• Interesting Facts
• Common Names
• Description
• Biology
• Taxonomy
• Similar Species
• Bibliography
• More Info
• Notes

Interesting Facts

Common Names

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Description

Physical Description

Habitat

As a general rule , the red-tailed hawk inhabits open areas interspersed with patches of trees . In open, grassland country, the red-tailed hawk prefers areas with more, and taller, perch sites than do the ferruginous , Swainson's, or rough-legged hawk. Habitat types include scrub desert, montane grasslands, plains , agricultural pastures, urban parklands, deciduous and coniferous woodlands and tropical rainforest. Possibly only the Peregrine Falcon shows an ability to utilize as many or more habitat types than does the red-tailed hawk.

During the nesting season , birds may be found from sea level to at least 9,000 feet (2,790 km ). Birds prefer a tall tree with good aerial access . They will nest in a wide range of habitats including spruce forests , aspen stands, wooded stream valleys, woodlands in canyons , woodlots, saguaro deserts, deciduous woodlands or even arid canyonlands. Only the treeless arctic tundra has not been occupied by nesting red-tailed hawks.Winter habitats may tend to be more open with upland pastures, grasslands and hardwood forests being more preferred in some regions. In general, however, the basic habitat types are similar on a year-round basis except for those birds that migrate from the more northerly boreal forests and winter in grasslands or other southern habitats.The availability of perches is critical for this "sit and wait" type of predator . The availability of tall trees for nesting with foraging habitat nearby is important in many areas but nest sites are not always in trees if the region is generally non-forested. In this latter situation, cliff sites or other elevated locations may be used for nesting.

Vegetation: tropical deciduous forests, tropical lowland evergreen forest, pine forests, tropical lowland evergreen forest, pine-oak forests, montaine evergreen forests, arid lowland scrubs, arid montane scrubs, tropical lowland evergreen forest, second-growth forests and woodlands • Maximum Elevation: 3,500 meters • Foraging Strata: Canopy • Center of Abundance: Lower subtropical: lowlands, lower than 500 m.; subtropics. • Sensitivity to Disturbancet: Low

Typically found at an altitude of 0 to 3,793 meters (0 to 12,444 feet).Mean = 1,643.690 meters (5,392.684 feet), Standard Deviation = 1,759.550 based on 20,000 observations. Altitude information for each observation from British Oceanographic Data Centre.

Ecology:
List of Habitats :1.5Forest - Subtropical/Tropical Dry 1.9Forest - Subtropical/Tropical Moist Montane 3.5Shrubland - Subtropical/Tropical Dry 3.7Shrubland - Subtropical/Tropical High Altitude 14.6Artificial/Terrestrial - Subtropical/Tropical Heavily Degraded Former Forest

Biology

Diet

Red-tailed hawks have a wide variety of dietary prey ranging in size from small mice to jackrabbits (0.5 ounces to about 4.5 pounds ). Prey will vary by location, season , availability or even between adjacent pairs or individuals, but in general, mammals make up the bulk of their diets either in the number of prey items or biomass . Many regional studies have been completed on the red-tailed hawks, making generalizations less useful, but mammals have comprised from 37 to 99 percent of the diets in some studies. Other studies have indicate the following range of dietary compositions:

Birds 4 to 58 percent Herptiles 0 to 41 percent Invertebrates 0 to 21 percent

In eastern North America, voles, various species of mice, rats , and cottontails make up a large part of the diet with other common prey including the ring-necked pheasant, northern bobwhite, and other birds. In the western portions of the red-tailed hawk's range, snowshoe hares, black-tailed jackrabbits, and various species of ground squirrels, are important components . Snakes are also common in western diets along with pocket gophers, waterfowl, and small birds such as the western meadowlark and European starling.

A partial list of prey species includes red squirrel, eastern cottontail, varying hare, black-tailed jackrabbit, shrews, moles , bats, voles, mice, rats, pocket gophers, Richardson's ground squirrel, Columbian ground squirrel, other ground squirrel species, chipmunks, muskrat, domestic fowl, ring-necked pheasant, northern bobwhite, ruffed grouse, gray partridge, quails, dabbling ducks, crows, black-billed magpie, screech-owls, burrowing owl, shorebirds, European starling, meadowlarks, other passerines , desert spiny lizard, yellow-bellied racer, gopher snake, garter snakes, western rattlesnake, turtles, various frogs and toads, salamanders, crayfishes, grasshoppers, centipedes, spiders, other insects, and carrion including fishes , cow , horse, sheep, jackrabbits, bobcat, coyote, and skunk.

The red-tail hawk is an adaptable predator able to change to a new prey base if one food source declines. Its numbers are not tied to a particular combination of prey species.

