Hawks

Buteos

Accipiters

Kites

Harriers

Characteristics and behavior

Hawks and humans

Resources

Hawks (family Accipitridae) are one of the major groups of predatory birds that are active during the day. They are members of the order Falconiformes, which also includes the falcons, vultures, and osprey, and like the other Falconiformes, they have the characteristic sharp, strong claws and hooked beak suited for catching and tearing up prey.

Found on all continents but Antarctica, hawks are a diverse group. There are 26 species in North America alone that have been breeding successfully in recent times. They include four species of eagles, five species of kites, and 17 species called hawks. These North American hawks vary from the small, 3-8 oz (85-227 g) sharp-shinned hawk, with a wingspan of about 2 ft (0.6 m), to the ferruginous hawk (Buteo regalis), with a wingspan of 4.5 ft (1.5 m). Eagles are different primarily because of their huge size; they may weigh from 8-20 lb (4-9 kg), with wingspans up to 8 ft (2.4 m).

Besides the hooked beak and strong claws already described, the hawks share several characteristics. Their wings are generally broad and rounded, well-suited for flying over land (kites’ wings are different, more like a falcon). Their nostrils are oval or slit-like, and open in the soft skin (the cere) where the upper mandible joins the head, which is round. The neck is short and strong. The large eyes are usually yellow, orange, red, or brown, and turn little in their sockets. Hawks move their heads to direct their vision, which is both monocular and binocular (especially when hunting).

Hawks’ plumage is subdued, usually mottled browns and grays on the back and lighter, often barred or streaked, below. Color phases have been found in many species: albinos in 10 species, melanism (a black phase) in five, and erythrism (a red phase) in one.

The North American hawks fall into four groups: the buteos, the accipiters, the kites, and the harriers.

Buteos

The buteos are like the eagles, but smaller. They have broad, rounded wings that are stubbier than those of the eagles, which help them cruise long distances over land searching for prey. Common prey items include mice and rabbits, for the buteos generally feed on mammals. A small prey item, such as a mouse, is swallowed whole. A larger item is brought to a secluded spot, held down with the feet, and pulled apart with the sharp beak. Representative buteos include the red-tailed hawk (Buteo jamaicensis), the rough-legged hawk (B. lagopus), and Swainson’s hawk (B. swainsoni).

Old World buteos include:

• Common buzzard (Buteo buteo). Resident of Eurasia, with some wintering in Africa.
• African mountain buzzard (Buteo oreophilus). Resident of the mountains of east and southern Africa.
• Madagascar buzzard (Buteo brachypterus). Resident of Madagascar.
• Rough-legged buzzard (Buteo lagopus). Besides residing in North America, this bird also makes it home in northern and arctic Eurasia.
• Long-legged buzzard (Buteo rufinus). Resident of southeastern Europe, North Africa, and Central Asia.
• African red-tailed buzzard (Buteo auguralis). Resident of West and Central Africa.
• Jackal buzzard (Buteo rufofuscus). Resident of Africa, south of the Sahara.
• North American buteos include:
• Crane hawk (Geranospiza caerulescens). Southwestern stray, normally resident of the tropical woodlands.
• Common black-hawk (Buteogallus anthracinus). Rare and apparently declining in the United States due to disturbance and loss of habitat. Today there are possibly 250 pairs left in the United States. However, the species does have a large global population of 10,000-100,000 birds.
• Harris’ hawk (Parabuteo unicinctus). Has disappeared from some former areas, such as the lower Colorado River Valley. Declining in parts of its range, but recently re-introduced in some areas. Has been threatened by illegal poaching for falconry.
• Gray hawk (Buteo nitidus). It is estimated that no more than 50 pairs nest north of Mexico. It is vulnerable to loss of its lowland stream forest habitat, but it remains common and widespread in the tropics.
• Roadside hawk (Buteo magnitostris). Status in North America not well known, but the species has a large range and global populations.
• Red-shouldered hawk (Buteo lineatus). Declining or now stabilized at low numbers. Accumulates organo-chlorine pesticides and PCBs, however, loss of habitat is the major threat. Although this bird is today far less numerous than historically in some areas, including the upper Midwest and parts of the Atlantic Coast, current populations are believed to be stable in most regions.
• Broad-winged hawk (Buteo platypterus). In the early years of the twentieth century, large numbers were sometimes shot during migration. Now legally protected, and their numbers appear stable.
• Short-tailed hawk (Buteo brachyurus). May be threatened by destruction of breeding grounds (mature cypress swamps and riparian hardwoods). Today, this bird is rare in Florida (with a population probably no larger than 500), but its numbers appear stable. The population may be increasing in Mexico.
• Swainson’s hawk (Buteo swainsoni). Breeds in western and central North America; winters mainly in southern South America. This species is relatively common in some areas, but pesticide use and habitat loss in breeding and nonbreeding range have resulted in declines. The population has declined seriously in California, for reasons that are not well understood but that probably include habitat loss, pesticide mortality, and declines in prey species populations.
• White-tailed hawk (Buteo albicaudatus). Marked decline from 1930s to 1960s largely due to loss of habitat. Significant eggshell thinning has been observed since 1947. Its decline in Texas from the 1950s to the 1970s has been attributed to the use of pesticides, but the population in that state now appears to be stable. Numbers may be declining in Mexico due to overgrazing of its habitat.
• Zone-tailed hawk (Buteo albonotatus). This bird has disappeared from some of its former breeding areas. Loss of nesting sites, such as tall cottonwoods near streams, may have contributed to its decline.
• Red-tailed hawk (Buteo jamaicensis). Greatly reduced in the east by early bounties. Continued decline due to human persecution and loss of habitat. Some egg thinning. The population has increased in some areas since the 1960s. Today the population is stable or increasing.
• Ferruginous hawk (Buteo regalis). The population has been estimated at 5,800-14,000 individuals, and is thought to be declining in several areas, especially at the edges of the species’ range. Considered a near threatened species by the World Conservation Union (IUCN), the decline in population is largely due to habitat loss and degradation, and declines in prey species populations.
• Rough-legged hawk (Buteo lagopus). Inadvertently poisoned by bait intended for mammals. Often shot when feeding off road kills in the winter. Local populations in the Arctic rise and fall with the rodent population there. The overall numbers appear healthy.

