HAWKS & OWLS

Hawks and owls are birds of prey and are frequently referred to as raptors— a term that includes the falcons, eagles, vultures, kites, ospreys, northern harriers, and crested caracaras. Food habits vary greatly among the raptors. Hawks and owls are highly specialized predators that take their place at the top of the food chain. Some are responsible for the loss of poultry or small game. In the past, raptors were persecuted through indiscriminate shooting, poisoning, and pole trapping. The derogatory term chicken hawk was used generically to identify raptors, especially hawks, but has fallen out of usage during the past two decades. Recently, many people have developed a more enlightened attitude toward raptors and their place in the environment.

People who experience raptor damage problems should immediately seek information and/or assistance. “Frustration killings” occur far too often because landowners are unfamiliar with or unable to control damage with nonlethal control techniques. These killings result in the needless loss of raptors, and they may lead to undesirable legal actions. If trapping or shooting is necessary, permits should be requested and processed as quickly as possible. Always consider the benefits that raptors provide before removing them from an area; their ecological importance, aesthetic value, and contributions as indicators of environmental health may outweigh the economic damage they cause.

Identification and General Biology
There are two main groups of hawks: accipiters and buteos. Accipiters are the forest-dwelling hawks. North American species include the northern goshawk (Accipiter gentilis), Cooper’s hawk (Accipiter cooperii), and sharp-shinned hawk (Accipiter striatus). They are characterized by distinctive flight silhouettes — relatively short, rounded wings and a long rudderlike tail. Their flight pattern consists of several rapid wing beats, then a short period of gliding flight, followed by more rapid wing beats. Accipiters are rarely seen except during migration because they inhabit forested areas and are more secretive than many of the buteos.

The largest and least common, but most troublesome, accipiter is the goshawk. It is a bold predator that feeds primarily on forest-dwelling rodents, rabbits, and birds. Occasionally, it is attracted by free-ranging poultry or large concentrations of game birds and can cause depredation problems. Its breeding range is limited to Canada, the northern United States, and the montane forests of the western United States. Spectacular autumn invasions of goshawks occur at irregular intervals in the northern states. These are probably the result of widespread declines in prey populations throughout the goshawk’s breeding range. Cooper’s hawks will occasionally cause problems with poultry; sharp-shinned hawks are rarely a problem because of their small size.

The buteos are known as the broad-winged or soaring hawks. They are the most commonly observed raptors in North America. Typical species include the red-tailed hawk (Buteo jamaicensis), red-shouldered hawk (Buteo lineatus), broad-winged hawk (Buteo platypterus), Swainson’s hawk (Buteo swainsoni), rough-legged hawk (Buteo lagopus), and ferruginous hawk (Buteo regalis). All buteos have long, broad wings and relatively short, fanlike tails. These features enable them to soar over open country during their daily travels and seasonal migrations.

The red-tailed hawk is one of our most common and widely distributed raptors. Redtails can be found over the entire North American continent south of the treeless tundra and in much of Central America. They demonstrate a remarkably wide ecological tolerance for nesting and hunting sites throughout their extensive range. Typical eastern redtails nest in mature forests and woodlots, while in the Southwest they often nest on cliffs or in trees and cacti. Their diet, although extremely varied, usually contains large numbers of rodents and other small mammals. Redtails occasionally take poultry and other livestock, but the benefits they provide in aesthetics, as well as in the killing of rodents may outweigh depredation costs. Other species of buteos rarely cause problems.

Owls, unlike hawks, are almost entirely nocturnal. Thus, they are far more difficult to observe, and much less is known about them. They have large heads and large, forward-facing eyes. Their flight is described as noiseless and mothlike. There are 19 species of owls in the continental United States. They range in size from the tiny, 5- to 6-inch (12-to 15-cm) elf owl (Micrathene whitneyi) that resides in the arid Southwest, to the large, 24- to 33inch (60-to 84-cm) great gray owl (Strix nebulosa) that inhabits the dense boreal forests of Alaska, Canada, and the northern United States.

The great horned owl (Bubo virginianus) is probably the most widely distributed raptor in North America. Its range extends over almost all the continent except for the extreme northern regions of the Arctic. These large and powerful birds are considered to be the nocturnal complement of the red-tailed hawk. Great horned owls generally prey on small-to medium-sized birds and mammals and will take poultry and other livestock when the opportunity presents itself. They are responsible for most raptor depredation problems.

Damage and Damage Identification
The most troublesome raptors are the larger, more aggressive species, such as the goshawk, red-tailed hawk, and great horned owl. The majority of depredation problems occur with free-ranging farmyard poultry and game farm fowl. Chickens, turkeys, ducks, geese, and pigeons are vulnerable because they are very conspicuous, unwary, and usually concentrated in areas that lack escape cover. Confined fowl that are chased by raptors will often pile up in a corner, resulting in the suffocation of some birds. Reproduction may also be impaired in some fowl if harassment persists.

For years, game farms have dealt with raptor depredation problems. Large concentrations of game farm animals are strong attractants to predators. Operators should consider the prevention of predation as part of their cost of operation. Other depredation problems include the loss of rabbits at beagle clubs, the loss of homing and racing pigeons, and occasionally the loss of farm or household pets. Cooper’s and sharp-shinned hawks occasionally prey on songbirds that are attracted to feeding stations. This should be viewed as a natural event, however, and control of the raptors is not advisable.

