Overview

Brief Summary

Buteo lineatus

A relatively large (17-24 inches) hawk, the Red-shouldered Hawk takes its name from the large rust-colored shoulder patches visible from above or while perching. This species may also be identified by its brown back, barred white-and-black wings, and broad black tail banded with white. A pale form, with washed-out plumage on the chest, back, and head, occurs in south Florida. Like most species of raptors, females are larger than males. The Red-shouldered Hawk primarily breeds in the eastern United States and southeastern Canada, withdrawing from northern portions of its range and expanding south into northern Mexico in winter. Unusually for a North American hawk, the Red-shouldered Hawk has another population, separated from the main population by thousands of miles, that is a permanent resident along the Pacific coast of California. Eastern Red-Shouldered Hawks inhabit mature forests with deciduous or mixed deciduous and evergreen trees. Western populations also inhabit these habitat types, but are also likely to be found in human-altered environments near woods. Red-shouldered Hawks primarily eat small vertebrates, including small mammals, amphibians, and occasionally small songbirds and doves. Red-shouldered Hawks may be most easily observed while hunting, when they drop down from high perches to capture terrestrial prey with their talons. This species may also be observed perching, although this hawk’s coloration and the dense vegetation of its preferred habitat help to provide camouflage. Red-shouldered Hawks are most active during the day.

Threat Status: Least Concern

  • Buteo lineatus. Xeno-canto. Xeno-canto Foundation, n.d. Web. 20 July 2012. .
  • Dykstra, Cheryl R., Jeffrey L. Hays and Scott T. Crocoll. 2008. Red-shouldered Hawk (Buteo lineatus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/107
  • Peterson, Roger Tory. Birds of Eastern and Central North America. Boston: Houghton Mifflin, 1980. Print.
  • Red-shouldered Hawk (Buteo lineatus). The Internet Bird Collection. Lynx Edicions, n.d. Web. 20 July 2012. .
  • eBird Range Map - Red-shouldered Hawk. eBird. Cornell Lab of Ornithology, N.d. Web. 20 July 2012. .
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Distribution

Red-shouldered hawks are found in the Nearctic region. They breed throughout the eastern and northeast United States into southern Canada, and west of the Sierra Nevada in California. Populations of red-shouldered hawks in the eastern U.S. and California are resident. Populations that breed in the northeast U.S. and southern Canada migrate to northern Mexico for the winter.

Biogeographic Regions: nearctic (Native )

  • Christopher, R. 1990. Book of North American Birds. Pleasantville: Reader's Digest.
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Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: northern California south, west of the Sierran Divide, to northern Baja California; and from eastern Nebraska, Iowa, central Minnesota, northern Wisconsin, northern Michigan, southern Ontario, southwestern Quebec and southern New Brunswick south to Veracruz, Tamaulipas, central and southern Texas, the Gulf Coast, and Florida (to the Florida Keys); also locally in the valley of Mexico (recorded in Zacatecas and Distrito Federal) (AOU 1983, Crocoll 1994). Now very scarce as a breeder in eastern and central Mexico. NON-BREEDING: California and throughout the breeding range, at least sporadically, in eastern North America, but primarily from eastern Kansas, central Missouri, the Ohio Valley, northwestern Pennsylvania, southern New York, and southern New England south to central Mexico (Crocoll 1994, AOU 1998). Most numerous in the Gulf coast states and Georgia (Root 1988).

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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Geographic Range

Red-shouldered hawks are found in the Nearctic region. They breed throughout the eastern and northeast United States into southern Canada, and west of the Sierra Nevada in California. Populations of red-shouldered hawks in the eastern U.S. and California are resident. Populations that breed in the northeast U.S. and southern Canada migrate to northern Mexico for the winter.