Accipiters

The accipiters are generally smaller than the buteos. Their shorter, rounded wings and long tails make them agile hunters of birds, which they catch on the wing. Familiar accipiters include Cooper’s hawk (Accipiter cooperii) and the sharp-shinned hawk (A. striatus).

Old World accipiters include:

• Japanese sparrowhawk (Accipiter gularis). Japan, China, and the eastern parts of the former Soviet Union.
• Besra (Accipiter virgatus). Resident of the Himalayas, Southeast Asia, and the East Indies.
• African goshawk (Accipiter tachiro). Resident of Africa, south of the Sahara.
• Crested goshawk (Accipiter trivirgatus). Resident of southern Asia, the Philippines, and Borneo.
• Australian goshawk (Accipiter fasciatus). Resident of Australia, New Guinea, Flores, Timor, and Christmas Island.
• France’s sparrowhawk (Accipiter francessi). Resident of Madagascar.

North American accipiters include:

• Sharp-shinned hawk (Accipiter striatus). Dramatic decline in the eastern United States in the early 1970s. Between 8% and 13% of the eggs showed shell thinning. Their numbers partially and in some portions of its range it us described as fairly common.
• Cooper’s hawk (Accipiter cooperi). A serious decline underwent a slight reversal after the ban of DDT in 1972. Their numbers appear to be stable in most areas.
• Northern goshawk (Accipiter gentilis). Population formerly declined in the north, while expanding in the southeast. Not as vulnerable to eggshell thinning as some other hawk species. Today the range is expanding in the northeast, but populations in the southwestern mountains may be threatened by loss of habitat.

Kites

The kites are more graceful in flight than either the buteos or the accipiters. Although they are hawks, the kites have long, pointed wings similar to those of falcons, and long tails. Found in warm areas, kites have shorter legs and less powerful talons than other members of the hawk family, but are adept at catching prey such as frogs, salamanders, insects, and snails—in fact, the Everglade kites (Rostrhamus sociabilis) prey solely on snails of the genus Pomacea. Also found in North America is a single species of harrier, the hen or marsh hawk (Circus cyaneus), which is common in Europe and in Asia, too. This slender little hawk (maximum weight, 1.25 lb/0.5 kg) eats mice, rats, small birds, frogs, snakes, insects, and carrion.

Old World kites include:

• Black-breasted buzzard kite (Hamirostra melanoster-no n). Resident of Australia.
• Brahminy kite (Hamirostra indus). Resident of southern Asia, East Indies, New Guinea, northern Australia, and the Solomon Islands.
• Black kite (Milvus migrans). Resident of Europe, Asia, Africa, and Australasia.
• Black-shouldered kite (Elanus caeruleus). Resident of Spain, Africa, and southern Asia.

