IDENTIFICATION

Field identificationaspects of some Red-tailedHawk subspecies

James W. Lish and William G. Voelker

sympatricin winter in someareas, par- in handbooks,are not presentedas they subspeciesof the Red-tailed Hawk ticularly in the southernGreat Plains. often have very little utility under field (ButeoHEPLUMAGE jamaicensis), VARIATION has AMONGbeen a It makes little difference to the field conditions. For in-the-hand descrip- source of confusion for both taxono- observer faced with an identification tions of Red-tailed Hawk forms see mists and field ornithologists.The tax- problem whether thesevariants are re- Taverner 1927, Lowe 1978, and Fried- onomy for this speciesis complicated ferred to as types, races,subspecies or mann 1950. by extensiveplumage variation, com- forms. Therefore, throughout the re- The important aspectsof Red-tailed bined with considerable unknown de- mainder of this treatment, the term Hawk identification deal mainly with greesof breedingrange overlap. It is not "forms" and/or common nameswill be the ventral featuresof flying birds(Figs. the objective here to investigatethese used,thereby avoiding taxonomic con- 1, 2), and in some caseswith the pat- problems(for a recentdiscussion of this flicts.The main objectivehere is to pro- terns and colors of the dorsal surface of topic see Mindell 1983), but rather to vide more accuratefield descriptionsof the tail (Fig. 3). Flying hawksare easier help clarify problems associatedwith Red-tailed Hawk forms than have pre- to identify than perchedbirds as larger the field identification of Red-tailed viously been available so that the field surfaceareas are visible,particularly in Hawks. observercan separateRed-tailed Hawks the underoAngs.The exact breedingand

Plumage characteristics of five subspeciesare discussedusing clues that are easily and consistentlyobserved in the field.

There are seven subspeciesof Red- from other Buteo specieswith a higher wintering rangesof most forms are not railed Hawks found north of Mexico (as degree of accuracy. We absolutely do well understood; however, because recognizedby the A.O.U. Check-listof not intend to indicate that the observer rangesize and boundariesare important North American Birds, 1957, 1973). can confidentlyplace Red-tailed Hawks considerations in field identification, These subspeciesare: B. j. fuertesi into subspecificcategories in the field. brief range descriptionsare presented. (Fuertes' Red-tailed Hawk), B. j. bo- This would be difficult at best, since The most consistent field characters realis (EasternRed-tailed Hawk), B. j. even in-the-hand, many Red-taileds that separateRed-tailed Hawks (with calurus(Western Red-tailed Hawk), B. cannot be subspecifically identified. the exception of the Harlan's Hawk) j. kriderii (Krider's Hawk), B. j. harlani This is especiallytrue of many imma- from other North American speciesof (Harlan's Hawk),* B. j. alascensis ture Red-railed Hawks (Friedmann Buteo are: the red dorsal aspectof mils (Alaska Red-tailed Hawk), and the sed- 1950, Lowe 1978). The central problem in adults, and patagial markings (Figs. entary peninsular subspeciesB. j. um- arises because various forms of Red- la, lc through If). Patagial markings brinus(Florida Red-tailed Hawk). This tailed Hawks intergradewith forms liv- are those dark rectangular areas along discussion does not include the last two ing adjacentand thus show featuresof the ventralsurface of the pamgium,near subspecies,as each has been little stud- both forms. This makes field and in- the leadingedge of the wing. They are ied and are morphologicallysimilar to hand identification oftentimes ex- excellent field charactersfor light-col- calurusand borealisrespectively. The tremely difficult. ored Red-taileds and no doubt have five subspeciesdiscussed here are all Only thosetraits that are easily and been used by many observersas good consistentlyobserved in the field are field marks for this species.Surprisingly, * SeeAmerican Birds Volume 39, Number 2, "Plu- discussedhere. Lengthy derailed plu- mage variationand winter range of Harlan's Hawk patagialmarkings were not mentioned (Buteojamaicensis bariant)" by David P. Mindell. mage descriptions,such as those found in any of the more popular field guides

