lbis (2002), 144, 665-675

On the taxonomic status of the lndian Spotted hastata S. J. PARRY,I*W. S. CLARK2a v. pnRxRsH3 l Group,Department of Zoology,The NaturalHistory Museum, Tring, Herts. HPn 6Ae UK and Departmentot Biology,Darwin Building, ' University College London, Gower Street,London WCl E 68T UK 2POBox 531467Harlingen, TX 78553,USA 38wHS,331 Rajendra Magar, Bharatpur, Rajasthan, 321 001lndia

We review the status of the two currently recognized subspecies of Aquila p. pomarina (western Eurasia) and A. p. hastata [Indian subcontinentJ on the basis of museum diagnosis and field observations.We present differences between these two allopatric taxa which demonstrate that they should be treated as distinct species. Specifi- cally, we present evidence of differences in plumage ftoth for adults and luveniles), external morphology, osteology, clutch size and behaviour. Particular emphasis is placed on differ- ences in gape size and general cranial structure.

Most recent authorities have recognizedonly two by Brehm (1831).Lesson, who appearsto havebeen speciesof'spotted '(hereafter spotted eagles): unawareof the latter description,described in detail the monotypic Greater Spotted EagleAquila the spottedplumage of immaturesand also noted that Pallas,l8l I and the polytypic LesserSpotted Eagle hastataexhibits an exceptionallylarge gape,stating: A. pomarinnBrehm, l83l 1965, Brown & 'La fVaurie commissurede la boucheest d'une trds grande Amadon 1968,Cramp & Simmons1980,Amadon ampleur; elle se trouve borde€ par un repli epaiset & Bull 1988,Sibley & Monroe 1990,del Hoyo et al. commecartilagineux, et s'etendjusque sous l'oeil. Elle I 994). However,earlier generationsof ornithologists a 2 poucesde longueurde l'onglei la pointedu bec.' treated the two subspeciesof the Lesser Spotted Eagle [migratory pomarirn, which breedsin western These important observationsappear to have been Eurasiaand winters in Africa, and sedentaryhastata ovedookedsubsequently. Lesson,1834 of the Indian subcontinent)as distinct A decadeafter the publication of Lesson'sdescrip- species(Blfh 1846, Hume 1873, Sharpe 1874, tion of hastata, Blyth I I B4 3 ) describedit asLimnaetus Anderson 1875a, 1875b,Blanford 1895, Whistler unicolor,this was later synonymized as Limnaetus 1930,Swann 1933, Baker 1935). More recendy,some hastatusin deferenceto Lesson'soriginal description authorities [e.g.Vaurie 1965, Cramp & Simmons [Blyth I 844).Jerdon (1844), followed by Gray(1845), 1980, del Hoyo et al. 1994) have suggestedthat the referredthe taxon to the genusSpizaetus.Aperiod of taxonomic status of pomarina and hastatashould taxonomic consensusthen followed with first Blyth be reviewed.The failure to recognizespecies due to (1846), and subsequentlyHume (1873),Anderson inconsistent may have important impli- (1875a,1875b) and Sharpe(1874) recognizing the cationsfor conservationmanagement (e.g. May 1990, taxon asthe specificallydistinct.4quila hastata. Hazevoet 1996) and, in recent years,a number of Brooks(1873) noted somesuperficial similarities authorities have emphasizedthe general need to between hastata and pomarina, which led him to reassessspecies limits in polytypic species[e.g. Zink regard the two taxa as synonymous;he combined & McKittrick 1995,Foggo er al.1997,Zink1997). them asA. naeui"a.Late4 howeveqafter examininga Aquil"ahastata was first describedfrom specimens largersample that included more immatures,Brooks from Bengalas Morphnus hastatus by Lesson( I 834) Q876) wrote that he had been mistaken in this three years afterA. pomarinawas formally described union. Furtheq,he enumeratedthe many differences between the taxa as the reasonfor their separate *Corresponding author. speciesstatus. Other authorities (e.g.Blanford 1895) Email: [email protected] maintainedthe separatestatus of the two eaglesuntil

