Blue jay
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Blue jay ( Cyanocitta cristata ) |
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| ( Linnaeus , 1758) |
The Blue Jay ( Cyanocitta cristata ) is a passerine art from the family of corvids (Corvidae). This blue jay is widespread in eastern North America and is one of the most colorful birds in the region.
features
The 24 to 30 cm long blue jay has a wing length of about 13 to 15 cm and weighs 65 to 109 g. It is characterized by the blue back, a short bonnet , a black collar, a blue-black-white banded wing pattern and a narrow, dark banded blue tail.
The blue jay wears a moderately shaped hood from the middle to the back of the head. In the nominate form , the nasal bristles are bluish white, the top of the head and hood are light purple-blue. Below the hood, a narrow black band runs around the head, a little wider at the back of the head and narrowest from the neck over the eyes and forehead. The strip extends into a narrow collar that runs across the upper chest. The ear covers, a short stripe above the eyes , the throat and the rest of the underside are white-gray and washed-out gray, mauve or purple-gray. The bluish-gray, violet-blue faded upper side merges into a light blue towards the rump and the upper tail-coverts.
The wings are sky blue with strong, black banding on the arm wings and large arm covers. The tips of the arm wings and large arm covers are broadly colored white. The underside of the wings, with the exception of the white tips, are gray. The tail is of medium length and graduated. Except for the central pair of control feathers, the tips of the tail feathers are broadly colored white, the underside of the tail is gray like the underside of the wings, also with the exception of the white tips.
The beak is black, the legs blackish and the iris blackish brown.
There is no clear sexual dimorphism , the males are on average slightly larger than the females. Juvenile animals are generally duller, more dull in color. Their upper side is grayer, the wing covers almost unbanded, the rest of the banding with the greatest distance and the white feather tips more restricted.
The four subspecies are similar to each other. They differ in size and almost imperceptibly in the color of the plumage. Cyanocitta cristata semplei is the smallest, Cyanocitta cristata bromia the largest. The variation of the subspecies is clinically determined.
distribution and habitat
The distribution area extends over the east of North America from Newfoundland , southern Québec and central Manitoba and Alberta ( Canada ) to Louisiana and eastern Texas on the Gulf of Mexico . To the west, the distribution extends to eastern Wyoming , Nebraska , eastern Colorado and western Texas. In the western part of North America to the Pacific coast on the other hand is of the Blue Jays closely related Steller ( Cyanocitta stelleri , Eng. Steller's Jay), with the Bluejays occasionally hybridize .
In English the bird is called the Blue Jay. The blue jay is a partial migrant , only the northernmost populations move south in winter. He is a resident of mixed and deciduous forests, especially if there is clearing. It can also be found in parks and gardens in cities.
Way of life
The blue jays usually live in pairs, but also form small schools after the breeding season. When birds migrate, 100 or more specimens can come together. In addition to the typical "piiieh-piiieh" call repeated two or three times, it has a wide repertoire of sounds and can call other types - e. B. the red-tailed buzzard - imitate. He visits feeding places in gardens and, if he is not disturbed, can become exceptionally trusting. When stalking, he becomes cautious and shy.
food
The blue jay looks for food in tree tops and in the ground vegetation. This consists mainly of nut fruits such as chestnuts, acorns and beechnuts as well as seeds. It also eats insects and occasionally other small animals such as nestlings or small rodents, eggs or food waste . He usually hides his excess food in the crevices of the tree bark or in the ground. This behavior apparently only shows the populations that stay at their location all year round. In a swamp oak forest in Virginia , more than half of the acorns were carried away by blue jays and a further 20 percent eaten on the spot. Through this behavior he contributes to the spread of trees. The postglacial repopulation of North America by tree species with heavy seeds such as beech, chestnut and oak species can only be explained by the distribution by blue jays, which increase the distance of spread by an order of magnitude (from meters to kilometers).
