Table Of ContentBonnerzoologische Beiträge Band 55 (2006) Heft 2 Seiten 159-162 Bonn, Juli 2007
Morphological differentiation of mainland Citril Finches,
Carduelis [citrinella] citrinella and insular Corsican (Citril) Finches,
Carduelis [citrinella] corsicanus
Marc Imanuel Förschler^'-^ & Karl Heinz Siebenrock-^
' Institut für Vogelforschung. "Vogelwarte Helgoland'', Germany
2 Max Planck Institut für Ornithologie, Vogelwarte Radolfzell, Germany
The Citril Finch is one ofthe few endemic bird species Only little data has been published on evidence for dif-
restrictedto European mountains (Voous 1960; Newton ferentiation in morphological charactertraitsbetweenthe
2003). Two allopatric forms may be distinguished. Insu- two fomis.Accordingtotheavailablenotesonmorphom-
lar Corsican (Citril) Finches, Carduelis [citrinella] cor- eti7, both species do not show large geographical differ-
sicamis, live exclusively on Corsica, Sardinia and some ences in body size (Alonso &Arizaga 2006; Borras et
Tuscany islands (Capraia, Elba, Gorgona) (ArCamone al. 1998; Brandl & Bezzel 1989; Cramp & Perrins
1993; Baccetti & Märki 1997; Cramp& Perkins 1994; 1994; Märki &Biber 1975),withtheexception thatCor-
Thibault 1983; Thibault & Bonaccorsi 1999; Molto- sican Finches seem to have generally slightly shorter
Ni 1975),whereasmainlandCitril Finches, Carduelis[ci- wings than nominate Citril Finches (Cramp & Perrins
trinella]citrinella,occurathigherelevationsinthemoun- 1994). Nominate birds in the Eastern Pyrenees appear to
tain ranges of central and south-western Europe (Alps, have longerwingsthandonominatebirds intheAlps,but
BlackForest,Vosges,Jura, MassifCentral,Cevennes, Py- evidence isweakandmaybealsoduetovariationbetween
renees, Cantabrians and Sierras ofcentral Spain), gene- different measurers (Brandl & Bezzel 1989; Borras et
rallyabove 800 masl. (Baccetti & Märki 1997; Cramp al. 1998; Märki & Biber 1975).AdultmaleCitril Finch-
& Perrins 1994; Glutzvon Blotzheim & Bauer 1997; eshaveanaveragepopulationweightof12.5 gin theEast-
Hölzinger 1997). ern Pyrenees (Borras etal. 1998), whileadult male Cor-
sican Finches are little bit lighter with 1 1.5 g in average
There isanongoing debate aboutthetaxonomic status of (Nicola Baccetti, Gilles Faggio, Sergio Nissardi &
Citril Finches and Corsican Finches. In spite ofrecently Philippe Perret, pers. comm.).
DNA
detected genetic differences (mitochondrial differs
by2.7 %),theauthorsofthese studiesstill regardthetwo We analysed 20 morphological charactertraits following
forms as conspecific (Pasouet & Thibault 1997; the methods ofLeisler & Winkler (1985, 1991, 2001),
Thibault & Bonaccorsi 1999). In contrast, Sangster Leisleretal. (1997)andKorner-Nievergelt&Leisler
(2000) assigned species status to the Corsican Finch, re- (2004). The following external features were measured.
ferring to the same genetic results. Based on his recom- (1) wing length (the distancebetween carpaljoint andtip
mendations in combination with data on variations in offalltened wing); (2) tail length (from insertion ofcen-
plumage colouration (Cramp & Perrins 1994; Pasquet tral pair offeathers to tip oflongest rectrix); (3) fork of
1994) and vocalization (Chappuis 1976; Cramp & Per- thetail (difference from longestto shortestinnerrectrix);
rins 1994; recently confirmed by Forschler & Kalko (4) wingwidth (the distancebetween caipaljointandthe
2007),theAssociation ofthe European Rarities Commit- tip ofthe longest secondary); (5) primary projection (the
tees(AERC)nowtreatsthetwoformsasfull specieswith distance between tip of 1^^ secondary and wing tip); (6)
their own evolutionary histories (Sangster et al. 2002). distal (the distance between tip of10"^ primaiy and wing
Furthermore the two species have been recently reclassi- tip); (7) alula (the distance between caipal joint and tip
fied within the genus Carduelis instead ofbeing a mem- ofthe longestalula); (8)notch P2i (length ofnotch on in-
beroiSerinus (Arnaiz-Villena etal. 1998, 1999). Both nerwebofsecondprimary); (9)notch P3o(lengthofnotch
forms are therefore members ofthe superspecies Cardu- onouterwebofthirdprimary); (10) Kipp Index(distance
elis [citrinella] (Barthel & Helbig 2005; Helbig2005). of secondary to wing tip x 100/ wing length see Kipp
160 Marc Imanuel Förschler & Karl Heinz Siebenrock; Moiphological differentiation of(Citril) Finches
1959) (11) bill length (from tip to skull); (12) bill width We found significant morphological differentiation be-
(at the rear end ofnostrils); (13) bill height (maximum tweenmainlandCitril FinchesandinsularCorsican Finch-
depth); (14)rictal bristles(the lengthofthevibrisseatthe es (see Table 1). Corsican Finches are generally smaller.