@ 2002 BritishOrnithologists' Union 666 S.J.Parry, WS Clark& V.Prakash

Hartert (1914-1922) reclassified hastata as a race breeding hastata have been observed in Keoladeo of A. pomarina. This reclassification conformed to National Park (27"7 .6'-27 " 72.22'N and 77 "29.5' - Hartert's theoretical perspectives on avian taxonomy 77"33.9'E),Bharatpur, , annually since 1986 and systematics following wider acceptance of tV.P.). Detailed breedingstudies were conducted the trinomial [cf. Stresemann 1975, Haffer 1992). from a hide I 5 m from the nest during three seasons Hartert dld acknowledge differences in the juvenile fPrakash1996). Tens of hastatawere observedin plumages of the two taxa but did not mention partsof India and [VP.,W.S.C.; Clark & Khan differences in gape size, behaviour or breeding bio- 1995).Tens of thousandsof pomarinahave been logy. Swann (1920) followed this treatment, but later observedover many yearsin Israeland southernAfrica fSwann 1933) in a more detailed work reversed W.S C.). Many individualswere photographedin himself and joined Whistler (1930) and others in the field and captivity and examinedin the hand and again consideringhastata as a distinct species.Peters nest[W.S.C. &V.P.). [1931, i940), on the other hand, followed Hartert (1914-1922) in treating hastata asa race of A.poma- RESULTS rina.Tbis is the treatment that has met with uncriti- cal acceptance for the last six decades. In this paper Major plumage and iris colour differencesbetween we demonstrate differences between hastata and adults and juveniles of hastata andpomarin4 were pomarinathat clearly indicate that these two allopat- identified and are summarizedin Table l. The two ric taxa should be considereddistinct speciesregard- taxa differ markedlyin both adult andjuvenile plum- lessof speciesconcept. agesand probably alsoin older immature plumages, but no certainmuseum specimens of hastataof these ilETHODS ageswere found. Statistical analysis of eight rostral biometrics External characters were examined on museum skins revealedsignificant differences[P < 0.05) between of pomarina [200+), hastata Q00+) anddanga [300+) pomarina andhastata flable 2). Specifically,hastata [mainly S.J.P.,but also W.S.C. & V.P.). Plumage has a broader rostrum and a shorter mandibular colours of skins were recorded according to Munsell symphysisthanpomarina. Howeveq the rnoststriking Q973) colour charts. Morphometric analyseswere differencebetween the two taxa is in the size of made of measurements taken from sftns of pomaina the gape:hastata has a much larger gapethan does (n = 36), hastata (n = 5 1) and clanga (n = 47) in the pomarina,even larger than that of A. danga (Fig. l). collections of the Natural History Museum (BMNH). Differencesin the rostro-cranialmorphology of the Measurements were taken with dial callipers and a spotted eaglesare alsoemphasized by the results of steel rule. The sex of museum skins was determined a PCA of theseeight rostral biometrics ffable 3 and from labels, or, in the absence of these data, by the Fig 2). The eigenvectorsindicate that PCI is a'size- multivariate methodology of Bortolotti [l984a, determined'axis (sensz Shea 1985), and that PC2 is 1984b). Two osteologicalspecimens of hastata were an index of rostro-cranialbreadth. All three taxa differ compared with three each of pomarina and clnnga. significantly [P < 0.05) in both rostro-cranial size Statistical analyseswere done using SPSS10.0 (SPSS IPC I ) andbreadth (PCz).Whil st hastatais interme- 1999a, 1999b). Interspecific and intraspecific sex diate betweenthe other taxa in PCI scores,it hasthe differences in biometrics were tested for by one-way highestPC2 scores.Specifically, hastata has a longer ANovAs and a post hoc test for unequal sample sizes: rictus than either of the othersand its caudalmargin Hochberg's GT2 test (Sokal & Rohlf l98l). Prin- extendsbeyond the eye,a feature not presentin the cipal Components Analysis (PCA) of a covariance others.This feature is obvious,even in the field, as a matrix of log-transformed data was used in inter- pronouncedwide flangeor'lip' [Fig.3). preting rostral differences and similarities of the three Further differences in cranial structure are also taxa. The significance of differences between sexes evident from t}re analysisof skeletal specimens.In and taxa in PCA scores were tested by one-way hastatathe palatinum is very broad; this element is ANovAs and Hochberg's GTZ tests. Clutch sizeswere far narrower in the other species(Fig. 4). The jugal determined from literature review, clutch record bars(sensz Bock 1964) of hastataare strongly bowed cards in the BMNH, and field observation by V.P. but straight in pomarina and clanga (Fig.4). The The results of museum specimen analyses were mandible is also strongly bowed in hastata and supplemented by field observations. Two pairs of the symphysisreduced, whilst in the other taxa the

