SPECIES

Red-tailed Hawk Buteo jamaicensis Scientific name definitions

C. R. Preston and R. D. Beane
Version: 1.0 — Published March 4, 2020
Text last updated May 20, 2009

Plumages, Molts, and Structure

Plumages

Red-tailed Hawks have 10 functional primaries (p7-p10 notched and p6-p9 emarginated), 14-16 secondaries (including three tertials), and 12 rectrices. Wings are moderately rounded and tail is moderately squared. No geographic variation in molt strategies has been published but it is possible that populations wintering in colder climates (e.g., eastern and northern resident subspecies) may undergo less-protracted molts and replace fewer flight feathers per year, on average, than those wintering in temperate and subtropical climates (e.g., western, southern, and highly migratory subspecies); see Definitive Prebasic Molt (below). Polymorphism occurs to various degrees geographically, with a light morph occurring in all subspecies, a dark morph occurring in most (especially western) subspecies, and a white morph ("Krider's Red-tailed Hawk") occurring in one or two subspecies. Morphs by age described here; geographic variation in plumage aspect and (to a lesser extent) size is also marked. See Systematics for descriptions of plumage aspect in 12 recognized subspecies.

Following general description based primarily on detailed descriptions of eastern subspecies B. j. borealis (for light and white morphs) and western subspecies B. j. calurus (for dark morph) in Friedmann (Friedmann 1950a), Roberts (Roberts 1932), Oberholser (Oberholser 1974), Palmer (Palmer 1988f), Wheeler (Wheeler 2003b, Wheeler 2003b), and examination of museum specimens by authors; see Pyle (Pyle 2008) for age-related criteria. See Systematics for comparative descriptions of other subspecies. Sexes similar in all plumage aspects.

Natal Down

(May-Jun). Protoptile down short, white; bare skin on femur. Nestlings downy until about 18 d post-hatching; down is whitish or pale neutral gray (Smithe 1975: 86) on days 5–7, becoming much longer and glaucous (80) (lighter on head) by day 9. A white occipital spot is visible in most hatchlings.

Juvenile Plumage

(Aug-Jul) characterized by uniform wear to all feathers including primaries, secondaries, and rectrices (Pyle 2005c,Pyle 2006, Pyle 2008).

Light morph with head, cheeks, scapulars, nape, upperwing coverts, inner secondaries, and tertials dark fuscous (21), with little or no cinnamon-brown or russet margins on the feathers and white bases resulting in somewhat ragged and patchy white appearance; rump and upper tail coverts pale neutral gray barred with fuscous. Tail with thin and tapered rectrices, hair brown (119A) crossed by 8-12 fuscous bands of approximately equal width, and narrowly tipped with whitish. Primaries and secondaries variably light neutral gray (85), the primaries paler along inner webs (contrasting with darker secondaries) and with indistinct sepia bars and tips, and the secondaries with narrow and distinct dusky band. Chin, throat, breast, thighs, flanks, and under tail coverts white, usually unmarked (throat and thighs sometimes spotted with fuscous), with an abdominal band of elongated sepia (119) markings. Underwing coverts white with dark markings to lesser coverts and tips of primary coverts; markings otherwise scattered, not as concentrated as in Definitive Basic Plumage. Photographs available in Moritsch (Moritsch 1983a), and illustrations available in Palmer (Palmer 1988f).

Dark morph has entire head, body, wings, except the remiges and thighs fuscous; upper tail coverts cinnamon-rufous (40) basally; under tail coverts pale cinnamon (39) subterminally very broadly marked with fuscous and edged with cinnamon-rufous; primaries, secondaries, and rectrices as in light morph (above).

White morph ("Krider's Red-tailed Hawk") generally similar to light morph (above; and see also Definitive Basic Plumage, below) but upperparts more heavily mottled white; underparts whiter with thinner and paler brownish streaking; tail white with more diffuse and curved dark bands of paler brown (illustration inPyle 2008).

