciences, Philadelphia, PA & American Ornithologists' Union, Washington, D.C. Online version, retrieved 2007-FEB-25. DOI|10.2173/bna.712 (requires subscription)] The Western Scrub-jay is nonmigratory and can be found in urban areas, where it can become tame and will come to bird feeders.

Description

The Western Scrub-Jay is a large songbird, about 27-31 cm (11.5 in) in length (including its tail), with a 39 cm (15 in) wingspan, and about 80g in weight. Coastal Pacific birds tend to be brighter in coloration than those of the interior, but all are patterned in blue, white and gray, though none as uniform in color as the related Mexican Jay. In general, this species has a blue head, wings, and tail, a gray-brown back, and grayish underparts. The throat is whitish with a blue necklace. The call is described as "harsh and scratchy".

Habitat

True to their name, Western Scrub-Jays inhabit areas of low scrub, preferring pinyon-juniper forests, oak woods and sometimes mesquite bosques. They also inhabit suburban gardens.

Behaviour

Foraging

Western Scrub-Jays usually forage in pairs, family groups or small non-kin groups, outside of the breeding season. They feed on small animals, such as frogs and lizards, eggs and young of other birds, insects, and (particularly in winter) grains, nuts and berries.

Food Storing

Western Scrub-Jays, like many other corvids, exploit ephemeral surpluses in food supply by storing food in scattered caches within their territories. In the process of collecting and storing this food, western scrub-jays have shown an ability to plan ahead in choosing cache sites to provide adequate food volume and variety for the future. [cite journal | last =Raby | first =C. R. | coauthors =D. M. Alexis, A. Dickinson and N. S. Clayton | title =Planning for the future by western scrub-jays | journal =Nature | volume =445 | pages =919–921 | date =22 February 2007 | url =http://www.nature.com/nature/journal/v445/n7130/abs/nature05575.html;jsessionid=B15C481557982A232B40A28507F20AC6 | doi =10.1038/nature05575 | accessdate =2008-01-21 | format =abstract] Western scrub-jays are also able to rely on their accurate observational spatial memories to steal food from caches made by conspecifics. To protect their caches from these potential 'pilferers', food storing birds implement a number of strategies to reduce this risk of theft. Western scrub-jays are also known for hoarding and burying brightly colored objects.Fact|date=July 2008

Nesting

Nests are built low in trees or bushes, 1m to 10m above the ground, primarily by the female while the male guards her efforts. The nests are sturdy, with an outside diameter of 33cm to 58cm, constructed on a platform of twigs with moss and dry grasses lined with fine roots and hair. Four to six eggs are laid from March through July with some regional variations. There are two common shell color variations: pale green background with irregular, olive-colored spots or markings, and pale grayish-white to green background with reddish-brown spots. The female incubates the eggs for about 16 days. The young leave the nest about 18 days after hatching.

Diseases

The Western Scrub-Jay is one of the species whose populations are being adversely affected by the West Nile Virus, particularly in California's Central Valley.

ystematics

The Western, Santa Cruz, and Florida Scrub-jays were once considered subspecies of a single species termed the "Scrub Jay". However, they are now known to be well distinct (Emslie 1996, [Emslie, Steven D. (1996): A fossil Scrub-Jay supports a recent systematic decision. "Condor" 98(4): 675-680. [http://elibrary.unm.edu/sora/Condor/files/issues/v098n04/p0675-p0680.pdf PDF fulltext] ] Curry "et al." 2002, Rice "et al." 2003Rice, Nathan H.; Martínez-Meyer, Enrique & Peterson, A. Townsend (2003): Ecological niche differentiation in the "Aphelocoma" jays: a phylogenetic perspective. "Biol. J. Linn. Soc." 80(3): 369–383. DOI|10.1046/j.1095-8312.2003.00242.x [http://www.ansp.org/research/biodiv/ornithology/pdf/Jay-phylogeny.pdf PDF fulltext] ] ). Beyond the close relationship of the "California" and Island Scrub-jays, resolution of their evolutionary history has proven very difficult.

Judging from mtDNA NADH dehydrogenase subunit 2 sequence data, it appears as if there are 2 clades, namely a Pacific one west and another one east of the Rocky Mountains; the relationships of populations in the latter are not resolvable to satisfaction though (Rice "et al." 2003). Thus, it is fairly likely that the Western Scrub-jay is actually another two distinct species, one belonging to the Pacific and another one to the eastern lineage(s); the latter's ancestors apparently gave rise to the Florida Scrub-jay too. Paleogeography of the Rocky Mountains range supports this scenario.

