Prairie Wanderings
By PAUL G. JANTZEN
Contributing writer
The American crow has been described as one of the best known of American birds. It has been characterized as clever, intelligent, resourceful, gregarious, vociferous, fearless, a nuisance, and mischievous. Its technical name is Corvus brachyrhynchos, which is Italian. This crow is 17 to 21 inches tall (43-53 cm), chunky, and all black, including its coarse bill and feet. The feet are built for walking.
The American crow is common from Canada to the southern United States, some in Canada migrating south for the winter.
To determine whether migrating crows learn or inherit their orientational skills, ornithologist W. Rowan of Alberta captured and banded young crows in late summer and released them in November after all adults had left for their winter range in Kansas and Oklahoma. Of the crows that traveled an appreciable distance, the recovered birds were flying toward their normal winter range.
Crows are most commonly seen during their nonbreeding season from late August to early December when they feed and roost in large flocks of hundreds or thousands of birds. In 15 of 49 Christmas Bird Counts in Harvey County, more than a thousand crows were observed on count day, compared to only 30 in a special count day in May of 1995.
The coordinated behavior of crows in a flock is evidence of their communication skills. Most naturalists agree that many birds communicate with others of their species by making different sounds. The American crow has 23 different calls ranging from a little warble to a harsh caw. Variations in its basic caw informs others or a source of food, or of intruders in "their woods."
An American crow discovering a perching owl sounds its rallying call and other crows in the vicinity answer the call and join the others in mobbing the owl. The amplified recordings of the crows' assembly call were played in a wooded area where crows were neither seen nor heard, within minutes crows congregated near the loudspeaker. Crow alarm calls quickly repelled the crows. When the tapes were played in France, French crows ignored the alarm calls of the American crows.
Crows also mimic other sounds, and captive crows can learn to utter human words. In the summer, crows spread out for nesting. Dwight Platt reports that south central Kansas supports a breeding population of about one pair per square mile.
During courtship, crows are active and boisterous. While nesting, however, they become secretive, "drifting like shadows among the trees."
Their nests are built in upper forks of large trees and are made of coarse sticks, twigs, and tree bark, lined with softer materials such as fine roots, straw, grasses, wool, or fur. The nests are well-built and often used later by owls and hawks.
The three to eight eggs are laid in March, April, or May. They are a pale bluish green botched with brown and olive gray. The eggs are incubated for about 18 days. The chicks are fed in the nest for about 36 days.
The diet of American crows includes a wide variety of foods of both plant and animal origin. Dwight Platt analyzed the pellets regurgitated by crows in Harvey and Reno counties in south central Kansas from December 1952 to February 1954. He found that "plant material amounted to 69 percent of the pellet residues." Of that amount, wheat was most common, but pellets of wintering crows contained significant amounts of grain sorghum, sunflower seeds, and corn. Other workers have noted that corn was popular especially when softened by germination or partial decay, or in the pre-ripe "milk stage." Much of the sorghum was waste grain taken from fields after harvest.
Seeing crows in crop fields can lead to false conclusions. An ornithologist tells of a letter received from a farmer who was concerned about the crows feeding in his low-yielding corn and asparagus fields. His solution was to shoot the crows. But when the stomach contents of some of the crows were analyzed, they were found to contain the remains of black beetles and cutworms. Visiting the fields the next day at the crows' usual feeding time, the farmer saw "great numbers of cutworms burrowing for shelter for the day." He welcomed the return of surviving crows which ate enough cutworms to allow a good harvest.
More than half the animal portion of the crows' diet, according to Platt's study, was beetles. In late June, scarab beetles alone made up 28.7 percent of the pellets collected in eastern Harvey County. Their larvae destroy wheat and alfalfa and live in the ground from one to three years before reaching adulthood.
The second most plentiful insect group found in the pellets was grasshoppers which Platt calls the most destructive insects in Kansas. During early October, they made up 59 percent of the crows' diet in eastern Harvey County. Smaller quantities of ants, crawfish, snails, fish, birds, eggshells, and mammals were noted, some probably found in roadkills and dumping grounds.
Captive crows exhibit a passion for stealing and hiding objects with bright colors or a shiny surface. This behavior and their mimicking of human words have provided observers much amusement.
