The Auk
A QuarterlyJournalof Ornithology
Vol.

111

No. 4 October

1994

The Auk 111(4):787-805, 1994

MONOPHYLY OF THE FALCONIFORMESBASEDONSYRINGEAL

MORPHOLOGYCAROLE S. GRIFFITHS

Department
ofOrnithology,
AmericanMuseumofNaturalHistory,Central
ParkWestat 79thSt.,
New York, New York 10024, USA; andDepartmentof Biology,
CityCollege
of CityUniversityof NewYork,
ConventAvenueand 138thStreet,New York,New York 10037,USA

ASSTRACT.--The
systematic
relationshipsof the diurnalbirdsof prey(Falconiformes)
areunresolved.
The monophylyof the orderhasnotbeenestablished,andthe relationshipsofthe familieswithintheorderandof generawithinthethreepolytypicfamiliesareunclear.
To derivea phylogeny
for the orderandto assesstheusefulnessof thesyrinxfor resolving

the systematics
of nonpasserines,
I analyzedvariationin syringeal
morphology
of genera
within eachof the currentlyrecognizedfamiliesin the orderaswell asamongfour ordersof outgroups.
Thephylogeny
derivedfromthesesyringeal
datasupports
themonophyly
of
theFalconiformes.
In addition,syringeal
dataprovidestrongsupport
forthemonophylyofthreeclades
withintheFalconiformes:
theCathartidae;
theFalconidae;
andan AccipitrinaeSagittariidae-Pandioninae
cluster.The Cathartidaeare positionedasbasalto the other two
clades.Overallresultsindicatethat syringealmorphologyis conservative,
with mostof theinformative
variationoccurring
at highersystematiclevels.Received
10May 1993,accepted
24
October 1993.

OF THEAPPROXIMATELY
30 orders of birds, thepreviously(Jollie 1976, Sibley and Ahlquist
1990),and only a summarywill be presented
interestingsystematicquestions;the monophy- here.Theorderhistoricallyhasbeenunitedby
ly of the order is in question,as are relation- several external morphological characters
shipsof familieswithin theorder,andof genera (hookedbeakandcurvedtalons)andby several
within each of the families. Falconiformes curinternal characters(bicepsslip absent,ambiens
rently consistsof 76 generaand 290 speciesdi- present, caeca rudimentary; Beddard 1898).
vided into four families (Stresemann and Area- However, four current classifications
disagreedon 1979):Accipitridae,includingAccipitrinae on the monophylyof the order, and on sub(hawksand eagles,59 genera,217 species)
and ordinaland familial relationships(Fig. 1). Two
Pandioninae(Osprey,monotypic);Falconidae considerthe order monophyletic(Stresemann(falcons, 10 genera, 62 species);Cathartidae and Amadon 1979,Storer1971),while the other(New World vultures,5 genera,7 species);
and two propose either removal of the Cathartidae
Sagittariidae(Secretarybird,
monotypic).
from the order (Sibley and Ahlquist 1990) or
Comprehensive
reviewsof the historyof fal- inclusionof Strigiformes(owls) within the orconiform classificationhave been published der (Cracraft 1981).
order Falconiformes

offers some of the more

787

788

CAROLE S. GRIFFITHS[Auk, Vol. III

Cathartidae

Cathartidae

Accipitrinae

F Accipitr

Pandioninae

Falconidae

Falconidae

Sagittariidae

Sagittariidae
StresemannStorer 1971--

Pandioninae

Cracraft
Fig. I.

1979

Cathartidae

Cathartidae

Accipitrinae

Ciconiidae--

Falconinae--

and Amadon

Accipitridae

Pandionidae

Pandionidae

Strigidae

Sagittariidae

Sagittariidae

Falconidae

Sibleyand Ahlquist1990

1981

Four recent,conflicting classificationsof the Falconiformes.

The idea that the Cathartidaemay not belong 1898, Brown and Amadon 1968) have been sugin the orderhasbeenproposedpreviouslybased gestedas links between falconiformsand strion morphologicaland behavioraldifferencesof giforms.
Relationships of the Falconiformes to otherthis family from othersin the Falconiformes.In
addition, similarities of cathartids to otherordershave alsobeen proposed,including thegroupshave been noted, including the Cicon- orders Pelecaniformes, Ciconiiformes and Psitiidae (Garrod 1873, Beddard 1898, Ligon 1967, taciformes(reviewed in Sharpe 1891, Shufeldt
Rea 1983), Pelecaniformes (Beddard 1898, Jollie
1976), Procellariiformes (Jollie 1976), and Grui-

formes (Pycraft 1902). Friedmann (1950:6)stated that the Cathartidaewere a primitive groupnot differentiatedfrom the "primitive stockfrom
which the Ciconiiformes,

Pelecaniformes and1909), Gruiformes (Shufeldt 1909), Cuculi-

formes and Columbiformes (Verheyen 1950,
reviewed in Jollie 1977). The AOU (1983) Check-list places the Falconiformesbetween Anseriformes and Galliformes, whereas Sibley andAhlquist (1990) position the order (with Cathartidae removed) as sister taxon to a group
includingthe Podicipedidae,Sulidae,Phalacro-

Procellariformeshave been developed."
Hypothesesof a falconiform-strigiformrelationship have been advancedat various times, coracidae, and Phaethontidae.
Syringeal morphology had been used in thebasedon similaritiesof palatal and myologicalcharacters(reviewed in Sharpe 1891, Cracraft classificationof the major subdivisionsof the1981, McKitrick 1991). Pandioninae (Sharpe Passeriformes at the end of the nineteenth cen1891, Pycraft 1902) and Falconidae (Beddard tury (Ames 1971). Within the last 20 years,sy-October
1994]

Falconiform
Monophyly

ringeal data have again becomeimportant in
the systematicsof oscinesand suboscines(e.g.
Ames 1971, Warner 1972, Lanyon 1984, Prum
1990, 1992), but have not strongly influenced789

cussedin the characterdescriptions(Appendix 2).
Multistatecharacters were coded as unorderedwere alternative

variations

if statesof a character.

I used outgroup information to polarize characters(Maddisonet al. 1984).However, the relationshipsof

the systematics
of otherorders.Therehavebeen other orders to the Falconiformes are unclear, and theno detailed reports on falconiform syringeal choiceof an appropriateoutgroupis not readily apanatomysinceBeddard(1903),and no system- parent. Species from four orders of birds were inatic analysisof that anatomy.
cluded in the analysis.A comprehensivesubsetof
I examinedpatternsof variation in syringeal generain the Ciconiiformesand Strigiformeswas exmorphologywithin the Falconiformesto assess amined becausethere are phylogenetichypothesesof
the usefulnessof the syrinx for systematicsof relationshipsof theseordersto the Falconiformes.In
nonpasserines(i.e. whether there are phylo- addition, specieswithin the Pelecaniformeswere
genetically informative syringeal characters) added becauseseveralauthors suggesteda relationand to answer two primary systematic questions: (1) Is the order monophyletic?(2) What

are the relationshipsof the majorcladeswithin
the order?

