j RaptorRes.39(4):386-393 ¸ 2005 The Raptor Research Foundation, Inc.
MORPHOMETRIC THEIR HYBRIDS
ANALYSIS OF LARGE FALCO SPECIES AND WITH IMPLICATIONS FOR CONSERVATION CHRIS P. EASTHAM 1
NationalAvian Research Centre,TheFalconFacility,PenllyninFarm, College Road, Carmarthen,WalesSA33 5EH UnitedKingdom MIKE K. NICHOLLS 2
Ecology Research Group,Canterbury ChristChurchUniversity College, Canterbury, Kent,CT1 1QU UnitedKingdom ABSTP•ACT.---Morphometric examinationof severallarge falcon speciesand their hybridswasconductedto ascertainwhether phenotypewasan accurateindicatorof hybrid parentage.Six externalbodymeasure-
mentswererecordedfrom 167 Gyrfalcons (Falcorusticolus), Saker(E chefrug), Peregrine(E peregrinus), and New ZealandFalcons(E novaezeelandiae) and from 100 F1, F2, and backcross hybridsof thesespecies. PrincipalComponentAnalysisseparatedpure speciesand alsoindicatedclustersfor F1 peregrineX saker, gyr X peregrine,and gyr X sakerhybrids.Gyr X peregrinehybridswere distinguishable from their parent species,but it wasimpossibleto discriminateaccuratelybetweena complex(F1, F2, and backcross) of gyr X saker hybridsand betweenthese and the parent species.Escapedor releasedfalconry hybridsare perceivedasa significantthreatto the conservation of wild falconpopulations. Under currentlegislation, gyrsand their hybridsare CITESAppendixI species, and sakersare AppendixII species. We suggest that phenotypiccharacteristics are not reliablefor identificationof suchhybridsfor legal purposes.Furthermore, analysisof measurementsalso identified a "paternal effect," wherebyF• hybrids,irrespectiveof gender,were phenotypically more similarto their paternalthan their maternalprogenitors.
KEYWOaDS: Peregrine Falcon; Falcoperegrinus; Gyrfalcon; Falcorusticolus; SakerFalcon; Falcocherrug;New Zealand Falcon; Falconovaezeelandiae; Falconhybrids, movphometric,, p•incipalcomponent analysis; PCA;CITES.
AN•LISIS MORFOM•TRICO
DE LAS ESPECIES DE FALCO DE TAMA•O
GRANDE Y DE SUS
HIBRIDOS, E IMPLICACIONESPARALA CONSERVACION RESUMEN.--Se analiz6 la morfologiade variasespeciesde halconesy de sushibridospara averiguarsi el fenotipo es un indicadorprecisode la paternidadde los hibridos.Se registraronseismedidascor-
poralesparaun totalde 167individuos pertenecientes alasespecies Falcorusticolus, E cherrug; E peregrinus y E novaezeelandiae, y para un total de 100 hibridos F1, F2 y retrocrucesde estasespecies.Un an51isis de componentesprincipalessepar6 alas especiespuras e identific6 grupos formadospor hibridos F1 E pereg•inus X E cherrug, E rusticolus X E peregrinus y E rusticolus X E cherrug. Los hibridosE rusticolus X E pereg•inus se diferenciaronde las especiesparentales,pero fue imposibledistinguirclaramenteentre un complejo (F1, F2, retrocruces)de hibridosF. rusticolus X E cherrug, y entre este complejoy las especiesparentales.Los halconeshibridos de cetreria que escapano son liberadosse consideranuna amenazapara la conservaci6nde las poblacionessilvestres. Bajo la actual legislaci6n,E rusticolus y sus hlbridosestrinregistradas en el Ap6ndiceI de CITES y E cherrug en el Ap6ndiceII. Consideramos que las caracteristicas fenotipicasno son confiablespara la identificaci6nde estoshibridoscon prop6sitos legales.Adem•s, el anrlisis morfom6trico identific6 "efectospaternos," en donde los hibridos F1, independientementede su sexo,fueron fenotipicamentemils similaresa susprogenitorespaternosque a los maternos.