There are occasions when raptors cause human safety and health hazards. For example, concentrations of raptors at airports increase the risk of bird-aircraft collisions and loss of human life. The vast majority of aircraft strikes involve gulls, starlings, and blackbirds, but a few raptor strikes have been documented. It is interesting to note that falconers with trained hawks have been used to clear airport runways of other birds so that airplanes can land. Although raptors are usually secretive and choose to avoid human contact, they occasionally nest or roost in close association with humans. At such times, noise, property damage, and aggressive behavior at nest sites can cause problems.

Poultry and other livestock are vulnerable to a wide range of predators. Frequent sightings of hawks and owls near the depredation site may be a clue to the predator involved, but these sightings could be misleading. When a partially eaten carcass is found, it is often difficult to determine the cause of death. In all cases, the remains must be carefully examined. Raptors usually kill only one bird per day. Raptor kills usually have bloody puncture wounds in the back and breast from the bird’s talons. Owls often remove and eat the head and sometimes the neck of their prey. In contrast, mammalian predators such as skunks or raccoons often kill several animals during a night. They will usually tear skin and muscle tissue from the carcass and cut through the feathers of birds with their sharp teeth.

Hawks pluck birds, leaving piles of feathers on the ground. Beak marks can sometimes be seen on the shafts of these plucked feathers. Owls also pluck their prey, but at times they will swallow small animals whole. Many raptors (especially red-tailed hawks and other buteos) feed on carrion. The plucked feathers can often determine whether a raptor actually killed an animal or was simply “caught in the act” of feeding on a bird that had died of other causes. If the feathers have small amounts of tissue clinging to their bases, they were plucked from a cold bird that died of another cause. If the base of a feather is smooth and clean, the bird was plucked shortly after it was killed.

Raptors often defecate at a kill site. Accipiters such as the goshawk leave a splash or streak of whitewash that radiates out from the feather pile, whereas owls leave small heaps of chalky whitewash on the ground.

Hawks and owls regurgitate pellets that are accumulations of bones, teeth, hair, and other undigested materials. These are not usually found at the kill site, but instead accumulate along with whitewash beneath a nearby perch or nest site. Fresh pellets, especially of owls, are covered with a moist iridescent sheen. They can be carefully teased apart and examined to learn what the hawk or owl had been eating. Owls gulp their food and swallow many bones along with the flesh. These bones are only slightly digested and persist in the pellets. A pellet that contains large bones, such as those from the leg of a rabbit, is undoubtably from a great horned owl. Hawks feed more daintily and have stronger digestive juices than owls. Thus, hawk pellets contain fewer bones.

Economics of Damage and Control
In 1985, we conducted a national survey of US Fish and Wildlife Service and Cooperative Extension personnel. Nearly all noted that the economic damage caused by raptors is minimal on a national scale, but can be locally severe if depredation occurs on fowl or livestock that are relatively valuable and vulnerable. Cost estimates of damage ranged from $10 to $5,000 per report and from $70 to $94,000 per year. The severity of raptor problems is influenced by several factors, including prey and carrion abundance, weather, time of year, husbandry methods, vegetative cover, and topography as well as density and local distribution of raptors.

Legal Status
All hawks and owls are federally protected under the Migratory Bird Treaty Act (16 USC, 703-711). These laws strictly prohibit the capture, killing, or possession of hawks or owls without special permit. No permits are required to scare depredating migratory birds except for endangered or threatened species , including bald and golden eagles.

In addition, most states have regulations regarding hawks and owls. Some species may be common in one state but may be on a state endangered species list in another. Consult your local USDA-APHIS-Animal Damage Control, US Fish and Wildlife Service (USFWS), and/or state wildlife department representatives for permit requirements and information.


Damage Prevention and Control Methods

Exclusion
Livestock confinement is the most effective control method, but it must be practical and economical. Confine free-roaming fowl in enclosures covered with netting or woven wire. Condition poultry and fowl to move into coops or houses by feeding and watering them indoors at dusk. House them at night to protect them from owls.

Habitat Modification
Eliminate perch sites near areas of potential damage by removing large, isolated trees and snags. Install utility lines underground and remove telephone poles near poultry-rearing sites. Cap poles with sheet metal cones, Nixalite®, Cat Claws®, or inverted spikes.

Frightening
Use scarecrows and pyrotechnics. Erect electric pole shockers when hawks or owls are observed around areas of potential damage.

Repellents
None are registered.

Toxicants
None are registered.

Trapping and Relocating
State and federal permits are required to trap and relocate hawks and owls. If possible, experienced bird banders or trappers should do the trapping. Landowners, however, can safely trap hawks and owls if they follow instructions and are careful when handling the birds.

Shooting
State and federal permits are required to shoot hawks and owls. They may be issued only when there is a serious public health or depredation problem and when nonlethal control methods fail or are impractical.




ACKNOWLEDGEMENTS
The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (Cooperative Extension Division, Institute of Agriculture and Natural Resources University of Nebraska-Lincoln, United States Department of Agriculture Animal and Plant Health Inspection Service, Animal Damage Control, Great Plains Agricultural Council Wildlife Committee).