Hawk

Hawks

Sharp-shinned Hawk

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Accipitriformes
Family:	Accipitridae
Subfamily:	Accipitrinae

Genera

Accipiter
Micronisus
Melierax
Urotriorchis
Erythrotriorchis

Hawk is the common name for various small to medium-sized diurnal birds of prey in the family Accipitridae of the bird order Falconiformes, characterized by a short, hooked bill, curved and sharp talons, and keen eyesight, and smaller size than the eagles of the same family. More specifically, the "true hawks" are considered any of those long-tailed birds with short, rounded wings that comprise the Accipitridae genus Accipiter (goshawks and sparrowhawks) or sometimes those belonging to both Accipiter and Melierax (chanting goshawks) (Olsen 2004). Broader still, as commonly used in Europe and Asia, the term "hawk" refers strictly to any of the species in the genera Accipiter, Micronisus, Melierax, Urotriorchis, or Megatriorchis, all of which belong to the Accipitrinae subfamily. However, the term hawk also is used as part of the common name for many other birds in the Falconiformes, such as many members in the genus Buteo (for example, red-tailed hawk, B. jamaicensis).

In human culture, hawks both have been admired for their power, vision, and hunting abilities and reviled by farmers for preying on livestock such as chickens. Hawks and humans have had a particularly close relationship in the sport of falconry, whereby humans hunted with trained hawks. This relationship is traced back at least to 2000 B.C.E. in Asia, and flourished in Europe and the Middle East from 500 to 1600 C.E., used both for recreation and to provide food (Olsen 2004). While the custom continues in some cultures, it is no longer allowed in many nations, both for reasons of animal rights and conservation (Olsen 2004). While the modern era has seen the killing of many hawks, there is currently a greater concern for their conservation. Still, many hawks migrating through China, Europe, and elsewhere are shot, poisoned, or trapped with the goal of protecting livestock, or for medicine, food, or collecting purposes (eggs and specimens) (Olsen 2004).

Overview and description

Hawks, eagles, kites, harriers, and Old World vultures are all part of the Accipitridae family, one of two major families within the order Falconiformes, the diurnal birds of prey. Most other raptors, but not all, belong to the Falconidae, or falcon family. In addition to skeletal differences, accripitrids differ from members of the other raptorial family in having well-developed nest-building behavior (versus poor or absent), forceful squirting of excreta (versus dropping of excreta), and yellow, red, or hazel eyes (versus brown) (Olsen 2004). The beaks of accipitrids are strong and hooked, and the base of the upper mandible is covered by a fleshy membrane called the cere, which is usually yellow in color.

The accipitrids have been variously divided into some two to ten subfamilies. Olsen (2004) and ITIS (1999) recognize two subfamilies, Pandioniane (ospreys) and Accipitrinae (hawks, eagles, and allies). Where several subfamilies are recognized, some recognize Accipitrinae as limited to the genera whose members are known as hawks: Accipiter, Micronisus, Melierax, Urotriorchis, and Megatriorchis.

The large and widespread genus Accipiter, whose members sometimes are known as the "true hawks," includes goshawks, sparrowhawks, the sharp-shinned hawk, and others. They are primarily woodland birds that hunt by sudden dashes from a concealed perch, with long tails, broad wings and high visual acuity facilitating this lifestyle.

The genus Buteo, which some place within Accipitrinae and some in the subfamily Buteoninae, includes medium-sized wide-ranging raptors with a robust body and broad wings. In the Old World, members of this genus are called "buzzards," but "hawk" is used in North America. As both terms are ambiguous, "buteo" is sometimes used instead, such as by the Peregrine Fund. Examples of members of this genus with the name hawk in North America include the red-tailed hawk (Buteo jamaicensis), red-shouldered hawk (Buteo lineatus), broad-winged hawk (Buteo platypterus), Swainson's hawk (Buteo swainsoni), roadside hawk (Buteo magnirostris), and Ridgway's hawk (Buteo ridgwayi).

Hawks, including the accipitrines, are believed to have vision several times as sharp as that of the human species, in part because of the great number of photoreceptors in their retinas (up to 1,000,000 per square millimeter for Buteo, against 200,000 for humans), a very high number of nerves connecting the receptors to the brain, and an indented fovea, which magnifies the central portion of the visual field.

