User:Jiwonej/California scrub jay

California Scrub-Jay
California Scrub-Jay in Seattle, Washington.
File:Aphelocoma californica - California Scrub-Jay - XC110976.ogg
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Corvidae
Genus:	Aphelocoma
Species:	A. californica
Binomial name
Aphelocoma californica (Vigors, 1839)
Subspecies
See text

The California Scrub-Jay (Aphelocoma californica) is a species of Scrub-Jay native to western North America. It ranges from southern British Columbia throughout California and western Nevada near Reno to west of the Sierra Nevada. The California Scrub-Jay was once lumped with Woodhouse's Scrub-Jay and collectively called the western Scrub-Jay. The group was also lumped with the Island Scrub-Jay and the Florida Scrub-Jay; the taxon was then called simply Scrub-Jay. The California Scrub-Jay is nonmigratory and can be found in urban areas, where it can become tame and will come to bird feeders. While many refer to Scrub-Jays as "blue jays", the blue jay is a different species of bird entirely.

Description

The California Scrub-Jay is a medium-sized bird, approximately 27–31 cm (11–12 in) in length (including its tail), with a 39 cm (15 in) wingspan, and about 80 g (2.8 oz) in weight. In general, this species has a blue head, wings, and tail, a gray-brown back, grayish underparts, and white eyebrows. The throat is whitish with a blue necklace. The call or "screech" is described as "harsh and scratchy".

Habitat

True to its name, the California Scrub-Jay inhabits areas of low scrub, preferring pinon-juniper forests, oak woods, and edges of mixed evergreen forests. It also inhabits suburban gardens.

California Scrub-Jay foraging.

Foraging

California 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. They will also eat fruit and vegetables growing in backyards. They can be hand-fed by humans.

Diet

California Scrub-Jays are omnivorous. Diets can vary during the season. They mostly eat a variety of insects and fruit, especially during spring and summer. In the winter, they eat lots of acorns. For plant material, jays also eat grass seeds, sunflower seeds, and peanuts at feeders, as well as cultivated corn, almonds, walnuts, and cherries. It is not rare though to catch jays eating small reptiles and amphibians like lizards.

Food storing

California Scrub-Jays, like many other corvids, exploit ephemeral surpluses by storing food in scattered caches within their territories. They rely on highly accurate and complex memories to recover the hidden caches, often after long periods of time. In the process of collecting and storing this food, they have shown an ability to plan ahead in choosing cache sites to provide adequate food volume and variety for the future. Western Scrub-Jays are also able to rely on their accurate observational spatial memories to steal food from caches made by conspecifics. Food storing birds implement a number of strategies to protect their caches from potential 'pilferers.' Western Scrub-Jays are also known for hoarding and burying brightly colored objects. Western Scrub-Jays have a mischievous streak, and they are not above outright theft. They have been observed stealing acorns from acorn woodpecker caches. Some Scrub-Jays snatch acorns from the hiding places of other jays. When these birds go to hide their own acorns, they check first that no other jays are watching.

Intelligence

Main article: Bird intelligence

Recent research has suggested that western Scrub-Jays, along with several other corvids, are among the most intelligent of animals. The brain-to-body mass ratio of adult Scrub-Jays rivals that of chimpanzees and cetaceans, and is dwarfed only by that of humans. Scrub-Jays are also the only non-primate or non-dolphin shown to plan ahead for the future (known as metacognition), which was previously thought of as a uniquely human trait. Other studies have shown that they can remember locations of over 200 food caches, as well as the food item in each cache and its rate of decay. To protect their caches from pilfering conspecifics, Scrub-Jays will choose locations out of sight of their competitors, or re-cache caches once they are alone, suggesting that they can take into account the perspective of others. California Scrub-Jays also summon others to screech over the body of a dead jay, according to new research from the University of California, Davis. The birds' cacophonous "funerals" can last for up to half an hour.

Behavior

As common as they are, California Scrub-Jays are also great to watch. They are known to be vocal and playful, often seen moving around in bold hops or looking around in sharp turns. The California Scrub-Jay is a permanent resident of its territory, and the mated pair is usually held responsible for defending it year-round. Specific details on nesting are provided in the section below. They also travel in flockings of around 20-30 during the fall and winter. Birds that do not have territories of their own are known as “floaters.” These floaters, who are non-breeding adult birds, join parents and immature birds.

Nesting and Eggs

Juvenile in California, USA

The chicks start off fully gray. The older they get, the more they turn blue. On their heads, chicks tend to have a red crest that resembles a comb. The chick will lose its crest at day seven, just like the way the baby chickens lose their egg tooth at 5–7 days. Nests are built low in trees or bushes, 1–10 m (3.3–32.8 ft) above the ground, primarily by the female, while the male guards her efforts. The nests are sturdy, with an outside diameter of 33–58 cm (13–23 in), 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 with irregular, olive-colored spots or markings; and pale grayish-white to green with reddish-brown spots. The female incubates the eggs for about 16 days. The young leave the nest about 18 days after hatching.

Unlike the Florida Scrub-Jay and Mexican Jay, the California Scrub-Jays species breeds in isolated pairs and not cooperative flocks. Nests are sited in a shrub or tree; usually they are fairly low, only standing a couple feet above the ground. Both partners actively cooperate in building the nest of a basket with twigs and grass. These nests are often well hidden due to, unfortunately, the nest predators that exist. These include raccoons, weasels, skunks, squirrels, king snakes, gopher snakes, rattlesnakes, magpies, crows, and other jays.

California Scrub-Jays usually lay around 2 to 7 eggs. Eggs are light green and spotted with olive or brown. Incubation is completed solely by the female jay for about 18 days, as the male feeds. The baby birds are born naked and dependent, requiring consistent feeding by the parents for up to two months. The hatchlings' first flights are witnessed several weeks after fledging.

Life span

The life span of wild California Scrub-Jays is approximately 9 years. The oldest known western Scrub-Jay was found in Castaic, CA, in 1991 and raised in captivity. "Aaron" lived to be 19 years, and 8 months old.

Conservation

California Scrub-Jays are common. Their population appears to be stable in numbers, with an estimate of 2 million. Not many conservation methods are used because there seems not to be an urgency for such yet. However, one subspecies in southeastern California may be vulnerable to disturbance and is currently listed as a species of concern in the state. Some populations are also being affected by West Nile virus.

75% are known to reside in the United States, with the remaining 25% in Mexico and less than 1% in Canada. These jays also hold a US-Canada Stewardship species, which guarantees a conservation and protection of their habitats from both nations.

Phylogeny

California Scrub-Jay (Aphelocoma californica immanis), showing the well-marked breast band of the coastal races. Acorns are a typical food.

Another California Scrub-Jay. Note bright white plume breaking the breast band. Prominent markings in eye region are typical of male birds.

California Scrub-Jay fledgling being fed by a relative.

California Scrub-Jay in flight in Ben Lomond, Santa Cruz County, California

Woodhouse's, California, Island, and Florida Scrub-Jays were once considered subspecies of a single "Scrub-Jay" species. They are now believed to be distinct. Beyond the close relationship of the "California" and Island Scrub-Jays, resolution of their evolutionary history has proven very difficult.

Woodhouse's Scrub-Jay differ in plumage (paler blue above, with an indistinct and usually incomplete breast band) from California Scrub-Jay which is darker blue above with a strongly defined – but not necessarily complete – blue breast band.

The following subspecies are recognized:

• 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 Scrub-Jay

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.