@2002 British Ornithologists' Union, /bls, 144, 665-675 Taxonomic status of the lndian Spotted Eagle 667

Tabfe 1. Principal plumage and iris colour differencesbetween hastata and pomarina.

Character Age hastata pomarina

Head colour Adult Uniformlyvery dark brown (10 YR2l2)- Palerbrown (10 YR 5/4) crown and nape withblack shaft streaks withoutblack shaft streaks Backand upperwing coverts Adult Sameas above Backdarker brown (10 YR 3/2) than head andcoverts Underuvingcoverts Adult Lessercoverts paler brown (10 YR 7/3), Greatercoverls darker yellowish brown othersuniform (10YR 5i4),others uniform Undertailcoverts Adult Uniformpale brown (10 YR 6/3) with buff baning Brown(10 YR 5/3) with pale tips lriscolour Adult Brown Yellodamber Nape Juvenile No rufouspatch Rufous/strongbrown (7.5 YR 5/8)patch Upperwingcoverts Juvenile Spotsonly on tips Spotson bothshafts and tips Tertiaries Juvenile Palebrown (10 YR 7/3)with diffuse Brown(10 YR 4/3) with well-delined whitetips spottedtips Uppertailcoverts Juvenile Verypale brown (10 YR 6/4)with white barring White Underparts Juvenile Lighlyellowish brown (10 YR 6/4) with Brown(7.5 YR 4l4l withvery pale brown darker(10 YR 4/3)streaks (10YR 7/3)slreaks on breast

.Figuresin parenthesesare Munsellcolour codes.

Table 2. Rostral biometrics in the spotted eagles; results of one-way aruovnsand Hochberg'sGT2 tests. x = Mean (mm), / = Lower 95% comparison interval, u = Upper 95% comparison interval. Means whose 95% comparison intervals do not overlap are significantly different(P < 0.05).

Gulmen Chord Rostrum Depth Fr.rr, = 64'3, P< 0'0001 Fr,r* = 96.5, P< 0.fi101 pomarinaMale Y 41.3 39.7 42.9 pomarinaMale I 17.9 17.3 18.6 pomarina Female 24 43.1 42.1 44.1 pomarina Female 20 18.8 18.3 19.2 hastataMale 33 42.9 42.1 43.8 hastataMale 25 19.0 18.6 19.4 hastata Female 18 44.6 43.4 45.7 hastata Female 12 19.5 18.9 20j clangaMale 17 46.2 45.0 47.3 clangaMale 16 21.4 20.9 21.9 clangaFemale 28 50.4 49.4 5't.3 clangaFemale 27 22.6 22.2 23.0 Cere Chord Mandibular Symphysis Length F"1s=7O.9, P< 0.q)01 Fs.rrl= 82.8,P< 0.0001 pomarinaMale 9 27.9 26.5 29.3 pomarinaMale 9 15.1 14.4 15.8 pomarina Female 24 30.2 29.3 31.1 pomarina Female 24 15.8 15.4 16.4 hastataMale 33 30.2 29.4 30.9 hastataMale 29 13.4 13.0 13.7 hastata Female 18 31.7 30.7 32.7 hastata Female 16 't4.2 13.7 14.7 clangaMale 17 33.7 32.7 34.8 clangaMale 15 't6.2 15.6 16.7 clangaFemale 28 36.7 35.9 37.5 clangaFemale 27 17.5 17.1 't8.0 Rostrum Breadth Gape Length Fu,r""=41'8, P< 0'fl)01 Fs,rzo= 61.4,P< 0.0001 pomarinaMale 10 13.5 12.9 14.2 pomainaMale 9 50.3 48.4 52.2 pomarina Female 26 13.9 13.5 14.3 pomarina Female 25 52.3 51.2 53.4 hastataMale 33 15.4 15.1 15.8 hastataMale 33 57.9 56.3 59.5 hastata Female 18 16.0 15.5 16.5 hastata Female 18 60.1 58.8 61.4 't7 clangaMale 15.7 15.2 16.2 clangaMale 't7 56.4 55.0 57.7 clangaFemale 30 16.6 16.2 16.9 clangaFemale 30 60.4 59.4 61.4 Premaxillary Depth Gape Breadth Fu,.nr=47.2, P< 0.(X)01 Fr,1ro= 86'4, P< 0'0001 pomarinaMale 8 15.2 14.5 15.8 pomarinaMale 10 36.9 35.2 38.6 pomarina Female 21 16.1 15.7 16.5 pomarina Female 26 37.4 36.3 38.4 hastataMale 31 17.0 16.6 17.3 hastala Male 25 46.1 45.2 47.0 hastataFemale 15 17.2 16.7 17.7 hastata Female 18 47.4 46.2 48.7 clangaMale 16 17.6 17.2 18.1 clangaMale 17 40.8 39.5 42.1 't8.7 clangaFemale 30 18.3 19.0 clangaFemale 30 43.0 42.0 43.9