In February 2005, Canadian ornithologist Louis Lefebvre announced a method of measuring avian "IQ" in terms of their innovation in feeding habits (Lefebvre 2005). Hawks were named among the most intelligent birds based on his scale.

Hawks have a world-wide distribution with the exception of the Antarctic. In particular, Accipiter is extremely widespread and occurs on many islands and all continents except Antarctic (Olsen 2004). Goshawks and sparrowhawks (Accipiter) prefer forest and woodland.

Behavior, diet, and reproduction

Hawks are generally active during the day, when their prey is most available. The majority of hawks are solitary. They vocalize mainly during the breeding season, to advertise and defend territories and for purposes of courtship and breeding. The range of calls is generally quite limited—usually repeated whistles, cackles, yelps, mews, barks, and so forth (Olsen 2004).

All hawks are carnivorous and eat mainly freshly caught prey, such as rodents and fish. The crab hawk (Buteogallus aequinoctialis) feeds almost exclusively on crabs from coastal mangroves, while the white-necked hawk (Leucopternis lacernulata) specializes on insects and only a few vertebrates. The bat hawk (Macheiramphus alcinus) swallows bats whole. Some of the goshawks and sparrowhawks are very swift and agile and can hunt in the air, capturing birds after pursuing in the woodland or forest. Smaller hawks feed more frequently than larger ones; sparrowhawks hunt at least daily (Olsen 2004).

Hawks typically are monogamous. All hawks build a nest of sticks that are lined with softer material, and most commonly are in trees or on a cliff. Eggs are oval, and generally are white with various colored markings (brown, red, purplish gray) (Olsen 2004).

Species list

The following taxonomy recognizes five genera within Acciptrinae, rather than the more inclusive taxonomies of Olsen (2004) and ITIS (1999). Additional species outside of these taxonomic groups may also have the common name "hawk."