Kites found in North America include:

• Hook-billed kite (Chondrohierax uncinatus). Decline in population with clearing of woods. Subspecies on Cuba has been listed as critically endangered.
• American swallow-tailed kite (Elanoides forficatus). Marsh drainage, deforestation, and shooting have reduced the population and range. Formerly more widespread in the southeast, and north as far as Minnesota. Current population appears stable.
• White-tailed kite (Elanus leucurus). The population has been increasing since the 1930s, and settling in places not known historically. Has also spread to American tropics with clearing of forest land.
• Snail kite (Rostrhamus sociabilis). The United States population is listed as an endangered species under federal legislation. The population in Florida had been reduced to 20 by 1964, due to marsh draining and shooting. By 1983, they were recovering (with an estimated population of 700). The Florida population is remains endangered due to disruption of water flow (and impact on habitat and snail population). Although widespread in the tropics, the species there is vulnerable to loss of habitat.
• Mississippi kite (Ictinia mississippiensis). Increasing since 1950s. Breeding range has expanded westward, possibly due to tree planting for erosion control. Since about 1950, the population in some areas (such as the southern Great plains) has greatly increased. The range has extended to parts of the Southwest, where the species was previously unknown.
• Black-shouldered kite (Elanus caeruleus). Range has greatly expanded since 1960. This kite is probably the only raptor to have benefited from agricultural expansion. Its expansion has been aided by its ability to adapt to habitat disruption and an increase in the number of rodents.

Harriers

Old World harriers include:

• Spotted harrier (Circus assimilis). Found throughout most of Australia, and sometimes in Tasmania.
• European marsh harrier (Circus ranivorus). Resident of northern Kenya, Uganda, eastern Zaire, and Angola.
• Marsh harrier (Circus aeruginosus). Resident of western Europe, central Asia, and Japan; winters in Africa and southern Asia.
• Black harrier (Circus maurus). Resident of southern Africa.

Harriers in North America include:

• Northern harrier (Circus cyaneus). Has disappeared from many of its former nesting areas. Decline attributed to loss of habitat and effects of pesticides. Today the population appears to be declining in parts of North America.

Characteristics and behavior

Generally, hawks kill their prey with their claws, unlike the falcons, which catch prey with the claws but kill with a blow of their beak. However, despite their fierce reputations, some hawks are quiet and gentle. In addition to their familiar scream, hawks’ vocalizations include a high plaintive whistle like the wood pewee (broad-shouldered hawk); a musical kee-you, kee-you (red-shouldered hawk); and a high-pitched squeal (short-tailed hawk).

Hawks are unusual among birds in that the female is generally larger than her mate. In some species, the females are twice the size of the males, as in the acci-piters. Some researchers have found a correlation between the size difference between the sexes and the diet of the species. For example, among Falconiformes like vultures, which eat carrion, the sexes are similarly sized. However, moving from there through the diets of insects, fish, mammals, and birds, the sexual dimorphism increases. So many other factors correlate with sexual dimorphism, it is difficult to say which is the major contributing factor. For instance, another hypothesis holds that a larger female bird of prey is better equipped to protect herself during contact with the potentially dangerous and certainly well-armed male. Yet another theory suggests that size is related to the vulnerability of the prey pursued. That is, the more agile the prey, the less likely the success of each hunt. Or, perhaps the secret to sexual dimorphism lies in a simpler explanation: that the larger female is better at catching some prey, and the male is better at catching others.

Courtship among the hawks is among the most spectacular of all animals. In the case of the red-tailed hawk, for example, the pair soar, screaming at each other; then the male dives at the female, who may roll in the air to present her claws to him in mock combat. The male marsh hawk flies in a series of graceful U-shaped patterns over the marsh where the female is watching. Hawks generally mate for life, and are strongly attached to their nesting territory; one pair of red-shouldered hawks (and their offspring) used the same area for 45 years.

Hawks usually build their nests high in trees. The nests are quite large, up to about 3-4 ft (0.9-1.2 m) across, and consist mostly of sticks, with twigs, bark, moss, and sprigs of evergreen. Nests are often used year to year, with the bird abandoning it only at death or when the nest has grown so large that it breaks the boughs it is built upon.

Generally, the pair will defend their territory against all who approach, but some species, including the ferruginous hawk, will abandon their nest if disturbed by humans. Some hawks will dive at humans who approach too near their nests, as in the case of a pair of red-tailed hawks nesting in a park in Boston, Massachusetts, who injured several curious passers-by before park officials removed the raptors and their eggs to a more secluded spot. The territory defended can range from 650 ft (198 m) between nests in small hawks to up to 18.5 mi (29.8 km) in larger ones. Some species, including the kites, are more gregarious and nest in loose colonies of about 10 pairs.