Reproduction

The nest site varies widely depending upon local topography and vegetation. In forested areas, the nest is typically placed in the upper canopy of tall trees within woodlots or other fragmented forest clumps . It may be located within large tracts of unbroken forest. The nest tree may be taller than surrounding trees or on a higher slope . The nest tends to be placed near the edges of dense stands with more open rather than closed canopies. In areas where trees are scarce or absent, cliff faces , or artificial structures providing elevation above the landscape are used. Saguaro cacti is used in some desert locations. A common trait of nest sites is an unobstructed access from above and a good view of the surrounding landscape.

Both sexes build or refurbish the nest. The main nest is generally sticks and twigs from 0.5 to nearly 1 inch (1.3 to 2.5 centimeters) in diameter. The lining may include strips of bark , greenery, catkins, herbaceous plant materials , lichens and so forth. Typically, nests are over 30 inches in diameter and more than 15 inches high. The bowl is 4 to 5 inches (10.2 to 12.7 centimeters) deep and about 14 inches wide (35.6 centimeters). Nests may be refurbished and reused in subsequent years and may become a little larger over time. Two or more nests may be built and not used.

Courtship flights include high-circling, tilting and sky-dancing. Other territorial and or courtship behaviors include high-perching, whirling flight and boundary patrol flights. "High-circling" has been seen in all seasons and may be a precursor to a number of activities. Birds rise high above the terrestrial territory and soar in wide circles, at times joined by other birds that may be from adjacent territories. This practice is an integral part of early phases in the breeding cycle and evolves into other flight activities that are preludes to copulation .

"Tilting" is performed by males in the spring and it may serve to reinforce the pair bond, although it does not seem to be performed on territory. With wings spread , tail partly spread, legs down and talons spread, the male circles slowly while tilting first one wing and then the other in a rocking motion. This position is maintained for some time and a female is always nearby.The "sky dance" consists of a bird rising to a high altitude , pushing the wings forward and holding the tips in tightly then plunging in a steep dive at a high rate of speed . At the bottom of the plunge, the bird checks its speed and then shoots upward at about the same angle as the dive. This is repeated in series until the bird vanishes from sight. The purpose is to designate territorial boundaries and occurs before and well into the incubation period . Whether both sexes undertake the activity is not known.While soaring fairly high, birds will suddenly "whirl" on one wing tip and rotate in a full circle. This may serve as territorial advertisement.Mostly, copulation occurs when the female finishes a courtship flight and lands on a perch from which she will posture by holding her back in a horizontal position and fluttering her wings. The male lands on her back and copulates for a period of five to 12 seconds. Afterwards, the pair may perch quietly or perform aerial acrobatics. The frequency and span of time over which copulation may occur seems to be unrecorded.

The clutch size varies from one to four, but is usually two or three eggs . The size averages about 2.4 by 1.9 inches (61.0 by 48.3 millimeters) with some geographic variation . The eggs are smooth and non-glossy, white, and may have a light buffy wash . They may be sparsely, or heavily-marked, with blotches that vary from reddish-brown, dark brown, or purple. These may be indistinct and combined with fine speckling. Clutch replacement may occur within three to four weeks of the loss of the first eggs and rarely, a third set may be laid. Egg-laying in the southern United States occurs as early as February but for much of the range south of the 49th parallel, March is typically the month for laying . In Canada, and the northern states, late March through early May is typical depending upon latitude and local climate, whereas in Alaska, laying occurs from April through late May.

Incubation begins before completion of the clutch or with the first egg that is laid and is undertaken by both sexes. The incubation period is variously estimated at 28 to 35 days. The female probably does the incubating at night and most of the daytime sitting as well. She will depart to hunt while the male incubates.

Hatching occurs over a two to four day period with fledging reported from 42 to 50 days but likely closer to 46 days on average. The young are active by the second day as they issue soft calls and bounce and wave their wings. By day seven, the young will peck at prey in the nest and spend less time bobbing and peeping. The young will sit up by day 15 and show aggression towards intruders at day 16. Striking with talons and wings will occur by day 21 and regular exercise and wing-stretching take place by day 30. The female will brood the young until the oldest is about 30 to 35 days old. For the first four to five weeks, prey brought to the nest is torn into small pieces by the female before being given to the young. After this period, the nestlings tear apart their own food.

After about 46 days, the young leave the nest but stay close for several days. They may remain quite sedentary or chase the parents begging for food. The young stay in the vicinity of the nest for 18 to 25 days with sustained flight possible about 18 days after fledging. The parents typically supply all of the food for the first three to four weeks after fledging. Capturing of small vertebrate prey occurs at about six to seven weeks but parents may still provide food until the eighth week after fledging. Association with the parents may last for 10 weeks in southern migratory populations and up to six months in non-migratory populations. After dispersal from the nesting territory, immatures from several territories may aggregate in an immature staging area.