Subfamily Accipitrinae
- Genus Accipiter
  - Northern goshawk, A. gentilis
  - Eurasian sparrowhawk, A. nisus
  - Grey-bellied goshawk, A. poliogaster
  - Crested goshawk, A. trivirgatus
  - Sulawesi goshawk, A. griseiceps
  - Red-chested goshawk, A. toussenelii
  - African goshawk, A. tachiro
  - Chinese goshawk, A. soloensis
  - Frances's sparrowhawk, A. francesii
  - Spot-tailed goshawk, A. trinotatus
  - Grey goshawk, A. novaehollandiae
  - Brown goshawk, A. fasciatus
  - Pied goshawk, A. albogularis
  - Fiji goshawk, A. rufitorques
  - White-bellied goshawk, A. haplochrous
  - Moluccan goshawk, A. henicogrammus
  - Grey-headed goshawk, A. poliocephalus
  - New Britain goshawk, A. princeps
  - Henst's goshawk, A. henstii
  - Meyer's goshawk, A. meyerianus
  - Black goshawk, A. melanoleucus
  - Chestnut-flanked sparrowhawk, A. castanilius
  - Nicobar sparrowhawk, A. butleri
  - Levant sparrowhawk, A. brevipes
  - Slaty-mantled sparrowhawk, A. luteoschistaceus
  - Imitator sparrowhawk, A. imitator
  - Red-thighed sparrowhawk, A. erythropus
  - Little sparrowhawk, A. minullus
  - Japanese sparrowhawk, A. gularis
  - Small sparrowhawk, A. nanus
  - Rufous-necked sparrowhawk, A. erythrauchen
  - Collared sparrowhawk, A. cirrocephalus
  - New Britain sparrowhawk, A. brachyurus
  - Vinous-breasted sparrowhawk, A. rhodogaster
  - Madagascar sparrowhawk, A. madagascariensis
  - Ovampo sparrowhawk, A. ovampensis
  - Rufous-chested sparrowhawk, A. rufiventris
  - Shikra, A. badius
  - Tiny hawk, A. superciliosus
  - Semicollared hawk, A. collaris
  - Sharp-shinned hawk, A. striatus
  - White-breasted hawk, A. chionogaster
  - Plain-breasted hawk, A. ventralis
  - Rufous-thighed hawk, A. erythronemius
  - Cooper's hawk, A. cooperii
  - Gundlach's hawk, A. gundlachi
  - Bicoloured hawk, A. bicolor
  - Besra, A. virgatus
- Genus Melierax
  - Gabar goshawk, M. gabar
  - Dark chanting goshawk, M. metabates
  - Eastern chanting goshawk, M. poliopterus
  - Pale chanting goshawk, M. canorus
- Genus Urotriorchis
  - Long-tailed hawk, U. macrourus
- Genus Erythrotriorchis
  - Red goshawk, E. radiatus
  - Chestnut-shouldered goshawk, E. buergersi
- Genus Megatriorchis
  - Doria's goshawk, M. doriae
Subfamily Buteoninae
- Genus Parabuteo
  - Harris's hawk, P. unicinctus
- Genus Buteogallus
  - Common black hawk, Buteogallus anthracinus
  - Mangrove black hawk, Buteogallus subtilis
  - Great black hawk, Buteogallus urubitinga
  - Rufous crab hawk, Buteogallus aequinoctialis
  - Savanna hawk, Buteogallus meridionalis
- Genus Busarellus
  - Black-collared hawk, Busarellus nigricollis
- Genus Leucopternis
  - Plumbeous hawk, Leucopternis plumbea
  - Slate-coloured hawk, Leucopternis schistacea
  - Barred hawk, Leucopternis princeps
  - Black-faced hawk, Leucopternis melanops
  - White-browed hawk, Leucopternis kuhli
  - White-necked hawk, Leucopternis lacernulata
  - Semiplumbeous hawk, Leucopternis semiplumbea
  - White hawk, Leucopternis albicollis
  - Grey-backed hawk, Leucopternis occidentalis
  - Mantled hawk, Leucopternis polionota
- Genus Buteo
  - Common buzzard, Buteo buteo
  - Red-tailed hawk, Buteo jamaicensis
  - Long-legged buzzard, Buteo rufinus
  - Rough-legged buzzard, Buteo lagopus
  - Ferruginous hawk, Buteo regalis
  - Red-shouldered hawk, Buteo lineatus
  - Broad-winged hawk, Buteo platypterus
  - Swainson's hawk, Buteo swainsoni
  - Roadside hawk, Buteo magnirostris
  - Ridgway's hawk, Buteo ridgwayi
  - White-rumped hawk, Buteo leucorrhous
  - Short-tailed hawk, Buteo brachyurus
  - White-throated hawk, Buteo albigula
  - White-tailed hawk, Buteo albicaudatus
  - Galápagos hawk, Buteo galapagoensis
  - Red-backed hawk, Buteo polyosoma
  - Puna hawk, Buteo poecilochrous
  - Grey-lined hawk, Buteo nitidus - formerly in Asturina
    - Grey hawk, Buteo nitidus plagiatus
  - Zone-tailed hawk, Buteo albonotatus
  - Hawaiian hawk, Buteo solitarius
  - Rufous-tailed hawk, Buteo ventralis
  - Mountain buzzard, Buteo oreophilus
  - Madagascar buzzard, Buteo brachypterus
  - Upland buzzard, Buteo hemilasius
  - Red-necked buzzard, Buteo auguralis
  - Jackal buzzard, Buteo rufofuscus

References
ISBN links support NWE through referral fees

Integrated Taxonomic Information System (ITIS). 1998. Accipitridae. Taxonomic Serial No.: 175280. Retrieved October 1, 2008.
Lefebvre, L. 2005. Bird IQ test takes flight. Eurekalert February 21, 2005. Retrieved October 1, 2008.
Olsen, P. 2004. Accipitridae. In B. Grzimek, D. G. Kleiman, V. Geist, and M. C. McDade, Grzimek's Animal Life Encyclopedia. Detroit: Thomson-Gale. ISBN 0307394913.
Thiollay, J. M. 1994. Family Accipitridae (Hawks and Eagles). In J. del Hoyo, A. Elliot, and J. Sargatal (eds.), Handbook of the Birds of the World, Volume 2: New World Vultures to Guineafowl. Lynx Edicions. ISBN 8487334156.

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