Female hawks lay between two and five eggs. Depending on the species, the female either incubates them alone or with the help of her mate. Incubation lasts about 28 days. The young hawks fledge at about 40 days of age.

Some young hawks may remain with their parents for a while after fledging, and these family groups have been observed hunting as a team. Generally, hunting buteos circle high in the air, watching the ground for any movement of prey. They then fold their wings and dive upon their prey. Accipiters are more likely to pursue their avian prey on the wing, darting into thickets and woods during the chase. Some accipiters are decried for their impact on the populations of songbirds; in fact, in the past some ornithologists considered the sharp-shinned hawk a “harmful” species because it preyed on –beneficial” songbirds. Such human prejudice is at the root of most human–raptor conflict.

After the breeding season ends, many hawk species conduct spectacular migrations. The most spectacular is that of the Swainson’s hawk. Huge flocks of these birds will travel overland from their North American summer range to their wintering grounds in South America, a total distance of 11,000–17,000 mi (17,699–27,353 km) annually. The broad–winged hawk (B. platypterus) is also noted for its large migrations: in one day (September 14, 1979), 21,448 broad–winged hawks passed over Hawk Mountain, Pennsylvania. Besides Hawk Mountain, other good sites to watch hawk migrations include Cape May, New Jersey; Duluth, Minnesota.; Port Credit and Amherstburg, Ontario; and Cedar Grove, Wisconsin.

Hawks and humans

Although more humans are enjoying watching these migrations and learning to appreciate these raptors, hawks still face persecution. Many are shot each year. Others die in traps set for fur–bearing animals. Still others are killed when they land on high–voltage power lines. Most species of hawks, like all other raptors, were hard hit by the effects of the pesticide DDT. Considered a miracle pesticide when it was introduced in the 1940s, DDT pervaded the environment, and became concentrated higher up in the food chain. The effect on the raptors was the production of eggs that were too thin–shelled to be incubated: when the female moved to sit on them, the eggs collapsed beneath her, killing the chicks inside. Recovery has been slow.

All hawks are protected by federal and state laws. Some, like the red–tail, are successfully adjusting to living in urban areas. Hawks have been known to live almost 20 years.

Resources

BOOKS

del Hoyo, J., A. Elliott, and J. Sargatal. Handbook of the Birds of the World. Vol. 2,New World Vultures to Guineafowl. Barcelona: Lynx Edicions, 2000.

Ehrlich, Paul R., David S.Dobkin, and Darryl Wheye. The Birder’s Handbook. New York: Simon & Schuster Inc.,1988.

Fox, Nic. Understanding Birds of Prey. Blaine, WA: Hancock House, 1995.

Liguori, Jerry. Hawks From Every Angle: How to Idnetify Raptors in Flight. Princeton, NJ: Princeton University Press, 2005.

Peterson, Roger Tory. North American Birds. Houghton Mifflin Interactive (CD–ROM). Somerville, MA:Houghton Mifflin, 1995.

F. C. Nicholson Randall Frost

Hawks

Hawks (family Accipitridae) are one of the major groups of predatory birds that are active during the day. They are members of the order Falconiformes, which also includes the falcons , vultures , and osprey, and like the other Falconiformes, they have the characteristic sharp, strong claws and hooked beak suited for catching and tearing up prey .

Found on all continents but Antarctica , hawks are a diverse group. There are 26 species in North America alone that have been breeding successfully in recent times. They include four species of eagles , five species of kites, and 17 species called hawks. These North American hawks vary from the small, 3-8 oz (85-227 g) sharp-shinned hawk, with a wingspan of about 2 ft (0.6 m), to the ferruginous hawk (Buteo regalis), with a wingspan of 4.5 ft (1.5 m). Eagles are different primarily because of their huge size; they may weigh from 8-20 lb (4-9 kg), with wingspans up to 8 ft (2.4 m).

Besides the hooked beak and strong claws already described, the hawks share several characteristics. Their wings are generally broad and rounded, well-suited for flying over land (kites' wings are different, more like a falcon). Their nostrils are oval or slit-like, and open in the soft skin, the cere, where the upper mandible joins the head, which is round. The neck is short and strong. The large eyes are usually yellow, orange, red, or brown, and turn little in their sockets. Hawks move their heads to direct their vision , which is both monocular and binocular (especially when hunting).

Hawks' plumage is subdued, usually mottled browns and grays on the back and lighter, often barred or streaked, below. Color phases have been found in many species: albinos in 10 species, melanism (a black phase) in five, and erythrism (a red phase) in one.