Biogeographic Regions: nearctic (Native )

  • Christopher, R. 1990. Book of North American Birds. Pleasantville: Reader's Digest.
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Physical Description

Morphology

Red-shouldered hawks are large, broad-winged hawks with a relatively long tails and heavy bodies. They show reverse sexual size dimorphism, meaning that females are larger than males. Female red-shouldered hawks average 700 g and 48 to 61 cm in length whereas males average 550 g and 43 to 58 cm in length. Adults have a wingspan of 92 to 107 cm (average 100 cm). Adult red-shouldered hawks have a brown head, a dark brown back and reddish underparts with dark brown streaks. Juveniles appear similar to adults, but have creamy underparts with dark brown spots and streaks. Both adults and juveniles have reddish lesser secondary upper wing coverts, which give the impression of red shoulders, giving this species its name. The tail of the both immature and mature red-shouldered hawks is dark brown with white bands.

Five subspecies of Buteo lineatus are recognized. These subspecies are separated based on geography and physical characteristics. The head and breast markings of the Florida subspecies, Buteo lineatus extimus and Buteo lineatus alleni, are slightly paler than other Red-shouldered hawks. The California subspecies, Buteo lineatus elegans, and the Texas subspecies, Buteo lineatus texanus, however, have vibrant, deep red markings on the lesser secondary upperwing coverts, underwing coverts and breast.

Range mass: 550 to 700 g.

Range length: 43 to 61 cm.

Range wingspan: 92 to 107 cm.

Average wingspan: 100 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry ; polymorphic

Sexual Dimorphism: female larger

Average basal metabolic rate: 2.11 W.

  • Clark, W., B. Wheeler. 2001. A field guide to hawks of North America, 2nd Edition. New York: Houghton Miflin Company.
  • Whetmore, A. 1965. Water, Prey, and Game Birds of North America. Chicago: National Geographic Society.
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Physical Description

Red-shouldered hawks are large, broad-winged hawks with a long tails and heavy bodies. Female red-shouldered hawks are larger than males. Female red-shouldered hawks average 700 g and 48 to 61 cm in length whereas males average 550 g and 43 to 58 cm in length. Adults have a wingspan of 92 to 107 cm (average 100 cm). Adult red-shouldered hawks have a brown head, a dark brown back and reddish underparts with dark brown streaks. Juveniles look similar to adults, but have creamy underparts with dark brown spots and streaks. Both adults and juveniles have reddish upper wing coverts (feathers), which make them look like they have red shoulders. They also have dark brown tails with white bands.

There are five subspecies red-shouldered hawks (Buteo lineatus).

Range mass: 550 to 700 g.

Range length: 43 to 61 cm.

Range wingspan: 92 to 107 cm.

Average wingspan: 100 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry ; polymorphic

Sexual Dimorphism: female larger

Average basal metabolic rate: 2.11 W.

  • Clark, W., B. Wheeler. 2001. A field guide to hawks of North America, 2nd Edition. New York: Houghton Miflin Company.
  • Whetmore, A. 1965. Water, Prey, and Game Birds of North America. Chicago: National Geographic Society.
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Size

Length: 48 cm

Weight: 643 grams

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Ecology

Habitat

Habitat and Ecology

Systems
  • Terrestrial
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Red-shouldered hawks usually inhabit mature deciduous or mixed deciduous-conifer forests and swamps. They build their nests 6 to 15 meters (20 to 60 feet) above the ground in the branches of deciduous trees in wet woodland areas. They prefer to have dead trees nearby, where they can perch and enjoy an unobstructed view of the forest floor.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Wetlands: swamp

  • Callahan, P. 1974. The Magnificent Birds of Prey. New York: Holiday House.
  • Crocoll, S. 1994. Red-shouldered hawk (Buteo lineatus). Pp. 1-20 in A Poole, F Gill, eds. The Birds of North America, Vol. 107. Washington, DC: The American Ornithologist's Union.
  • Woodward, C., A. Howell, N. Mayo. 1931. Florida Birds. Tampa: Florida Grower Press.
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Comments: BREEDING: varies from bottomland hardwoods and riparian areas (Stewart 1949, Henny et al. 1973, Bednarz and Dinsmore 1981, Kimmel and Fredrickson 1981, Woodrey 1986, Preston et al. 1989) to upland deciduous or mixed deciduous-conifer forest (Titus and Mosher 1981, Armstrong and Euler 1983, Morris and Lemon 1983, Crocoll and Parker 1989). Nesting areas are almost always found near some form of water, such as a swamp, marsh, river, or pond (Preston et al. 1989, Bosakowski et al. 1992), and the habitat is usually well forested (Portnoy and Dodge 1979, Kimmel and Fredrickson 1981, Titus and Mosher 1981, Morris and Lemon 1983, Ebbers 1989). Further, nesting habitat typically is mature forest with a well-developed high canopy and variable amounts of understory vegetation (Postupalsky 1980, Titus and Mosher 1981, Armstrong and Euler 1983, Morris and Lemon 1983, Titus 1984, Preston et al. 1989.). Sometimes occurs in coniferous stands in the West. In California, has been expanding range of occupied habitats to include various woodlands, including stands of eucalyptus trees amid urban sprawl (Ehrlich et al. 1992).