Cooperative breeding involving two females and one male attending a single brood has been recorded at least twice. In both cases, the male provided food to the females who in turn fed the young. Reproductive success generally, depends upon prey abundance, perch density and distribution as well as the proximity of nests to congeners . Weather and its impact on hunting may impact reproductive success.

Nesting densities have been recorded as low as one pair per 18 square miles in sub-optimal Alaskan habitat to as high as one pair per 0.5 square miles in California. The average has been suggested as one pair for every 2.2 square miles. The pair-bond typically is lifelong monogamy. In non-migratory birds, the bond is maintained throughout the year. In the event of a lost mate, acquisition of a new partner can occur quickly and has occurred within one day.

Inter-nest distances vary considerably and have been measured at slightly more than 0.5 miles to as much as 5 miles in one study area in Alaska. Territories may have common boundaries based upon interactions between adjacent pairs of birds.

• Clutch Size: 1-3
• Length of Incubation: 30-35 days
• Days to Fledge : 45-46

Migration

Migratory

Behavior

Red-tails are in the group of "soaring hawks" which is one of their common behaviors. They use their long, broad wings to effortlessly ride on warm, rising air currents . In general, the red-tailed hawk flaps less than other buteos, except the ferruginous hawk. Ground speed for red-tails has been estimated at about 40 miles per hour and air speeds at 55 miles per hour. Soaring is done with the wings held in a slight dihedral . It is capable of holding motionless in the wind (kiting) with no wing beats . During migration, soaring has been reported to about 3,000 feet (4,800 km ) above ground. Other reasons for soaring include hunting, exploration, territorial advertisement and courtship .

Hunting strategies are versatile but may be grouped into the following 11 broad categories:

• Perch and Wait - this successful technique is used more than 80 percent of the time. Any elevated site may be used but, frequently trees , fence posts, power lines or other man-made structures are used.
• Ground Pursuit - hopping across the ground in pursuit of invertebrates is often seen in younger birds.
• Flap or Glide - maintaining an altitude of 200 feet or lower, the birds will quarter over the countryside much like a harrier. This style may be used closer to the ground as the hawks will dodge behind and between bushes, rocks or other obstacles to remain unseen as they approach prey .
• Hovering - using quickened wing beats in order to maintain position, redtails will survey the ground in search of prey.
• Soaring - it has been suggested that this is an inefficient, and ineffective, method for hunting, but stoops on potential prey are sometimes made from a high soar.
• Cooperative Hunting - mated pairs may close in on a quarry and cooperate on the kill.
• Piracy - the red-tailed hawk has been seen robbing other raptors .
• Aerial Foraging - birds will occasionally sail in mid-air to catch large flying insects such as grasshoppers.
• Accipiter Method - often, in combination with the flap-glide flight, the red-tailed hawk will maneuver through stands of conifers in a goshawk-like manner.
• Falcon Method - the red-tailed hawk has been seen making fast stoops, like a falcon, specifically in pursuit of bats.
• Carrion Eating - the eating of freshly-killed animals is well-documented.

When swooping on prey, the wings are set into a glide pattern about 15 feet from the animal. At 10 feet, the legs are extended and the final strike usually made with one foot farther ahead than the other. On impact , the bird then drops onto its "heels." The relative impact is less than that of large falcons, the Northern goshawk or even the Cooper's hawk. Small prey is carried to a feeding perch and may be swallowed whole. Birds are beheaded and plucked and larger mammals may be beheaded. If the prey is large, it may be partially dismembered and consumed before being taken to a feeding perch. Caching has been noted. Excess food not consumed at the nest is carried away.

Buteos tend to have separate territories or if they do overlap with another species, behavioral routines are adjusted to minimize interactions . The red-shouldered and red-tailed hawk are intolerant of each other and antagonistic with the red-tailed hawk being more dominant. The red-tailed hawk is also very antagonistic towards the golden eagle in California but little inter-action has been noted on other study sites. The hawk has shown aggression towards the great horned owl but inter-nest distances between the two species have been recorded as close as 100 feet. In a number of studies, where these two species attempted to nest in close proximity, the owl nests tended to be more successful.

During the winter, the red-tailed hawk exhibits varying degrees of aggressive interaction towards each other, in attempts to maintain a winter territory. Behaviors vary from posturing, feather ruffling and eye contact through to full in-flight displays. Most red-tailed hawks typically occur singly or in pairs, except during migration or around aggregated food supplies. Social interactions during these occasions seem to be minimal and the phenomena appear to be related to temporarily favorable environmental conditions as opposed to furthering social functions.

Nesting red-tailed hawks were shown to habituate to helicopter overflights with no apparent decrease in nesting success in one study. Other studies suggest that populations of red-tails that have been exposed to human beings for long periods of time show less aggression towards human intruders than do populations that have had a shorter period of exposure.