The North American hawks fall into four groups: the buteos, the accipiters, the kites, and the harriers.

Buteos

The buteos are like the eagles, but smaller. They have broad, rounded wings, which are stubbier than those of the eagles, which help them cruise long distances over land searching for prey. Common prey items include mice and rabbits, for the buteos generally feed on mammals . A small prey item, such as a mouse, is swallowed whole. A larger item is brought to a secluded spot, held down with the feet, and pulled apart with the sharp beak. Representative buteos include the red-tailed hawk (Buteo jamaicensis), the rough-legged hawk (B. lagopus), and Swainson's hawk (B. swainsoni ).

Old World buteos include:

• Common buzzard (Buteo buteo). Resident of Eurasia, with some wintering in Africa .
• African mountain buzzard (Buteo oreophilus). Resident of the mountains of east and southern Africa.
• Madagascar buzzard (Buteo brachypterus). Resident of Madagascar.
• Rough-legged buzzard (Buteo lagopus). Besides residing in North America, this bird also makes it home in northern and arctic Eurasia.
• Long-legged buzzard (Buteo rufinus). Resident of southeastern Europe , North Africa, and Central Asia .
• African red-tailed buzzard (Buteo auguralis). Resident of West and Central Africa.
• Jackal buzzard (Buteo rufofuscus). Resident of Africa, south of the Sahara.

North American buteos and their status are as follows:

• Crane hawk (Geranospiza caerulescens). Southwestern stray, normally resident of the tropical woodlands.
• Common black-hawk (Buteogallus anthracinus). Rare and apparently declining in the United States due to disturbance and loss of habitat . Today there are possibly 250 pairs left in the United States.
• Harris' hawk (Parabuteo unicinctus). Has disappeared from some former areas, such as the lower Colorado River Valley. Declining in parts of its range, but recently re-introduced in some areas. Has been threatened by illegal poaching for falconry.
• Gray hawk (Buteo nitidus). It is estimated that no more than 50 pairs nest north of Mexico. It is vulnerable to loss of its lowland stream forest habitat, though it remains common and widespread in the tropics.
• Roadside hawk (Buteo magnitostris). No information available.
• Red-shouldered hawk (Buteo lineatus). Declining or now stabilized at low numbers. Accumulates organochlorine pesticides and PCBs, however, loss of habitat is the major threat. Although this bird is today far less numerous than historically in some areas, including the upper Midwest and parts of the Atlantic Coast, current populations are believed to be stable in most regions.
• Broad-winged hawk (Buteo platypterus). In the early years of the twentieth century, large numbers were sometimes shot during migration . Now legally protected, and their numbers appear stable.
• Short-tailed hawk (Buteo brachyurus). May be threatened by destruction of breeding grounds (mature cypress swamps and riparian hardwoods). Today, this bird is very uncommon in Florida (with a population probably no larger than 500), but its numbers appear stable. The population may be increasing in Mexico.
• Swainson's hawk (Buteo swainsoni). Current status is unclear. Many have been shot while perched along roads. But expanding cultivation has increased breeding opportunities, especially in the Great Plains. The population has declined seriously in California, for reasons that are not well understood.
• White-tailed hawk (Buteo albicaudatus). Marked decline from 1930s to 1960s largely due to loss of habitat. Significant eggshell thinning has been observed since 1947. Its decline in Texas from the 1950s to the 1970s has been attributed to the use of pesticides, but the population in that state now appears to be stable. Numbers may be declining in Mexico due to overgrazing of its habitat.
• Zone-tailed hawk (Buteo albonotatus). This bird has disappeared from some of its former nesting areas. Loss of nesting sites such as tall cottonwoods near streams may have contributed to its decline.
• Red-tailed hawk (Buteo jamaicensis). Greatly reduced in the east by early bounties. Continued decline due to human persecution and loss of habitat. Some egg thinning. The population has increased in some areas since the 1960s. Today the population is stable or increasing.
• Ferruginous hawk (Buteo regalis). Currently rare in many parts of its range. Many have been shot while perched along roadsides. Today this bird is a threatened species. The current population may be less than 4,000. The decline in population is due to hunting and to loss of habitat.
• Rough-legged hawk (Buteo lagopus). Inadvertently poisoned by bait intended for mammals. Often shot when feeding off road kills in the winter. Local populations in the Arctic rise and fall with the rodent population there. The overall numbers appear healthy.

