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Harris's hawk ( Parabuteo unicinctus), formerly also known as bay-winged hawk or dusky hawk, and known in Latin America as the peuco, is a medium-large bird of prey that breeds from the southwestern United States south to Chile, central Argentina, and Brazil.
The name is derived from the Greek language para, meaning beside, near or like, and the Latin buteo, referring to a kind of buzzard; uni meaning once; and cinctus meaning girdled, referring to the white band at the tip of the tail. John James Audubon gave this bird its English name in honor of his ornithological companion, financial supporter, and friend Edward Harris.
Harris's hawk is notable for its behavior of hunting cooperatively in Pack hunter consisting of tolerant groups, while other raptors often hunt alone. Harris's hawks' social nature has been attributed to their intelligence, which makes them easy to train and has made them a popular bird for use in falconry.Beebe, Frank (1984). A Falconry Manual. Hancock House Publishers, , page 81.
They exhibit sexual dimorphism with the females being larger by about 35%. In the United States, the average weight for adult males is about , with a range of , while the adult female average is , with a range of .Hamerstrom, F. (1978). "External sex characters of Harris' Hawks in winter". Raptor Res. 12:1–14. They have dark brown plumage with chestnut shoulders, wing linings, and thighs, white on the base and tip of the tail, long, yellow legs, and a yellow beak. The vocalizations of Harris's hawk are very harsh sounds.
The lifespan of Harris's hawk is 10–12 years in the wild, though up to 25 years has been recorded in captivity.
The wild Harris's hawk population is declining due to habitat loss; however, under some circumstances, they have been known to move into developed areas.
Very often, there will be three hawks attending one nest: two males and one female. Whether or not this is polyandry is debated, as it may be confused with backstanding (one bird standing on another's back). The female does most of the egg incubation. The eggs hatch in 31 to 36 days. The young begin to explore outside the nest at 38 days, and fledge, or start to fly, at 45 to 50 days. The female sometimes breeds two or three times in a year. Young may stay with their parents for up to three years, helping to raise later broods. Nests are known to be predated by ( Canis latrans), ( Aquila chrysaetos), ( Buteo jamaicensis), great horned owls ( Bubo virginianus), and flocks of ( Corvus corax), predators possibly too formidable to be fully displaced by Harris's hawk's cooperative nest defenses. No accounts show predation on adults in the United States and Harris's hawk may be considered an apex predator, although presumably predators like eagles and great horned owls would be capable of killing them.Dawson, J. W. and R. W. Mannan. (1991). Dominance hierarchies and helper contributions in Harris' Hawks. Auk 108:649–660. In Chile, black-chested buzzard-eagles ( Geranoaetus melanoleucus) are likely predators.Jiménez, J. E., & Jaksić, F. M. (1989). Behavioral ecology of grey eagle-buzzards, Geranoaetus melanoleucus, in central Chile. Condor 913–921.
When Pack hunter, Harris's hawk can take large prey effectively, such as desert cottontail ( Sylvilagus auduboni), the leading prey species in the north of Harris's hawk's range, usually weighs or less.Bednarz, J. C. (1988). A comparative study of the breeding ecology of Harris's and Swainson's hawks in southeastern New Mexico. Condor 90:311–323.Bednarz, J. C., J. W. Dawson, and W. H. Whaley. (1988). Harris' Hawk. Pages 71–82 in Proceedings of the southwest raptor management symposium and workshop. (Glinski, R. L., B. G. Pendleton, M. B. Moss, M. N. LeFranc, Jr., B. A. Millsap, and S. W. Hoffman, Eds.) Natl. Wildl. Fed. Washington, D.C. Even adult black-tailed jackrabbits weighing more than can be successfully taken by a pack of Harris's hawks.Coulson, Jennifer O., and Thomas D. Coulson. "Reexamining cooperative hunting in Harris's Hawk (Parabuteo unicinctus): large prey or challenging habitats?." The Auk 130.3 (2013): 548-552.