The red-tails call is usually used in television shows and movies to represent any raptor flying overhead. The common call is a down-slurred scream given in flight or from a perch. Sometimes described as "tsee-eee-arrr", it is hoarse, sibilant and may vary in pitch, reminding one of a cat scream at greater distances . The function is likely territorial . Following a territorial encounter, individuals of mated pairs will utter a loud "chwirk" call. Other notes include a series of low, raspy "hrrrr" sounds , grunting or quacking "gank" calls and hunger calls similar to those of the nestlings. During courtship , a loud "chirk-chirk-chiruk" is given but perhaps this is the "chwirk" of other authors . The young utter soft, peeping notes and as they grow, softer versions of the adult scream as well as two-syllable "klee-uck" calls are given.

Taxonomy

Unambiguous Synonyms

1. Buteo jamaicensis (Gmelin) 1788
2. Buteo jamaicensis (J. F. Gmelin, 1788)

Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 17-Oct-2001.

Similar Species

Rough-Legged Hawk, Swainson's Hawk

Members of the genus Buteo

There are approximately 170 species in this genus. Here are just 100 of them:

B. abbreviatus · B. albicaudatus (White-Tailed Hawk) · B. albicaudatus albicaudatus (White-Tailed Hawk) · B. albicaudatus colonus · B. albicaudatus hypospodius (White-Tailed Hawk) · B. albicaudatus sennetti · B. albigula (White-Throated Hawk) · B. albonotatus (Zone-Tailed Hawk) · B. albonotatus albonotatus · B. anceps · B. aquilinus · B. archeri · B. areophilus · B. augur (Augur Buzzard) · B. augur archeri · B. augur augur · B. auguralis (Red-Necked Buzzard) · B. borealis · B. brachypterus (Madagascar Buzzard) · B. brachyurus (Short-Tailed Hawk) · B. brachyurus albigula · B. brachyurus brachyurus · B. brachyurus fuliginosus · B. burmanicus · B. buteo (Common Buzzard) · B. buteo arrigonii · B. buteo bannermani · B. buteo burmanicus · B. buteo buteo · B. buteo harterti · B. buteo insularum · B. buteo japonicus · B. buteo menetriesi · B. buteo oshiroi · B. buteo pojana · B. buteo refectus · B. buteo rothschildi · B. buteo ssp · B. buteo toyoshimai · B. buteo vulpinus · B. buteo zimmermannae · B. cabanisii · B. calurus · B. canescens · B. cirtensis · B. conterminus · B. erythronotus · B. erythronotus simonsi · B. eximus · B. exsul · B. ferox · B. ferrugineus · B. fluviaticus · B. fuliginosus · B. galapagoensis (Galapagos Hawk) · B. hemilasius (Upland Buzzard) · B. hypospodius · B. jamaicensis (Red-Tailed Hawk) · B. jamaicensis abeiticola · B. jamaicensis abieticola · B. jamaicensis alascensis (Red-Tailed Hawk) · B. jamaicensis borealis (Red-Tailed Hawk) · B. jamaicensis borealis; · B. jamaicensis buteo · B. jamaicensis calurus (Red-Tailed Hawk) · B. jamaicensis costaricensis · B. jamaicensis fuertesi (Red-Tailed Hawk) · B. jamaicensis fuertesii · B. jamaicensis fumosus · B. jamaicensis hadropus · B. jamaicensis harlani (Red-Tailed Hawk) · B. jamaicensis jamaicensis (Red-Tailed Hawk) · B. jamaicensis kemsiesi · B. jamaicensis krideri · B. jamaicensis kriderii (Red-Tailed Hawk) · B. jamaicensis socorroensis · B. jamaicensis solitudinis · B. jamaicensis suttoni · B. jamaicensis umbrinus (Red-Tailed Hawk) · B. jamaicensis x · B. japonicus · B. lagopus (Rough-Legged Hawk) · B. lagopus johannis · B. lagopus kamtschatkensis (Rough-Legged Hawk) · B. lagopus lagopus (Rough-Legged Hawk) · B. lagopus menzbieri · B. lagopus pallidus (Rough-Legged Hawk) · B. lagopus sancti-johannis · B. lagopus sanctijohannae · B. lagopus sanctijohannis (Rough-Legged Hawk) · B. lagopus ssp · B. latissimus · B. leucocephalus · B. leucorrhous (White-Rumped Hawk) · B. leucurus · B. lineatus (Red-Shouldered Hawk) · B. lineatus alleni (Red-Shouldered Hawk) · B. lineatus elegans (Red-Shouldered Hawk) · B. lineatus extimus (Red-Shouldered Hawk) · B. lineatus lineatus (Red-Shouldered Hawk)

Bibliography

• Alsop, Fred J. III. Birds of North America - Eastern Region. First American Edition. Smithsonian Handbooks. DK Publishing, Inc. 2001.
• Banks, R. C., R. W. McDiarmid, A. L. Gardner, and