@ 2002 British Ornithologists'Union, lbr'b1tt4, 655-675 668 S.J.Parry, W.S. Clark & V.Prakash

GapeBreadth (mm) o pomarinaMale o pomarina Female 35.0 37.0 39.0 41.0 43.0 45.0 47.0 49.0 51.0 v hastafa Male v hastata Female a clanga Male t clanga Female ANOVA Fs.tzo=86.4,P< 0.0001 v Vov + wq' ryo "t pomarinaMale (10) (\ " Ji flvt v E1 vWv o vvt |+ c o vvvv v pomarina Female (26) t E o vot l' 9o(U oo-otr hastataMale (25) o '6 o _ a-, i td [: c oo '"S_o ...:_ . o- 1r o:b o:' ' ilJr" F-"."r"(rg) -1 e3t:." . ^^-oo "to o. --;;;rMate (17) oa -2 oo o -3 -2 -1 *En"Female (30) PrincipalComponent 1 Figure1. Gapebreadth in the spotted eagles; results of one-way Figure2. Summaryresults ot a PrincipalComponents Analysis nrovaand Hochberg'sGT2 test. of eightrostral biometrics in the spottedeagles. mandibular rami are straight (Fig. 5). These osteo- primary slots in accipitrid raptors reduce induced drag, logical differences between hastata andpomarina are and that slotted primary apices function as winglets, far greater than those between pomarina and dnnga. making wings non-planaq, and spreading vorticity.Thus In short, hastata andpomarina exhibit very different hastata and pomarina drffer significantly in this key skull morphologies. flight adaptation. Whilst no significant difFerences (P > 0.05) were A number of authorities (e.g.Swann 1933, Brown found between hastata and pomarina in their outer- & Amadon 1968, Cramp & Simmons 1980) have most five primary chords, the primary slots fsersz stated that hastatahas relatively longer legs and larger Kerlinger 1989) were significantly deeper (P < 0.05) feet than pomarina. Howeve4 this is not supported in hastata than in pomarina flable 4). Recent work by measurements;no significant differences (P > 0.05) by Tucker fl991, 1993, 1995) has demonstratedthat were found in analysesof I I pedal biometrics, apart

Table3. Correlationcoefficients and summarystatistics for the firstfive principal components in a PCAof eightrostral biometrics in spottedeagle skin specimens.