[Traducci6n del equipo editorial]
One of the first domestichybrid falconswaspro• Presentaddress: Klumpstugevfgen 1, 61892Kolmarden, duced in 1971 from a female Saker Falcon (Falco Sweden. cherrug)and male Peregrine Falcon (E peregrinus; 2 Correspondingauthor'saddress:LEAP, Universityof Morris and Stevens1971, Morris 1972). Since then, Greenwich at Medway, Chatham Maritime, Kent ME4 4TB, United Kingdom. Email:
[email protected] 386
falconersand raptor breedershaveproducedmany different hybrids from members of the Falconifor-
DECEMBER 2005
MORPHOMETRICS OF FALCON HYBPdr>S
387
Table 1. Identity of hybrid falcons used in the analysis. HYBRID
IDENTITY a
SAMPLES SIZES
1VIALE PARENT
FEMALE PARENT
Fls
Gyr X Peregrine Gyr X Saker Peregrinex Saker Peregrinex Gyr Peregrine x New Zealand Gyr/Saker X Peregrine
6 7 3 1 1 1
c•, 7 9 c•, 5 9 c•, 13 9 c• c• c•, 1 9
Gyr Gyr Peregrine Peregrine Peregrine Gyr X SakerF2 hybrid
Peregrine Saker Saker Gyr New Zealand Peregrine
Gyr X SakerF1 hybrid
Gyr X SakerF1 hybrid
Gyr Saker Gyr X SakerF1 hybrid Gyr X Peregrine F1 hybrid
Gyr X SakerF1 hybrid Gyr X SakerF1 hybrid Saker Peregrine
F2s
Gyr X Saker
4 c•, 5 9
Backcrosses•lst generation
Gyr X Gyr/Saker SakerX Gyr/Saker Gyr/Saker X Saker Gyr/Peregrine x Peregrine
3 c•, 1 9 3 c•, 3 9 14 c•, 17 9 2 c•
Backcrosses•2nd generation
Gyr (3/8)b/Saker
1 c•
Gyr X SakerF1 hybrid
Gyr/SakerX Saker
Gyr (5/8)b/Saker
1 c•, 1 9
Gyr
Gyr/SakerX Saker
(backcrosshybrid)
(backcrosshybrid) • When naminghybrids,the paternalspeciesis cited first. For example,a crossbetweena male gyr and female sakeris a gyr X saker (or gyr/saker) hybrid, whereasa male sakercrossedwith a female gyr is a saker X gyr (saker/gyr) hybrid. bThesenumbersrepresenta simplewayto showthe proportionof genesfrom the parentspecies, assuming that a F1 hybridinherits % of the genesfrom both the male and femaleparent species.For example,a gyr (•/s)/saker,producedby backcrossing a gyr X saker F1 hybridwith a gyr/sakerbackcross hybrid,has•/sgyrfalconand % sakergenes.
mes (Boydand Boyd1975,Cade and Weaver1976,
ropean, and Arabian falconry markets (Fox and Bunnell 1986, Weaver and Cade 1991), including Sherrod 1999b) has prompted conservationconintergeneric hybrids (e.g., Harris's Hawks [Para- cerns. Escapeddomestichybridsmay be merely a buteounicinctus]X Cooper's Hawk [Acdpitercoope- curiosity (Forseman 1999), a nuisance for bird nz] and Harris's Hawk X FerruginousHawk [Buteo watchers (Gantlett and Millington 1992), or a regalis];Fox and Sherrod 1999a) for falconry pur- threat to the integrity of wild populations.Indeed, poses. falcon pairs made up of an escapedhybrid and a Many F1 hybrids are fully viable (Heidenreich wild, pure individual have been documented sev1997), in their turn producingF9hybridsor back- eral times (e.g., Kleinst/uber and Seeber 2000, crosses(B1 and B9 representing 1st and 2nd gen- Lindberg 2000). A further conservationissuepreeration backcrosses)to one or other parent spe- sumablyconcernsillegal-tradein falcons,whereby cies. Indeed, hybrids from within the subgenus protected falcon speciesmay be "laundered" as Hierofalco, the "desertfalcon" group (Heidenreich domestichybrids.In this study,we examine the re1997), exhibit full fertility,presumablyover