The nest is usually built in the main crotch of a large, living tree in mature forest, although in Florida, palmettos may be used. In eastern North America, nests generally are far from forest edges. At least 43 species of mainly deciduous trees have been chosen, so that the size and shape seem more important than the actual species (Bednarz 1979, Apfelbaum and Seelbach 1983, Titus and Mosher 1987, Palmer 1988, Ebbers 1989). The bulky structure of twigs, rather flat on top, is typically placed approximately halfway up the tree in the lower portion of the canopy (Morris et al. 1982, Titus and Mosher 1987). The typical height is between 11-15 m but can range from 1.5-33.5 m (Peck and James 1983, Ebbers 1989). The nest is lined with stems, leaves, lichen, and bark. Active nests are decorated with greenery and other materials. Hemlock and other conifer sprigs are often mentioned as nest greenery, as are deciduous sprigs once they have leafed out, and Bent (1937) mentioned such plants as flowering violets and nightshade. Other materials have included cornstalks, ears, and husks, dried tent caterpillar webs, tissue paper, twine, and nests of eastern wood-pewee, red-eyed vireo, and northern oriole (Palmer 1988).

In eastern North America, may use nest used previously by barred owl (STRIX VARIA) (and vice versa) (Palmer 1988). See Dijak et al. (1990) for information on nest-site characteristics affecting success and reuse of nests in Missouri.

NON-BREEDING: less restricted than that used for breeding; favors lowland areas near water, either standing or running, including river valleys, swamps, marshes, and perhaps canyon bottoms (Palmer 1988), and level, open country with scattered large trees (Bent 1937). In Florida, Bohall and Collopy (1984) found hawks most often in open areas such as pastures and fallow fields.

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Red-shouldered hawks live in forests and swamps. They build their nests 6 to 15 meters (20 to 60 feet) above the ground in the branches of hardwood trees in wet woodland areas. They prefer to have dead trees nearby, where they can perch and see the forest floor.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Wetlands: swamp

  • Callahan, P. 1974. The Magnificent Birds of Prey. New York: Holiday House.
  • Crocoll, S. 1994. Red-shouldered hawk (Buteo lineatus). Pp. 1-20 in A Poole, F Gill, eds. The Birds of North America, Vol. 107. Washington, DC: The American Ornithologist's Union.
  • Woodward, C., A. Howell, N. Mayo. 1931. Florida Birds. Tampa: Florida Grower Press.
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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

North of a line roughly from southern Minnesota to the southern border of Ohio, to central New Hampshire, most red-shouldered hawks are resident only during the breeding season, though a few may overwinter in the region. The migratory tendency is expressed most strongly in the Northeast population, although there are also flights in the Midwest and Southeast, and a light fall movement in California. From the latitude of about Virginia southward, populations are mainly resident.

In Maryland, montane populations are migratory whereas those in the Piedmont and coastal areas are not.

Spring migration is early; birds move by 15 February in Maryland and the District of Columbia (Palmer 1988). Overall, the northward movement peaks in March. Migrants begin to arrive in Massachusetts in mid-March, in southwestern Quebec from March to mid-April. In Michigan, migrating birds arrive at nesting grounds between late February and early April.

Fall migration begins in early September in the Northeast, extending into November and even late December for a few tardy individuals. Dates are similar across the northern part of the range.