PC1

Cere Choi'd 0.95 -0.15 0.04 -o.17 -o.17 CulmenChord 0.92 -0.17 0.07 -0.20 -0.14 Rostrum Depth 0.87 -0.11 0.28 -0.11 0.28 PremaxillaryDepth 0.83 0.13 0.20 0.21 0.29 Rostrum Breadth 0.78 0.4'l 0.04 0.42 -0.14 Gape Length 0.74 0.50 -0.03 -0.02 -0.20 Gape Breadth 0.33 0.89 -o.25 -0.13 0.13 MandibularSyrnphysis Length 0.63 -0.69 -0.33 0.08 0.09 Eigenvalue 4.8 1.8 0.3 0.3 0.3 Cumulativevariance (%) 60.5 82.6 86.3 90.4 94.1

@ 2002 BritishOrnithologists' Union, /b,b,1/t4, 665-675 Taxonomicstatus of thelndian Spotted Eagle 669

for pomarina,one of three eaglespecies in which this trait is obligatory(Meyburg l974,Edwards& Collopy 1983). In contrast,siblicide has not been reported for hastatabut it is obviously impossiblewhen the clutch is one.Unfortunately, none of the nestswith multiple egg clutches had been observed to see whether siblicideoccurs or not. Thus,on the basisof available evidence, the two taxa probably differ markedly in their brood reduction strategies. Hastata and pomarina further differ in their dis- persal strategies.The Indian hastata is sedentary throughout its range (Ali & Ripley 1978, Prakash Figure3. Adult and nestling hastata at nest in Keoladeo 1996), whereaspomarina is an obligate, long dis- NationalPark, India. Note large gape and thick'lips'. tance trans-Saharanmigrant to Africa (Christensen & Sorensen1989, Meyburg et al. 1996). In the field hastata,comparedto pomarina,appears from differences between male pomarina and male closerto cl^angain being overall a darker brown and hastata in Digitus III dimensions flable 5). having a more similar wing-shapeand deeply The two taxa also differ in clutch size and whether emarginatedouter primaries.Perhaps this similarity or not siblicide occurs. The mean clutch size of in appearanceand the relativepaucity ofobserversare pomarina is just under 2, with 839o of 178 clutches other reasonswhy there are few valid sight records from central and eastern Europe having two or three of hastatain India (samant et al.1995) and Pakistan eggs (Meyburg 1970). On the other hand, out of [Clark & Khan I 995). Howeveq,the readilyobservable 26 records of clutch size for hasteta,23 were of differencesin gape outlined above provide a ready single eggs (Thble 6). Siblicide is regularly reported meansof field idenfificationof hastatainall plumages.

Table4. Primaryslot chords in thespotted eagles; results of one-waymovas and Hochberg's GT2 tests. x= Mean(mm), /= Lower95% comparisoninterval, u = Upper95% comparisoninterval. Means whose 95% comparisonintervals do not overlapare significantly ditferent(P< 0.05).

Primary 10 Slot Ghord Primary 7 Slot Chord Fr..,* = 59.5,P< 0.0001 Fs.gs= 59.4, P< 0.0001 pomarinaMale 7 122 116 128 pomarinaMale 7 150 143 157 pomarina Female 19 131 127 135 pomarina Female 19 161 156 165 '132 hastataMale 23 129 135 hastataMale 23 168 164 171 hastata Female 15 140 136 144 hastata Female 14 174 169 179 clangaMale 16 147 143 151 clangaMale 12 175 170 181 't52 clangaFemale 30 155 158 clangaFemale 30 190 186 193 Primary 9 Slot Ghord Primary 6 Slot Chord Fs.gs= 57.9, P< 0.0001 Fs.gs= 67.6, P< 0.q)01 pomarinaMale 7 155 148 161 pomarinaMale 7 138 131 145 pomarina Female 19 162 158 166 pomarina Female 18 't47 142 151 hastataMale 22 164 161 167 hasfafa Male 23 157 153 160 hastata Female 15 174 169 181 hastata Female 14 162 156 167 clangaMale 13 175 170 180 clangaMale 12 't67 161 172 clangaFemale 29 188 184 191 clangaFemale' 28 181 180 183 Primary 8 Slot Chord Fsjoo= 47.3,P< 0.(X)01 pomarinaMale 7 159 15'l 167 pomarina Female 20 169 164 173 hastataMale 21 170 165 176 hastata Female 15 180 176 184 clangaMale 14 180 174 185 clangaFemale 29 195 191 199

@ 2002 British Ornithologists'Union,lbrs, ltl4, 665-675 670 S.J.Parry, WS. Clark& V. Frakash

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O 2002British Ornithologists' Union, /brs, 1.14, 665-675 Taxonomicstaius c! the lndian SpottedEagle 67'l

Figure 4. Comparisonof craniaol hastata(left, BMNH S/1995.22.1 ) and pomarina(right, BMNH S/1898.5.7.5). Note the expanded palatinumand bowed jugal bars of hastata and relativelysmall palatinum and essentiallystraight jugal bars of pomarina.