Volume 40, Number 2 197 until recently, when Clark and Pram- w•ndows, and in adult Fermginous have light eyes rather than the dark staller (1981) noted the importance of Hawks, a conspicuousdark "V" formed brown eyestypical of adult Red-tmleds this trait. In erythristic (rufous) and by the brown feathersof the legscan be Fuertes' Red-tailed Hawks are not melanistic (black) phasesof Western seen. known to exhibit melanism and are less Red-tailed Hawks the patagial marks Iramatures: Krider's Hawks in im- variable than other Red-tailed Hawks. are not visible, but the red tail is still mature plumagesare very variable, but conspicuousin adults. in general, are quite similar to adults. Eastern Red-tailed Hawk

General range:core of the breeding Fuertes' Red-tailed Hawk range is in easternNorth America but Field identification with poorly known westernrange bruits characteristics of Generalrange: breeds throughout the Winters in the eastern United States and Red-tailed Hawks southwesternUnited States and adja- adjacent portions of the Great Plains cent portions of Mexico (Sutton and (Friedmann 1950). Krider's Hawk Van Tyne 1935). The easternand Main fieM characteristicsof adults northern limits of its breedingrange are (Figs. ld, 2c):the ventralsurfaces of this General range:breeds in southwest- not well known. These hawks are sed- form appearwhitish or slightly creamy ern central Canada and adjacent por- entary in winter in many parts of their in color. The abdominal band is typi- tions in the United States. The core range. cally quite dark and can be easilyseen w•nteringrange is in the southernGreat Main fieM characteristicsof adults in flight.The trailingedges of the sec- Plains. It is sporadicallyseen in winter (Figs. lc, 2b): ventrally, Fuertes' Red- ondaries form a definite dark margin in many states(Friedmann 1950). tailed Hawks appearwhitish or slightly and the barring of the primaries and Main fieM characteristicsof adults buffy. The underparts are almost as secondaries is noticeable in the field (Figs. la, lb, 2a): characterized by white as Krider's Hawks and, in the Many birds have a wide collar con- overall light color both dorsally and field, appearimmaculate or with a very necting the dark cheeksand forming a ventrally.Krider's Hawks typically have faint abdominal band. The markings of hood, but the chin and throat still ap- immaculate underparts. At a distance, thefaint abdominal band are often light, pear white or buffy. The dorsal aspect the dorsalaspect of the tail (Fig. 3j) ap- very attenuated streaks.The barring of of the tail (Fig. 3h) is rufouswith a thin pearswhite, but at closerange, it is less primary and secondarywing feathers black subterminal band. The black white and typically washedwith a light appearsfaint under field conditions. subterminalband may be quite faint or rufous color near the tips of the tail The sidesof the head(cheeks) are brown absent on some individuals. Eastern feathers.At closerange, the tail hasa and the area of the chin and throat is Red-tailedsare sometimesimpossible to faint subterminal band. Upperwing co- white. Some birds have a thin necklace distinguishfrom either Fuertes'or hght- vers are very speckled.The head of this or collar connecting the dark cheeks. phaseWestern Red-taileds. The heavier form is white and the dark eyesof adults The dorsal aspectof the tail of this form wing barring, heavier abdominal band, stand out sharply against the white (Fig. 3i) is usuallyvarious shades ofru- and overall darker color (especially head. There is usually a faint line fous with a narrow subterminal band, dorsally)of the Easterncan sometimes through the eye, sometimeswith a faint no band, or a subterminal band with be usedto separateit from Fuertes'Red- collar or dark cheeks.Light coloredpri- other lighter and often incomplete tailed Hawk. When compared w•th maries form conspicuouswhite trape- bands(Lowe 197•8). In general,Fuertes' light-phaseWesterns, Easterns tend to zoidalshaped wing windows dorsally Red-tailed Hawks are most similar to bemuch less rufous. Also, Western Red- (Fig. 1b). This form is the palestof the light-phaseWestern Red-tailed, Eastern taileds often have heavily barred or ru- Red-tailed forms. Its white tail, head Red-tailed, and Krider's hawks. They fouscolored "flags" or thighsnot found and wing windows make it one of the generallydiffer from both Westernsand on Easterns;the heavier barring on the easiestto identify. Individuals of this Easterns by the lack of a well-defined secondariesand primaries is much form can be easily mistaken for nor- abdominal band and from Krider's darkerdorsally and ventrally,and the mally plumaged Ferruginous Hawks Hawks by the dark head. abdominal band of Western Red-tmleds (Buteo regalis), which also have white Iramatures: quite similar to adults is typicallymuch heavier than that of heads, tails, and wing windows. How- (Fig. le), exceptfor their heavilybarred Easterns.If the dorsal aspect of the tail ever,Krider's Hawks are shorterwinged brownish tails (Fig. 3a) instead of red is visible,Western Red-taileds (Fig 3g) than FerruginousHawks and havetyp- tails.Immatures are also more heavily can sometimes be told from Eastern ical Red-tailed patagial markings;Fer- barred on the lower abdomen and typ- Red-taileds (Fig. 3h) by their much ruginousHawks have silvery undertails ically have a largewhite area on the up- wider subterminal band and heavier tail with dusky tips on the tail feathers. per breast. The area around the eye is banding in general. The Eastern Red- Dorsally,Ferruginous Hawks have oval muchlighter in immatureFuertes' than tailed Hawk does not have a melamstic rather than trapezoidal shaped wing in adults,and all immature Red-taileds phase.