MATERIALS AND METHODSSpecimens.--Iexamined syringesfrom collectionsat
the American Museum of Natural History (AMNH),
the National Museum of Natural History (USNM),
the Royal Ontario Museum (ROM), the University of
KansasMuseum of Natural History (KUMNH), theMuseum of Vertebrate Zoology of the University ofCaliforniaat Berkeley(MVZ), and the LouisianaState
University Museum of Natural Science(LSUMNS),
someof which I dissectedfrom fresh or alcohol-preserved specimens.These were cleared and doublestainedto distinguishcartilaginousand ossifiedtissue(Cannell 1988).Observationswere made using a Wild
M5A dissectingmicroscope,and drawingsmadewith
a camera lucida. Drawings were scannedinto a Macintosh computerand final illustrationsprepared using Aldus Freehand 2.0.
I analyzed124falconiformsyringesand 66 syringes
from purportedoutgroups(Appendix 1). Three of thefive cathartid genera and all falconid genera were
included. Within the Accipitridae,genera were chosento representeachof the previouslyproposedsubgroups;thesetotaled60%of the currentlyrecognizedgenera.In general,samplingwithin the ingroup wasconstrainedby the availability of specimens.Two or
more individuals from 27 specieswere analyzed toassessvariation at the intraspecificlevel.
Analysis.--Variationin morphologywas codedusing both binary and multistatecharacters.Multistatecharacters were ordered

if eitherof two criteria wasship of this order to the Falconiformes(Beddard1898,
Shufeldt 1909, Friedmann 1950, Jollie 1976). Becausemonophyly of the Falconiformescould not be assumed,speciesfrom theseother orderswere not treated as outgroupsin the analysis,nor was there a constraint on monophyly imposed in the analysis(Maddisonet al. 1984).Specieswithin the Galliformes
were used to root the cladogram.I used PAUP 3.0s
(Swofford1991)to derive the most-parsimonious
resolutionof the data.The sizeof thisdatasetprecluded
the use of exact algorithms for resolving the data;
therefore,the heuristicalgorithm wasused.However,this option does not guaranteeoptimality and may
identify a solution that is only locally optimal. To
increasethe probabilityof finding solutionsthat weregloballyoptimal,analyseswere repeatedvarying boththe branch-swappingand taxa-additionoptions.
Three indiceswere used to assessthe congruenceof the charactershypothesizedas synapomorphies(Farris1989):(1) consistencyindex, which is the minimum amountof changeof a characterdivided by theamountobservedon the tree; (2) rescaledconsistency
index, which is a linear rescalingof the consistency
index sothat valuesvary from 0 to 1;and (3) retention
index, which is the proportion of original charactersremaining as synapomorphies.Consensusmethods
wereused to summarize

informationfrom the set of

most-parsimonioustrees. I used strict-consensustrees,

which include groups found in each of the mostparsimonious cladograms,and majority-rule trees,
which includegroupsfound in a definedproportionof cladograms.Consensustrees must be interpretedwith care as they may not be parsimoniousreconstructionsof the original data (Swofford 1992). Nevertheless,consensus
treesremainan efficientway forhighlighting congruentclades,and the charactersand
taxa causing incongruence.

satisfied.Similarityof derivedstateswasthe primary
criterion used (Patterson 1982). Thus, transformation

serieswere proposedif adjacentderived stateswere
similar, and eachsucceedingstatewas a modificationof the previous state (i.e. the derived statesformed anestedsetof synapomorphies).Transformationseriesalso were proposed using ontogenetic information(character7). Justificationsused for ordering are dis-

RESULTS

Syringeal
morphology.--The
main components
of a typical accipitridsyrinx (i.e. supporting
elements, membranes, and muscles) are illus-

tratedin Figure2. Definitionsof syringealstruc-

790

CAROLE
S. GmFHTHS[Auk, VoL 111

t

p
al
bl

Fig. 2. Accipitridaesyrinx(Broad-wingedHawk, Buteoplatypterus,
AMNH 20008).Left-dorsalview andright-ventralview.Abbreviations(numbersfollowingreferto charactersin Appendix2):(a)A elements(1.2);(al) A1 elements(3, 23); (ac) completedouble A elements(5); (bl) B1 elements(34.4, 36); (c) accessory
cartilaginousstructure(44, 45.2);(ce)cartilaginous
extensionof A1 and A2 (12);(im) internalmembrane;(p)pessulus(22.4);(t) tympanum(20,21.124.2,29.3);(m) M. tracheolateralis.
Seetextfor definitionsof structuralelements.In all illustrations,scalebar is 1 mm, stippling indicatescartilaginoustissue,and gray shading
indicates

ossifiedtissue.

turesfollow Ames(1971) and include four types tures to the tracheo-bronchialjunction. Thereof supporting elements:A and B ringlike ele- are no homologiesthat canbe postulatedusing
ments,the pessulus,and accessory
cartilaginous traditional names. For example, the external
structures. Ames (1971) used three criteria formembrane in falconid genera is located bedefining A and B elements:composition,cross- tween the second and third, third and fourth,
sectionalshape,and orientation of concavity.A or fourth and fifth bronchialrings.When theseelements are ossified and flattened in cross secrings are recognizedasA and B elements,howtion, occurring on the trachea as single rings ever, this membraneis alwaysbetweenA1 andbut sometimesextending onto the bronchi as B1,a synapomorphyfor the family. Definitions
paired double rings. They may be complete of rings asA and B elementshave been used in(forming a closedring) or incomplete.In ad- systematicstudies of oscines and suboscinesdition, they maybe fusedpartially or complete- (Ames 1971, Lanyon 1984, Prum 1990, 1992,
ly near the tracheo-bronchialjunction,forming 1993)and, in limited detail,to a broadrangeofa drum or tympanum.B elementsare generally orders (Cannell 1986). My analysisis the firstcartilaginousand D-shapedin crosssection,oc- application of these definitions to detailed
curring as paired rings on the bronchi. These structures in orders other than Passeriformes.
maybe completerings or may havean opening
Ames' (1971) criteria for defining A and B
on themedialsurfaceof each bronchus.

The

pessulus,a cartilaginousor ossifiedbar, is located on the midsagittal plane between the
bronchi.The dorsaland ventral endsof the pessulusmaybe free or mayfuseto A or Belements.
Finally, accessory
cartilaginousstructuresoccur
on the craniadedge of the internal membranes.
Thedefinitionsof A and

B elements

differfrom traditional terminology in which ringed
structuresare tracheal or bronchial rings (King1989)basedon the relative positionof the struc-elements

are sufficientfor most of the families

usedin this analysis.A1 and B1 can be differentiated by cross-sectional
shape and composition in the Cathartidae, Ciconiidae, Ardeidae,

Falconidae, and Strigiformes. However, becausethe first B elementsin severalAccipitridae
speciesare highly ossified,thesecriteria alone
couldnot alwaysdifferentiateA and B elements.
I used an additional

criterion,

the distinctive

shape of the B1 element, for the accipitridsin
this analysis.The first B element is wider me-

October
1994]

Falconiform
Monophyly791

specimen,laterally on the trachea,ending cranial to the junction. These muscleshave also
congruenceof muscleinsertion;the M. tracheo- been describedin Cathartes(Maynard 1897)and
lateralis always inserted on B1 when B1 was are probably the M. tracheolateralis,but thisdiagnosismust be confirmed in intact specidefined using these criteria.

dially than other A and B elements, withnarrower ends. This was corroboratedby the

In additionto structuralelements,the syrinx
is composedof two kinds of syringeal mem-

mens.

producing structures(Gaunt and Gaunt 1985)
and occur in all speciesexamined except the

Intraspecificvariationin morphology.--Assessment of intraspecificvariation revealed several
charactersthat were polymorphic in species
within the Falconidaeand Accipitridaeand were
not used in this analysis.The number of A elementsfusedventrally in the tympanumvariedin Buteoplatypterus(5, 6, or 7), in Accipiterstriatus

ciconiids.

(5 or 6), and in Falcosparverius(3 or 4). The size

branes. The internal
the medial

membranes

are located on

surface of the bronchi

betweenthedorsaland ventral ends of incompleteA and B
elements. These are considered to be the sound-The

external

membranes

are on theof the ventral, ossifiedpatchcoveringthe fused
tympanumrings varied within Buteoand LeuAlthough the locationof an externalmembrane copternisspecies.Finally, the B1 element, alis a synapomorphyfor the Falconidae,the ex- though normally cartilaginous,was partially toistence of external membranes is variable withtotally ossified within several species, thein most of the other families examined and may amountof ossificationvarying intraspecifically.
be correlatedwith structuralmodifications
in
I found no sexualdimorphism in the species
elementsborderingthe membranes.Therefore, for which this information was available. Genthis characterwasof limited usein my analysis. eral patterns in ontogenetic variation were
There are also two classesof syringeal mus- found. Ossificationof the tympanum and A elcles. Intrinsic musclesoriginate and insert on ements increasedin adults comparedto juveAccipiterandsyringealelementsand are important in the sys- niles in Tyto,Buteo,Falco,Pandion,
tematics of the Passeriformes. These do not exist
Cathartes.Fusion of the elementsin the tymin falconiforms.The two extrinsicmusclesorig- panum also increasedslightly in adults cominate outsidethe syrinx. The M. sternotrachealis pared to juveniles of Pandion,Tyto and Falco.
lateralwalls of the bronchi,usuallybetweenA1

and one or two of the first four

B elements.

originates on the internal surface of the coracoldor costalprocessof the sternumand inserts
on several A elementson the trachea.