Figure 5. Comparisonof mandibulaeot hastata(left, BMNH S/1995.22.1)and pomarina (right, BMNH S/1898.5.7.5).Note the bowed rami and reduced symphysisoI hastata and relativelystraight rami of pomarina.

DtscussroN analysesfSeibold 1994, Seibold et al.1996) andby morphologicalcriteria (e.g.Sharpe 1874, Brown & There is little doubt that the spotted eaglesform a Amadon I 968).The questionis, should there be two monophyletic group,as this is supportedby mtDNA or three speciesin the group? We believe that we

@ 2002 British ornithologists'union, /bls, 144, 665-675 672 S.-t Parry, W.S. Clark & V.Prakash

Tabfe 6. Clutch size records tot hastata.

Clutchsize Nest locality Observer/Collector Source

2 Sylhet,Mysore 4.3.1848 J. Davidson BM (NH)Record Card 1 Delhi 14.5.1876 C.T.Bingham BM (NH)Record Card I Syhlet,E. Pakistan 31.3. 1900 H.N.Coltart BM(NH) Record Card AgroreValley 6.5.1870 W.H.Unwin BM(NH) Record Card Madhubaur.Tirhut 20.6.1899 ? BM(NH) Record Card AgroreValley 28.4.1870 W.H.Unwin BM (NH)Record Card BotanicalGardens, Calcutta 9.5.1877 J.C.Parker BM(NH) Record Card Fureedpore,E. Bengal 16.5.1878 J.R.Cripps BM(NH) Record Card Saharunpore 30.4.'t872 W.E.Brooks BM(NH) Record Card Champaran,Behar 2.5.1892 F. Field BM(NH) Record Card Darbhanga 16.5.? C. Inglis Baker(1935) Saharunpore ?.6.1873 A. Anderson Anderson(1875b) Saharunpore ?.6.1873 A. Anderson Anderson(1875b) Saharunpore ?.6.1873 A. Anderson Anderson(1875b) Saharunpore ?.6.1873 A. Anderson Anderson(1875b) Saharunpore ?.6.1873 A. Anderson Anderson(1875b) Saharunpore ?.6.1873 A. Anderson Anderson(1875b) Saharunpore ?.6.1873 A. Anderson Anderson(1875b) KeoladeoNational Park, Bharatpur 2.5.1985 V. Prakash Prakash,pers. obs. KeoladeoNational Park, Bharatpur 4.5.1987 V. Prakash Prakash,pers. obs. KeoladeoNalional Park, Bharatpur 15.5.1990 V. Prakash Prakash,pers. obs. KeoladeoNational Park, Bharatpur 5.5.1992 V. Prakash Prakash,pers. obs. 2 KeoladeoNational Park, Bharatpur 3.5.1993 V. Prakash Prakash,pers. obs. 1 KeoladeoNational Park, Bharatpur 7.5.1997 V. Prakash Prakash,pers. obs. 1 KeoladeoNational Park, Bharatpur 11 .5. 1998 V. Prakash Prakash,pers. obs. 1 KeoladeoNational Park, Bharatpur 7.5.1999 V. Prakash Prakash,pers. obs.