Accipiters

The accipiters are generally smaller than the buteos. Their shorter, rounded wings and long tails make them agile hunters of birds, which they catch on the wing. Familiar accipiters include Cooper's hawk (Accipiter cooperii) and the sharp-shinned hawk (A. striatus).

Old World accipiters include:

• Japanese sparrowhawk (Accipiter gularis). Japan, China, and the eastern parts of the former Soviet Union.
• Besra (Accipiter virgatus). Resident of the Himalayas, southeast Asia, and the East Indies.
• African goshawk (Accipiter tachiro). Resident of Africa, south of the Sahara.
• Crested goshawk (Accipiter trivirgatus). Resident of southern Asia, the Philippines, and Borneo.
• Australian goshawk (Accipiter fasciatus). Resident of Australia , New Guinea, Flores, Timor, and Christmas Island.
• France's sparrowhawk (Accipiter francessi). Resident of Madagascar.

North American accipiters and their status are as follows:

• Sharp-shinned hawk (Accipiter striatus). Dramatic decline in the eastern United States in the early 1970s. Between 8-13% of the eggs showed shell thinning. Their numbers recovered somewhat through the early 1980s, but more recently, the numbers in the east have declined.
• Cooper's hawk (Accipiter cooperi). A serious decline underwent a slight reversal after the ban of DDT in 1972. Their numbers appear to be stable in most areas.
• Northern Goshawk (Accipiter gentilis). Population formerly declined in the north, while expanding in the southeast. Eggshell thinning was reported in some areas in the early 1970s. Today the range is expanding in the northeast, but populations in the southwestern mountains may be threatened by loss of habitat.

Kites

More graceful in flight than either the buteos or the accipiters are the kites. Although they are hawks, the kites have long, pointed wings similar to those of falcons, and long tails. Found in warm areas, kites have shorter legs and less powerful talons than other members of the hawk family, but are adept at catching prey such as frogs , salamanders , insects , and snails—in fact, the Everglade kites (Rostrhamus sociabilis) prey solely on snails of the genus Pomacea. Also found in North America is a single species of harrier, the hen or marsh hawk (Circus cyaneus), which is common in Europe and in Asia, too. This slender little hawk (maximum weight, 1.25 lb (0.5 kg) eats mice, rats , small birds, frogs, snakes , insects, and carrion.

Old World kites include:

• Black-breasted buzzard kite (Hamirostra melanosternon). Resident of Australia.
• Brahminy kite (Hamirostra indus). Resident of Southern Asia, East Indies, New Guinea, northern Australia, and the Solomon Islands.
• Black kite (Milvus migrans). Resident of Europe, Asia, Africa, and Australasia.
• Black-shouldered kite (Elanus caeruleus). Resident of Spain, Africa, and southern Asia.

Kites found in North America and their status are as follows:

• Hook-billed kite (Chondrohierax uncinatus). Decline in population with clearing of woods. Subspecies on Grenada and Cuba have been listed as endangered.
• American swallow-tailed kite (Elanoides forficatus). Marsh drainage, deforestation , and shooting have reduced the population and range. Formerly more widespread in the southeast, and north as far as Minnesota. Current population appears stable.
• White-tailed kite (Elanus leucurus). The population has been increasing since the 1930s, and settling in places not known historically. Has also spread to American tropics with clearing of forest land.
• Snail kite (Rostrhamus sociabilis). Endangered species . The population in Florida had been reduced to 20 by 1964, due to marsh draining and shooting. By 1983, they were recovering (with an estimated population of 700). But today the Florida population is endangered due to disruption of water flow (and impact on habitat andsnail population). Although widespread in the tropics, the species there is vulnerable to loss of habitat.
• Mississippi kite (Ictinia mississippiensis). Increasing since 1950s. Breeding range has expanded westward, possibly due to tree planting for erosion control. Since about 1950, the population in some areas (such as the southern Great plains) has greatly increased. The range has extended to parts of the Southwest, where the species was previously unknown.
• Black-shouldered kite (Elanus caeruleus). Range has greatly expanded since 1960. This kite is probably the only raptor to have benefited from agricultural expansion. Its expansion has been aided by its ability to adapt to habitat disruption and an increase in the number of rodents.

Harriers

Old World harriers include:

• Spotted harrier (Circus assimilis). Found throughout most of Australia, and sometimes in Tasmania.
• European marsh harrier (Circus ranivorus). Resident of northern Kenya, Uganda, eastern Zaire, and Angola.
• Marsh harrier (Circus aeruginosus). Resident of western Europe, central Asia, and Japan; winters in Africa and southern Asia.
• Black harrier (Circus maurus). Resident of southern Africa.