Reproduction
Blue jays are monogamous and stay together for a lifetime. Both parents build a messy bowl-shaped nest out of twigs, grass, and stems in a tree or bush, rarely in old buildings. The clutch is incubated by the female, and very rarely by the male, for sixteen to eighteen days. Blue jays breed, at least in the north, usually once a year. But two successful breeding trades are not uncommon and there are reports of third broods as well. The clutch consists of two to six, usually four to five eggs. The eggs are from pale yellow-brown to pale greenish in color and mottled brown, olive, or gray. After seventeen to twenty-one days, the young birds fledge.
Subspecies
There are four subspecies :
- Cyanocitta cristata bromia Oberholser , 1921 - The largest subspecies, distributed north and west of the nominate form. North to Manitoba and Newfoundland, west to Illinois .
- Cyanocitta cristata cristata (Linnaeus , 1758) - The nominate form. US East Coast from North Carolina south to central Florida and North Texas.
- Cyanocitta cristata cyanotephra Sutton , 1935 - Slightly paler and more colorless than the other subspecies. In the interior and in the western parts of the entire distribution area, up to the foothills of the Rocky Mountains and south to western Texas.
- Cyanocitta cristata semplei Todd , 1928 - The smallest subspecies, southern Florida.
particularities
The species has become known as one of the examples of tool use in animals . A captive blue jay has been seen repeatedly tearing strips of newspapers lying around and twisting them to pull up chunks of food that were scattered outside the cage and out of reach.
Trivia
Bluejays (Blue Jay) is namesake and mascot of the Canadian Major League - Baseball teams Toronto Blue Jays .
The blue jay is the namesake and logo of the Java programming environment BlueJ .
The blue jay is an inspiration for the cartoon character "Mordecai" in the Regular Show series .
A poem by Marcel Beyer is called My Blue Jay .
In episode 5.9 of The Big Bang Theory series , Sheldon is afraid of a bird that he calls the blue jay several times. In fact, these are a kind of Langschwanzhäher Black-throated Elsterhäher (Calocitta colliei), also Schwarzwangenhäher called.
The Beatles' album Magical Mystery Tour featured a song called Blue Jay Way by George Harrison .
Web links
- Cyanocitta cristata inthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved February 5, 2014.
- BirdLife International: Species Factsheet - Blue Jay ( Cyanocitta cristata ) . Retrieved February 9, 2014.
- Videos, photos and sound recordings of Blue Jay (Cyanocitta cristata) in the Internet Bird Collection
- Blue jay ( Cyanocitta cristata ) at Avibase; Retrieved February 9, 2014.
- Cyanocitta cristata in the Integrated Taxonomic Information System (ITIS). Retrieved February 9, 2014.
- xeno-canto: Sound recordings - Blue Jay ( Cyanocitta cristata )
Individual evidence
- ↑ a b c d e f g h i j k l m Steve Madge: Crows and Jays. Christopher Helm, 2010, ISBN 978-1408131695 , pp. 67-68.
- ↑ Susan Darley-Hill & W. Carter Johnson (1981): Acorn dispersal by the blue jay (Cyanocitta cristata). Oecologia Volume 50, Issue 2: 231-232.
- ↑ JE Moore, RK Swihart: Nut selection by captive blue jays: importance of availability and implications for seed dispersal. 2006 In: The Condor 108: 377-388.
- ^ W. Carter Johnson & Thompson Webb, III (1989): The Role of Blue Jays (Cyanocitta cristata L.) in the Postglacial Dispersal of Fagaceous Trees in Eastern North America. Journal of Biogeography Vol. 16, No. 6: 561-571.
- ^ Thony B. Jones & Alan C. Kamil (1973): Tool-Making and Tool-Using in the Northern Blue Jay. Science Vol. 180, No. 4090: 1076-1078.
- ↑ M. Beyer, graphite. Poems. Berlin 2014. pp. 175–190.
- ↑ Black- cheeked jay on zootierliste.de