Eurasian Jay - Garrulus glandarius

[OldGreenVulture]

Eurasian Jay - Garrulus glandarius.



Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Garrulus
Species: Garrulus glandarius

The Eurasian Jay (Garrulus glandarius) is a species of bird occurring over a vast region from Western Europe and north-west Africa to the Indian Subcontinent and further to the eastern seaboard of Asia and down into south-east Asia. Across its vast range, several very distinct racial forms have evolved to look very different from each other, especially when forms at the extremes of its range are compared.
The bird is called jay, without any epithets, by English speakers in Britain and Ireland.



Taxonomy
The Eurasian Jay was one of the many species originally described by Linnaeus in his 18th century work Systema Naturae. He recognised its affinity with other corvids, naming it Corvus glandarius.
Eight racial groups (33 subspecies in total) are recognised by Madge & Burn (1994):
the nominate group (nine European races), with a streaked crown.

the cervicalis group (three races in North Africa), with a rufous nape, grey mantle, very pale head sides, and a streaked or black crown.

the atricapillus group (four races in Middle East, Crimea & Turkey), with a uniform mantle & nape, black crown and very pale face.

the race hyrcanus (Caspian Hyrcanian mixed forests of Iran), small with black forecrown and broadly-streaked hindcrown.

the brandtii group (four races in Siberia and northern Japan), with a streaked crown, reddish head, dark iris and grey mantle.

the leucotis group (two races in south-east Asia), with no white in the wing, a white forecrown, black hindcrown and much white on the sides of the head.

the bispecularis group (six races in the Himalayan region), with an unstreaked rufous crown, and no white wing-patch.

the japonicus group (four races in the southern Japanese islands), with a large white wing-patch, blackish face and scaled crown.



A member of the widespread jay group, and about the size of the Jackdaw, it inhabits mixed woodland, particularly with oaks, and is an habitual acorn hoarder. In recent years, the bird has begun to migrate into urban areas, possibly as a result of continued erosion of its woodland habitat.

Behaviour
Its usual call is the alarm call which is a harsh, rasping screech and is used upon sighting various predatory animals, but the Jay is well known for its mimicry, often sounding so like a different species that it is virtually impossible to distinguish its true identity unless the Jay is seen. It will even imitate the sound of the bird it is attacking, such as a Tawny Owl, which it does mercilessly if attacking during the day. However, the Jay is a potential prey item for owls at night and other birds of prey such as Goshawks and Peregrines during the day.


Diet
Feeding in both trees and on the ground, it takes a wide range of invertebrates including many pest insects, acorns (oak seeds, which it buries for use during winter), beech mast and other seeds, fruits such as blackberries and rowan berries, young birds and eggs and small rodents.

Breeding
It nests in trees or large shrubs laying usually 4–6 eggs that hatch after 16–19 days and are fledged generally after 21–23 days. Both sexes typically feed the young.



From Carnivora

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[OldGreenVulture]

Clever jays switch food-finding tactics

By Ella Davies
Reporter, BBC Nature
25 September 2012 Last updated at 12:29



Jays are one of the more colourful species of the corvid family

Jays demonstrate "flexible tactics" by switching between storing food and stealing from others' stashes, scientists have found.

The woodland birds are known as the shy members of the notoriously intelligent corvid family.

But birds were observed boldly stealing food from subordinates' hiding places in the University of Cambridge study.

Researchers found that the jays' strategy was dependent on the relative social rank of their opponent.

The results are published in the journal Animal Behaviour.

Eurasian jays live in woodlands and feed primarily on acorns. Past studies by the University of Cambridge team have highlighted the birds' remarkable ability to plan for the future by storing thousands of the nuts and returning to them later.

Researchers were able to ascertain the social hierarchy of 14 birds after systematically introducing them in an outdoor aviary.

To further understand the jays' food-storing behaviour, scientists observed interactions between pairs of the birds after introducing a bowl of food, including their favourite acorns, to the test area.

"When dominant, jays in our study hid many food items, moved these items frequently and boldly approached food that had been hidden by their subordinate competitor, often stealing it in full view," said Professor Nicky Clayton who supervised the study led by Rachael Shaw.

"In contrast, when subordinate, the same jays were secretive when hiding food and when attempting to steal from others, preferring to wait until the competitor was at a distance before attempting to approach and steal their food stores."

Prof Clayton told BBC Nature that these changes in behaviour indicated that the birds were thinking about the situations.

"The flexible response to social context, both when hiding food and when stealing food, suggests that the [jays'] different hiding and stealing tactics may be based on cognitive strategies, rather than learned or innate rules," she said.



A dominant jay showed no shyness when it came to pilfering from another bird's cache

The results raise further questions about how intelligence has evolved in the corvid family.

Many species in the family, including ravens and jackdaws, are social animals; meaning that they live together in groups some or all of the time.

In the past, scientists have theorised that managing relationships within these social groups may have contributed to the birds' high intelligence.

But Eurasian jays are very territorial, emitting screeching calls and performing threatening behaviour to keep others away.

"The evidence from Eurasian jays therefore suggests that current social environment alone cannot explain the cognitive abilities of corvids," said Prof Clayton.

www.bbc.co.uk/nature/19660267

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