indef- lationship between falcon speciesand their hyinite generations.Lessclosely-relatedpairs of spe- brids, particularly the accuracyof using morphocies,suchas gyr (E rusticolus) and peregrine, pro- metric characters for identification, and discussthe duce hybrids with reduced fertility, manifest as conservationissuesconcerningfalcon hybrids. deformed spermatozoa,completelysterilefemales METHODS (Heidenreich and Kuspert 1992), or unviable emWe investigatedfour large falcon species,namely Perbryos (Rosenkranz1995). egrine, Gyr, Saker,and New Zealand falcons (E novaezeeThis extended viability of some falcon hybrids landiae)and severalof their hybrid typesusedfor falconcoupled with increasingdemand over the last 10 ry. Hybrid falcons were all bred in captivity and, yr for domesticfalconsfrom North American, Eu- therefore, their parentagewasknown. Six external body
388
EASTHAM AND NICHOLLS
VOL. 39, NO. 4
Table 2. Principal Component Analysis(PCA) of six anatomical measurementsfrom juvenile male Gyrfalcon,Saker, Peregrine, and New Zealand falcon speciesand hybridsof thosespecies.Eigenvaluesand eigenvectors(basedon the correlation matrix). PRINCIPAl.
1
COMPONENT
2
3
4
Eigenvalue Percent of variability
3.0328 0.5055
1.3691 0.2282
0.7459 0.1243
0.6833 0.1139
Cumulated
0.5055
0.7336
0.8580
0.9718
0.1490 -0.0688 -0.2347 0.7536 -0.1598 0.5697
- 0.3852 -0.1697
Percent
CHARACTERS
EIGENVECTORS
Wing chord Wing width
0.4990 0.5552
- 0.2324 -0.0321
Tail length Tail step Tarsuslength D•git three length
0.5195 0.0247 0.3536 0.2170
0.2308 0.6402 0.3591 - 0.5940
-0.1471 -0.1395 0.7769 0.4221
measurementswere collected from live juvenile Gyrfalcons (N = 7 males and 6 females), Saker (N = 34 males and 40 females), Peregrine (N = 17 males and 24 females), and New Zealand falcons (N = 25 males and 14 females), and their varioushybrids (Table 1). Apart from European Peregrine Falcon subspecies,the majority of which were E peregrinus peregrinus, no other differentiation was made between subspecies or geographic morphs. All birds were kept at the National Avian Research Center's Falcon Facility in Carmarthen, Wales, U.K. The majority of F9 and backcross1 and 2 hybrids were between gyrs and sakers.This is becausehybrids between membersof the subgenusHierofalco remain fertile for an indefinite number of generations,whereashybrids between more out-crossedfalcon species,such as peregrinesand sakers,have a reduced fertility. Some of the hybrids included are produced in very low numbers (e.g., Peregrine Falcon X New Zealand Falcon), and pub-
and females, as this measurementwasreported by Wyllie and Newton (1994) and Eastham (2000) to be the most reliable indicator of overall body size.
1968, Cade 1982), or other sex-linked or sex-limited characters. We used wing chord length to distinguishmales
kers showed a wide variation in PC 2 values, with
RESULTS
Males. Principal Component (PC) 1 (Table 2, Fig. 1) accountedfor the majority (50.5%) of variation. Because all eigenvectorsfor PC1 showed positiveand nearly equal values,we concludedthis component represents overall body size (Wiley 1981). Male gyrsand F1 and F2 gyr/saker hybrids had the largest body size, whilst male peregrines and New
Zealand
Falcons
were
the smallest.