Typically avoids crossing large bodies of water (Palmer 1988).

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Trophic Strategy

The diet of red-shouldered hawks consists primarily of small mammals, the largest of these being rabbits and squirrels. Other food items include reptiles and amphibians, such as snakes, toads, frogs and lizards, small birds and large insects. Crayfish are important prey for red-shouldered hawks in some regions.

Red-shouldered hawks search for prey while perched on a treetop or soaring over woodlands. When they sight prey, they kill it by dropping directly onto it from the air. They may cache food near their nest for later consumption.

Red-shouldered hawks use sight and hearing to hunt successfully. They do not hunt by smell. Some key characteristics that make red-shouldered hawks especially well-adapted to hunting are sharp eyesight and broad wings. The shape and structure of red-shouldered hawks’ wings allow them to soar effortlessly for extended periods of time searching for prey. The hawks’ large eyes are situated to look forward. Although this means that the birds must turn their heads in order to keep prey in view, the orientation of their eyes affords them excellent depth perception. The high concentrations of light-sensitive cone cells in red-shouldered hawks’ eyes also provide good resolving power and very sharp vision.

Animal Foods: birds; mammals; amphibians; reptiles; insects; aquatic crustaceans

Foraging Behavior: stores or caches food

Primary Diet: carnivore (Eats terrestrial vertebrates)

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Comments: Diet varies regionally and seasonally, sometimes annually depending on availability. Common prey items include snakes of moderate size; amphibians up to bullfrog size; mammals mostly from shrew to chipmunk size; small lizards and young turtles; relatively few birds to grackle size; a few small fishes; a few crayfishes; insects in considerable numbers, usually of cricket and large grasshopper size; and miscellaneous invertebrates such as centipedes, earthworms, and snails (Palmer 1988). In northeastern North America, juvenile chipmunks are important prey during the hawk nestling period (Portnoy and Dodge 1979, Morris 1980, Johnson 1989, In Iowa, Bednarz and Dinsmore (1985) Iowa observed that the proportion of prey types changed dramatically between years, with mammals dominating one year and amphibians and arthropods the next year. Apparently the change in prey type had no effect on productivity between the two years.

Hunts beneath forest canopy and in more open nearby terrain that is preferably moist or near water; hunts from perch or flies low and attacks prey from close range (Palmer 1988). In Iowa, hunted in small clearings averaging a few hectares (see Bushman and Therres 1988).

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Food Habits

Red-shouldered hawks eat small mammals as big as rabbits and Sciuridae. They also eat reptiles, such as serpents and Sauria, and amphibians, including Anura. They also eat small birds and large insects. Astacidae cambaru are an important food for red-shouldered hawks in some regions.

Red-shouldered hawks search for prey by perching on top of a tall tree or soaring over woodlands. When they sight prey, they kill it by dropping down onto it from the air. They may store food near their nest to eat later. There is no information available about how red-shouldered hawks drink water.

Red-shouldered hawks use sight and hearing to hunt successfully. They do not hunt by smell. Red-shouldered hawks have very sharp eyesight and broad wings which allow them to be very successful hunters.

There is no information available about how red-shouldered hawks obtain water.

Animal Foods: birds; mammals; amphibians; reptiles; insects; aquatic crustaceans

Foraging Behavior: stores or caches food

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Associations

Red-shouldered hawks compete with other large birds, including golden eagles, prairie falcons, red-tailed hawks, barred owls and great-horned owls for territories. They provide food for their predators; primarily great horned owls and raccoons. They also host at least one blood parasite (Leucocytozoa) and several external parasites.

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Incubating red-shouldered hawk adults, nestlings and eggs are vulnerable to predation by great-horned owls and raccoons. Non-incubating adults are not usually vulnerable to predation.

Known Predators:

  • raccoons (Procyon lotor)
  • great horned owls (Bubo virginianus)

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Ecosystem Roles

Red-shouldered hawks compete with other large birds, including Aquila chrysaetos, Falco mixicanus, Buteo jamaicensis, Strix varia and Bubo virginianus for territories. They provide food for their predators; primarily Bubo virginianus and Procyon lotor. They also host at least one blood parasite (Leucocytozoa) and several external parasites.

