Western Scrub Jay - Aphelocoma californica

[OldGreenVulture]

Western Scrub Jay - Aphelocoma californica.



Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Aphelocoma
Species: Aphelocoma californica

The Western Scrub Jay (Aphelocoma californica), is a species of scrub jay native to western North America. It ranges from southern Washington to central Texas and central Mexico. It comprises three distinct subspecies groups, all of which may be separate species. They are California Scrub Jay (coastal), Woodhouse's Scrub Jay (interior US and northern Mexico), and Sumichrast's Scrub Jay (interior southern Mexico). The Western Scrub Jay was once lumped with the Island Scrub Jay and the Florida Scrub Jay; the taxon was then called, simply, the Scrub Jay. The Western 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. In recent years, the California Scrub Jay has expanded its range north into the Puget Sound region of Washington.

Description
The Western Scrub Jay is a medium-sized bird, approximately 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 its name, the Western Scrub Jay inhabits areas of low scrub, preferring pinon-juniper forests, oak woods, edges of mixed evergreen forests and sometimes mesquite bosques. The coastal population also inhabits suburban gardens. Western Scrub-Jays are very common west of the Rocky Mountains, and can be found in scrub-brush, boreal forests, temperate forests, coastal regions, and suburban areas.



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. They can be aggressive towards other birds, for example, they have been known to steal hoarded acorns from Acorn Woodpecker granary trees. They will also eat fruit and vegetables growing in backyards.

Food storing
Western 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. To protect their caches from 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.[citation needed] Western Scrub Jays have a mischievous streak, and they’re not above outright theft. They’ve been caught stealing acorns from Acorn Woodpecker caches and robbing seeds and pine cones from Clark’s Nutcrackers. They even seem aware of their guilt: some scrub jays steal acorns they’ve watched other jays hide. When these birds go to hide their own acorns, they check first that no other jays are watching. You might see Western Scrub Jays standing on the back of a mule deer. They’re picking off and eating ticks and other parasites. The deer seem to appreciate the help, often standing still and holding up their ears to give the jays access. The Scrub Jay even will eat peanuts off of a human hand.

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 shown to plan ahead for the future, 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.

Nesting
Nests are built low in trees or bushes, 1-10m (3–30 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.

Life Span
The life span of wild Western Scrub Jays is approximately 9 years. The oldest known Western Scrub Jay was 15.75 years old.

Diseases
Populations are being adversely affected by the West Nile virus, particularly in California's Central Valley.



Phylogeny
The Western, Santa Cruz, and Florida Scrub Jay were once considered subspecies of a single "Scrub Jay" species. They are now believed to be distinct (Emslie 1996, Curry et al. 2002,[2] Rice et al. 2003).] 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 there are two clades, namely a Pacific one west and one east of the Rocky Mountains; the relationships of populations in the latter are not resolvable to satisfaction. Thus, it is fairly likely 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 as well. Paleogeography of the Rocky Mountains range supports this scenario.
Inland birds (Woodhouse's Scrub Jay, woodhouseii group and Sumichrast's Scrub Jay, sumichrasti group) differ in plumage (paler blue above, with an indistinct and usually incomplete breast band) from the coastal birds (California Scrub Jay, californica group) which are darker blue above with a strongly defined - but not necessarily complete - blue breast band. The three groups also differ in ecology and behavior. The beaks of the California and Sumichrast's groups are strong and hooked at the tip, as they feed on acorns, whereas the pinyon-nut feeding Woodhouse's group has a longer, slimmer and straighter bill with little or no hook.
Each group contains a number of subspecies. "Sumichrast's Scrub Jay" stands apart from the others in its altruistic breeding behavior. Its remaining races are generally not quite as pale but have washed-out colors with indistinctly marked borders. Certainly, some gene flow among these populations occurs, but while the hybrid zone between the californica and woodhouseii groups is very limited.

Subspecies

California Scrub Jay, Aphelocoma (californica) californica


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


Woodhouse's Scrub Jay, Aphelocoma (californica) woodhouseii



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[OldGreenVulture]

Birds hold 'funerals' for dead.



By Matt Walker
Editor, BBC Nature
1 September 2012 Last updated at 02:27

Some birds, it seems, hold funerals for their dead.

When western scrub jays encounter a dead bird, they call out to one another and stop foraging.

The jays then often fly down to the dead body and gather around it, scientists have discovered.

The behaviour may have evolved to warn other birds of nearby danger, report researchers in California, who have published the findings in the journal Animal Behaviour.

The revelation comes from a study by Teresa Iglesias and colleagues at the University of California, Davis, US.

They conducted experiments, placing a series of objects into residential back yards and observing how western scrub jays in the area reacted.

The objects included different coloured pieces of wood, dead jays, as well as mounted, stuffed jays and great horned owls, simulating the presence of live jays and predators.

Alarming reaction
The jays reacted indifferently to the wooden objects.

But when they spied a dead bird, they started making alarm calls, warning others long distances away.

The jays then gathered around the dead body, forming large cacophonous aggregations. The calls they made, known as "zeeps", "scolds" and "zeep-scolds", encouraged new jays to attend to the dead.

The jays also stopped foraging for food, a change in behaviour that lasted for over a day.

When the birds were fooled into thinking a predator had arrived, by being exposed to a mounted owl, they also gathered together and made a series of alarm calls.

They also swooped down at the supposed predator, to scare it off. But the jays never swooped at the body of a dead bird.

The birds also occasionally mobbed the stuffed jays; a behaviour they are known to do in the wild when they attack competitors or sick birds.

The fact that the jays didn't react to the wooden objects shows that it is not the novelty of a dead bird appearing that triggers the reaction.

The results show that "without witnessing the struggle and manner of death", the researchers write, the jays see the presence of a dead bird as information to be publicly shared, just as they do the presence of a predator.

Spreading the message that a dead bird is in the area helps safeguard other birds, alerting them to danger, and lowering their risk from whatever killed the original bird in the first place, the researchers say.

Other animals are known to take notice of their dead.

Giraffes and elephants, for example, have been recorded loitering around the body of a recently deceased close relative, raising the idea that animals have a mental concept of death, and may even mourn those that have passed.

www.bbc.co.uk/nature/19421217

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