The M.

tracheolateralisoriginates on the lateral surfaceof the cricoid cartilage of the larynx and descendslaterally down the trachea.In many taxa
it is contiguouswith or underlies the M. sternotrachealis, and the insertion of this muscle
can be somewhat

obscured as a result. Becausemuscle fibers are damaged in cleared specimens, the insertions of these muscles were notalways apparent in specimensI examined andwere of limited use phylogenetically.Where
visible, the M. tracheolateralis inserts: on A1,

Both of these patterns are consistentwith observationsin the Passeriformes(Ames 1971). An
additional pattern was found in the Catharti-

dae.In nestlingCathartes,
singleA elementsimmediatelycranialto the tracheo-bronchialjunction are complete rings. In adults, these areincomplete,with gapsdorsally (character7).

Phylogenetic
analysisof Falconiformes.--Variation in syringeal morphology was coded initially for 103 taxa as 49 characters,of which 33
were binary and 16 were multistate (Appendix
2). Redundant species (those with identicalcharacterstates)were merged, resulting in a
final matrix of 88 taxa (Table 1). Analysis of

B1 and possiblyB2 in the Ardeidae;on B1 in these data resulted in more than 5,000 mostthe accipitrids(includingPandionand Sagittar- parsimonious cladograms,which is not unexius)and in the Strigiformes;and on the lateral pected for a matrix with more taxa than charmembrane in the falconids. This muscle has beenacters.The shortesttreesfound had a length ofclaimed to be lost in Struthio,Casuarius,
Dromaius, 195, consistencyindex of 0.401, rescaledconRhea,Apteryx,the Cathartidae,Ciconiidae,most sistencyindex of 0.358, and retention index of
Pelecaniformes, and some Galliformes (Bed-0.865.

dard 1898,King 1989).Within the ratites,how-

The strict-consensustree (Fig. 3) indicates

ever, the muscle exists but ends where the M.

supportfor the monophylyof the order Fal-

sternotrachealisbegins (King 1989). Similarly,

coniformes. Within

the order, Cathartidae

isI observedmusclefibersin a Coragyps
syringeal basal to a clade of two sister taxa, the Falconidae

792

CAROLE
S. GRIFFITHS[Auk, Vol. 111

TABLE1. Distributionsin 88 taxa of statesof 49 syringeal charactersused in phylogeneticanalysis.See
Appendix 2 for descriptions.
Character
1

Taxon

2

1234567890123456789012345678901234567890123456789

Accipitddae
Accipitercooperii
A. gentilis
A. virgatus
A. striatus

Aegypius
Aquila1010100000012011001114120000400003010012000120101
1010100000010011001114120000400002010010000120011
1010100000011011001114120000400002010001000120010
1010100000011011001114120000400002010010000120001
1010100000012011001112120000200003010000000120000

Pandion

1010100000010011001112110000300003010001000110000
1010100000002011001123110000300003010012000120000
2010100000012011001124130000400004010012000120000
1010100000010011001113021000400001010001000120000
1010100000010011001114120000300004010000000110000
0010100000010011001112120000300004010000000110000
1010100000011011001114120000300004010000000120000
1010100000010011001112120000300003010000000120000
1010100000010011001112110000300004010002000110000
1010100000011011001102110000300003010002010110000
1010100000012011001114120000400002010002000120010
1010100000011011001112120000300003010001000120000
2010100000000011001122110000100003010000000110000
2010100000000011001122130000400001000000000110000
2010100000010011001123120000300002010011000120100
1010100000010011001112120000300003010000010121000
1010100000010011001112110000300003010000000110000
1010100000011011001112121000300003010001000120000
1010100000010011001112120000300005010001000120000
1010100000010011001123120000300005010000000120000
1010100000010011001112120000300003010002000120000
1010100000011011001113120000300003010001000120000
1010100000012011001112120000300003010001000120010
1010100000011011001112120000300003010002000120100
1010100000011011001123120000400001010002000120000
2010100000010011001123130000300002000000000120000
1010100000010011001113120000300003010000000120000
1010100000010011001114120000300004010001000120000
1010100000010011001112120000300005010000000120001
1010100000011011001112121000300003010001000120010
1010100000010011001112120000200003010000000111000
1010100000000011001112121000200003010000010111000
1010100000011011001114120000300004010001000120000
1010100000010011001112120000300003010000010110010
1010100000011011001122120000400004010001000120001
1010100000011011001112120000300003010002000120000
1010100000011011001112121000300003010002010120000
1010100000011011001112110000300003010002000120000
1010100000013011001115010000300001000002100120000

Sagittarius

2010100000000011001122130000020000110002010120000

Daptrius americanus

2010100000000011001121000100030010004100100130000
2010100000000011001121000100030010004100100140000
2010100001000011001121000202020010003300100130000
2010100000000011001121000201020010003301100130000
2010100000000011001121000201020010003200100130000
2010100000000011001121000201020010003300100130000
2010100001000011001121000201020010003200100130000
2010100000000011001121000101020010003000100000000

AvicedaBusarellus
Butastur

Buteo albicaudatus
B. buteoB. jamaicensis
B. magnirostris
Buteogallus
Circaetus
CircusElanoides
ElanusGampsonyx
Geranospiza
Gypaetus
Haliaeetus
Haliastur

Harpagus
Henicopernis
H eterospiz
ias
Hieraaetus

Ichthyophaga
Ictinia

Kaupifalco
Leptodon
Leucopternis
kuhli
L. albicollis
Melierax
MilvusNecrosyrtes
Neophron
Parabuteo

Pithecophaga
Rostrhamus

Spilornis
Spizaetus
Terathopius

Sagittariidae
Falconidae
D. ater

Falcoberigora
F. columbarius
F. mexicanus

F. rufigularis
F. sparverius
H erpetotheres

3

4

October 1994]
TABLE 1.

Falconiform
Monophyly

793

Continued.

Character

Taxon

Micrasturgilvicollis
M. semitorquatus
Microhierax

Polihieraxinsignis
P. semitorquatus
Polyborus
Spiziapteryx

12
31234567890123456789012345678901234567890123456789
20101000000001110011210001100100100
20101000000001110011210002100100100

20101000010000110011210003020200100
20101000000000110011210001100200100
20101000000000110011210003010200100
20101000000000110011210001000300100
20101000000000110011210001020200100

401100100130000
01100100140000
02100100130000
03200100140000
02100100130000
04100100130000
03000100130000

Cathartidae
Cathartes

Coragyps
Vultur20101121000000110110000000000000000
20101111000000110010000000000000000
20101121000000110100000000000000000

00000000000000
00000000000000
00000000000000

Ardeidae

Egretta
Ixobrychus
Nycticorax

20110000000000111000000000000000000
20100000000000111000000000000000000
20100000000000111000000000000000100
10100000000000111000000000000000000
20110000000000111000000000000000000
20100000000000111000000000000000000

Mycteria

21000000000000100000000000000010000

A rdeaBubulcus
Butorides

10000001000000
00000011000000
00000001000000
00000001000000
00000001000000
00000001000000

Ciconiidae

00000000000000

Tytonidae
Phodilus

Tyto20100000100000210100000000000000020
20101000100000110100000000000000020

00000000000000
00000000130000

Strigidae

Otus asio
O. watsonii

20110000101000110100000000000001020
20110000101000210100000000000001030
20110000101000110100000000000001030
20111000101000210100000000001001030
20110000101000210100000000000001020
10110000101000210100000000000001020
00110000101000210100000000001001030
20110000100000110100000000000001030
20111000101000110100000000001001030
20110000101000210100000000001001030
10110000100000210100000000001001030
20111000101000210100000000000001030
20111000101000110100000000000001030

Sula

20100000000000110000000000001000000

Aegolius
Asio otus

A. stygius
Bubovirginianus
Ciccaba huhula

C. virgata
Ketupaketupu
Ninox connivens
N. odiosaN. jacquinoti
Nyctea00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000130000
00000000000000
00000000000000
00000000000000
00000000000000

Sulidae
00000001000000

Pelecanidae
Pelecanus
Galliformes

00100000000000000000000000000000000
00100000000000110000000000000000000

and the Accipitridae(including Sagittarius
andPandion).Two derived charactersunite the three

00000100000000
00000000000000

19). Four characters unite the Falconidae andthe Accipitridae as sistertaxa. Speciesin thesecladesin the order. All specieshave complete, familieshave a tympanumcomposedof A eledouble A elements on the bronchi; these also
ments fused ventrally and dorsally, to which
occurin severalstrigiform genera(character5). the pessulusis attached(characters20, 22). In
Speciesalsohave an ossifiedpessulus,which is addition, these specieshave sheetsof cartilagconnecteddorsallyand ventrally to A elements; inous tissueforming a border cranially on thethe dorsal attachment is lost in Vultur (characterinternal membranes(character44). The tym-

794

C•ROLES. GmFRTHS[Auk, Vol. 111.