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Predation

Incubating red-shouldered hawk adults, nestlings and eggs are vulnerable to predation by Bubo virginianus and Procyon lotor. Non-incubating adults are not usually vulnerable to predation.

Known Predators:

  • raccoons (Procyon_lotor)
  • great horned owls (Bubo_virginianus)

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Known prey organisms

Buteo lineatus preys on:
Insecta
Amphibia
Reptilia
Mammalia

This list may not be complete but is based on published studies.
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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: Eleven states or provinces report more than 100 EOs. In the early 1990s, ranked S4 or S5 in at least 15 states/provinces.

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Global Abundance

10,000 - 100,000 individuals

Comments: Rangewide numbers not available. According to Risley (1983 COSEWIC report), probably there were at least 468 breeding pairs in Canada as of the early 1980s. Kirk et al. (1995) reported the estimated number of breeding pairs in Canada as 2000-5000.

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General Ecology

Mortality has been reported to occur during the incubation, nestling, and fledgling stages of the breeding season (Craighead and Craighead 1956, Janik and Mosher 1982, Bosakowski and Speiser 1986, Crocoll and Parker 1989). Adults and juveniles have also been reported to suffer mortality (McCrary and Bloom 1984, Crocoll and Parker 1989). Mortality has taken the form of wind-destroyed nests (Wiley 1975, Portnoy and Dodge 1979, Dijak et al. 1990), addled eggs (Janik and Mosher 1982, Crocoll and Parker 1989), starvation of nestlings (Crocoll and Parker 1989), human disturbance at or near the nest-site (Craighead and Craighead 1956, Wiley 1975), and predation of eggs, nestlings or adults (Craighead and Craighead 1956, Wiley 1975, Portnoy and Dodge 1979, Bosakowski and Speiser 1986, Crocoll and Parker 1989). The most frequent predators on eggs and young are raccoons (PROCYON LOTOR) and great horned owls (BUBO VIRGINIANUS).

Breeding density is highly variable; recorded values include one pair per 48.7 ha in central Maryland (Stewart 1949), one pair per 171 ha in western New York (Crocoll and Parker 1989), one pair per 417 ha in Massachusetts, one pair per 455-588 ha in Indiana, one pair per 645 ha in Michigan (Craighead and Craighead 1956), and 1 pair/1000 ha in Wisconsin (see Peterson and Crocoll 1992). Stewart (1949) found nests a mean distance of 1072 m apart in the wide upper Patuxent River drainage in Maryland, and Parker (1986) found similar internest distances in Missouri. Crocoll and Parker (1989) found nests a mean distance of 1271 m apart in the Canadaway Creek Wildlife Management Area of western New York. Adjacent nests were 0.37-1.27 km apart in creek bottoms in southern California. Breeding home range of radio-tagged birds in California averaged 62 ha for males, 37 ha for females; used less space when not breeding. In northern New Jersey, nesting density was 0.22 nests per 100 ha, the highest density yet reported (about twice that reported in the few comparable studies in other states) (Bosakowski et al. 1992).

Often uses nests of previous years (Terres 1980). Nesting territories can be used for many years by a succession of pairs, even in the face of logging and (formerly) egg collecting. Bent (1937) reported an unbroken record of 26 years for a territory that was occupied for at least 42 years, until the woods were nearly ruined by cutting. His longest record was 47 years, but he knew of a tract that was occupied for over a half-century, from 1872 until 1923.

LEUCOCYTOZOA sp., a hematozoan, was detected in the blood of hawks tested in Oklahoma (Kocan et al. 1977). Two lice (COLPOCEPHALUM FLAVESCENS and PHILOPTERUS TAUROCEPHALUS) and one bird fly (LYNCHIA AMERICANA) have been found on red-shoulders (Peters 1936). In New York, the ears of nestlings commonly were full of maggots (PROTOCALLIPHORA SPLENDIDA) (Sargent 1938). These maggot infestations seemingly did not cause deafness or hinder survival (Hands et al. 1989).

