AMERICAN CROW (Corvus brachyrhynchos)
General Characteristics
Male and female crows look alike. They are 17 to 21 inches long and coal-black in color. The crow call is a loud caw. Crows are known to roost together at night which may help individual crows find food, attract a mate, and remain safe and warm. Crows usually use the same roost each night and roosts are usually in a heavily treed area.
Food Habits
Crows are not picky eaters and will eat insects, grubs, spiders, snails, fish, frogs, snakes, eggs, nestling birds, cultivated fruits, nuts, and vegetables especially corn. They also scavenge dead animals and garbage. Crows will post a sentinel who alerts the other feeding birds of danger.
Distribution and Abundance
Crows are found throughout Indiana in places that are a mix of open fields and woodlands. This includes farmland, orchards, wooded stream corridors, city parks, landfills, and residential neighborhoods.
Reproduction
Crow nests are usually built at least 15 feet off the ground in tall trees, but may be placed in lower shrubs when tall trees are lacking. Nesting may occur as early as February and run through May. Nests are 1½ to 2 feet in diameter and are constructed from twigs. They are lined with plant fibers, mosses, hair, twine, cloth, and other soft material. Both sexes build the nest and take care of the 4-5 young. Crows in Northern climates usually have 1 brood per year. Crows have only a few predators which include eagles, hawks, owls, raccoons, canids and humans. Their average lifespan is 4 to 6 years, though a few have been documented into their teens.
Prevention and Control
Exclusion:
Keep lids tightly secured on garbage cans and keep cans upright by fastening to a post. Trash cans may also be place in tight-fitting bins, a shed, or a garage. Put garbage cans out for pickup in the morning. Don’t leave trash bags out without the protection of a can.
Protect fruit crops with four-inch mesh bird netting that is tied at the base of the shrub or tree to prevent crows from gaining access from below. Netting can be purchased from hardware stores, garden centers, or farm supply stores in a variety of sizes.
Crows are capable of pulling nestlings out of nest boxes. Never put up a shallow box. There should never be less than 6 inches from the entry hole to the bottom of the box. Also, clean out used nests annually so the nesting birds do not fill the lower part of the box. Never put up a box designed with a perch or ledge under the hole.
Harassment Techniques:
Visual scare devices such as pie tins hung in trees, Mylar scare tape, scarecrows, and eye-spot balloons may help move crows to another location, though the relief may be only temporary. Lighting up the interior of the roost with bright fluorescent lights may discourage crows. Lasers can be pointed a couple of feet in front of the bird and moved toward them. Lasers have been proven to work well in low light situations. Crows seem to be easier to scare when in flight.
Audio scare devices include hazing with pyrotechnics such as cracker shells, blanks, propane cannons, and/or firecrackers. Scaring should stop with darkness or the crows will become accustomed to the sounds. Be sure to check local ordinances prior to using pyrotechnics.
Spraying crows with water from a high pressure hose (some cities have used a fire hose) has worked. One recent innovation is a motion sensor combined with a sprinkler that attaches to a spray hose. When a crow comes into its adjustable, motion-detecting range, a sharp burst of water is sprayed at the bird. This device appears to be effective by combining a physical sensation with a startling stimulus.
Modify the Night Roost:
Modifying the structure of the crows’ night roost can discourage the birds from using it. This includes thinning up to 50 percent of the branches of roost trees, or removing trees from dense groves to reduce the availability of perch sites and to open the trees to the weather.
Lethal Control:
Crows are regulated under state and federal laws. However, a person can shoot crows without a permit if the crows are committing or about to commit depredation upon ornamental trees, agricultural crops, livestock, or wildlife, or are concentrated in numbers and in a manner that constitutes a health hazard or nuisance. There is also a hunting season for crows.
Large-scale chemical strategies should be undertaken with the guidance of the U.S. Department of Agriculture - Wildlife Services.
Disease Threat
Crows have been implicated in the spread of transmissible gastroenteritis and histoplasmosis is a concern under their roosts where droppings accumulate. West Nile Virus has been found in crows.