Inland birds (Woodhouse's Scrub-Jay, "woodhouseii" group) differ in plumage (paler blue above, and with an indistinct and usually incomplete breast band) from the coastal birds (California Scrub-Jay, "californica" group; darker blue above, and with a strongly defined - but not necessarily complete - blue breast band). They also differ in ecology and behavior; the beaks of the Pacific group are usually strong and hooked at the tip as they feed on acorns, whereas the pinyon-nut feeding inland group has a longer, slimmer and straighter bill with little or no hook (Curry "et al." 2002).

Each group contains a number of subspecies. In the "woodhouseii" group, the quite pale but distinctly patterned southernmost subspecies "sumichrasti" and "remota" ("Sumichrast's Scrub-Jay") stand apart; its remaining races are generally not quite as pale but have washed-out colors with indistincly marked borders. Although these were considered to constitute well-marked groups, the molecular data of Rice "et al." (2003) was unable to distinguish "woodhouseii" and "sumichrasti". Thus, these differences seem to reflect patterns independent of phylogeny such as adaptations to local conditions, or perhaps character displacement with the Mexican Jay which is more similar to the northern inland than to the southernmost taxa; its range overlaps with the latter but not the former. Certainly, some gene flow between these populations occurs, but while the hybrid zone between the "californica" and "woodhouseii" groups is very limited, the geographically isolated southern populations seem genetically far less distinct (Curry "et al." 2002, Rice "et al." 2003).

Following Curry "et al." (2002), the subspecies are:

California Scrub-Jay, "Aphelocoma (californica) californica"

* "Aphelocoma californica immanis" Grinnell, 1901 - Interior Scrub-Jay:From Puget Sound through the Willamette Valley to Douglas County, Oregon:A large subspecies. Somewhat duller and lighter in color than "californica" due to gene flow from inland populations. Blue of head and neck less purplish than in "woodhouseii" group. Back usually quite brownish, underside and especially breast quite whitish, undertail coverts usually tinged pale blue or gray in males. Bill strong, wings and tail fairly short.

* "Aphelocoma californica caurina" Pitelka, 1951:Coastal SW Oregon from Rogue River valley south to Napa and Sonoma Counties; eastern limit the inner California Coast Ranges.:Similar to "californica", but head and back more intensely colored, with bright purplish tinge to blue of head. Color similar to nominate , thus darker than immanis and most oocleptica. Relative to nominate californica, blue areas more purplish and brighter, breast darker than rest of underside.

* "Aphelocoma californica oocleptica" Swarth, 1918 - Nicasio Scrub-Jay. Includes "A. c. superciliosa":From Jackson, Klamath, and Lake Counties, Oregon, through Sacramento and San Joaquin Valleys and surrounding mountains to Kern County, San Francisco Bay area, and Alpine County. Eastwards to Inyo County and Virginia Mountains (Washoe County, Nevada), where it intergrades with "nevadae" of the "woodhouseii" group.:Quite variable according to the extent of gene flow between this taxon and "nevadae". Generally similar to "californica" but larger; color of head and neck varies in lightness and amount of purplish hue. Back grayish; undertail coverts usually white. Bill usually heavy but variable according to habitat type (less heavy in birds of pinyon woodland).

* "Aphelocoma californica californica" (Vigors, 1839):California Coast Ranges from San Mateo County and SE Alameda County to SW Ventura County.:Blue of head usually strongly tinged purple. Back bluish-brownish gray, bluer towards the rump. Incomplete bluish-violet breast band. Underside greyish white, darker on the breast. Undertail coverts white tinged with blue. Thighs gray. Rectrices and remiges dark blue, the larger feathers duller. Bill heavy, tip strongly hooked.

* "Aphelocoma californica obscura" Anthony, 1889 - Belding's Scrub-Jay:Coastal SW California, east to Little San Bernardino Mountains, some isolated mountain ranges in W Mojave Desert, and Whale Peak (San Diego County). Southwards through N Baja California, Mexico (Sierra de Juárez, Sierra San Pedro Mártir) to Todos Santos Bay:Smaller and darker than "californica", with more intense purplish and brown coloration on head and back, respectively; prominent gray streaking on throat and distinct breast collar. Belly with smoky gray wash, lighter in the middle. Generally more intense coloration overall. Bill heavy.

* "Aphelocoma californica cana" Pitelka, 1951 - Eagle Mountain Scrub-Jay:Only occurs in Single-leaf Pinyon woods on Eagle Mountain, Joshua Tree National Park.:Smaller, lighter and grayer than "californica". Bill not as heavy. Apparently an isolate of hybrid origin between "A. c. obscura" and "nevadae" of the "woodhouseii" group.

* "Aphelocoma californica hypoleuca" Ridgway, 1887 - Xantus' Scrub-Jay. Includes "A. c. cactophila":Arid regions of central and southern Baja California south of a line through Bahía Magdalena, Sierra de Calamajué, and Loreto, Baja California Sur:Smaller and somewhat lighter than "californica" with less purplish hue to blue of head. Underside, including blue on breast, very light. Some have blue or gray tinge to undertail coverts. Bill proportionally longest in "californica" group.