Formative Plumage

(Sep-Jul) shown by some but not all individuals. Aspects of each morph similar to those of Juvenile Plumage (above) but some body feathers fresher and intermediate in appearance between those of Juvenile and Definitive Basic (below) plumages, the upperpart feathers darker and without extensive white basally. Uniformly juvenile wing and tail feathers retained.

Second Basic Plumage

(Aug-Jul). Aspects of each morph similar to those of Definitive Basic Plumage (below) but some juvenile body (especially rump) feathers and/or wing coverts, 1-4 juvenile outer primaries (among p7-p10), 1-6 juvenile secondaries (among s3-s4 and s6-s9), and/or 1-4 juvenile rectrices (usually among r2 and r5) retained, contrastingly worn, and showing aspect of Juvenile Plumage (above). Replaced second basic rectrices sometimes with distinct narrow bars near shaft or (rarely) extending across both webs (illustration in Pyle 2008). Small proportion (~5-10%) of individuals can undergo a complete molt and can be indistinguishable from birds in Definitive Basic Plumage.

Definitive Basic Plumage

(Sep-following Feb) characterized by mixed generations of basic body (especially rump) feathers, and 2-5 sets of basic feathers among primaries and secondaries, in Staffelmauser patterns; replacement sets in primaries defined by a worn feather immediately distal to a fresh proximal feather, and those of secondaries showing mixed generations in various sequences (Clark et al. 2004; Pyle Pyle 2005c, 2006, Pyle 2008). Number of sets equates to minimum ages of 2-5 years; individuals wintering to north and east may average more sets in older birds than those wintering to south and west.

Light morph with upperparts, including the head, auriculars, occiput, nape, scapulars and interscapulars margined with cinnamon-brown (33) to russet (34), these edges broadest and most conspicuous on the nape and anterior interscapulars, which are more uniformly fuscous than in Juvenile Plumage (above); forehead generally whitish; upperwing coverts hair brown to dusky brown (19); lower back and rump somewhat paler, rarely hair brown washed with rufescent; uppertail coverts variable, whitish washed with cream (54) and buff (24) to nearly solid robin rufous (340) and more or less barred with cinnamon-brown. Retrices hazel (35) to cinnamon-rufous narrowly tipped with whitish and crossed by a subterminal band of sepia; the subterminal band variable from nearly absent or incomplete to complete and as much as 13 mm in width. Primaries and secondaries hair brown to grayish, the outermost two primaries (p9-p10) broadly tipped with sepia and remaining primaries barred fuscous along inner webs (not contrasting substantially with pattern of secondaries), the secondaries with indistinct and wider dusky band and narrowly tipped with pale hair brown and sometimes some whitish, and the tertials generally washed with cinnamon-brown and with much white. Lores whitish with black shafts to the feathers; malar stripe dark fuscous; chin and middle of throat usually plain whitish, sometimes streaked with dark olive-brown (28); sides of throat and breast dark olive-brown, the feathers fuscous centrally, bordered with ferruginous (41), and edged with whitish; remaining underparts whitish with the upper abdomen and sides barred and streaked with olive-brown, dusky brown, or warm sepia (pale brown shafts sometimes occur on the feathers of the lower breast) and thighs often washed pale buff and sometimes indistinctly barred with pale hazel; undertail coverts whitish. Underwing coverts whitish with lesser coverts and tips to primary coverts VanDyke brown (121); rest of coverts occasionally marked with sepia.

Dark morph uniformly fuscous to tawny (38) including the entire head, body, upperwing and underwing coverts, and thighs. Rectrices, primaries, and secondaries similar to light morph but dark areas on the tips of the remiges more extensive.

White morph ("Krider's Red-tailed Hawk") paler overall, with aspect generally similar to light morph (above) but upperparts, especially head, nape, back, upperwing coverts, and upper tail coverts noticeably streaked or spotted with white, and white on interscapulars washed pale tawny; underparts much whiter with less brownish; tail variable from pure white subterminally barred with fuscous and with several small incomplete bars along the shaft, with a single subterminal band, or uniformly sayal brown (223C), tipped with white and subterminally banded with fuscous. See also Systematics.