Oppositepage: Figure 1. Diagramshowing main field characters'of variousRed-tailed Hawk forms (see text for descriptions9.a. adult Krlder's Hawk. b. adult Krider's Hawk. c. adult Fuertes' Red-tailed Hawk. d. adult Eastern Red-tailed Hawk. e. immature Fuertes' Red-tailed Hawk f adultnormal-phase Western Red-tailed Hawk. g. adultrufous-phase Western Red-tailed Hawk. h. adultblack-phase Western Red-faded Hawk. i. adult Harlan's Hawk. Illustration/JamesLish.

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Volume40, Number 2 199 Immatures slmfiar to adults (Figs stockier bodies than the more slender their largersize and obviouslydifferent 2d, 2e) but with lighter irides, lighter Swainson's Hawk. Also, erythristic proportions--FerruginousHawks have headand a brown barred(Fig. 3a) rather Swainson'sand Ferruginoushawks lack much largerheads and longerwings-- than a red tail. Also, immatures are the dark lower breast and abdomen and lack of white speckling.Melamstlc more heavily barred on the lower ab- typicalof erythristicWestern Red-tailed Rough-leggedHawks alsohave a much domen. Hawks. differentflight profile than Red-taileds; Black-phase(Figs. lh, 2h): very dark, the Rough-leggedHawks having no- appearingeither dark brown or black ticeably longer and narrower wings in the field. The typical Red-tailedpa- Normally plumaged Rough-legged tagial markingsare not visible.Black Hawks have a well-defined subterminal Western Red-tailed Hawks are most band--usually more well-definedand Western Red-tailed Hawk easilyconfused with Harlan's Hawks, broader than that of Harlan's Hawk-- but adult Westernscan be distinguished andthey tend to frequentlyhover. Very Generalrange: breeds throughout the from adult Harlan'sHawks by their red dark-phase Rough-leggedsonly rarely western United States north to Alaska. tailcoloring, lack Of mottling or lackof have white areas visible on the upper Eastern and southern range limits are tail surfaces. not well defined. Winters in the western light color in the tails (Mindell 1983). Black-phaseWestern Red-tailedshave Immatures.'very similar to adults United States and the Great Plains and upper tail surfacesthat may be very (Fig. 3d) exceptthat the tail is banded sporadicallyin the east. heavily barred on a red background rather than mottled on the dorsal sur- Main field characteristicsof adults: (Fig. 3f), or appear similar to other face. this form has a light phase,almost as Western Red-tailed Hawks (Fig. 3g). light as the Eastern Red-tailed Hawk, Immatures: black-phaseWesterns are an erythristic(rnfous) phase, a verydark usuallyvery difficultto distinguishfrom melanistic(black) phase,and all plu- immature Harlan's Hawks, under field magesintermediate to those.The phases conditions. Albinistic Red-tailed Hawks described here are at the extremes and middle of this range of variation. Althoughvery uncommon, albinlstlc Light-phase (Figs. If 2f): ventral individuals are regularly reported surfacestypically noticeably more rn- throughoutthe rangeof the Red-tailed fous than either Fuertes' or Eastern Harlan's Hawk Hawk (Fig.2j). Thedegree of albinism Red-taileds. In addition, this phase of varies from a few white feathers