PC 2 (Table 2, Fig. 1) accountedfor 22.8% of the variation, as indicated by a contrastin eigenhshed data on these are rare. Therefore, we included vectorsbetween the positivelyweighted tail step, them in the analysis. tail and tarsuslength, the negativelyweighteddigit One of us (C. Eastham) took six measurements, namely wing chord length and width, tail length, tail step (the three length, and wing chord length and width (Table 2). This component summarizesvariation difference between the outermost tail feather [rectrix 6] and the tip of the center tail feather [rectrix 1] on the related to body shape. Tail step and digit three same side), tarsus length, and third digit length from length showedthe strongestpositiveand negative each bird. Measurement protocols followed standard weightings, respectively. With a low negative methodsdescribedby Baldwinet al. (1931), Fox (1977), Biggset al. (1978), Kemp (1987), and Fox et al. (1997). weighting, wing width wasof limited use in further Feather characters were measured to the nearest 1 mm analysisof PC 2. New Zealand Falconshad the reland non-feather charactersto the nearest 0.1 mm using ativelylongesttail step (indicatinga more rounded a pair of digital calipers,a steel ruler, and tape measure. tail), tail and tarsuslength, and shortestdigit three Inclusion of single individuals,for example, a male Peregrine Falcon X New Zealand Falcon, allowed us to em- and wing chord, whilst peregrines,the single perploy Principal Component Analysis(PCA) on XLSTAT- egrine x New Zealandhybridand gyr/sakerx perPro (Fahmy 1998) statisticalsoftwareasa suitablemethod egrine hybrid had the relativelylongestdigit three for data analysis.Male and female data were analyzed and wing chord length and shortesttail step and separatelyto eliminate background variation due to reversed sexual size dimorphism (Brown and Amadon tail and tarsuslength. F1 gyr X peregrinesand saan individual saker having the highestPC 2 value.
DECEMBER 2005
MORPHOMETRICS OF FALCON Hy•mr)s
389
Gyr / Peregrines• Sakers New Zealand Falcons
-.,
Gyrfalcons
o
o
0
I
I
I
I
-3
-2
-1
Peregrin
0_
-3
-4
Peregrine /Sakers[F1 & F2 Gyr /Sak 0
1
2
3
PrincipalComponent1
Gyrfalcon mSaker Peregrine / Saker
)K Peregrine -New Zealand falcon AGyr /Peregrine +Gyr /Saker -F1
ß Peregrine / New Zealand OGyrxGyr / Saker
[] Gyr/ Saker xSaker
OSaker xGyr/ Saker
;;Gyr(5/8)/ Saker
ßGyr /Saker -F2
OGyr/ Saker xPeregrine
Figure 1. Principal component scoresfrom morphometric comparison of various male falcon speciesand their hybrids.
PC 3 and 4 (Table 2) accountedfor only 12.4% positivelyweightedtail step,tail and tarsuslength, and 11.3% of the residualvariation, respectively. the negatively weighted digit three length, and Tail stepand digit three length had a high positive wing chord length and width (Table 3). Positively weighting in PC 3, and in PC 4, there was a con- weighted tail step and negativelyweighted digit trast between positivelyweighted tarsusand digit three and wing chord length had the highest eithree length and negativelyweighted wing chord genvectorsfor this PC. New Zealand Falcons had length. As PC I and 2 together accountedfor the the longest tail step and the shortestdigit three majority (73%) of variation, we did not consider and wing chord length, whilstF1 gyr X peregrines PC 3 and 4 further. and peregrineshad the shortesttail length and the Females. The PCA for juvenile female falcons longest digit three and wing chord length. PC 3 showeda similar pattern of variation as that seen and PC 4 (Table 3) accounted for 18.4% and in juvenile males.Again PC 1 (Table 3, Fig. 2) ac- 11.4% of the variation, respectively. As for males, countedfor the largestproportion (44.7%) of var- we did not consider these principal components iation and asindicatedby mostlypositiveand near- further. ly equal values represents,as with males, overall size (Wiley 1981). Gyrs and the variousgyr/saker DISCUSSION F1, F2 and backcrosses had the largestsize,whilst UsingPCAwe found that the four falcon species, Peregrine and New Zealand falconswere the smallest. irrespective of sex, were clearly separated into PC 2 (Table 3, Fig. 2) accountedfor a further groups: New Zealand Falcons with a small size, 21.8% of the variation, and we concluded that this, long rounded tails and tarsi, and short wings;peragain like males,wasrelated to shape.This wasin- egrines, also with a small size, long digit three dicated by a contrast in eigenvectorsbetween the lengths, and long narrow wings;sakerswith a large