Molts

Molt and plumage terminology follows Humphrey and Parkes (Humphrey and Parkes 1959) as modified by Howell et al. (Howell et al. 2003, Howell et al. 2004). Red-tailed Hawk exhibits a Modified Basic Strategy (Howell et al. 2003), including complete prebasic molts and a limited preformative molt in some individuals (Pyle 2005a), but no prealternate molts (Palmer 1988f, Johnsgard 1990b, Wheeler 2003b,Wheeler 2003b;Pyle 2008; Figure 6). The third prebasic molt typically results in definitive plumage aspect, with juvenile and/or formative feathers usually retained through the second cycle.

Prejuvenile (First Prebasic) Molt

complete, May-Aug, in the nest. Primary sheaths begin erupting at 13–15 d and primaries and secondaries apparent at 17–19 d. Juvenile tail feathers visible at 21–23 d. At 29–31 d, head is 90% downy (white occipital spot evident), dorsal wing is 90% feathered, and breast is 50% feathered; legs beginning to feather, upper tail coverts are well-developed, and ear openings are completely covered. By 33–35 d, head is 50% feathered, dorsal body feathering is 95% complete, and breast is 90% feathered (Moritsch 1983a). Juvenile plumage well developed at time of first flight.

Preformative Molt absent to limited, Sep-Mar, primarily on non-breeding grounds; often begins in fall, suspends over winter, and resumes in spring (Pyle 2005a). Can include up to 20% of body feathers but appears to be absent in many individuals (Pyle 2005a, Pyle 2008). No wing coverts or flight feathers replaced.

Second Prebasic Molt

(formerly considered "First Prebasic Molt") incomplete-complete, Feb-Oct, primarily on breeding grounds (although individuals not breeding during this cycle); can occasionally commence or complete on non-breeding grounds. Wing molt often begins in late Apr or in early May; tail molt begins after the wings, is conspicuous in Jun, and continues through Aug. Molt typically without suspensions during breeding season (see Definitive Prebasic Molt, below) but occasionally suspends for northbound or southbound migrations. Replacement of juvenile body feathers sometimes complete but some rump and scattered other body feathers and/or wing coverts often retained. Sequence of flight-feather replacement as in Definitive Prebasic Molt but outer 1-4 juvenile primaries (among p7-p10) and corresponding primary coverts, 1-6 juvenile secondaries (among s3-s4 and s6-s9), and/or 1-4 juvenile rectrices (usually among r2 and r5) typically retained, to commence Staffelmauser (stepwise) replacement patterns (Pyle 2005c, 2006); molt can be complete in 5-10% of individuals.

Definitive Prebasic Molt

incomplete, Apr-Nov; commences on breeding grounds but sometimes can complete on non-breeding grounds. Often suspended during the breeding season: breeding females typically begin replacing primaries during egg laying, and males a bit later, while mates are incubating. Nonbreeders and failed-breeders probably begin molting earlier. Primaries replaced distally (p1 to p10), secondaries replaced proximally from s1 and s5 and distally from the tertials, and rectrices replaced in sequence r1-r6-r3-r4-r2-r5 on each side of tail. Molt pattern among primaries and secondaries exhibits Staffelmauser (Bierregaard 1974; Clark et al. 2004; Pyle 2005c, 2006) whereby incomplete molts result is a series of commencement points, beginning with termination points of previous prebasic molt and also initiating new series commencing at p1, s1, s5, and/or the tertials. Replacement thus typically proceeds in 2-4 (rarely 1 or 5) waves through the wing. Staffelmauser appears to be a product of insufficient time to undergo a complete wing-feather molt but has adaptive benefits in producing multiple small gaps in the wing during molt, which retains wing integrity and ability to fly and forage (Tucker 1991, Shugart and Rohwer 1996,Pyle 2005c).