have demonstrated here that pomarina and hastata Following criterion 2, we have shown that the mor- differ sufficiently for species status, regardless of the phological differences between hastata and pomarinn speciesconcept followed. Proponents of the difFerent are greater than those betweenpomarina and clanga, Phylogenetic Species Concepts [e.g. Cracraft 1983, two recognized species (Figs I and 2). Nixon &Wheeler 1990) will have no problem con- Measurements of variation between taxa have been sidering them as separate species,but for those who used by advocates of the BSC when evaluating the adhere to the Biological Species Concept [BSC) speciesstatus of two allopatric taxa [e.g. Mayr 1969, (Mayr 1969, 1982), the problem of how to treat Mayr & Ashlock I 99 I ). The Coefficients of Variation allopatric taxa clouds the issue. Mayr and Ashlock [CV) for gape breadth and length in female booted (1991) suggestedfour ways in which the taxonomic eagles (sensu Amadon 1982) are given in Table 7. status of allopatric taxa can be tested: These values are derived from samples that include I experimental testing of isolation mechanisms by traditional subspecies combinations. These results captive breeding; reveal that the -4. pomarina (smsu lnto) sample 2 comparison of the degree of morphological differ- [including both pomarina and hastata) exhibits an entiation between the two taxa with related species exceptionally high level of variation with a CV for that have two or more races; breadtlr of 13.2o/o,almost double that of any of the 3 in more widespread species:comparison ofthe degree other taxa considered. Phenotypic variation in avian of differentiation between intergrading subspecies; rostral dimensions has been intensively studied in a 4 in related species: comparison of the degree of diverse array of taxa and the most variable popula- differentiation between hybridizing populations. tion identified to date is that of the Large Ground Captive breeding experiments are impractical Finch Geospiza magnirosrrds Gould 1837 of Isla for these taxa, and furthermore, few tests of this Darwin, Gal6pagos, with a CV for gape breadth of technique have been conducted [cf Grant & Grant l3.l% fBowman 1961, Grant & Grant 1989). 1997). There are no similar hybrid populations of Howeve4 even in this instance, it is possible that related species, so criteria 3 and 4 are ruled out. Bowman's sample may have been composed of more

O 2002 British Ornithologists'Union,/bls, 1t14,665-675 Taxonomicstatus of the lndianSpofted Eagle 673