2, 3, 32

33, (s)9,18

Ardeidae
Sula

Mycteria
Strigidae
Tyro
Phodilus
Haliastur
Elanoides
Ictinia

Accipiterstriatus
A. gent#is

39,49

Circus

Accipitercooperii

13.2,
39

Busarellus
Aviceda!

Leucopternisalbicollis
Parabuteo

Spilornis
Buteojarnaicensis

Terath.opiusAegyplus
PandionHaliaeetus

Ichthyophaga
Gypaetus
Necrosyrtes
Neophron
Pithecophaga
Butastur

Kaupifalco
Accipitervirgatus
Melierax
Milvus
Rostrharnus

Henl•opernis
Buteo albicaudatus
Buteo buteo
Circaetus
Hieraaetus

36

Buteogallus
Geranospiza
Heterospizias
Leptodon
Leucopterniskuhli
Spizaetus
Buteomagnirostris
Harpagus
AquilaSagittarius

22.2, 23, 24.3

20
21.2,

ElanusGarnpsonyx

41

-19

Falconidae. ß

Vulturß

Cathartes

Coragyps
Pelecanus
Galliformes

Fig.3. Summaryof strict-consensus
treederivedfromthesetof 5,000most-parsimonious
treesfoundfrom
analysisof syringealdata.Synapomorphies
supportingnodesare numbered;descriptionsof charactersinAppendix 2.

October1994]

Falconiform
Monophyly

795

t

al

be

Fig.4. Falconidae
syrinx(BrownFalcon,Falcoberigora,
AMNH 193358).Left-dorsal
viewandright-ventral
view. Abbreviations:(a) A elements(1.1);(al) A1 elements(3); (ac)completedoubleA elements(5); (bl) B1
elements(33,37);(be)fusionof elementends(38.3);(c)accessory
cartilaginous
structure(44,45.3);(e)external

membrane(41);(im) internalmembrane;(p) p.essulus(15,16);(r) ossified
ridge(9);(t) tympanum(20,21.2,
26.2, 28.2, 30.2).

panumis ossifiedtotally in falconidspeciesandin the mostbasalaccipitridspecies,but an al-ventrally to the tympanum,a lateralmembrane
located between

A1 and B1 on which

the M.

ternativepattern(lack of ossification
dorsally) tracheolateralisinserts, B1 elements evenly
existsin mostof the other accipitrids(character wider than other B elements, and fusion of the21).
endsof incompleteA1 and B1 elements(charThereis strongsupportfor the monophyly acters26, 28, 33, 37, 41). A phylogenyof theof the Falconidae.
The falconidsyrinx(Fig.4) Falconidae
ispresented
in aseparate
paper(Grif-is characterized
by a completely
ossified
tym- fiths 1994).
panum,an ossified
pessulus
fuseddorsallyand
The three genera of cathartidsincluded in

Fig.5. Cathartidae
syrinx(TurkeyVulture,Cathartes
aura,AMNH 20933).Left-dorsal
view and rightventralview.Abbreviations:(a)complete
doubleA elements(6,8);(al) A1 elements;(as)incomplete
singleA element(7);(bl) B1elements;(im)internalmembrane;(p) pessulus(16,18).

796

CAROL•
S. GPdl•I•ITHS[Auk, VoL 111
Haliastur

991.
MilvusElanoides
Ictinia

ß

96•
Spilø
Terathopius

98

PandionCircaetus

Spizaetus
Heterospizias

I-'--

Accipiterstriatus

86,_•--L• A. gentills

93

8_• •

A.virgatus

II

Circus96-Lj

Accipitercooperii

83I_[---93

Busarellus

98L--- Aviceda

88 Leucopternis
albicolliParabuteo

90

Buteojamaicensis

Rostrhamus
Butastur

93

911"Kaupifalco
Hieraaetus

Ichthyophaga
Aegypius
94

96I---- Melierax--

Harpagus
Henicopernis
Geranospiza

991 Leptodon
Leucoptemis kuhli
Buteo magnirostris

98

•_•_•

Gypaetus
Necrosyrtes
Neophron
Pithecophaga

99

96]"
Buteo
albicaudatus•
Buteo buteo
Haliaeetus

99•--

Buteogallus
AquilaElanus

Sagittarius
Gampsonyx
Fig. 6. An 80%majority-ruleconsensus
tree of generain Accipitridae.Cladesillustratedare supportedin
at least80%of the most-parsimonious
trees.Numbersindicatepercentsupport;nodeswithout numbersare
supportedin 100%of most-parsimonioustrees.

October
1994]

Falconifortn
Monophyly

797

my studyare unitedby three unambiguoussyn~ not supportedby syringealdata. The serpent
Spilornis,and Circaetus)areapomorphies.Coragyps
is the sistertaxonto Ca- eagles(Terathopius,thartes(Fig. 5) and Vultur.Cathartid speciesare in a clade with four other speciesand are notcommonlyconsideredas lacking a syrinx (Li- sister taxa. The five genera of sub-buteonines
gon 1967, Rea 1983, Gill 1990). Although the included in this analysisare widely separated.
cathartid syrinx does lack somemodifications However, two taxa, Parabuteo and one of thespecies,form a monophyleticgroupoccurringin other falconiform syringes,it has Leucopternis
internal membranes,an ossifiedpessulus,char- with Buteojarnaicensis.
acteristicossificationof A elements,and probThereare no syringealcharacters
uniting theably (as noted above) the M. tracheolateralis. four Old World vultures included in this analis separatedfrom a cladeof three
The unique modificationscharacterizing ca- ysis.Aegypius
thartidsyringesincludedorsalgapsin the most genera (Gypaetus,Necrosyrtes,and Neophron),caudal single A elements, and a minimum of which are united by one unambiguoussynafour complete, medially thin, double A ele- pomorphy (character47). Similarly, there arements on the bronchi (characters 6, 7, 8).
no derived characterssupporting the monoPhylogenyof Accipitridae.--Syringeal data phyly of the two largest genera, AccipiterandgroupSagittarius
and Pandion
with the accipitrid Buteo.Three of the Accipiterspeciesare clusteredis in agenera;this cladeis supportedby three derived together, while the fourth, A. cooperiL
characters (characters 22.2, 23, 24.3). In thesesister clade with Circus, Busarellus and Aviceda.

genera, A1 is not fused ventrally to the tym- There are alsono characterssupportingthe sisand Buteopanum, although fusion and ossificationof the ter taxa relationship of Heterospizias
tympanum is more extensive ventrally than gallus,two speciesthat haverecentlybeensyndorsally.In addition, the dorsalattachmentof onymized(Areadon1982).
Outgrouprelationships.--Iused outgroupsin
the pessulusto the tympanumformscharacteristic patterns different from the falconid pat- this study to polarize characters.Sampling oftern.
generawithin the four ordersof outgroupswas
Limited sampling of genera and the lack of not comprehensiveenough, nor were enoughphylogenetically informative variation of the ordersincluded to derive a phylogenyat thesyrinx preclude my deriving a fully resolved ordinal level. Findingsof my study,therefore,phylogeny for the Accipitridaeand imposecon- should be interpreted with care. Nevertheless,straints

on the inferencesthat can be derived

as a result of the more extensive

examinationfrom this analysis.Nonetheless,there are some of genera within the Ciconiiformes and Strifindings of interest, illustrated in the majority- giformes,someconclusionscan be drawn. Syrule tree (Fig. 6), and someresultsthat indicate ringeal characterssupport the monophyly of
the need for further

research.