Bare Parts

Bill

Black in newly hatched birds, becoming dark (dusky brown to sepia), becoming lighter basally; gape cream to buff (124).

Iris

Dark in newly-hatched birds, becoming grayish then buff yellow (53) in juveniles, spectrum yellow (55) during first winter, and slowly grading to hair brown in older hawks.

Legs And Feet

Buff-yellow to sulfur yellow (57) with dark talons. Tarsus unfeathered.

Measurements

Linear Measurements

No overall geographic trends in size evident (Appendix 3). Wing chord, culmen, and toe of females average consistently longer than in males across range, but tail length in males and females is nearly the same along the west coast of Canada (alascensis), and males average same or slightly longer tarsus in 6 of 14 populations measured (CRP). Largest birds from Florida (umbrinus), and sw. Texas (fuertesi), smallest from nw. coast (alascensis) and Jamaica and Puerto Rico (jamaicensis) (Brown and Amadon 1968). Within calurus, wing chord, tarsus depth, tail length, hallux claw and culmen vary concordantly across geographic range, but tail length varies independently of these, and tarsus length shows an opposite pattern of variation (Fitzpatrick and Dunk 1999). In general, largest calurus individuals occur in arid southwestern deserts and California grasslands, smallest in Pacific Northwest, although birds from the Pacific Northwest have the longest tarsi.

This pattern of variation does not follow the traditional Bergmann/Allen ecogeographic rules, and may reflect adaptations to prey size and water conservation (James 1970a, Fitzpatrick and Dunk 1999). Birds captured and measured during fall migration from three different flyways indicate that eastern birds (n = 12, measured at Cape May, NJ) have significantly shorter tail, wider tarsus, longer hallux, and longer culmen (p 0.001) than birds in the Goshute Mountains, NV (n = 152) and Manzano Mountains, NM (n = 62) (Pearlstine and Thompson 2004. Birds flying through Manzano Mountains have significantly longer wings than birds passing through Goshute Mountains or Cape May.

Mass

Individuals during the breeding season (presumably mostly juvenile and adult borealis and calurus) averaged 1,224 g for females (n = 100) and 1,028 g for males (n = 108; Craighead and Craighead 1956). Juvenile males trapped during migration in Wisconsin averaged 945.3 g (698–1,296; n = 32), and juvenile females averaged 1,222 g (904–1,455; n = 24) (H. Mueller in Palmer 1988f).

Mean body mass of birds captured at Cape May, NJ during fall migration was 1,134.4 g (sd = 143.6, n = 12), significantly heavier (p 0.001) than birds from Manzanos, NM (950.2 g; sd = 124.3, n = 62) or Goshutes, NV (933.4 g; sd = 150.5, n = 152). Mean body masses of two adult males and two adult females trapped in the rain and cloud forests of Puerto Rico were 795 g and 1023 g, respectively. Sexual dimorphism in body weight is most pronounced in the Puerto Rican population (Snyder and Wiley 1976). No seasonal variation noted.

Red-tailed Hawk Adult dark-morph "Harlan's" Red-tailed Hawk, Cache Valley, Utah, December 2003.
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Adult dark-morph "Harlan's" Red-tailed Hawk, Cache Valley, Utah, December 2003.

Harlan's is among the darkest of the Red-tailed Hawk subspecies, often jet black below with contrasting whitish tail.  Note the pale flecking on the upper breast, typical of harlani.  The mottled gray blurry barring on the flight feathers is also typical of harlani.; photographer Jerry and Sherry Liguori

Red-tailed Hawk Juvenile dark-morph "Western" Red-tailed Hawk, Lake Valley, Utah, November 2003.
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Juvenile dark-morph "Western" Red-tailed Hawk, Lake Valley, Utah, November 2003.

Juvenile dark and rufous-morph calurus are very similar in overall appearance, with dark-morphs presumably more heavily marked below than rufous-morphs.  This bird is at the heavily marked end of the spectrum.; photographer Jerry and Sherry Liguori

Red-tailed Hawk Adult "Eastern" Red-tailed Hawk, Swainton, New Jersey, August 1996.
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Adult "Eastern" Red-tailed Hawk, Swainton, New Jersey, August 1996.