Table 7. Coefficientsof variation in gape biometrics for female broad, can accommodate two avian taxa with such bootedeagles (sensu Amadon 1 982) in descendingorder. divergent skulls in the same species. One adaptive hypothesis for the large gape of CV of hastata is that it allows hyperventilation, especially n Breadth Length when confined to the nest. One of us [V.P.) has often seen both incubating and attending adult females Aquila pomarina(sensu latof 43 13,2 8.3 and nestlings of hastata hyperventilating. Tempera- Polemaetusbellicosus 7 8.3 5.6 tures encountered at hastata nests regularly exceed Spizaetuscirrhatus 6 7.2 3.9 45 oC, whereas temperatures at pomarit4a nests Hieraaetusspilogaster 22 7.1 3.5 Spizaetusnipalensis I 6.5 3.4 rarely reach 35'C. Howeve4 experimental work is Lophaetusoccipitalis 6 6.3 2.6 necessaryto test this hypothesis. A second hypothe- Aquilachrysaetos*** 51 6.2 3.2 sis, again untested, is that tle marked differences in Stephanoaetuscoronatus 7 6.2 3.6 gape size between hastata and pomarina are related Aquilaaudax 11 5.9 4.6 to differences in diet and prey size. Hieraaetuspennatus 11 5.8 6.6 Aquilapomarina (sensu strlc'pf. 25 5.6 4.8 It was not uncommon in the early 20tl century for Hieraaetusmorphnoides 3 5.5 2.2 two or more allopatric taxa of to be combined Aquilanipalensis*"* 25 5.4 3.9 in a single polytypic species, especially by Hartert lctinaetusmalayensis*'* 20 5.3 4.2 (1914-22). Such mergers were usually justified on Hieraaetuskienerii*.. 10 5.3 4.5 similarities of adult plumages, with little or no other Aquilaclanga 30 5.2 3.9 Aquilarapax*'" 44 5.'l 3.3 biological information considered. Recendy, some Aquilaheliaca & A. adalberti 35 4.9 3.8 Aquila taxa have been restored to species level on Spizaetustyrunnus 7 4.9 2.1 the basis of differences in plumages, morphology and Hieraaetusayresii 7 4.6 5.2 behaviou4 e.g.Spanish Imperial EagleAquil"a adaherti Aquila hastata 18 4.6 3.8 Brehm 1861 and Eastern Imperial Ea{e Aquila. heliaca Aquila wahlbergi 5 4.6 3.8 Hieraaetusfasciatus 27 4.3 3.4 Savigny 1809 fHiraldo et al.1976) and Spizaetusnanus 6 4.3 5.7 Aquiln nipabnsis Hodgson 1833 and Tawny Eagle Spizaetusornatus*** 11 4.3 3.6 AquilarapacQemminck) 1828 (Clark 1992, Olson Aquila verreauxii 5 3.9 3.8 1994). We believe that the differences between Spizaetuslanceolatus 4 3.9 5.6 hastata and pomarin4 are greater than the differ- Spizasturmelanoleucus 11 3.4 3.0 Oroaetusisidori 6 3.1 4.8 ences between the pairs of eagle specieslisted here. Aquilagurneyi 4 1.0 5.0 Earlier common names used for hastata were' Long- legged Eagle' Reid 1887, Swann 1920, 1933) t [e.g. A. pomarina(sensu lato) includes hastata. and'Small Indian Spotted Eagle' (e.g. Baker 1928, ". A. pomarina(sensu stricto) excludes hastata. 1930J. As our measurements clearly show .-.lncludesall recognized subspecies. Whistler flable 5), its legs are no longer and it is no smaller than pomarfun.Wetherefore recommend the more descript- 'lndian than one taxon (Grant et al. 1985, Grant & Grant ive and appropriate name of Spotted Eagle'. 1989). Thus, as presently constituted, the polytypic Whilst the adaptive significance of the morpho- species A, pomarina exhibits a greater level of phe- logical differences between hastata and pomarina is notypic variation in rostral dimensions than any currently under review, it is clear that they are rep- other avian species. resentative of diversification into two very different The CV for gape length in the z{. pomarina (smsu niches [one temperate, one tropical). Mayr (1982) in l^ato) sample is likewise substantially greater than his last major statement of the BSC emphasized that '... those calculated for the other eagle taxa considered a biological species occupies a specific niche in (Table 7). In contrast, the CVs for the separate treat- nature'. In conclusion, in light of the many differ- ments of hastata and pomaina (smsu stic-to) corre- ences enumerated herein, the Indian Spotted Eagle, spond with the levels of variation exhibited by the as we prefer to name it, should again be considered other related species [Table 7). Thus, their proposed by taxonomists as a separate specieq Aquila' hastata separate species status accords with the require- (Lesson) 1834, and the Lesser Spotted Eagle Aquila ments of the BSC. These results further emphasize pomaina Brehm t83l should be consideredmono- the marked cranial differences between hastata and typic. We believe that the merger of hastata and pomarina and no species concept, no matter how pomarina was not justified.

O 2OO2British Ornithologists' Union, ,bis, 144, 665-675 674 S.J. Parry,W.S- alerk & V.Prakash

Specimenswere examined in the American Museum of Clark,W.S. 1992. The taxonomy of Steppeand Tawny Eagles, Natural History,the National Museum of Natural History, with criteriafor separationof museumspecimens and live the Natural History Museum Oii"gJ and at the Bombay eagles.Bul/. Brit. Orn. Club 112:1 50-157. Natural History Society;the curatorsare thanked for per- Clark,W.S. & Khan,A.A. 1995.Sightings of two rareraptors, mitting accessto the specimens.This work was conducted LesserSpotted Eagle Aquila pomarina and PiedHarrier while S.J.P.was in receipt of an NERC grant. Support for Circusmelanoleucus, in Pakistan.Forktail 1O:'173-175. most of W.S.C.'sfield work in India was provided by the Cracraft,J. 1983.Species concepts and speciationanalysis. Offrceof InternationalAffairs, U.S. Fish & Wildlife Service, Curr.Ornithol. 1 : 159-187. thanks to D. Ferguson.The U.S. Fish & Wildlife Service Cramp,S. & Simmons,K.E.L. (eds) 1980. 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