Because it often pursues large prey, this hawk has larger and stronger feet, with long talons, and a larger, more prominent hooked beak, than most other raptors of similar size. Locally, other larger buteonine hawks, including the ferruginous hawk, the red-tailed hawk, and the white-tailed hawk also hunt primarily cottontails and jackrabbits, but each is bigger, weighing about , and , respectively, more on average than a Harris's hawk.Smith, D. G. and J. R. Murphy. (1978). Biology of the Ferruginous Hawk in central Utah. Sociobiology 3:79–98.Thurow, T. L., C. M. White, R. P. Howard, and J. F. Sullivan. (1980). Raptor ecology of Raft River valley, Idaho. EG&G Idaho, Inc. Idaho Falls.Smith, D. G. and J. R. Murphy. (1973). Breeding ecology of raptors in the East Great Basin Desert of Utah. Brigham Young Univ. Sci. Bull., Biol. Ser. Vol. 18:1–76.Farquhar, C. C. (1986). Ecology and breeding behavior of the White-tailed Hawk on the northern coastal prairies of Texas. PhD. diss. Texas A & M Univ. College Station.Dunning Jr., John B. (Editor). (1992). CRC Handbook of Avian Body Masses. CRC Press. .
In the Southwestern United States, the most common prey species (in descending order of prevalence) are desert cottontail ( Sylvilagus auduboni), eastern cottontail ( Sylvilagus floridanus), black-tailed jackrabbit ( Lepus californicus), ( Ammospermophilus spp. and Spermophilus spp.), Pack rat ( Neotoma spp.), ( Dipodomys spp.), ( Geomys and Thomomys spp.), Gambel's quail ( Callipepla gambelii), scaled quail ( C. squamata), northern bobwhite ( Colinus virginianus), cactus wren ( Campylorhynchus brunneicapillus), northern mockingbird ( Mimus polyglottos), desert spiny lizards ( Sceloporus magister), and ( Eumeces spp.)Mader, W. J. (1975). Biology of the Harris' hawk in southern Arizona. Living Bird 14:59–85.Brannon, J. D. (1980). The reproductive ecology of a Texas Harris's hawk (Parabuteo unicinctus harrisi) population. Master's Thesis. Univ. of Texas, Austin. In the tropics, Harris's hawks have adapted to taking prey of several varieties, including those like and introduced by man.Nutting, C. C. (1883). On a collection of birds from the Hacienda "La Palma," Gulf of Nicoya, Costa Rica, with critical notes by Robert Ridgway. Proc. U.S. Natl. Mus. 1982(5):382–409.Johnson, A. W. (1965). The birds of Chile and adjacent regions of Argentina, Bolivia, and Peru. Platt Establecimientos Graficos, Buenos Aires. In Chile, the common degu ( Octodon degus) makes up 67.5% of the prey.Jaksic, F. M., J. L. Yanez, and R. P. Schlatter. (1980). Prey of the Harris' hawk in central Chile. Auk 97:196–198.
Trained Harris's hawks have been used to remove an unwanted columbidae population from London's Trafalgar Square, and from the tennis courts at Wimbledon.
Trained Harris's hawks have been used for Bird control by falconry experts in Canada and the United States at various locations including airports, resorts, landfill sites, and industrial sites.
Harris's hawks have frequently escaped from captivity in Western Europe, especially Great Britain; they have occasionally bred in the wild, but have not to date become naturalized.
Juvenile
The juvenile Harris's hawk is heavily streaked with white or buff on the underparts, and appears much lighter than the solidly dark-breasted dark adults. When in flight, the undersides of the juveniles' wings are buff-colored with brown streaking, and the primary feathers are whitish except at their tips, giving a pale panel on the outer wing; the tail band is also paler than on adults. They can look very unlike adults at first glance, but the identical chestnut plumage is an aid for identification.
Taxonomy
Robert Ridgway placed Harris's hawk in its own new subgenus Urubitinga (Antenor) in 1873, Antenor Ridgeway Nov. subgen. is on page 63. and introduced the generic name Parabuteo On page 248, the heading is "Genus Antenor Ridgway", but the subspecies heading is " Parabuteo unicinctus var. harisii (Ridgway)". in 1874. Richard Bowdler Sharpe also separated Harris's hawk to a monotypic genus, Erythrocnema, in 1874. In his Catalogue of Birds in the British Museum, Sharpe gives an extensive synonymy, with various authors having earlier placed P. u. harrisi in three genera and P. u. unicinctus in eleven.
Subspecies
There are two subspecies of Harris's hawk:
A third subspecies P. u. superior sometimes accepted in the past in the northwest of the species' range (Arizona to Baja California) was believed to have longer tails and wings and to be more blackish than P. u. harrisi; however, the sample size of the original study was quite small, with only five males and six females. Later research concluded that there is not as strong a physical difference as was originally assumed. Other ecological differences, and evidence of a latitudinal cline, were also brought up as arguments against the validity of the subspecies segmentation.