bill base) (15) tarsus length (from notch ofthe inteitarsal Wingsareconsiderably longerandmorepointed(KippIn-
joint to the lower edge ofthe last complete scale); (16) dex) in Citril Finches.Accordingly, significantvariations
tarsusdiameter 1 (lateralmaximaldiameteroftarsus); (17) may bealsofoundbetweenotherwingmeasurements(sec-
tarsus diameter 2 (sagittal maximal diameter ofthe tar- ondary, primaryprojection, distal, alula,notch P2i, notch
sus; (18) hind toe (length of digit 1); (19) middle toe P3o). Corsican Fincheshavea shortertail andtheirtail is
(length ofdigit 3); (20) hind claw (the cord from the tip lessforked. FurthermoreCitril Finchespossesssignificant-
to dege ofthe skin ofnail); (21) middle claw (the chord ly broader, higher and longer bills than Corsican Finch-
ofnail 3); (22) index ofwing length/ tarsus length. es. No significant difference was found for the length of
the rictal bristles. Citril Finches have longer and stonger
In total we measured 23 individuals of mainland Citril tarsi, a longermiddle toe and longerclaws. Howeverthe
Finches from the NorthernAlps and 13 individuals ofin- length ofthehindtoe (maybeduetomeasurementerrors)
sularCorsican Finches fromCorsicaandSardinia. Forour and the ratio ofwing length to tarsus length are not sig-
study we used only adult males to guarantee comparabil- nificantly different.
ity. All measurements were conducted by Karl Heinz
SlEBFNROCK. Museum specimens from the followingmu- Climate is known to play an important role in geograph-
seum collections were used exclusively: Zoologische ic size variation (James 1970; Johnston & Seleander
Staatssammlung München (Munich), Zoologisches Mu- 1973). Corsican Finchesappeartoinhabitgenerallyareas
seum derHumboldt Universität(Berlin)and Naturkundc- of warmer clime than do Citril Finches (Thibault &
musem Rosenstein (Stuttgart). BoNACCORSi 1999) and may therefore have developed
Table 1. Mean values of20 morphological traits and 2 indices ofCitril and Corsican Finches. Comparisonswere conductedwith
t-tests (parametric distributed datasets) and Mann Whitney U tests (non-parametric distributed data sets).
Citril Finch Corsican Finch Statistical comparison Sign-Level
mm mm
(n=23) in (n=13) in
Flifjht apparatus
Wing length 76.4±1.5 SD 72.5±2.2 SD t-test; t=6.569; df=34; p<0.001
Tail length 53.3±1.8 SD 50.4±2.2 SD t-test; t=4.336; df=34; p<0.001
Fork ofthe tail -10.0±1.1 SD -7.2±1.1 SD MWU; T=94; psO.OOl ^:Ji
Wing width 53.5±1.6 SD 51.0±1.6 SD MWU; T=126.0; p<0.001 ***
Primary projection 22.6±l.2 SD 20.1±1.5 SD t-test; t=5.319; df=34; p<0.001
Distal ' 54.1±1.4 SD 50.3±2.1 SD MWU; T=118.5; psO.OOl ***
Alula 56.4±1.5 SD 52,8±2.3 SD MWU; T=119; p<0.001
Notch P3o 23.1±1.4 SD 21.0±1.2 SD t-test; t=4.692; df=33; p<0.001
Notch P2i 19.8±0.8 SD 17.7±1.1 SD MWU; T=94; p<0.001 ^*^
Kipp index 29.6±1.3 SD 27.8±1.9 SD t-test; t=3.439; df=34; p=0.002 **
Feeding apparatus
BBiillll wleindgtthh 51.23.±20±.20.S6DSD 41.18.±60+.03.5SSDD MMWWUU;; TT==1l3135..05;; pp<<00..000011 ****
Bill height 6.2±0.3 SD 5.6+0.3 SD t-test; t=6.432; df=34; p<0.001 **
Rictal brisdes 2.6±0.7 SD 2.4±0.7 SD t-test; t=4.950; df=34; p=0.420 ns
Hind limb
Tarsus length 14.4±0.6 SD 13.5±0.5 SD t-test; t=4.653; df=34; psO.OOl
Tarsus diameter 1 0.88±0.08 SD 0.82±0.06 SD t-test; t=2.278; df=34; p=0.034 *
Tarsus diameter 2 1.34±0.13 SD 1.15±0.06 SD t-test; t=4.950; df=34; psO.OOl
Hind toe 6.5±0.4 SD 6.4±0.3 SD t-test; t=0.599; df=34; p=0.553 ns
Middle toe 10.9±0.6 SD 10.2±0.6 SD t-test; t=3.240; df=34; p=0.003
Hind claw 6.1±0.5 SD 5.6±0.5 SD t-test; t=2.926; dt=34; p=0.008
Middle claw 5.4+0.4 SD 4.7±0.4 SD t-test; t=5.534; df=34; p<0.001
Wing length/ tarsus index 5.3±0.2 SD 5.4±0.2 SD MWU; T=267; p=0.392 ns
\
.
Bonnerzoologische Beiträge 55 (2006) 161
Arnaiz-Villena,a.,Alvarez-Tejado,M.,Ruiz-del-Valle,V.,
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majorityofCorsican Finches, livingonthehighestmoun- Southern Hemisphere speciation of goldfinches during the
tainslopesofCorsica,whereclimatic conditionsarequite MioceneandPlioceneEpochs.CellularMolecularLifeScien-
comparable to theAlps or Pyrenees. Furthennore, meas- ce 54: 1031-1041.
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