or the Western is much more heavily patchesto completelywhite birds.To- barred than either the Fuertes' or the General range: core breedingarea in tally albinisticRed-tailed Hawks are not southwestern Alaska, north of the Eastern Red-tailed Hawk. Streaking on likely to be confusedwith any other the upper breast may be quite heavy. Alaska peninsula, but breeding birds raptor north of Mexico exceptperhaps can be found south and east to northern The abdominalband is heavyand dark the Gyrfalcon(Falco rusticolus), which and the head is typically dark with a British Columbia (Mindell 1983); core is quite rare in the contiguousUnited light throat. Heavily barredand rnfous wintering area in the southern Great States,and is also strikingly different in Plains, but has been reported in winter coloredthighs or "flags" are typical of size,behavior, general shap e andflight Western Red-tailed Hawks but not of in many states. style. Partially albinistic Red-tailed Eastern or Fuertes' Red-taileds. Dor- Main field characteristicsof adults Hawks typically have somenormally- sally, even light-phase Westerns are (Figs'. li, 2i): main field charactersare colored flight featherswhich give the darker than either Eastern or Fuertes' the overall dark appearance, whitish bird an irregular and patchy pattern Red-taileds and have tails with heavy basal areas of the uppertail (Figs. 3c quitedifferent from any of thevery light subterminal bands and other lighter through 3e), centrally located whitish Red-tailed forms, e.g., Krider's Hawks bands (Fig. 3g). area of the upper breastand a tendency Rufous-phase(Figs. l g, 2g): relatively for white mottling, particularly on the easyto identify owing to its overall rn- underwing coverts, nape, and upper- fous color (which has also been de- wing coverts,but somebirds are totally scribedas reddish or cinnamon), and black having no white areas (Mindell red uppertail surface. In this interme- 1983; Lavers 1975). Rarely, Hadan's diate phase,the upper breast and un- Hawks have tails that appear quite ACKNOWLEDGMENTS derwing coverts are uniformly rnfous barred (Fig. 3b), but the typical adult with heavy wing and tail banding and tail (Fig. 3d) has a rather wide subter- We would like to extend our thanks dark wing margins. The lower breast minal band, longitudinalmottling and to the following personswho made andabdomen are typically dark brown white basal areas, often with varying helpful editorial and technical com- in this phase. Both Swainson's Hawk degreesofrufous near the tips of the tail mentsand also provided photographs (Buteo swainsoni) and Ferruginous feathers.This form, which is typically foruse in thispaper: William C. Clark, Hawks also have erythristicphases, but dark, is easilyconfused with melanistic David P. Mindell, Craig Patterson, rufous-phase Western Red-tailed Ferruginous Hawks and melanistic Harry Darrow, Larry Talent and O. Hawks have shorterwings and shorter Rough-leggedHawks (Buteo lagopus). EugeneMaughan. We would alsolike bodies than rnfous-phaseFerruginous Melanistic FerruginousHawks can be to thankHelen Murrayfor typingthe Hawks as well as broader wings and distinguishedfrom Harlan's Hawks by manuscript.