390
EASTHAM AND NICHOLLS
VOL. 39, NO. 4
Table 3. Principal Component Analysis(PCA) of six anatomical measurementsfrom juvenile female Gyrfalcon, Saker,Peregrine, and New Zealand falcon speciesand hybridsof thosespecies.Eigenvaluesand eigenvectors(based on the correlation matrix). PRINCIPAL
i
Elgenvalue Percentof variability Cumulatedpercent
2
2.6826 0.4471 0.4471
3
1.3071 0.2179 0.6649
CHARACTERS
W•ng chord W•ng width Tail length Tail step Tarsuslength D•git three length
COMPONENT
4
1.1023 0.1837 0.8487
0.6864 0.1144 0.9631
-0.1963 - 0.0356 - 0.0642 0.1871 0.6899 0.6672
0.4118 - 0.0129 - 0.1107 0.6869 -0.4484 0.3809
EIGENVECTORS
0.4717 0.5765 0.5737 0.0866 0.3077 - 0.1177
-0.3853 - 0.1767 0.1670 0.6865 0.2169 - 0.5236
size, long rounded tails, and short digits;and gyrs with the largest size. Using these external body measurements,we alsofound it possibleto identify three main hybrid groups: a complex of F1, F2 and backcrossgyr/ sakers;F1 gyr X peregrines and F1 peregrine X sakers.Further, it was possibleto separate gyr X peregrinesfrom their parent species,but impossible to separate completely the F1, F2, and backcrossgyr/sakers hybrid-complexfrom pure sakers or particularly,from pure gyrs. Overall, we found that the hybrids were gener-
homogameticsex (male in birds; Mittwoch 1977) and only one third by the heterogameticsex (Falconer 1967). Therefore, falcon sires (the homogameticsex) will contribute more sex-linkedalleles to their hybrid offspring than will (heterogametic) dams.
International trade in endangeredspecies,such assomefalcons,can be a profitableenterpriseand, if unregulated, can threaten their conservation. Regulation of the trade in such endangeredspecies is by international agreements,such as the Conventionon International Trade in Endangered ally of intermediatephenotypebetweentheir par- Speciesof Wild Fauna and Flora (CITES). Accordents. However,beyond this it appearsthat the pa- ing to their degree of endangerment in the wild, ternal progenitor influences the phenotype to a all speciesare classedin one of three CITES apgreater extent than maternal. For example, for pendices.Specialconditionsapply to the most enboth males and females,the clustersrepresenting dangered, known asAppendix I species(i.e., those with extinction and whose survival F1 gyr X peregrine hybrids, hybridswhose male threatened parentswere gyrs,were spatiallycloser to the gyr could be impaired by trade), which allowsrestrictclustersthan to the peregrine clusters(Fig. 1, 2). ed trade in captive and domesticbred individuals. Thus, both male and female gyr x peregrine hy- Appendix II includes species considered less brids have a morphologycloserto that of gyrsthan threatened. The saker is an Appendix II species, to peregrines.Further, that the single female per- and although trade is regulated,this is lessexactegrine x gyr,whosesire was a peregrine, wasspa- ing than for Appendix I species.Despiterelatively tially closer to the peregrine cluster than the gyr healthy world populations and for reasonswhich cluster,adds further weight to this proposedgen- are largelypolitical (White and Kiff 1998), gyrsand erality.Similarly,the male and female F1 gyr X sa- peregrines and their hybrids are included in Apkers, both with gyrsas male parent, appear more pendix I. The resultswe present here showthat it can be gyr-likethan saker-likein morphology.Except for male F1 peregrine X sakersthis "paternal effect" difficult to discriminatefalcon speciesaccurately seems true for all speciescombinations. We ex- from their hybrids,especiallyhybridsof Appendix plain this by consideringthat two thirds of the sex I gyrsand Appendix II sakers.Similarly,plumage linked genes in a population are carried by the variation, especiallyin juvenile falcons,is difficult
DECEMBER 2005
MORPHOMETRICS OF FALCON HYBm•)S
391
3.5
New Zealand falcons •
T
2.5
F1 & F2 Gyr / Sakers
1.5
o
........