Syringealdatasupportthe polyphyly of the
kites.The 17 generacurrentlyconsideredto be
kites have been grouped based on their predatory and socialbehavior and have been consideredprimitive to the otheraccipitrids(Brown
and Areadon 1968),but the monophylyof thisgroup has been questioned(Areadonand Bull
1988).There is supportfor the closerelationshipof the Old World railvine kites, Haliastur and
Milvus, which are sister taxa in 99% of the trees(Fig. 6). Two kites, Elanusand Garnpsonyx,
cur-rently groupedtogetherwith Chelictiniain theElaninae (Brown and Areadon 1968) are not sis-each of the two familiesof Ciconiiformesin-cluded in the analysisbut do not supportthe
monophylyof the order. Three derived characterscluster the three genera of Ciconiidae(characters3, 4, 47; Fig. 7), while one derived
character(character20) unites the six genera of
the Ardeidae

examined.

Syringeal data also support the monophylyof the Strigiformes.Of the two currently recognizedfamilies,Tytonidaeand Strigidae,there
are derived charactersuniting only one, theStrigidae (characters6, 12, 48, 52). Tyto andPhodilusare in unresolved positions relative to
the Strigidae.

ter taxa,but are among the mostbasalaccipitrid
genera.

DISCUSSION

Butasturand Kaupifalcoare thought to be
Systematics
andthesyrinx.--Syringealdata,intheyaresistertaxain thisanalysis.Severalother particular the variation in intrinsic musculaof
speciesgroupingswithin the Accipitridaeare ture, havebeen importantin the systematics

closely related (Areadon and Bull 1988), and798½^ROLE
S.GmF•rHs[Auk,Vol. 111

a2
al
bl
--

b2

P

Fig. 7. Ciconiidaesyrinx (White Stork, Ciconiaciconia,AMNH 1936).Left-dorsalview and right-ventral
view. Abbreviations:(al) A1 element;(a2)A2 element(2); (bl) B1elements;(b2)B2elements(31);(p) pessulus.

the oscines and suboscines, but these data have

beenvirtually ignoredin the systematics
of mostother orders of birds. This may have been the
result of a perception that the structuralelementsof the syrinxoffer minimal phylogenetic
information,and that only the intrinsicmuscles
are informative. One goal of my researchwas
to assessthe usefulnessof syringealdatain resolving phylogenetic relationshipsfor orders
other than the Passeriformes.This analysishasdemonstrated

that there is sufficientvariationin the morphologyof syringealstructuralelementsto derive crediblephylogenetichypotheses for the Falconiformes.

There are, however, a limited

charactersto resolve relationshipswithin the
Accipitridae,a family of approximately60 genera and more than 200 species,there is sufficientvariationto producea robustphylogenyfor afamily with 10 genera (Griffiths 1994).

Phylogenetic
relationships.--Estimatesof phylogeneticrelationshipsof the five generawithin the Cathartidaeare ambiguous,but there isconsensusthat the smaller cathartids (Cathartes

andCoragyps)
aresistertaxato the othergenera(Fisher1944,Emslie1988).Syringealdata support the basalpositionof Coragyps,
whereasCathartes and Vultur are sister taxa. A more com-plete taxonomicsamplingis neededto resolve
number ofstructurescomprisingthe syrinx and a limit to
the variation. Thus, the presenceof majorstructural elements (e.g. presenceof a tympanum,
presenceand location of lateral membranes,ordifferentpessulusmorphologies)providessynapomorphiesdefining ordersor familiesof birds.
Minor structuralvariantsprovidecharactersthat
define genera and resolve some generic relationshipswithin families.Theseincludechanges
in the shapeof B1 or A! elements,the shapeof
the ends of incomplete elements,and variationsin the degree of ossificationor fusion of the
tympanum. Although there are not enoughthe phylogeny of the cathartids.
Syringeal data resolve relationships in thefalconids(Griffiths1994),but not the Accipitridae. One surprising result is the inclusion of

Sagittarius
and Pandionwithin the Accipitridae.
Sagittarius
is divergentin externalmorphology,
behavior,and osteologyfrom the other accipitrid genera, and has been consideredcloser tothe Gruiformesthanthe Falconiformes(Pycraft! 902,Mayr andAmadon! 95!). Thisdivergencehasbeenthe justificationfor elevatingSagittariusto a monotypicfamily separatefrom the other clades within the order. Pandion has received
similar taxonomic treatment. The distinctiveOctober
1994]

Falconiform
Monophyly

treatment of these two specieshas not been
supportedby my phylogeneticanalysis.Thus,
the characterssuggestingthe distinctivenessof
these two speciesmay be autapomorphiesand
may suggesthigh ratesof phenotypicevolution
in thesespeciesrelative to other accipitrids.
Monophylyof Falconiformes.--The
composition of the Falconiformeshas been a point ofcontentionsincethe order was defined.At present, the mostproblematictaxonis the family of
New World vultures (Cathartidae). There is a799

angle above the antitrochanterin the Ciconiidae and Cathartidae, and a 45ø angle in the
Accipitridae. However, my observationsindicate that the curvaturetermediate

betweenin the Cathartidae

is in-

the other two families.

Us-

ing this characterto unite the cathartidswith
either of the other two groups requiresan extremely subjectivedecision.Similarly, the location of the anterior

iliac crest is intermediatein the Cathartidaecomparedto the other two
families,as is the crossingof the coracoidalsul-

growing consensus
that this family is the sister ci, the shape of the ilioischiatic fenestra, andtaxonto the Ciconiidae(Emslie1988,Holdaway the angle at which the bicipital crestjoins the1991),with three studiesofferedas support:Li- humeral shaft. In addition, several of Ligon's
gon (1967), Rea (1983), and Sibley and Ahlquist characters are composites that oversimplify(1990).
variation or ignore variation in the accipitrids
Ligon (1967) and Rea (1983) each reviewed a (e.g. the cathartidsand ciconiidshave a stocky
rangeof charactersfor taxain the Ciconiiformes or stoutand sigmoidalhumeral shaft). Within
and Falconiformes, and each concluded that Cithe accipitrids, the shaft is "often slender"; itconiidae and Cathartidae
were sister taxa. Howappearedto be stockyin my observationof Hiever, these studieswere produced before cla- eraaetus.
Rea (1983) presentedlists that are diagnoses
distic methodology was in general use inornithologicalanalyses,and the data in these of the Ciconiiformes(including the Cathartistudies were not analyzed phylogenetically. dae) and major groupswithin that order. His
Each study simply lists the taxa and the char- choiceof charactershas similar problemsto Ligon's. For example, Rea listed charactersunitacterstatesdiagnosingthe taxa.
There are additional problemswith their con- ing Ciconiidae and Cathartidae,which should
clusions because of the limited number of taxa
be absentin Accipitridae,but are presentin thatsampled.Ligonlisted49 osteologicalcharacters family. These include the presenceof M. amand examined three genera within the Cathar- biens(Georgeand Berger1966,McKitrick 1991),
tidae, three within the Accipitridae, and six the presence of full spread-wing posturesin
within the Ciconiidae. Of these, 27 cluster Cisunning (Simmons1986), and the absenceof
M. femorocaudal(Georgeand Berconiidae with Cathartidae, and only 6 cluster the accessory
Accipitridae with Cathartidae. I examined skel- ger 1966).Someof his charactersignore or overetons of 10 genera (Ciconia,Leptotillus,Sarcor- simplify variation. Thus, a "variably degenerhamphus,
Vultur,Hieraaetus,
Buteo,Aquila,Accip- ate" syrinx unites Ciconiidae and Cathartidae.
iter, and Falco) and researched additional
However, the syrinx is not one organ but a seanatomicalstudies.At best,only 8 of Ligon's27 ries of modificationsof structures,and my analcharacters
supportgroupingthe Ciconiidaeand ysis indicates that the variation in syringeal
Cathartidae.
Several characters he used to unite
morphologycannotbe describedin one charciconiids and cathartids, or to separatecathar- acter. When fully described,the variations dotids and accipitrids, occur in accipitrids or ca-

not unite

Ciconiidae

and Cathartidae.

thartids that he did not sample. Ligon listed
Finally, Rea (1983) listed charactersuniting
basipterygoidprocessesas not present in the Ciconiidaeand Cathartidae,which are, presumAccipitridae.However, they existin severaltaxa ably, unique to those two families. However,(Shufeldt 1909, pets. obs.),and his illustration these also can be found in other orders of birds.
on page 5 showstheseprocessesin Necrosyrtes. Thus, urohydrosis(urination usedas a cooling
He lists a prominent foramen on the humeral mechanism),listedas occurringonly in Ciconshaft, and one pair of sternal manubrial fenes- iidae and Cathartidae, also occurs in the Sulidae
trae as occurringin Accipitridae only. These (order Pelicaniformes; Carboneras 1992). The
also occur in the Cathartidae.

