Corvids (crows and their relatives)
Corvidae
INDEX
WHAT ARE CORVIDS?
CORVID FEATURES
TYPES OF CORVIDS
DIET AND FORAGING
INTELLIGENCE
CORVIDS AND MAN
CORVIDS OF ARDASTRA
WHAT ARE CORVIDS?
There are about 119 different species of corvids, including birds such as the crows, ravens, magpies and jays. These are a group of birds that belong to the largest order of birds known as the Passiformes or passerines, commonly known as “perching birds” or “song birds”. The corvids represent the largest of the song birds; the raven being the largest.
Corvids are generally bold, noisy and gregarious (tending to form a group with others of the same kind), with evidence they originated from Australia. Today, this family has representatives on all continents except Antarctica. These birds are mostly confined to forested areas but in Europe and North America, they prefer a more open habitat.
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CORVID FEATURES
Corvids, like all perching birds, have the typical bird toe arrangement, three toes pointing forward and one toe pointing backward. This is known as anisodactyl toe arrangement. They also have very strong, sturdy legs and feet, with very strong grasping toes.
Corvids do not show any difference between the male and female (sexually monomorphic) and they tend to be “dressed” in colors of black, brown, grey, white and blue. The more colorful and spectacular corvids are found in the tropics.
Most of the larger corvids have a strong, slightly curved bill shape with nasal bristles, whilst the smaller corvids often have a straight, pointed bill shape and no nasal bristles.
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TYPES OF CORVIDS
The corvids can be divided into nine well defined groups.
- The Crows, including the ravens - this group accounts for one third of all corvid species.
- The Jays
- The Choughs
- The Magpies
- The Treepies
- The Nutcrackers
- The Ground Jays
- The Piapiac (includes one bird)
- The Stresemann's Bush Crow (includes one bird)
DIET AND FORAGING
Most corvids are omnivorous (eating plants and animals), however, there are variations in diet depending upon the species. The smaller species being typically insectivorous (insect eating) and the larger species typically eating carrion (remains of dead animals). Many are also significant predators of bird nests, feeding on the eggs and chicks. In addition, all species will eat a variety of fruits and seeds, and many species, especially the crows, have become adept at exploiting food made available by people, ie waste, crops etc.
All corvids store extra food, mostly burying it in the ground or hiding it in trees. The grey jay has special glands that produce sticky saliva, which is used to fasten the food to the branches of trees far above snow cover. Some species store vast quantities of food in all different places and this requires a good memory to retrieve them. Thus the species that rely on “caching” food the most tend to have the best memories.
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INTELLIGENCE
In the scientific world, corvid intelligence is highly noted. Ornithologist John Terres suggests that corvids have the “highest degree of intelligence”. Naturalist Tony Angell claims that the crow family has “superior intelligence to all other avian species tested”. Zoologist Bernd Heinrich notes that the raven is “assumed to be the brains of the bird world”, while animal behaviorist Konrad Lorenz credits the raven with “the highest mental development”. A 1991 paper by Irene Pepperberg, of the University of Arizona, affirms that corvids may share “the cognitive capacities of many primates”. In several tests, the corvids performance was put on par with gorillas and chimps, our own species’ closest relative.
A birds brain is setup quite differently than that of a mammal. Technically, they don’t have an elaborate cerebral cortex, which is what we attribute as an indication of intelligence. Instead, they have developed a part of their forebrain called the hyper-striatum that seems to be used for similar functions. The corvids appear to have the largest hyper-striatum of all birds, as well as the largest overall brain size among birds.
Many scientists have shown that some of the larger corvids, such as ravens, have the ability to count – up to seven - they recognize groups of different sizes up to seven. It has also been documented that in areas where people hunt crows, when hunters enter the “hunting blind” the crows would disappear from view. The hunters would try to fool the crows by sending out a few of the hunters but the crows would remain out of sight until the exact number of hunters came out.
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CORVIDS AND MAN
Many birds belonging to this family have been a major part in many folklore and superstition, especially the crows and ravens. They have been written about in many myths as a sign of death approaching, advisors to the gods, and messengers from the netherworlds.
Corvids are often killed by grain and sheep farmers who blame them for huge loses. Crows, Rooks and Jackdaws were killed by law in the UK from 1457 and during the reign of Elizabeth I a bounty was paid on their heads. They have been similarly persecuted in the USA and Australia, yet still they have managed to survive and some species even thrive in developed areas, especially now that they are protected by law.
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CORVIDS OF ARDASTRA
Ardastra has one species of corvid, the Plush capped Jay.
Plush-crested Jay - Cyanocorax chrysops
Jays are a medium-sized corvid and are closely allied with the Magpies. They are colorful birds, often bearing some blue plumage. There are about 44 different species in the world, 37 of these are only found in the Americas, of which 30 of these are found in the Central and South American region, where they are the only corvid representatives.
The plush-capped jay is a striking bird with its head, neck and back covered in very dark metallic blue-purple feathers. The very top of the head is covered in stiff, plush-like feathers which give this bird its name. The back of the neck and above the eyes are a violet-blue adding much character to the face.
They are found in the forested regions of central South America namely; Argentina, Bolivia, Brazil, Paraguay and Uruguay. They are omnivores, feeding mainly on insects, small animals (including eggs and nestling birds), fruits, and seeds.
A typical jay, noisy and inquisitive, which is often observed in small flocks and occasionally in mixed company with other jay species, foraging through the forest. Similar to other jays, it is a vocal mimic of other birds.
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