0.5
../
-0.5
-1.5
Peregrines
Gyr / Peregrines
-2.5 -3.5
-2.5
-1.5
-0.5
0.5
1.5
2.5
3 5
PrincipalComponent1 ß Gyrfalcon
ß Saker
• Peregnne
ß Gyr/ Saker - F2
X Peregnne/ Saker
• Peregnne/ Gyr
O Gyr x Gyr/ Saker
- New Zealand falcon
O Saker x Gyr/ Saker
•-'Gyr (5/8) / Saker
-- Gyr (3/8) / Saker
•:,•Gyr/ Saker x Peregrine
,&Gyr/ Peregrine
+Gyr / Saker - F1
ß Gyr/ Peregnnex Peregnne
[] Gyr/ Saker x Saker
Figure 2. Principal component scoresfrom morphometric comparisonof variousfemale falcon speciesand their hybrids.
thing that will corrupt them. Thus, if the species conceptfor birds is much looserthan conservation law dictates,then perhaps it is the legislation and not the speciesconcept that must be challenged. For example, the so-called"Altai falcon" (FalcoaltaicusMenzbier), whose phenotype seemsto share characterswith both gyrsand sakers,is believedby someto be the result of introgressivehybridization between gyrs and sakers, rendering all these as 1998). Mayr and Short (1970) estimatedthat up to allospecieswithin a single superspecies(Pfander 10% of North American bird speciesregularlyhy- 1987, Ellis 1995a, 1995b). This being so, then to bridize; it's so common that hybrids are even in- discriminatebetween Appendix I gyrsand Appencluded in birdwatchers'field guides (Sibley2000). dix II sakersmay be irrelevant,and artificiallyproThe presenceof natural hybridsis not believed to duced crossesbetween thesetwo may be of no evobe a threat to the integrity of a species, even lutionary threat should they escapeto the wild. If, though they may challenge the biological species however, the Altai Falcon is merely a large, dark concept of taxonomists(Brookes 1999). Amongst race of the saker (Eastham and Nicholls 2002), and free-living, wild birds of prey such hybridization is any resemblanceto gyrsis merely superficial,then increasinglydocumented at the subspecific(Fefe- escaped hybrids between these speciescould polov 2001), specific (Hamer et al. 1994), and even tentially compromisewild populations, and the into the intergeneric levels (Corso and Gildi 1998, tegrity of gyrsand sakersmust be recognized and Yosef et al. 2001). CITES regulations enforced. A different view of the role of natural hybridizaIntrogressivehybridization may therefore be a processby which speciesevolve,rather than some- tion acceptsthat avian speciesare dynamicentities,
to assessobjectively and make comparisons between speciesand their hybrids. These observations may provide fuel for two separatearguments. Ornithologists are increasingly aware of the widespread genomic compatibility and potential for hybridization amongst what appear to be very dissimilar species (Grant and Grant 1992), such that hybridization between avian speciesis considered more common than originally thought (Gill
392
EASTHAMAND NICHOLLS
VOL. 39, NO. 4
which in certain circumstances,freely exchange geneswith other suchentities.Despite theseinteractions,the integrity of the whole is a fragile one, and to short circuit gene flow via artificial hybrids is a danger to this integrity. CITES protocolsare the responseto perceivedconservationstatus,and therefore, it should be mandatory to discriminate between speciesas we know them. Accurate identification to assistin controlling the trade in falconsis paramount,and we haveshownthat criteria other than phenotypic characteristics(e.g., DNA markers) must be employedto identify individuals and species.This is imperative if CITES is to remain an effective means of regulating legitimate trade and protectingspeciesin the wild.
allied species.Ph.D. thesis,Universityof Kent at Canterbury, Canterbury, Kent, England. --AND M.K. N•CHOLLS.2002. Morphological classification of the so-called"Altai Falcon." Pages211-219 in R. Yosef,M.L. Miller, D. Pepler lEDS.],Raptors•n the new millennium. Int. Birding and Res. Centre,
ACKNOWLEDGMENTS
FEFELOV,I.V. 2001. Comparative breeding ecology and hybridizationof eastern and westernMarsh Harriers Circusspilonotus and C. aeruginosus in the Baikalregion
Thanks to His HighnessSheikh Khalifa bin Zayed AI Nahyan and His HighnessSheikh Hamdan bin ZayedA1 Nahyan for sponsoringthis research.Thanks also to M. A1 Bowardi,managingdirector of the EnvironmentalResearchand Wildlife DevelopmentAgency (ERWDA), Drs. Nick Fox, Director of the ERWDA Falcon Programme, Robert Kenward, and Juan Negro and Violeta Munoz for comments on this manuscript. LITERATURE
CITED
BALDWIN, S.P., H.C. OBERttOLSER,AND L.G. WOOLLY.1931. Measurements
of birds.