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Life History and Behavior

Behavior

Red-shouldered hawks use physical displays, such as courtship flights, and vocalizations to communicate. Biologists recognize seven different calls given by red-shouldered hawk adults. The most common call is "kee-aah". This call is used to announce that a territory is occupied, and when the birds are alarmed.

Communication Channels: visual ; acoustic

Perception Channels: visual ; tactile ; acoustic ; chemical

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Communication and Perception

Red-shouldered hawks use physical displays, such as courtship flights, and vocalizations to communicate. Biologists recognize seven different calls given by red-shouldered hawk adults. The most common call is "kee-aah". This call is used to announce that a territory is occupied, and when the birds are alarmed.

Communication Channels: visual ; acoustic

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Life Expectancy

Wild red-shouldered hawks live an average of 25.6 months. The oldest known red-shouldered hawk lived 19 years and 11 months.

Range lifespan

Status: wild:
20 (high) years.

Average lifespan

Status: wild:
25.6 months.

Average lifespan

Status: wild:
239 months.

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Lifespan/Longevity

Wild red-shouldered hawks live an average of 25.6 months. The oldest known red-shouldered hawk lived 19 years and 11 months.

Range lifespan

Status: wild:
20 (high) years.

Average lifespan

Status: wild:
25.6 months.

Average lifespan

Status: wild:
239 months.

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Lifespan, longevity, and ageing

Maximum longevity: 20 years (wild) Observations: One animal was caught and released at age 20 (John Terres 1980).
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Reproduction

Red-shouldered hawks are monogamous and territorial. Courtship displays occur on the breeding grounds, and involve soaring together in broad circles while calling, or soaring and diving toward one another. Males may also perform the "sky-dance" by soaring high in the air, and then making a series of steep dives, each followed by a wide spiral and rapid ascent. These courtship flights usually occur in late morning and early afternoon.

Mating System: monogamous

Red-shouldered hawks breed once per year between April and July, with peak activity occurring between early April and mid June. They often use the same nest from year to year, refurbishing it each spring. Both the male and female build or refurbish the nest, which is large and deep, constructed from sticks, twigs, shredded bark, leaves and green sprigs.

The female lays 3 to 4 white eggs with brown or lavender blotches over the course of 2 to 3 days. Incubation begins when the first or second egg is laid, and lasts for 33 days. Hatching is asynchronous, with up to 7 days between the first and last chick. The nestlings are altricial, and are brooded nearly constantly by the female for at least a week. The male brings food to the nest for the female and nestlings during the nestling stage, which lasts approximately 6 weeks. Chicks begin to leave the nest at 6 weeks, but are fed by the parents for another 8 to 10 weeks. Chicks become independent of the parents at 17 to 19 weeks old. After becoming independent, they may still roost in or near the nest at night. Red-shouldered hawks begin breeding when they are 1 year old or older.

Breeding interval: Red-shouldered hawks breed once yearly.

Breeding season: Red-shouldered hawks breed between April and July, with peak activity occurring between early April and mid June.

Range eggs per season: 3 to 4.

Average time to hatching: 33 days.

Average fledging age: 6 weeks.

Range time to independence: 17 to 19 weeks.

Range age at sexual or reproductive maturity (female): 1 (low) years.

Range age at sexual or reproductive maturity (male): 1 (low) years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

Average time to hatching: 33 days.

Average eggs per season: 3.

Male and female red-shouldered hawks both protect the nest and incubate the eggs. The female broods the chicks during the nestling stage while the male does most of the hunting for the female and the chicks. Both parents feed the young during the nestling and fledgling stages.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female); post-independence association with parents

  • Callahan, P. 1974. The Magnificent Birds of Prey. New York: Holiday House.
  • Crocoll, S. 1994. Red-shouldered hawk (Buteo lineatus). Pp. 1-20 in A Poole, F Gill, eds. The Birds of North America, Vol. 107. Washington, DC: The American Ornithologist's Union.
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Courtship, territory establishment, and nest building (or refurbishing) occur shortly after arrival on the breeding grounds. In New York, Crocoll and Parker (1989) recorded birds back on territories and relining nests during the second and third weeks of March. Portnoy and Dodge (1979) in Massachusetts observed courtship flights during March and nest relining during the last week of March and first week of April. Morris et al. (1982) in southwestern Quebec observed territorial hawks soaring from early March to mid-April. Farther south, nesting activities begin several weeks earlier. Records from Alabama, Louisiana, and Oklahoma indicate that breeding begins in February.