200 American B•rds, Summer 1986 a b

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i j Figure 2. Photographsof major Red-tailedHawk forms inflight. a. adult Krider • Hawk in winter.Noble County.Oklahoma. Photograph/J.W Lish. b. adult Fuertes'Red-tailed Hawk, residentbird in Ellis Count.v,Oklahoma. Photograph/J.W. Lish. c. adult Eastern Red-tailed Hawk in winter.Osage County. Oklahoma. Photograph/J.W. Lish. d. immature Eastern Red-tailed Hawk during migration at Kittatinne.vMts.. New Jerse_,:Photograph/H.C. Darrow. e. immature Eastern Red-tailed Hawl[ during migration at Fairview Lake. New Jersey.Photograph/H.C. Darrou: f. adult normal-phase 14i,stern Red-tailed Hawk. resident bird Medicine Bow, l•),oming. Photo•,raph/C.T. Patterson. g. adult nt.fous-phase 14Fstern Red-tailed Hawk. residentl•)'oming bird. Photograph/C.T. Patterson.h. adult black-phaseI4i,•tern Red-tailed Hawk in winter.Noble County. Oklahoma Photograph/I4•S Clark. i. adult Harlan • Hawk (barred-tailedmorph}. resident bird from the YukonRiver area, ,41aska.Photograph/D.P Mindell. j. adult albino lz2tsternRed-tailed Hawk. residentbird near Tarrytown.New York Photograph/H.C Darrou:

Volume40, Number 2 201 I I

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Figure3. Dorsaltail patternsof majorRed-tailed Hawk forms. a. immatureRed-tailed Hawk (most forms similar} b. adultHarlan • Hawk (barred-tailedmorph} c. adultHarlan's Hawk (dark-phase} d. adultHarlan • Hawk(normal-phase} e. adult Harlan's Hawk (light-phase} f. adultl$•stern Red-tailed Hawk showing heavy barring g. adultl$•stern Red-tailed Hawk showing typical barred pattern h. adultEastern Red- tailedHawk i adult Fuertes'Red-tailed Hawk j. adult Krider• Hawk.

LITERATURE CITED

AMERICAN ORNITHOLOGISTS' UN- identification in the field. Western Birds ION. 1957. Check-list of North American 6:55-62. birds,Fifth edition.Baltimore, Maryland, LOWE, C. M. 1978. Certain life history as- Amer. Ornithol. Union. pects of the Red-tailed Hawk in central 1973. Thirty-secondsupplement to the Oklahoma and interior Alaska. M.S. American Ornithologists'Union Check- Thesis, Fairbanks, University of Alaska. list of North American birds. Auk 90: MINDELL, D. P. 1983. Harlan's Hawk 411-419. (Buteojamaicensis harlani) a valid sub- CLARK, W. S., and M. E. PRAM- species.Auk 100:161-169. STALLER. 1981.Field I.D. Pamphletfor SUTTON, G. M., and J. VAN TYNE. 1935. North American Raptors, National A new Red-tailed Hawk from Texas. Oc- Wildlife Federation,Raptor Information cas. Papers. Museum of Zool., Univ. of --Oklahoma CooperativeFish and Center. 14 pp. Michigan, No. 321. pp. 1-6. WiM!ife ResearchUnit, 404 LSW. FRIEDMANN, H. 1950. The Birds of North TAVERNER, P. A. 1927. A studyof Buteo and Middle America. U.S. NatL Mus. borealis, the Red-tailed Hawk, and its Oklahoma State University, Bull. 50, part II. varieties in Cannon. Canada Dept. Stillwater.Oklahoma 74078 (Lish), LAVERS, N. 1975. Status of the Harlan's Mines, Victoria Mem. Mus., Mus. Bull. RR #2. Box 64, Mi!lstadt, Hawk in Washington,and notes on its No. 48, Biol. SeriesNo. 13. Illinois 62260 (Voelker)

202 AmericanBirds, Summer 1986