Harriers in North America and their status are as follows:

• Northern harrier (Circus cyaneus). Has disappeared from many of its former nesting areas. Decline attributed to loss of habitat and effects of pesticides. In 1970, 20% of the eggs examined were found to exhibit shell thinning. Today the population appears to be declining in parts of North America.

Characteristics and behavior

Generally, hawks kill their prey with their claws, unlike the falcons, which catch prey with the claws but kill with a blow of their beak. However, despite their fierce reputations, some hawks are quiet and gentle. In addition to their familiar scream, hawks' vocalizations include a high plaintive whistle like the wood pewee (broad-shouldered hawk); a musical kee-you, kee-you (red-shouldered hawk);and a high-pitched squeal (short-tailed hawk).

Hawks are unusual among birds in that the female is generally larger than her mate. In some species, this difference—called sexual dimorphism—can be as great as the female being twice the size of the males, as in the accipiters. Some researchers have found a correlation between the size difference between the sexes and the diet of the species. For example, among Falconiformes like vultures, which eat carrion, the sexes are similarly sized. However, moving from there through the diets of insects, fish , mammals and birds, the sexual dimorphism increases. So many other factors correlate with sexual dimorphism, it is difficult to say which is the major contributing factor. For instance, another hypothesis holds that a larger female bird of prey is better equipped to protect herself during contact with the potentially dangerous and certainly well-armed male. Yet another theory suggests that size is related to the vulnerability of the prey pursued. That is, the more agile the prey, the less likely the success of each hunt. Or, perhaps the secret to sexual dimorphism lies in a simpler explanation: that the larger female is better at catching some prey, and the male is better at catching others.

Courtship among the hawks is among the most spectacular of all animals. In the case of the red-tailed hawk, for example, the pair soar, screaming at each other; then the male dives at the female, who may roll in the air to present her claws to him in mock combat. The male marsh hawk flies in a series of graceful U's over the marsh from where the female is watching. Hawks generally mate for life, and are strongly attached to their nesting territory; one pair of red-shouldered hawks (and their offspring) used the same area for 45 years.

Hawks usually build their nests high in trees. The nests are quite large, up to about 3-4 ft (0.9-1.2 m) across, and consist mostly of sticks, with twigs, bark , moss , and sprigs of evergreen. Nests are often used year to year, with the bird abandoning it only at death or when the nest has grown so large that it breaks the boughs it is built upon.

Generally, the pair will defend their territory against all who approach, but some species, including the ferruginous hawk, will abandon their nest if disturbed by humans. Some hawks will dive at humans who approach too near their nests, as in the case of a pair of red-tailed hawks nesting in a park in Boston, who injured several curious passers-by before park officials removed the raptors and their eggs to a more secluded spot. The territory defended can range from 650 ft (198 m) between nests in small hawks to up to 18.5 mi (29.8 km) in larger ones. Some species, including the kites, are more gregarious and nest in loose colonies of about 10 pairs.

Female hawks lay between two and five eggs. Depending on the species, the female either incubates them alone or with the help of her mate. Incubation lasts about 28 days. The young hawks fledge at about 40 days of age.

Some young hawks may remain with their parents for a while after fledging, and these family groups have been observed hunting as a team. Generally, hunting buteos circle high in the air, watching the ground for any movement of prey. They then fold their wings and dive upon their prey. Accipiters are more likely to pursue their avian prey on the wing, darting thickets and woods during the chase. Some accipiters are decried for their impact on the populations of songbirds; in fact, in the past some ornithologists considered the sharp-shinned hawk a "harmful" species because it preyed on "beneficial" songbirds. Such human prejudice is at the root of most human-raptor conflict.

After the breeding season ends, many hawk species conduct spectacular migrations. The most spectacular is that of the Swainson's hawk. Huge flocks of these birds will travel overland from their North American summer range to their wintering grounds in South America , a total distance of 11,000-17,000 mi (17,699-27,353 km) annually. The broad-winged hawk (B. platypterus) is also noted for its large migrations: in one day (September 14, 1979), 21,448 broad-winged hawks passed over Hawk Mountain, Pa. Besides Hawk Mountain, other good sites to watch hawk migrations include Cape May, NJ; Duluth, MN.; Port Credit and Amherstburg, Ont.; and Cedar Grove, WI.