Someof the describedcharacterstatesgrade
into one another. The curvature of the pelvic
girdle is describedby Ligon as having a slightpattern of macrochromosomes
sharedby Ciconiidae and Cathartidae are, in fact, more closelysharedby the Cathartidae,Galliformes,Gruiformes,and Phoenicopteriformes(de Boer1975).

800

CmtOLE
S. GPd•m•HS

M. pectoralis major is described as double instorks and cathartids. However, it is also double
in Gruidae, Procellariiformes, and Pelecani-formes (George and Berger 1966). The most serious problem in both studies is that, withouta phylogeneticanalysis,none of the characters
describedby Ligon and Reacanbe usedto demonstratea relationship between the Ciconiidae[Auk, Vol. 111

within the Falconiformes.In addition, syringeal data provide support for the monophylyof three major cladeswithin the Falconiformes:
the Cathartidae, the Falconidae, and an Accipitrinae-Sagittarius-Pandion
group.
ACKNOWLEDGMENTS

and Cathartidae;the charactersmay all be ple-

This studywould not havebeencompletedwithout
the guidanceand supportof G. Barrowcloughand R.
er any of their dataare derivedcharactersshared F. Rockwell.I thank the following curatorsfor lend-siomorphicor convergent.Determining wheth-by thesetwo familiesawaitsan extensivesurvey ing me specimensfrom their collections;G. Barrowof generawithin eachof thesetwo familiesand clough,R. Zusi, V. Remsen,A. Baker,and N. Johnson.
other familieswithin the two orders,and a phy- Discussionswith R. Prum and P. Cannell provided
insightinto the useof the syrinxin systematics.
Comlogeneticanalysisof the resulting data.
ments on earlier versions of this manuscript wereSibley and Ahlquist (1990) used DNA-DNA
provided by C. Farquahr, E. Griffiths, J. Groth, M.
hybridization data to generatephylogeniesfor Novacek, S. Rather, and P. Sweet. Final versions were
all birds.Although widely cited,there are some improvedby reviewsfrom J. Bates,J. Cracraft,F. Gill,
problemswith the methodology,analysis,and S. Hackett,and D. Zusi. This researchwassupported
results of these data (e.g. Barrowclough 1992, by grantsfrom the FrankM. ChapmanMemorialFund
Cracraft1992,Lanyon 1992,Mindell 1992).One of the AmericanMuseumof Natural History,a Chapprimary claim of these data is the sister-taxa man Pre-doctoralFellowship,and a City University
relationship of the cathartidsand ciconiids.Sib- of New York DissertationImprovement Grant.
ley and Ahlquist (1990) presentedtwo different
hypothesesof cathartid relationships:a Fitch
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Falconiform
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WARNER,
R.W. 1972. The anatomy of the syrinx inpassefinebirds. J. Zool. (Lond.) 168:381-399.

[Auk,Vol. 111

193358. F. biarmicus, AMNH
15927. F. cenchroides,
AMNH 193394. F. columbarius, AMNH 19752, 14713.

F. femoralis,LSUMNS 123309.F. mexicanus,
KUMNH
053827.F. peregrinus,
AMNH 8499,19751.F. rufigularis,
KUMNH 041874.F. sparverius,
AMNH 8430 male, 8688
female, 8413 male, 15808, 15931, 16307, [CSG9210],(UNS) AMNH [CSG21, 1216 male, 1217imm. female].

APPENDIX 1

H erpetotheres
cachinnans,
AMNH unnum.MicrasturgilSyringealspecimensexamined.Specimenscleared vicollis,LSUMNS 98021. M. semitorquatus,
USNM
and double-stainedunless designatedas unstained 507797. Microhieraxerythrogonys,
AMNH 8623. Mil(UNS). Abbreviations for institutions from which
vagochimachima,
LSUMNS 120427.M. chimango,
USNM
specimenswere borrowedare given in the Materials 346421. Phalcoboenusaustralis,USNM 511795, LSUMNSand Specimenssection.Uncatalogedspecimensiden- 120728.Polihieraxsemitorquatus,
USNM 615218.P. intified by a collector'snumber in brackets.
signis,AMNH 8627. Polyborus
plancus,AMNH 9094.
ACCIPITRIDAE: Accipiterstriatus,AMNH 18761, Spiziapteryx
circumcinctus,
LSUMNS 8 Sep 1990.
18762,8686,8482,15938imm. female,[CSG9212,9215],
CATHARTIDAE: Coragypsatratus,AMNH 19607,
1 Dec 1985 imm. female, (UNS) AMNH unnum. 1985 (UNS) [PRS 245]. Cathartesaura, AMNH 20933, unmale,[CSG9213].A. gentilis,AMNH 17Dec 1984male, hum. Dec 1985, [PFC443], nestling. C. melambrotus,

11 Apr 1991imm. male.A. virgatus,
AMNH 8030.A.

LSUMNS 114336. C. burrovianus,USNM 227269. Vultur

cooperii,AMNH

gryphus,AMNH 8498.

20007, 20623, [CSG 16, 9217, 9218,

ARDEIDAE: Ardea herodias, AMNH 8933. Bubulcus
9264 imm. female]. Aegypiustracheliotus,
KUMNH
81668. Aquila audax,USNM 289389. A. chrysaetos, ibis, AMNH 8624. Butorides striatus, AMNH 20736.
LSUMNS 126432. Aviceda subcristata,AMNH unnum.
Egrettacaerulea,AMNH [PFC 427 imm. female]. Ixob1950. Busarellus
nigricollis,LSUMNS 120424. Butastur rychussinensis,AMNH 8621. Nycticoraxnycticorax,

indicus,AMNH

8497. Buteoalbicaudatus,AMNH

8683.

B. buteo,USNM 541690.B. jamaicensis,
AMNH 18764,
20546, unnum. 1985. B. magnirostris,
ROM 104270.B.
platypterus,AMNH 18763, 8687, 20008, [CSG 9211],

AMNH 8625, 20335, (UNS) AMNH 8432.
CICONIIDAE: Ciconiaciconia,AMNH unnum. 1936.

C. nigra,AMNH 6377.Ephippiorhyncus
asiaticus,
USNM
510447(incomplete).Mycteriaamericana,
AMNH 8513,(UNS) AMNH 21464.B. regalis,AMNH 19629.Buteo- (UNS) AMNH 9038, 9062, 9063, [MYC 85003, 85004,
gallus urubitinga,LSU 114340. Circus approximans, 85006-85009].
AMNH 4-24. C. macrourus,
USNM 615215.C. cyaneus,
TYTONIDAE: Tyto alba,AMNH 14715, 8680, 8682,

USNM 226415.Elanoides
forficatus,
AMNH [ROP270].

