The Auk 116(3):737-748, 1999 COMPARATIVE ANALYSIS OF PERCH-COO VOCALIZATIONS IN STREPTOPELIA DOVES ' HANS SLABBEKOORN,• SELVINO DE KORT, AND CARELTEN CATE BehavioralBiology, Institute of Evolutionaryand EcologicalSciences, Leiden University, P.O. Box 9516, 2300 RA Leiden, The Netherlands ABSTRACT.--Someof the 16 dovespecies in the genusStreptopelia are very similarwith respectto plumagepattern, but all seemto producespecies-specific "perch-coo" vocaliza- tions.Here, we describevariation in perch-coorecordings of all 16 species.All individuals couldbe correctlyclassified by speciesin a discriminantfunction analysis, which means that the overlapin inter- and intraspecificvariation was limited for the total set of acousticpa- rameters.Interspecific similarity in acousticparameters was compared with taxonomicclas- sification,based upon qualitative morphological characteristics and geographic distribution (Goodwin1983). The clusteringof speciesusing the acousticdata set showed little congru- encewith taxonomicclustering. This indicatesthat differentiationin plumagepattern does not necessarilycoincide with differentiationin acousticcharacteristics. However, our anal- ysisdid not completelycontradict the subdivisioninto four taxonomicgroups based on mor- phologyand distribution.Two of the four putativegroups differed significantly from the othergroups in oneof the componentsof a principalcomponents analysis. Vocal differen- tiation in Streptopeliadoves was strongestin temporalcomponents, which is in line with expectationsbased on the evolutionarilyconservative syringeal constraints. Received 29 Sep- tember1997, accepted 4 January 1999. DIFFERENTSPECIES of a particular taxonomic Perch-coovocalizations of dovesare regard- groupof birdsoften share vocal characteristics. ed as functionallysimilar to advertisingsongs At the same time, some vocal characteristics in songbirds;they servein male-maleconflict serve as accurateindicators of speciesstatus. and for female attraction (Jacksonand Basket For this reason,song comparisons have been 1964;Davies 1970, 1974;Goodwin 1983;Cramp widely usedto evaluaterelationships among 1985;Baptista 1996).Sexual selection may lead species(see Payne 1986). Comparative analyses to intraspecificexpansion of variancein the of vocalizations have been used to evaluate in- acousticparameters of sucha signal.However, tra- and interspecificvariation in severalavian the samesignal also may servein speciesrec- genera(e.g. Zann 1974,Miller 1978,Collins and ognition(Becker 1982, Nelson 1989). In this Goldsmith1998) and haveled to suggestions context,the negativeconsequences of hybrid- for taxonomicsubdivisions within somegenera izationmay lead to intraspecificcontraction of of doves(Geopelia, Harrison 1969;Zenaida, Bap- varianceand interspecificdivergence (see Mil- tista et al. 1983). Other studieshave evaluated ler 1982).Sexual selection may shapeacoustic vocalvariation among species in the contextof parameterssuch as frequencyrange or repeti- phylogeneticreconstruction (e.g. G•ttinger tion patternof vocalizations,but acousticlimits 1970, Miller et al. 1988, Islam and Crawford areaffected by environmentaland phylogenet- 1996, Miller 1996, McCracken and Sheldon ic constraints(Ryan and Brenowitz 1985). Phy- 1997).In this study,we use a comparativeap- logeneticconstraints make it likelythat closely proachto matchvocal similarity among Strep- related speciesare more similar in vocal pa- topeliadoves with their taxonomicclassifica- rameters than are distantly related species. tion. We usedphenetic analyses of the "perch- Featureslike body size (Wallschl•iger1980, Tu- coo" vocalization, and, as our taxonomic ref- baro and Mahler 1998)and syrinxmorphology erence, we used a clustering suggestedby (Gaunt 1988, Podos 1997) may impose limita- Goodwin (1983),based on the qualitativein- tions on sound production,and the auditory terpretationsof differencesamong speciesin sensitivityof receiversmay restrictthe char- morphologyand distribution. acteristics of communicative sounds to those of the species-specifichearing range (Dooling E-mail: [email protected]. nl 1982,Ryan et al. 1990).In addition,the evolu- 737 738 SLABBEKOORN,DE KORT,AND TEN CATE [Auk, Vol. 116 tionaryand ontogenetic flexibility of theneural pathwaysinvolved in vocal controland audi- hypopyrrha tory processingmay play an important role, orientalis potentiallyaffecting acoustic character diver- bitorquata gence and convergencevia constraints on sound productionand perception(Bass and Baker 1991, Smith 1994). For selection to act on behavioral traits, var- Streptopefia-- d•cipiens sernitorquata iance in the traits must have a heritable basis. capicola Dovesdevelop vocal characters independent of decaocto learning(Nottebohm and Nottebohm1971). Darwin (1868)reported that RockDoves (Co- PI picturata lumbalivia) could be artificially selectedfor -- cs - chinonsis temporalqualities of their coos(see also Bap- senegalensis tistaand Abs 1983).Vocalizations of hybridsof F•G. 1. Dendrogramreconstructed after Good- variousStreptopelia doves either resembled one win (1983) on the classificationof 16 Streptopeliaspe- parentaltype, were intermediatebetween the cies.The classificationis basedupon qualitativemor- parents,or resembledneither of the parents; phologicaland distributionalcharacteristics. TD = the degreeof disruptionin coocharacteristics turtle-dove group, RD = ringed dovegroup, PI S. increasedas the relatednessof the parental picturata,and CS S. chinensis/ S. senegalensis group. formsdecreased (Lade and Thorpe1964, Da- vies 1970, Baptista 1996). The aim of this paper is to examinea repre- necessarilyreflect common ancestry, but it is of sentativeset of recordingsfor all 16 speciesof interestto seewhether they show the same pat- Streptopeliadoves and to give a descriptive tern of clustering.Insight into how evolution- overviewof theirperch-coo characteristics. The ary pathwaysled to thesimilarities and dissim- coos of Streptopeliaare relatively simple and ilaritiesin suchfeatures has to await a phylo- well suited for extensivequantitative analyses, geneticanalysis of the genusStreptopelia based as was shown for S. decaocto(ten Cate 1992;ten on an independentdata set. Cateand Ballintijn1996; Ballintijn and ten Cate 1997a,b). Speciesof Streptopeliashow little di- METHODS vergencein allometry,and their syrinx appears Subjects.--The16 speciesof Streptopelia,commonly to be anatomicallyrestricted in producingvar- referred to as "turtle-doves," are slender,relatively iation in frequencyrange or frequencymodu- long-tailed,gray or brownpigeons (Goodwin 1983). lation patterns(Warner 1972, Ballintijn et al. Neck or collarpatterns are the mostconspicuous ex- 1995).Gaunt (1988) remarkedthat evenbirds ternal plumagecharacteristics. The turtle dovesare with a relativelysimple syrinx morphology can native to temperateand tropicalregions of Europe, produce rather differently structuredvocali~ Asia, and Africa. Someof the speciesare expanding zationsby varyingthe rate and patternof air- their distribution in Pacific, Australian, and Nearctic flow. If this has affected vocal evolution in regionswhere they were introducedrelatively re- cently.Most speciesinhabit open woodlands and a Streptopeliaspecies, then onemight expectvo- wide rangeof humansettlements. They feed mainly cal differentiationin temporal featuresin par- on grainsand seeds,although the forest-dwelling ticular. speciesfrequently eat berries and other small fruits. We compared interspecific similarity in Streptopeliadoves are usually abundant within their perch-cooswith the taxonomicclustering pro- range.They are territorialbut oftenform large for- videdby Goodwin(1983). This is theprime ref- agingor sleepinggroups, particularly outside of the erencefor the taxonomyof doves(Howard and breedingseason. All speciesare strongfliers, and Moore 1991,Baptista et al. 1997) and is based someare long-distancemigrants. Goodwin (1983) divided the 16 speciesinto four on the qualitativeinterpretation of morpholog- groupsbased on appearanceand geographicdistri- ical characteristicsand geographicdistribution bution (seeTable 1). The four speciesof typical "tur- (seeFig. 1). Pheneticclassifications, like those tle doves"are darkerthan the otherspecies and have basedon plumagepattern (Goodwin 1983) or a mottledpattern on the backof their wingsand ei- acousticcharacteristics (this study), need not ther a black-and-whitestriped patch or a completely July1999] Perch-coosin Doves 739 TABLE1. Overviewof thegenus Streptopelia. A description of theneck pattern is givenbecause it is themost conspicuousfield characteristic.We alsolist brief descriptionsof geographicdistribution based on Good- win (1983) and Howard and Moore (1991). Species Groupa Sizeb Neck pattern Distribution S. turtur TD 26 to 28 Stripedpatch Europe,W Asia, N Africa S. lugens TD 28 to 31 Blackpatch E Africa, SW Arabia S.hypopyrrha TD 29 to 31 Blackpatch E Nigeria,W Cameroon S. orientalis TD 33 to 35 Stripedpatch Centralto E India S. bitorquata RD 29 to 31 Blackcollar Philippines,Indonesia S.decaocto RD 31 to 33 Blackcollar Europeto E China,India S. roseogrisea RD 29 to 30 Blackcollar SahelianAfrica S. reichenowi RD 26 to 28 Blackcollar S. Somalia,NE Kenya S. decipiens RD 28 to 30 Blackcollar Africa S of Sahara S. semitorquata RD 33 to 36 Blackcollar Africa S of Sahara S. capicola RD 25 to 28 Blackcollar S and E Africa S. vinacea RD 24 to 26 Blackcollar Africa S of Saharaand N of equator S. tranquebarica RD 22 to 24 Blackcollar SE Asia S. picturata PI 27 to 33 Side