Aerial nuptial displays are impressive and include "high-circling" and "sky-dancing," both extremely vocal performances. In the sky-dance, one individual (presumably the male) rides an upward thermal, crying as it circles, then drops with folded wings into a steep dive, pulling up and then shooting upward again. Neighboring pairs often join in, with as many as ten birds involved. The sky-dance can be immediately followed by copulation, which "occurs repeatedly and over considerable time" (Palmer 1988).

Clutch size varies from one to six (Palmer 1988), with two to four eggs being the most common sizes throughout the range. Clutch size is commonly two in Florida, three to four in the northern U.S. A mean of 3.45 eggs from 42 clutches was reported for the Great Lakes States (Henny 1972). Eggs are laid January-June (mostly March-April) in the southeastern U.S., March-June (mostly April) in northern U.S., mostly March-April in California (Palmer 1988). Nests late March to late May in Maryland (Bushman and Therres 1988) and New York (Bull 1974).

Incubation is by both sexes, but mainly by the female, who is fed by the male, and commences with the laying of the first egg. The incubation period is around 33 days per egg (Newton 1979), and the young hatch asynchronously and thus vary in size, as with many raptors (Newton 1979). The semi-altricial young are inactive at first, becoming active at about 10 days. Feathering begins in about two weeks. The nestling period lasts from five to six weeks (Harrison 1978, Crocoll and Parker 1989). Young leave the nest at 5-6 weeks; in California, first flight occurs at about 45 days (sometimes at considerably older age). Fledging generally occurs in mid-June in Maryland (Janik and Mosher 1982), June to mid-July in New York (Bull 1974, Crocoll and Parker 1989), and late June-early July in Massachusetts (Portnoy and Dodge 1979). Dates are similar throughout the northern range of the species, and are advanced 4 to 8 weeks in the south. In southern California, parents supplied food to young for 8-10 weeks after fledging.

Although a few nest at one year of age (Apanius 1977), most first breed when at least two years old (Palmer 1988). There has been evidence of polyandry with copulation and trio bonding at the nest recorded (Palmer 1988).

Nesting success (measured as the percentage of nests that fledge at least one young) has been reported to vary from 52.9% in Maryland to 100% in Missouri with an average of 68.7% over nine North American studies (Crocoll and Parker 1989). Two one-year studies reported lower nest success rates: 47.4% for 19 nests in northern Lower Michigan in 1986 (Ebbers 1986), and 25% for 1966 at the Patuxent Wildlife Research Center, Maryland (Henny et al. 1973).

The average number of young fledged per nest over the previously cited nine studies varied from 1.11 young to 2.9. Henny et al. (1973) used a mathematical model and field data to predict that in a stable population each pair should fledge an average of 1.95 young. Four of the nine above mentioned studies had fledging numbers below the Henny et al. (1973) standard. Three of the studies were conducted in the Northeast: New York (1.11 young fledged, Crocoll and Parker 1989), Western Maryland (1.8 young fledged, Janik and Mosher 1982), and central Maryland (1.58 young fledged, Henny et al. 1973). One Michigan population produced a mean 1.2 young fledged (n = 44) over three years of study, while another population fledged 2.2 young (n = 29) over the same time period (Ebbers 1989). Ebbers (1989) noted that there is concern that the 1.95 standard may be too high because of possible biases in the data used to scale the model values. Nevertheless, it does appear that some populations produce excess young ("source" populations), while others would not survive without immigration ("sink" populations).

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Red-shouldered hawks are monogamous and territorial. They perform courtship flights by soaring together in broad circles while calling, or soaring and diving toward one another. Males may also perform a "sky-dance" by soaring high in the air, and then making several steep dives. These courtship flights usually occur in late morning and early afternoon.