Note the bulging full crop on this bird, which is feeding on a prey item.  The crop is used to store food temporarily, allowing quick ingestion of large prey items.  The pale throat is typical of the eastern race, B. j. borealis.; photographer Jerry and Sherry Liguori

Red-tailed Hawk Juvenile light-morph "Western" Red-tailed Hawk, Bountiful Peak, Utah, October 2003.
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Juvenile light-morph "Western" Red-tailed Hawk, Bountiful Peak, Utah, October 2003.

Juvenile Red-tailed Hawks of all subspecies lack red tails throughout their first year of life.  Starting in late spring, they start to replace their brown tail feathers with adult plumage brick red feathers.; photographer Jerry and Sherry Liguori

Red-tailed Hawk Figure 6. Annual cycle of breeding, migration, and molt in the Red-tailed hawk
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Figure 6. Annual cycle of breeding, migration, and molt in the Red-tailed hawk

Annual cycle of breeding, migration, and molt in the Red-tailed hawk in the eastern U.S. Thick lines equal peak activity, thin lines off peak.

Red-tailed Hawk Adult light-morph "Western" Red-tailed Hawk, Goshute Mtns., Nevada, October 1998.
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Adult light-morph "Western" Red-tailed Hawk, Goshute Mtns., Nevada, October 1998.

This relatively colorful light-morph calurus Red-tailed Hawk, differs from light-morph borealis in having more rufous tones on the underparts, a dark throat and barred leggings.  ; photographer Jerry and Sherry Liguori

Red-tailed Hawk Juvenile "Western" Red-tailed Hawk, Jackpot, Nevada, September 2002.
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Juvenile "Western" Red-tailed Hawk, Jackpot, Nevada, September 2002.

Juvenile western Red-tailed Hawks are very similar to their eastern borealis counterparts.  Most are more heavily marked below overall than easterns, but throat color varies from light to dark.; photographer Jerry and Sherry Liguori

Red-tailed Hawk Juvenile light x intermediate "Western" Red-tailed Hawk, Bountiful Peak, UT, October.
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Juvenile light x intermediate "Western" Red-tailed Hawk, Bountiful Peak, UT, October.

Most likely, this type of juvenile will become a very rufous-toned light-morph adult with a prominent bellyband and marked underwings. These kind of light morphs appear much like a rufous (intermediate) morph overall, but they are atypical and uncommon.; photographer Jerry and Sherry Liguori

Red-tailed Hawk Adult rufous-morph "Western" Red-tailed Hawk, Goshute Mtns., Nevada, October 2000.
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Adult rufous-morph "Western" Red-tailed Hawk, Goshute Mtns., Nevada, October 2000.

Rufous-morph calurus are encountered more frequently than pure dark-morphs across much of the West.  Characters typical of this morph are a dark belly band, with solid rufous breast and dark rufous underwing coverts.; photographer Jerry and Sherry Liguori

Red-tailed Hawk Adult dark-morph "Western" Red-tailed Hawk, Minnesota, October.
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Adult dark-morph "Western" Red-tailed Hawk, Minnesota, October.

An usually patterned dark-morph calurus individual, perhaps with some harlani genes.  Typically, Red-taileds that are this dark, lack pale markings in the underwing coverts and belly.; photographer Rick and Nora Bowers

Red-tailed Hawk Juvenile Harlan's Hawk, British Columbia, January.
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Juvenile Harlan's Hawk, British Columbia, January.

Aldergrove, BC. The following link is to this contributor's Flickr stream or website. http://www.flickr.com/photos/waslin/, Jan 19, 2009; photographer Wes Aslin

Recommended Citation

Preston, C. R. and R. D. Beane (2020). Red-tailed Hawk (Buteo jamaicensis), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.rethaw.01