Abstract
DID YOU KNOW THAT ...
• Crows have been taught to speak?
• Crows can learn to count?
• Crows can recognize and match shapes?
• Crows feed in flocks with sentinels used as lookouts?
• Crows are empathetic to nonavian creatures?
MOSES AND CASSIE is a popular film that documents the case study of a wild crow that raised an orphaned kitten.
Basic Information About Crows
Crows are members of the family, Corvidae, and the genus, Corvus, which includes ravens, magpies, jays, nuthatches, rooks, jackdaws and choughs, stout-bodied birds with a large and heavy bill. The average size of a crow is between seventeen and twenty-one inches when measuring from the tip of the bill to the end of the tail. When fully grown, they weigh approximately one pound. Most crows appear to be jet black but their feathers actually include purple and green. Their physical appearance does not differ between the sexes. Only surgical sexing or DNA testing can distinguish male from female crow with any certainty unless reproductive behavior such as egg laying or mating is observed. Its usual call is a loud and raucous "cawcaw" and they fly cautiously. In captivity, both crows and ravens have been known to live for about thirty years but in the wild, the average life span of a crow is seven or eight years.
Crows do not migrate over long distances, but thousands will sometimes spend the night at a common center, and disperse the next morning to visit various feeding grounds. Crows are omnivorous and eat seeds, nuts, berries, insects, frogs, mice, eggs, crustaceans, nestlings, and even carrion. Crows regurgitate "pellets" consisting of indigestible fur, bones, and other material. Curiosity and memory, as well as skills of invention and problem solving, are required for crows to discover and remember a large variety of food sources.
lntellegence of Crows
Corvids are considered to be the most intelligent of all birds. In comparison to their body size, Corvids have the largest cerebral hemisphere of all birds. The American crow has a brain the size of a pecan. They learn fast and share knowledge with each other. There is evidence that they make complex decisions and exhibit many signs of enjoying a high level of awareness. Most Corvids, especially ravens and crows, display behaviors considered by scientists to indicate higher intelligence. Here are a few of those behavtors:
• They display skills of problem solving.
•They create and use tools. • They engage in communal hunting.
• The raising of young crows is a group effort.
• They create and play gam_es.
• They exhibit evidence of good short term and long term memory.
• They have a communication system within the flock.
• They are able to mimic human speech and other sounds.
Problem Solving Skills of Crows
Crows have been observed dropping palm fruits, walnuts, clams, and mussels onto hard-surface roads. Then they wait nearby until a passing car has crushed the hard shells to return and retrieve the food. Few animals are intelligent enough to employ such complex behaviors related to planning in order to find a solution to a problem.
Nature writer, Candace Savage, relates another amazing demonstration of the crow's ability to solve problems. At the University of Chicago, a crow kept by researchers was partly fed with dry food, which it preferred to eat after it was moistened. Sometimes the keepers forgot to add water to the food. The crow, in an apparently spontaneous and untrained act, picked up a small plastic cup that had been provided as a toy, dipped the cup into its water trough, carried the filled cup across the room to the feeder, and emptied the water onto the dry food. If the crow spilled the water in the course of carrying the cup, it would return to the trough for more water rather than continuing to the feeder with an empty cup. This sequence of behaviors is clearly a wellthought out plan and not simply an accidental discovery on the part of the crow.
life is a large part of their social structure. Male crows will court a desired female by fluffing their feathers, strutting, and flying around her. Crows usually mate for life but in some circumstances, they split up and find another partner. Both members ofa breeding pair participate in the building of the nest. Often juveniles from prior years help gather the nesting material. Flocks of crows separate for breeding in late spring or early summer, but gather together again when breeding season is over. During the winter, hundreds or even thousands of them congregate in roosts, usually in the tallest trees or buildings. Flocks of 50,000 roosting crows are not an uncommon sight in the United States and there have been reports of roosts in rural areas of Oklahoma and Nebraska numbering over a million crows.
Just before time to go to roost at sunset, crows gather at the roosting site for social interaction with flock mates. They enjoy chases, mock fights, and loud calling which becomes quite raucous due to the sheer number of voices. Crows are known for nesting in inaccessible places like the tops of tall pine or oak trees. They prefer to build in coniferous trees at least sixty feet tall. The nests are built of branches and twigs and are lined with bark, moss, twine, roots, various plant fibers, and an interesting assortment of other materials. Owls, (especially the great horned owl), hawks, raccoons, snakes, and sometimes squirrels pose a danger to the eggs and nestlings so crow pairs go to great lengths to hide their nest sites. The female does the final arrangement of nesting material into a safe and comfortable place for the eggs and babies. A mated pair of crows sometimes is assisted by several non-breeding members of the flock in nest building, defending the territory, and feeding the nestlings.