20624, [CSG 9216]. T. tenebricosa,
AMNH 7495. Phodilus

Elanusleucurus,KUMNH 56804. Gampsonyx
swainsonii, badius, AMNH 6419.
AMNH 8529.Geranospiza
caerulescens,
LSUMNS 120423.
STRIGIDAE: Aegoliusacadicus,
AMNH 8489, [CSG
Gypaetusbarbatus,
AMNH 6398. Haliaeetusleucoceph- 9214].Asiootus,AMNH 8312.A. stygius,
AMNH 7466.
alus, KUMNH
46189, ROM 132599. Haliastur indus,
A. fiammeus,
AMNH 8684. Bubobubo,AMNH 7450. B.
AMNH 8496. Harpagusbidentatus,
LSUMNS 114345. shelleyi,
AMNH 8414.B. virginianus,
AMNH 16092,[SC
Henicopernis
longicauda,
USNM 615210. Heterospizias 957 imm.]. Ciccaba
huhula,AMNH [SC407]. C. virgata,meridionalis,
AMNH unnum. Hieraaetusmorphnoides, (UNS) AMNH 7408.Ketupaketupu,BM A1981. Glau-AMNH unnum.Ichthyophaga
nana,AMNH 8399.Ictinia
plumbea,
AMNH [ROP271].I. mississippiensis,
KUMNH
049239.Kaupifalco
monogrammicus,
USNM 615217.Leptodoncayanensis,
LSUMNS 120426. Leucopternis
albicoilis,AMIqH 8492,[ROP377].L. kuhli,LSUMNS 114338.
Melieraxcanorus,USNM 615216.Milvusmigrans,
USNM
615213.Necrosyrtes
monachus,
USNM 34631.Neophron
percnopterus,USNM 615217. Parabuteounicinctus,
AMNH 19590.Pithecophaga
jefferyi,AMNH 6396.Rostrhamus sociabilis,USNM 615212, AMNH

[CSG 232,

cidiumbrasilianum,
AMNH [SC302,410,268].G.gnoma,
AMNH 7404.Ninoxjacquinoti,
AMNH 7422.N. odiosa,
AMNH 7423. N. connivens,
AMNH 7442.N. philippensis,AMNH 8490. N. scutulata,AMNH 8615. Nyctea
scandiaca,AMNH

8836. Otus asio,AMNH

ia, AMNH 7439.
PHALACROCORACIDAE:

Phalacrocorax auritus,711]. Spilornischeela,AMNH 8616. Spizaetusornatus, (UNS) AMNH unnum.
SULIDAE: Sula bassanus,AMNH
LSUMNS 3053.Terathopius
ecaudatus,
AMNH unnum.
PANDIONINAE:

Pandion haliaetus, AMNH

8488

8310, 20625.

O. watsoniœ
AMNH 8685.O. nudipes,
AMNH 7438.O.
guatemalae,
AMNH 7437.Pulsatrix
perspicillata,
AMNH
2784.Speotyto
cunicularia,
AMNH 8679,7447.Strixvar-

8618, 8846. Sula

imm. male, 18808 female, [PFC445 female], USNM

nebouxi,(UNS) AMNH 8618.
PELECANIDAE: Pelecanus roseus, (UNS) AMNH

615209.

8619.

SAGITTARIIDAE:Sagittarius
serpentarius,
YPM 3721,
MVZ

4611.

FALCONIDAE: Daptriusamericanus,
AMNH 8667,[ROP266].D. ater,KU068951.Falcoberigora,
AMNH

CRACIDAE: Craxalector,AMNH 15006, (UNS) [PFC412].

PHASIANIDAE: Tetraoparvirostris,(UNS) AMNH
14100.

October
1994]

Falconiform
Monophyly
APPENDIX

2

Descriptionsof 49 syringealcharactersusedin analysis. Derived statesare describedfirst. Characters7,
26, 28, 38, 40 are multistate, ordered characters;justification for ordering follows descriptions.Characters I, 13, 15, 21, 22, 24, 29, 30, 34, 37, and 45 are
multistate

unorderedacter states shown

characters.
in Table

Distribution

1. Charactersin Figures 2, 4, 5, and 7.
A elementsof charillustrated

803

9. Incomplete
A1 elements
widerlaterally,thickerandmoreossified
thanotherdoubleA elements.--(1)Yes.In
Strigiformes.(0) No.
10. Dorsalendsof incomplete
A1 elementsconnected
mediallyformingridgeof ossified
tissue.--(1)In several
Falcospeciesand in Microhierax.
(0) Not present.
11. Ventralendsofincomplete
A1 elements
extendontointernalmembrane
formingamorphous,
ovoidaccessory
cartilaginous
structures.--(1)In strigid genera.(0) Not
present.

12. Ventralendsof incomplete
A1 and A2 elements
extendontocranialsurfaceof internalmembrane.--(1)In

accipitrid genera. (0) Not present.
of caudaledgesof dorsalendsof in1. OssificationofA elements
cranialtotracheo-bronchial 13. Modifications
A1 elements.--(1)Slight pointed cartilaginous
junction.--(1)Completelyossifiedin all generain Fal- complete
extensionof ends. (2) Large cartilaginousextension
conidae and Cathartidae, and in most genera in Striedgeof internal
membrane.
(3)Endsfused
giformes,Ardeidae,and in severalaccipitrids.(2) Os- borders
siftedventrally and laterally,but cartilaginousdorsally to ends of B2 elementsforming rings in Pandion.(0)in most accipitrid genera. (0) No ossification.Ele- A1 ends unmodified or single element.
14. Dorsalendsofincomplete
A1 elements
fiattenedandments cartilaginousin Pelecanus,
the two speciesof
forminga paddleshape.--(1)In MicrasturspeGalliformes,and in juveniles in Strigiformes,Acci- enlarged
cies. (0) Not present.
pitridae, Cathartidaeand Falconidae.
2. A elementsimmediatelycranialto tracheo-bronchialjunctionthinnerthansubsequentelements
andincomplete
Pessulus
laterally.--(1) In the Ciconiidae. (0) Not present. A
15. Pessulus
composition.--(1)Pessulusossified.(2)elementscompleterings in lateral view.
3. IncompletedoubleA elementson bronchicaudalto Pessuluscartilaginousin several strigid genera. (0)Phalacrocorax,
Podtracheo-bronchialjunction.--(1)Yes.One or two present Pessulusnot presentin Pelecanus,
Struthio,Casuarius,
Dromaius,or Apin speciesin all families examinedexceptCiconiidae. iceps,Spheniscus,
Gapsbetweenendsof incompleteelementson medial teryx.
16. Pessulus
an extension
of A elements.--(1)Yes. (0)walls of bronchi, forming lateral bordersof internal
membranes. (0) No A elements on bronchi in ciconiid
No. Pessulusnot presentin Pelecanus.
In Ciconiidae,
pessulusan extensionof B elements,an autapomorgenera.
4. More thanthreeincomplete
doubleA elements.--(1) phy for that family and not included in this analysis.
17. Ossifiedridgesat dorsaland ventralendsof pesAt leastfourincompletedoubleA elements;in several
generain the Ardeidae;in all generawithin the Stri- sulus.--(1) In Ardeidae. (0) Not present.
18. Dorsally,pessulus
endsmedially.--(1) In Strigigidae. (0) No. A4 either single element or complete
double elements.
dae, Vultur; Cathartespolymorphic for this character
5. CompletedoubleA elementson bronchicaudalto (see character 19). (0) No.
19. Dorsalandventralendsof Pessulus
extendcaudally
tracheo-bronchialjunction.--(1) Yes. In all genera in
Cathartidae,Accipitridaeand Falconidae;in several from A elements.--(1)Yes. In all specieswithin Falconidaeand Accipitridae.In Coragyps,
in someadultgenera in Strigiformes.(0) Not present.
and in juvenal Cathartes.
(0) No.
6. More than three completedoubleA elements.--(1) Cathartes
Yes.All cathartidgenerahave at leastfour complete
double A elements. (0) No.