Sci. Publ. Clevel. Mus. Nat. Hist.
2:1-65.
BIGGS, H.C., R. BIGGS,AND A.C. KEMP. 1978. Measure-
ments of raptors.Pages77-82 in A.C. Kemp [ED.], Proceedingsof a Symposiumon African Predatory Birds.Northern TransvaalOrnithologicalSociety,Pretoria, South Africa.
BOYD,L.L. AND N. BOYD.1975. Hybrid falcons. Hawk Chalk 14:53-54.
BaoOI•ES, M. 1999. Live and let live. New Scientist2193: 32-36.
BaOWN,L. ANDD. AMADON.1968. Eagles,hawksand falcons of the world. Vol. 2. The Wellfleet Press, Secau-
cus, NJ U.S.A. BUNNELL,S. 1986. Hybrid falcon overview--1985. Hawk Chalk 25:43-47.
Eilat, Israel.
ELLre,D.H. 1995a. The Altai falcon: origin, morphology, and distribution. Pages143-168 in Middle EastFalcon ResearchGroup [EDS.],Proceedingsof the Specialist Workshop.Abu Dhabi, United Arab Emirates. ß 1995b. What is FalcoaltaicusMenzbier?J. Raptor Res. 29:15-25.
FAHMY, T. 1998. XLSTAT-PRO statistical software. Paris, Franceß
FALCONER, D.S. 1967.Introductionto quantitativegenetics. Oliver and Boyd, London, England.
of eastern Siberia. Ibis 143:587-592.
FOaSEMAN, R. 1999. The raptors of Europe and the Middle East: a handbook
for
field
identification.
T. and
A.D. Poyser,Ltd., London, England. Fox, N.C. 1977. The biologyof the New ZealandFalcon (Falconovaezeelandiae; Gmelin 1788). Ph.D. dissertation, Universityof Canterbury,New Zealand. , C.P. EASTHAM, ANDH.J. MACDONALD. 1997. The ERWDA handbook of falcon protocols.Environmental Researchand Wildlife Agency,Abu Dhabi, United Arab
--AND
Emirates.
S. SHERROD.
1999a.
The
use of exotic
and
hybrid raptors in falconry. Information arisingfrom the International Committee on Hybrids.International Wildlife ConsultantsLtd., Carmarthen,Wales,England.
--AND S. SHEPmOD. 1999b. Cited in "Scaleproduction and use of hybridsin falconry."Falco13, Middle East Falcon Research Group, International Wildlife ConsultantsLtd., Carmarthen, Wales, England. GANTLETY, S. AND R. MILLINGTONß 1992. Identification
of
large fhlcons.Birding World5:101-106. G•LL,F.B. 1998. Hybridization in birds.Auk 115:281-283. GP,ANT,P.R.ANDB.R. GP,ANT. 1992. Hybridization of bird species.Science 256:193-197.
BURTON, J.F. 1995. Birds and climate change.Christopher Helm Publishers,London, England. CADE,T:J. 1982. Falcons of the world. William Collins Sons and Co. Ltd., London, England.
HAMER, T.E., E.D. FORSMAN,A.D. FUCHS, AND M.L. WAL-
--ANDJ.D. WEAVER. 1976.GyrfalconX peregrinehybrids produced by artificial insemination.J. NorthAm.
agement.BlackwellScientificLtd., Oxford, England. --AND H. KUSPERT. 1992. Metodos de la reproduccion en cautividadde las diferentesespeciesde halcones.E1 problema de los hibridos y la cooperacion entre criadoresy autoridades.Proc.Cong•Nac. Cria.