Woodhouse's Scrub-Jay, "Aphelocoma (californica) woodhouseii"

* "Aphelocoma californica/woodhouseii nevadae" Pitelka, 1945a - Nevada Scrub-Jay:Great Basin from N Nevada southwards, some isolated mountain ranges in Death Valley and Mojave Desert from E California to the SW of New Mexico, south to NE Sonora and extreme NW Chihuahua. Some hybridization with "A. c. oocleptica" ("californica" group) at the north-western edge of its range.:Lighter and duller than "woodhouseii"; light blue undertail coverts. Bill longish, quite pointed, and tapering, not hooked at tip.

* "Aphelocoma californica/woodhouseii woodhouseii" (Baird, 1858):Rocky Mountains foothills, from N Utah/S Wyoming south through NW Chihuahua and W Texas, sometimes ranging farther into that State.:Blue of neck with dull grayish hue; back grayish brown. Undertail coverts blue. Bill heavy but straight, hardly hooked at tip.

* "Aphelocoma californica/woodhouseii texana" Ridgway, 1902 - Texas Scrub-Jay:Hitherto only known from Edwards Plateau (Texas); area and extent of possible contact with "woodhouseii" undetermined. Possibly this subspecies at Caprock Escarpment, where species settled in the 1950s.:Darker than "woodhouseii" with hint of breast collar. Lower breast with brownish hue, large white patch on lower belly. Undertail coverts white; in adult males usually with some blue feather tips. Back quite brown. Young birds conspicuously paler than in "woodhouseii". Heavy, fairly blunt bill.

* "Aphelocoma californica/woodhouseii grisea" Nelson, 1899:Sierra Madre Occidental, primarily in Chihuahua; intergrading with "nevadae" at NW of range.:Lighter and larger than "woodhouseii", with a hint of a blue collar. Undertail coverts white. Long wings and fairly short, heavy bill.

* "Aphelocoma californica/woodhouseii cyanotis" Ridgway, 1887 - Blue-eared Scrub-Jay:Lower Sierra Madre Oriental, Mexico, from S Coahuila to Tlaxcala; generally separated from "texana" "woodhouseii"; range adjacent to "grisea" in S Chihuahuan Desert. Apparently replaced by Mexican Jay at higher-altitude woodland towards S of range.:Larger and duller than "woodhouseii". Back brown with blue tinge, sometimes quite bluish. Supercilium faint and small. Underside qhite light; lower belly white. Undertail coverts dull white. Bill and wings as in "grisea", young birds browner than "texana".

* "Aphelocoma californica/woodhouseii sumichrasti" (Baird and Ridgway, 1874) - Sumichrast's Scrub-Jay:From Distrito Federal southeastwards through Veracruz, Puebla, and Oaxaca.:Bright blue head color, with blackish ear patches. Faint white supercilium. Back grayish-brown, blue towards the tail. Light gray streaks on throat; traces of a faint grayish or grayish-blue breast collar. Thighs smoky gray. Remiges and rectrices dark dull blue. Large, with very long wings. Heavy, slightly hooked bill.

* "Aphelocoma californica/woodhouseii remota" Griscom, 1934 - Chilpancingo Scrub-Jay:SW Oaxaca and central Guerrero. Apparently separated from "sumichrasti" by Rio Balsas valley.:Duller and lighter than "sumichrasti". Largest of all Western Scrub-jays.

References

Further reading

* Madge, Steve & Burn, Hilary (1994): "Crows and jays: a guide to the crows, jays and magpies of the world". A&C Black, London. ISBN 0-7136-3999-7

Footnotes

:note label|etymology|A|A Etymology: "Aphelocoma", from Latinized Ancient Greek "aphelo-", "soft" (Ancient Greek: apalos, απαλός) + Latin "coma" "hair", in reference to the smooth plumage of birds of this genus compared to other corvids. "californica", Latin: "from California".

External links

* Cornell Laboratory of Ornithology: [http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Western_Scrub-Jay.html Western Scrub-Jay ("Aphelocoma californica")] . Includes a sample of its call. Retrieved 2007-FEB-25.

* University of Cambridge Comparative Psychology of Learning and Cognition Lab: [http://www.psychol.cam.ac.uk/ccl/Scrub_jays.html It takes a thief to know a thief] - article on studies of the cognitive abilities of western scrub-jays. Retrieved 2007-FEB-25.

* USGS Patuxent Bird Identification InfoCenter: [http://www.mbr-pwrc.usgs.gov/Infocenter/i4810id.html Western scrub-jay "Aphelocoma californica"] . Retrieved 2007-FEB-25.