Southwestern United States, Mexico, much of Central America, and western South America south to western Peru. Smaller than the northern subspecies, tail and wings are proportionally longer, and the adult's dark brown ventrum is streaked or flecked with white or whitish.Blake, Ferguson-Lees and Christie cited in Birds of the world "Parabuteo unicinctrus"
/ref>Eastern and southern South America.
Distribution and habitat
Harris's hawks live in sparse woodland and semi-desert, as well as (with some trees) in some parts of their range (Howell and Webb 1995), including mangrove swamps, as in parts of their South American range. Olmos Fábio & Robson Silva e Silva (2003). Guará-Ambiente, Flora e Fauna dos Manguezais de Santos-Cubatão Empresa das Artes, Harris's hawks are permanent residents and do not bird migration. Important perches and nest supports are provided by scattered larger trees or other features (e.g., , woodland edges, standing dead trees, live trees, boulders, and ).Bednarz, J. C. and J. D. Ligon. (1988). A study of the ecological bases of cooperative breeding in the Harris' hawk. Ecology 69:1176–1187.
Behavior
This species occurs in relatively stable groups. A dominance hierarchy occurs in Harris's hawks, wherein the mature female is the dominant bird, followed by the adult male and then the young of previous years. Groups typically include from two to seven birds. Not only do birds cooperate in hunting, but they also assist in the nesting process.Dawson, J. W. and R. W. Mannan. (1991). The role of territoriality in the social organization of Harris' hawks. Auk 108:661–672. No other bird of prey is known to hunt in groups as routinely as this species.Griffin, C. R. (1976). A preliminary comparison of Texas and Arizona Harris' Hawks ( Parabuteo unicinctus) populations. Raptor Res. 10:50–54.
Breeding
They nest in small trees, shrubby growth, or cacti. The bird nest are often compact, made of sticks, plant roots, and stems and are often lined with leaves, moss, bark, and plant roots. They are built mainly by the female. There are usually two to four white to blueish-white bird egg sometimes with a speckling of pale brown or gray. The nestlings start light buff, but in five to six days turn a rich brown. (1997). 9780691122953, Princeton University Press. ISBN 9780691122953
Feeding
The majority of Harris's hawks' prey are mammals, including ground squirrels, , and larger black-tailed jackrabbits ( Lepus californicus). from the size of small passerines such as diuca finch ( Diuca diuca) to adult great egret ( Ardea alba) and half-grown wild turkey ( Meleagris gallopavo) can be taken.Ferguson-Lees, James, and David A. Christie. Raptors of the world. Houghton Mifflin Harcourt, 2001.Santander, Francisco J., et al. "Prey of the Harris' Hawk (Parabuteo unicinctus) during fall and winter in a coastal area of central Chile". The Southwestern Naturalist (2011): 417-422.Houcke, H.H. (1971). Predation By a White-tailed Hawk and a Harris' Hawk on a Wild Turkey Poult. Condor 4: 475. In one instance, a lone Harris's hawk successfully killed a subadult great blue heron ( Ardea herodias).Woodward, H.D. (2003). Lone Harris' Hawk Kills Great Blue Heron. The Raptor Research Foundation 1:85–86. Reptiles such as and are additionally taken as well as large .
Hunting
While most raptors are solitary, only coming together for breeding and migration, Harris's hawks will Pack hunter of two to six. This is believed to be an adaptation to the lack of prey in the desert climate in which they live. In one hunting technique, a small group flies ahead and scouts, then another group member flies ahead and scouts, and this continues until prey is bagged and shared. In another, all the hawks spread around the prey and one bird flushes it out. Harris's hawks will often chase prey on foot and are quite fast on the ground; their long legs are adapted for this, whereas most other hawks do not spend as much time on the ground. Groups of Harris's hawks tend to be more successful at capturing prey than lone hawks, with groups of two to four individuals having ~10% higher success rates per extra individual.
Relationship with humans
Falconry
Since about 1980, Harris's hawks have been increasingly used in falconry and are now the most popular hawks in the West (outside of Asia) for that purpose, as they are one of the easiest to train and the most social.
In art
John James Audubon illustrated Harris's hawk in The Birds of America (published in London, 1827–38) as Plate 392 with the title "Louisiana Hawk - Buteo harrisi". The image was Engraving and colored by the Havell family, London workshops in 1837. The original watercolor by Audubon was purchased by the New York History Society where it remains to this day (January 2009).
External links
Historical material
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