Falconers Assoc. 15:42-47.
CoP, so, A. ANDR. GILDL 1998. Hybrids of Black Kite and Common Buzzard in Italy in 1996. Dutch Birding20: 226-233.
TEAS.1994. Hybridization between Barred and Spotted owls. Auk 111:487-492.
HEIDENREICH, M. 1997.Birdsof prey:medicineandman-
Aves Cetre•a 1:15-17.
EASTHAM, C.P. 2000. Morphological studiesof taxonomy HOELLEa, T. AND P. WEGNEa. 2001. Der Wanderfalke ist of the Saker (Falco cherrug: Gray 1833) and closely in Gefahr! Die zweite Hybridfalken-Wildbrut in
DECEMBER 2005
MORPHOMETRICS OF FALCON HYBRIDS
Deutschlandzeigt die Brisanzder Hybridfalkenzucht. Greifvb•elu. Falknerei2000:64-66. KEMP,A.C. 1987. Taxonomyand systematics. Pages251259 in B.A. Giron Pendleton, B.A. Millsap, K.W. Cline, and D.M. Bird [EDS.], Raptor management techniques manual. National Wildlife Federation Scientif-
393
tical calculation manual. Oxford UniversityPrcss,Oxford, England.
PFANDER, P.V.1987.OnceagainconcerningtheAltayGyrfalcon.
Selevinia 2:38-42.
ROSENKRANZ,D. 1995. Cited in M. Heidenreich.
1997.
Birds of prey: medicine and management. Blackwell Scientific Ltd., Oxtbrd, England. ic and Technical Series No. 10. S•BLEY, C. 2000. The North American bird guide. ChrisKEEINST•UBER, G. ANDHJ. SEEBER. 2000. Die erfolgreiche topher Helm, London, England. Brut eines Gerfalke-X-Wanderfalke-Hybriden (Falco WE^VER,J.D. AND T.J. CADE.1991. Falcon propagation. rusticolusX Falco peregrinus)in freier Wildbahn-ReThe Peregrine Fund, Inc., Boise, ID U.S.A. port, MaBnahmen, SchluBfolgerungen.Poplations6- WHITE, C.M. ANDL.F. KIFF.1998. Languageuse and m•skol. Greifvogelu. Eulenarten4:323-332 applied, selective "science;" their roles in swaying LINDBERG, P. 2000. Hybridfalk hSckarigen. Vc•rFdgelviirld public opinion and policy as shown with two North 8:28-29.
Americanraptors.Pages547-560 in R.D. Chancellor,
MAY•, E. 1963. Animal speciesand evolution. Belknap Press of Harvard University Press, Cambridge, MA U.S.A.
--AND American
L.L. SHORT.1970. Speciestaxa of North birds.
No.
9 Publ. Nuttal
Ornithol.
Club.
M•TTWOCH,U. 1977. Genetics of sex differentiation. Ac-
B.-U. Meyburg, andJJ. Ferrero lEDs.], Holarctic birds of prey. ADENEX-WWGBP,Badajoz,Spain. Wn.EY,E.O. 1981. Phylogenetics:the theory and practice of phylogenetic systems.Wiley/Interscience, Hoboken, NJ U.S.A. WYLLIE, I. AND I. NEWTON. 1994. Latitudinal variation •n
the body-sizeof Sparrowhawks(Accipiternisus)within ademic Press,Burlington, MA U.S.A. Britain. Ibis 136:434-440. MORRIS, J. 1972. Peregrine/Saker breeding. Cap. Breed. YOSEF,R., AJ. HELmG, AND W.S. CLAPre.2001. An intraDiurn. Birdsof Prey1:14-15. generic Accipiterhybrid from Eilat, Israel. Sandgrouse
--AND R. STEVENS. 1971. Successful cross-breeding 23:141-144. of Peregrine tiercel and a Saker falcon. Cap. Breed. Diurn. BirdsofPrey,1:5-7. Received 13 April 2004; accepted 24 March 2005 PENNYGUIGK, C.J. 1989. Bird flight performance: a prac- Former AssociateEditor:Juan Jos• Negro