Animal Diversity Web

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. (Christo­pher, 1990)

• Biogeographic Regions
• nearctic
  • native

Habi­tat

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. (Calla­han, 1974; Cro­coll, 1994; Wood­ward, et al., 1931)

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• forest

• Wetlands
• swamp

Phys­i­cal De­scrip­tion

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. (Christo­pher, 1990; Clark and Wheeler, 2001; Cro­coll, 1994; Whet­more, 1965; Wood­ward, et al., 1931)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry
• polymorphic

• Sexual Dimorphism
• female larger

• Range mass

  550 to 700 g

  19.38 to 24.67 oz

• Range length

  43 to 61 cm

  16.93 to 24.02 in

• Range wingspan

  92 to 107 cm

  36.22 to 42.13 in

• Average wingspan

  100 cm

  39.37 in

• Average basal metabolic rate

  2.11 W

  AnAge

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. (Cro­coll, 1994)

• 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. (Calla­han, 1974; Cro­coll, 1994)

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

• 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 eggs per season

  3

  AnAge

• Average time to hatching

  33 days

• Average time to hatching

  33 days

  AnAge

• 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

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. (Cro­coll, 1994)

• 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

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. (Cro­coll, 1994)

• Range lifespan
  Status: wild

  20 (high) years

• Average lifespan
  Status: wild

  25.6 months

• Average lifespan
  Status: wild

  239 months

  Bird Banding Laboratory

Be­hav­ior

Red-shoul­dered hawks are soli­tary and ter­ri­to­r­ial. They do not form flocks, even in the win­ter.

Most pop­u­la­tions of red-shoul­dered hawks do not mi­grate. They stay in the same area year-round. Red-shoul­dered hawks that breed in the north­ern parts of their range (the north­east United States and south­ern Canada) mi­grate to north­ern Mex­ico for win­ter. (Calla­han, 1974; Christo­pher, 1990; Cro­coll, 1994; Wood­ward, et al., 1931)

• Key Behaviors
• arboreal
• flies
• diurnal
• motile
• migratory
• sedentary
• solitary
• territorial

• Average territory size

  1.92 km^2

Home Range

Male red-shoul­dered hawks tend to have larger home ranges than fe­males. The home range of both sexes is usu­ally larger dur­ing the non-breed­ing sea­son than dur­ing the breed­ing sea­son. Home ranges typ­i­cally range from 1.0 to 3.4 square kilo­me­ters. (Cro­coll, 1994)

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. (Cro­coll, 1994)

• Communication Channels
• visual
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

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. (Calla­han, 1974; Cro­coll, 1994; Whet­more, 1965)

• Primary Diet
• carnivore
  • eats terrestrial vertebrates

• Animal Foods
• birds
• mammals
• amphibians
• reptiles
• insects
• aquatic crustaceans

• Foraging Behavior
• stores or caches food

Pre­da­tion

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. (Cro­coll, 1994)

• Known Predators

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

Ecosys­tem Roles

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. (Cro­coll, 1994)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Red-shoul­dered hawks prey on ro­dents that are agri­cul­tural pests. (Calla­han, 1974)

• Positive Impacts
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Though red-shoul­dered hawks pri­mar­ily eat ro­dents and other small mam­mals, they oc­ca­sion­ally at­tack poul­try, mak­ing them a nui­sance to farm­ers. Many of these hawks are killed an­nu­ally by farm­ers for this rea­son. The nick­name "hen hawk" for red-shoul­dered hawks comes from their ten­dency to take ad­van­tage of poul­try farms. (Calla­han, 1974)

• Negative Impacts
• crop pest

Con­ser­va­tion Sta­tus

Prior to 1900, this species was one of the most com­mon hawks in east­ern North Amer­ica. Pop­u­la­tion den­si­ties de­clined sub­stan­tially through most of the 20th cen­tury, prob­a­bly due to hunt­ing and de­struc­tion of wet hard­wood for­est habi­tat. Poi­son­ing from in­sec­ti­cides and in­dus­trial pol­lu­tants and loss of habi­tat are major threats to this species. Dis­tur­bance of nest­ing pairs by human ac­tiv­ity such as log­ging and climb­ing of nest trees also pre­sents a se­ri­ous threat to some pop­u­la­tions.

This species is listed as threat­ened or en­dan­gered in sev­eral U.S. states, in­clud­ing Michi­gan. It is pro­tected in the U.S. under the Mi­gra­tory Bird Treaty Act. This species is also listed under CITES Ap­pen­dix II, lim­it­ing in­ter­na­tional trade of in­di­vid­u­als or body parts. (Cro­coll, 1994)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Migratory Bird Act

  Protected

• US Federal List

  No special status

• CITES

  Appendix II

• State of Michigan List

  Threatened

Con­trib­u­tors

Kari Kirschbaum (au­thor, ed­i­tor), An­i­mal Di­ver­sity Web.

Stephanie Miller (au­thor), Cocoa Beach High School, Penny Mc­don­ald (ed­i­tor), Cocoa Beach High School.

Ref­er­ences

Calla­han, P. 1974. The Mag­nif­i­cent Birds of Prey. New York: Hol­i­day House.

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

Clark, W., B. Wheeler. 2001. A field guide to hawks of North Amer­ica, 2nd Edi­tion. New York: Houghton Mi­flin Com­pany.

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.

Whet­more, A. 1965. Water, Prey, and Game Birds of North Amer­ica. Chicago: Na­tional Ge­o­graphic So­ci­ety.

Wood­ward, C., A. How­ell, N. Mayo. 1931. Florida Birds. Tampa: Florida Grower Press.