Mating System: monogamous

Red-shouldered hawks breed once per year between April and July. They often use the same nest for several years, fixing it up each spring. The male and female both build the nest, which is large and deep and made from sticks, twigs, shredded bark, leaves and green sprigs.

The female lays 3 to 4 white eggs with brown or lavender blotches. This takes 2 to 3 days. The eggs are incubated for 33 days. The egg that was laid first hatches first. The nestlings are altricial, meaning that they are helpless and need to be cared for by the parents. The female broods the chicks for at least a week after they hatch. The male brings food to the nest for the female and nestlings during the nestling stage. Chicks begin to leave the nest at 6 weeks old, but are fed by the parents for another 8 to 10 weeks. Chicks become independent of the parents at 17 to 19 weeks old. After becoming independent, they may still roost in or near the nest at night. Red-shouldered hawks begin breeding when they are 1 year old or older.

Breeding interval: Red-shouldered hawks breed once yearly.

Breeding season: Red-shouldered hawks breed between April and July, with peak activity occurring between early April and mid June.

Range eggs per season: 3 to 4.

Average time to hatching: 33 days.

Average fledging age: 6 weeks.

Range time to independence: 17 to 19 weeks.

Range age at sexual or reproductive maturity (female): 1 (low) years.

Range age at sexual or reproductive maturity (male): 1 (low) years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average time to hatching: 33 days.

Average eggs per season: 3.

Male and female red-shouldered hawks both protect the nest and incubate the eggs. The female broods the chicks during the nestling stage while the male does most of the hunting for the female and the chicks. Both parents feed the young during the nestling and fledgling stages.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female); post-independence association with parents

  • Callahan, P. 1974. The Magnificent Birds of Prey. New York: Holiday House.
  • Crocoll, S. 1994. Red-shouldered hawk (Buteo lineatus). Pp. 1-20 in A Poole, F Gill, eds. The Birds of North America, Vol. 107. Washington, DC: The American Ornithologist's Union.
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Buteo lineatus

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 3 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

NNNNNNNNNNNNNNNNNNNNNNNNNNAGCCGGTATAGTCGGCACCGCCCTCAGCCTACTTATTCGTGCAGAACTCGGCCAACCAGGCACACTCCTAGGTGACGACCAGATCTACAACGTAATTGTTACCGCACATGCCTTCGTAATAATTTTCTTCATAGTCATACCAATTATGATCGGAGGATTCGGAAACTGACTTGTCCCACTCATAATCGGCGCCCCTGACATAGCCTTCCCACGCATAAACAACATAAGCTTCTGACTACTTCCCCCATCCTTCCTCCTCCTCCTAGCCTCCTCAACAGTAGAAGCAGGAGCCGGCACTGGATGAACTGTCTATCCCCCACTGGCTGGCAACATAGCCCATGCCGGAGCTTCAGTAGACCTAGCCATCTTCTCCCTTCACTTAGCCGGAGTCTCATCTATTCTAGGAGCAATCAACTTTATCACAACCGCCATCAACATAAAACCCCCAGCCCTCTCCCAGTACCAAACACCCCTATTTGTATGATCTGTCCTCATTACCGCTGTCCTTCTACTACTCTCACTCCCAGTCCTAGCCGCCGGTATTACTATGCTGCTTACAGACCGAAACCTAAACACAACATTCTTTGACCCCGCTGGCGGAGGAGATCCCATCCTATACCAACATCTCTTTTGATTCTTCGGACACCCAGAAGTTTACATCCTAATCCTG
-- end --

Download FASTA File

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Statistics of barcoding coverage: Buteo lineatus

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 7
Specimens with Barcodes: 7
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Butchart, S. & Symes, A.

Contributor/s

Justification
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

History
  • Least Concern (LC)
  • Least Concern (LC)
  • Least Concern (LC)
  • Lower Risk/least concern (LR/lc)
  • Lower Risk/least concern (LR/lc)
  • Lower Risk/least concern (LR/lc)
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