Tympanum

7. SingleA elementsimmediatelycranialto tracheo20. Fusionof A elements
cranialto tracheo-bronchialbronchialjunctionincomplete,with gap in elementdorsally.-(1) One or two A elementsincompletewith junction.--(1)In accipitridand falconidgeneraand in
tympanumformed from lateral, ventral,small gaps between ends in Coragyps(2) More than Sagittarius,
threeA elementsincompletewith largegapsbetween and dorsal fusion of A elements. Patterns of fusion
the ends of each element, in Cathartes and Vultur.
and ossificationvary among families; describedin
Unique to Cathartidae.Transformationfrom state 1 following characters.(0) No fusion of A elements.
to 2 observedin ontogeny of Cathartes.(0) No. In all
21. Degreeofdorsalossification
oftympanum.--(1)Osother families, single A elements complete when siftedmedially and laterally only in most accipitrid
genera.(2) Ossifiedcompletelyin all falconidgenera
viewed dorsally.
8. Medial cartilaginous
sectionof complete
A elements and severalaccipitrids.(0) Tympanum not present.
22. Dorsal pessulusattachmentto tympanum.--(1)narrowerthan lateral,ossified
section.--(1)Yes. In Cathartidae. (0) No.
Narrow, more highly ossifiedmedial strip extends

804

CAROLE
S. GRIFFITHS[Auk, Vol. 111

B elements
cranially connectingseveralA elements;in falconid
genera.(2) Ossifiednarrowly, ends at or just above
tracheo-bronchialjunction; in some accipitridsand
31. All B elementscompleterings.--(1) In Ciconiidae.
Sagittarius.
(3) Ossifiedbroadly, ends at or just above
tracheo-bronchialjunction in ovoid- or diamond- (0) In other taxa,B elementswith medial gaps.
32. B1at obliqueangletransversely.--(!)In Strigidae.
shaped pattern; in some accipitrids. (4) Ossified
broadly, extendscranially connectingone or two sin- (0) In othertaxa,B1perpendicularto transverseplane.
33. B1 evenlywider than other B elements,concave
gle A elementsmedially; in someaccipitrids.(5) Os(0) B! notsiftedbroadly,extendscraniallyand laterallyforming caudally.--(!) In all falconids;in Butorides.
a cross-likepattern, in Pandion.(0) Tympanum not concavecaudallyin any other genera;samewidth asother B elementsin all other taxa exceptaccipitrids
present.

(character 35).

23. A1 not fusedventrallyto tympanum.--(1)In all
34. Modifications
ofshapeofincomplete
B1elements.-accipitridsand Sagittarius.
(0) A! fusedin the Falcon(!) Wider at dorsalends. (2) Slightly wider laterally,idae. In other taxa, there is no tympanum.
24. Patternof partialdorsalfusionof A elements.--(!) with narrowed ends. (3) Small arc-shapedextension
Slight fusionmedially along caudaland cranialmar- on cranial margin laterally. (4) Largearc-shapedexgins of two elements.(2) Medial, triangular-shaped tension on cranial margin laterally. (5) Very wide
cartilaginousplug fusesseveralelements.(3) Medial dorsally,with slight narrowing at ventral ends. In
plug ossified,elementsalso fused somewhatalong accipitridsand somestrigids.(0) Not present.
35. B1, B2 andB3 concave
cranially.--(1) In Sagittarmargins.Derived unorderedstatesdescribeaccipitrid
ius. (0) No.
tympanum. (0) Total fusion in Falconidae;in other
36. B1 overlapsA1 laterally.--(!) In accipitrid gentaxa, no fusion of elements.
era. (0) Membrane separatesA1 and B! in other taxa.
25. More thansevenringsfusedto dorsalcartilaginous
37. Modificationof shapeof dorsalendsof B1 elements
plug.--(!) In five accipitrid genera.(0) Six or fewer
fusingwith
A1elements.--(!)
Endsvery thick and wide,
rings fusedin all other accipitridsand falconids.No
ascendsharply in L-shapeto fuse with A! ends. (2)dorsal fusion in other families.
26. Shapeof ossified
andfusedtympanum.--(!)Grad- Endsthin, ascendgradually to fuse with A1 ends.(3)Knobbingof craniadedges;craniadextensionfuses
uated,widens caudally.(2) Almost cylindrical. (3) Almost cylindrical, A1 flattened laterally. In the Fal- with A! ends. (4) Endsthick, rounded, ascendgradually to fusewith A1. Derived statesin falconidgenconidae. State 3 modification of state 2. (0) No
systematicvariation in accipitrid tympanum shape. era. (0) B! elementscompletein Ciconiidae;endsnot
modified in other species.
In other taxa, no tympanum present.
38. Fusionof A1 andB ventralends.--(!) A! and B1
27. DorsalfusionoffirsttwosingleA elements
medially
endsfused.(2) B2endsalsofused.State2 modification

byossified
bar.--(!) Yes.In Micrastur.(0) Not present.
of state 1. (3) B3 ends also fused. State 3 modification
28. DorsalfusionoffirstthreeorfourA elements
along
their margins.--(!)Margins apparentalong edgesof of state2. In falconidgenera.(0) Not present.
39. Fusionof B1 andB2 dorsalends.--(!) In Accipitereachring. (2) Marginssomewhatobliteratedand only
light suturesapparentmedially.Derived statesin fal- and three other accipitrid genera. (0) Not present.
40. Fusionof B ventralendsformingridgebordering
conidgeneraexceptMicrastur.State2 modificationof
state 1; fusion increased.(0) No. Partial fusion in theaccipitrids(character29), and in Micrastur(character
27). In other taxa, no dorsal fusion.

29. Patternofpartialventralfusionoftympanum.--(!)
Slight roedialfusionof A elementsalongmargins.(2)Triangular-shapedossifiedpatch coversmedial fusionof A elements.(3) Irregular, smallovoid ossified
patch coversroedial fusion. (4) Large ossifiedpatch
coversfusion of A elements medially and laterally.
In Accipitridae,SulaandsomeStrigiformes.
(0) Fusion
total in falconids,lacking in other taxa.
30. Patternof total ventralfusionof tympanum.--(!)
First three or four A elementsfusedalong margins.
Spacesapparentbetweenelements.(2) First three orfour A elementsfusedlightly, suturesapparentalong
margins.(3) At least five A elementsfused entirely
alongmargins,suturesapparentonly laterally.In falconids.

(0) Fusionpartial in accipitrids,lackingin other taxa.

internal membranes.--(!) B! and B2 ends fused. (2) B3
ends fused also. State 2 modification of state !. (0)Not present.
Membranes

and muscles

41. External membrane between A1 and B1 elements.--(1) In all falconid genera;in Pandionwhich hasmembrane between B! and B2 also. (0) Not present.
42. External membranesbetweenB2-4 elements.--(1)In severalaccipitridsand Sagittarius.
Thesehave external membranebetweenB1 and B2, alsooccurringin many accipitridgeneraand not usedasa characterbecausegenerallysmall,with intraspecificand individual variation in its occurrence;may be an artifactof preservation.(0) Not present.
43. M. tracheolateralis
insertslaterallyon A1.--(!) In
the Ardeidae and in Sula. (0) In Falconidae, M. tracheolateralisinsertson lateral membrane, in Accipit-

October1994]

Falconiform
Monophyly

ridae and Strigiformes,inserts on B1. Not coded inanalysisbecausecorrelatedwith other characters.See
text for discussionof M.

tracheolateralis

in Galli-

formes, Cathartidae and Ciconiidae.

Accessorystructures

44. Cartilaginous
borderlocatedon cranialedgeof internalmembrane,
extendingfromdorsalto ventralendsof
membrane.--(1)Present.(0) Not present.
45. Shapeof cartilaginous
border.--(1)Narrow, thicker dorsallythan ventrally.(2) Wide, thickerdorsallythan ventrally. (3) Wide and even. (4) Narrow andeven. (0) Not present.

805

46. Borderossified.--(1)In three taxain Accipitridae.
(0) Not present.
47. Smallcartilaginous
paddle-shaped
accessory
structuresextendontointernalmembranes
fromdorsal
A 1 ends.(1) In severalaccipitridspecies.(0) Not present.
48. Smallcartilaginous
peaksextendcaudallyontointernal membranes
medially.--(1) In several accipitrid
species.(0) Not present.
49. Internalmembranes
almostparallel.--(1) In Accipiter (0) No internal membranes in Ciconiidae. Internal
membranesat angle to each other when viewed dor-sally in all other species.