Hawks and humans

Although more humans are enjoying watching these migrations and learning to appreciate these raptors, hawks still face persecution. Many are shot each year. Others die in traps set for fur-bearing animals. Still others are killed when they alight on high-voltage power lines. Most species of hawks, like all other raptors, were hard hit by the effects of the pesticide DDT. Considered a miracle pesticide when it was introduced in the 1940s, DDT pervaded the environment, and became concentrated higher up in the food chain. The effect on the raptors was the production of eggs that were too thin-shelled to be incubated: when the female moved to sit on them, the eggs collapsed beneath her, killing the chicks inside. Recovery has been slow.

All hawks are protected by federal and state laws. Some, like the red-tail, are successfully adjusting to living in urban areas. Hawks have been known to live almost 20 years.

Resources

books

Ehrlich, Paul R., David S. Dobkin, and Darryl Wheye. The Birder's Handbook. New York: Simon & Schuster Inc., 1988.

Peterson, Roger Tory. North American Birds. Houghton Mifflin Interactive (CD-ROM). Somerville, MA: Houghton Mifflin, 1995.

F. C. Nicholson
Randall Frost

hawk¹ / hôk/ • n. 1. a diurnal bird of prey (Accipiter and other genera, family Accipitridae) with broad rounded wings and a long tail, typically taking prey by surprise with a short chase. Compare with falcon. ∎  a bird of prey related to the buteos. ∎ Falconry any diurnal bird of prey used in falconry. 2. a person who advocates an aggressive or warlike policy, esp. in foreign affairs. Compare with dove¹ (sense 2). • v. [intr.] 1. (of a person) hunt game with a trained hawk. 2. (of a bird or dragonfly) hunt on the wing for food. PHRASES: have eyes like a hawk miss nothing of what is going on around one.watch someone like a hawk keep a vigilant eye on someone, esp. to check that they do nothing wrong.DERIVATIVES: hawk·ish adj.hawk·ish·ly adv.hawk·ish·ness n.hawk² • v. [tr.] carry around and offer (goods) for sale, typically advertising them by shouting: street traders were hawking costume jewelry.hawk³ • v. [intr.] clear the throat noisily: he hawked and spat into the flames. ∎  [tr.] (hawk something up) bring phlegm up from the throat.hawk⁴ • n. a plasterer's square board with a handle underneath for carrying plaster or mortar.

HAWK

HAWK , bird of prey. Two genera of hawk are found in Israel, the Accipiter and the Falco, these being referred to respectively in the Bible as neẓ (av, jps = hawk) and taḥmas (av, jps = "nighthawk"), mentioned among the unclean birds that are prohibited as food (Lev. 11:16; Deut. 14:15). The neẓ is generally identified with the sparrow hawk (Accipiter nisus), which nests on trees in various places in Israel, pounces in flight on its victims, particularly small birds, and is recognizable by its bright abdomen streaked with dark lateral stripes. It winters in Israel and some migrate to southern lands, as mentioned in Job (39:26). The Pentateuch refers to "the neẓ after its kinds." In Israel there are two other transmigratory species that belong to this genus. But the expression neẓ may also include other genera of birds of prey. Thus, for example, the aggadah says that Israel is like a dove which the neẓ seeks to devour (Song R. 2:14, no. 2), the reference here being to a bird of prey larger than the hawk, such as the *buzzard which preys upon doves (the Accipiter hunts only small birds: see Ḥul. 3:1) or the saker falcon (Falco cherrug) which in certain countries is trained to pursue birds and animals. Of the genus Falco there are several species in Israel, the most common being the non-migratory kestrel (Falco tinnunculus) which preys upon birds and field mice and is apparently the biblical taḥmas, a word meaning "robber, bandit."

bibliography:

E. Smolly, Ẓipporim be-Yisrael (1959²), 85; R. Meinertzhagen, Birds of Arabia (1954), 366ff.; J. Feliks, Animal World of the Bible (1962), 64f. add bibliography: Feliks, Ha-Ẓome'aḥ, 255.

[Jehuda Feliks]

hawk in falconry, any diurnal bird of prey, used in falconry.

Hawk is also used to denote a person who advocates an aggressive or warlike policy, especially in foreign affairs; the opposite of a dove.
have eyes like a hawk miss nothing of what is going on around one.
hawks will not pick out hawks' eyes powerful people from the same group will not attack one another (compare dog does not eat dog). The saying is recorded from the late 16th century.
know a hawk from a handsaw have ordinary discernment, chiefly with allusion to Shakespeare's Hamlet, when Hamlet, who has been feigning madness, says, ‘I am but mad north-north-west; when the wind is southerly, I know a hawk from a handsaw.’ (Handsaw is generally taken as an alteration of heronshaw, a heron.)
watch someone like a hawk keep a vigilant eye on someone, especially to check that they do nothing wrong.