Jønsson, Knud Andreas

Ortvad, Troels Eske

Thorup, Kasper

English

Copenhagen University Research Information System

u n i ve r s i t y  o f  co pe n h ag e n  Københavns UniversitetTwo Western Bonelli's Warblers Phylloscopus bonelli from Christiansø, Denmark,confirmed by DNAThorup, Kasper; Ortvad, Troels Eske; Jønsson, Knud AndreasPublished in:Dansk Ornitologisk Forenings TidsskriftPublication date:2009Document versionPublisher's PDF, also known as Version of recordCitation for published version (APA):Thorup, K., Ortvad, T. E., & Jønsson, K. A. (2009). Two Western Bonelli's Warblers Phylloscopus bonelli fromChristiansø, Denmark, confirmed by DNA. Dansk Ornitologisk Forenings Tidsskrift, 103, 28-29.Download date: 02. Feb. 2020Western Phylloscopus bonelli and Eastern Bonelli's Warblers P. orientalis occur as vagrants in northwest Europe. Up until 2006, a total of ten Western and five Eastern Bonelli's warblers were recorded in Norway, Sweden and Finland. Only recently have the two taxa attained full species rank, primarily based on differ-ences in DNA, but also in differences in vocalization and minor differences in morphology (BOU 1997).The two Bonelli's warblers are very similar and iden-tification in the field and even in the hand can prove very difficult. Consequently, many records of vagrants have not been assigned to species, thus obscuring the occurrence pattern of the two species. The Danish Ornithological Society's Rarities Committee is currently reconsidering all records of Bonelli's warblers.The best way to tell the two species apart in the field is by the contact- and alarm calls, which are strikingly different between the species. The song, on the con-trary, are very similar but can perhaps be separated based on sonograms (Helb et al. 1982, Snow & Perrins 1998). Identification based on plumage characters alone is generally considered very difficult, although – at least in spring – there appear to be minor but consistent differences in the coloration of the upper body and the fringes of the greater wing-coverts (Occhiato 2007). The two species also show minor differences in wing length and wing formula, Western Bonelli's Warbler having a shorter wing (57-68 mm), compared to 63.5-73 mm for Eastern Bonelli's Warbler (Svensson 1992). However, the two species differ by 8% in the cytochrome-b gene region – a substantial difference, equivalent to the dif-ference between either species and the Wood Warbler Phylloscopus sibilatrix (Helbig et al. 1995). A differ-ence of this magnitude makes identification based on DNA straightforward and reliable.To this day, the Danish Rarities Committee has accepted 14 Danish records of Bonelli's warblers, com-prising nine individuals caught at ringing stations and five field observations. Four of the ringed birds had wing lengths below the range of Eastern Bonelli's Warbler, four had intermediate wing lengths, while no measure-ments were taken from the last bird. Only one of the birds observed in the field has been identified to species: a singing male Western Bonelli's Warbler at Dollerup Bakker 23/5-5/6 1990, which was also heard calling.Here we consider the identification of two Bonelli's warblers trapped on the island of Christiansø in eastern Denmark on 25/8 1990 and 17/10 1991, respectively (the Mindre meddelelserTwo Western Bonelli's Warblers Phylloscopus bonelli from Christiansø, Denmark, confirmed by DNAKasper Thorup, Troels Eske Ortvad and Knud A. JønssonTable 1. Differences in base pair composition of 375-380 base pairs of the mitochondrial cytochrome-b gene from two birds trapped at Christiansø (B90 and B92), and from two Western Phylloscopus bonelli and one Eastern Bonelli's Warbler P. orientalis from Genbank. Forskelle i basepar inden for et 375-380 basepar-område af det mitochondrielle cytochrom-b gen mellem henholds-vis to fugle (B90 og B92) fanget på Christiansø og tre sekvenser fra Genbank (to Vestlige P. bonelli og én Østlig Bjergløvsanger P. orientalis).Base # 14 20 26 29 35 65 80 104 107 110 122 125 128 131 147 155 165B90 G A C C C C C T C A C C T C T T CB92 A A C C C C C T C A C C T C T T CP. bonelli a A A C C C C C T C A C C T C T T CP. bonelli b A A C C C C C T C A C C T C T T CP. orientalis A G T A T T T C T C T A C T C C TBase # 176 192 194 200 215 248 260 263 267 269 284 293 314 350 356 365 371B90 G C C C C G T C T C A G A C C A CB92 G C C C C G T C T C A G A C C A CP. bonelli a G C A C C G T C T C A G A C C A CP. bonelli b G C A C C G T C T C A G A T C A CP. orientalis A T A T T A G T C A C A G C T T TDansk Orn. Foren. Tidsskr. 103 (2009): 28-29 Mindre meddelelser 29latter (Fig. 1) also seen on 18/10). For both the wing length indicated Western Bonelli's Warbler. DNA from blood samples from the two birds was sequenced and compared to DNA sequences from Genbank. Frag-ments (375 and 380 base pairs) of the mitochondrial gene cytochrome-b clearly demonstrate that both indi-viduals were Western Bonelli's Warblers (Table 1).Thus, until now only Western Bonelli's Warbler has been recorded with certainty in Denmark. Eastern Bonelli's Warbler remains a great rarity in Northwest Europe, whereas the western species is more common and in addition seems to be expanding its range north-wards (Hagemeijer & Blair 1997). We are grateful to Martin Irestedt at the Molecular Laboratory (Molekylärsystematiska Laboratoriet) as-sociated with the Museum of Natural History in Stock-holm, Sweden, who helped sequencing the DNA, and to Arnoud B. van den Berg for supplying data on Bonelli's Warblers in the Netherlands.Resumé: Artsbestemmelsen af to Vestlige Bjerg-løvsangere Phylloscopus bonelli bekræftet af DNA-analyseVestig og Østlig Bjergløvsanger Phylloscopus (bonel-li) bonelli hhv. orientalis blev af BOU (1997) givet artsstatus (P. bonelli, P. orientalis) med henvisning til en konstateret 8,3-8,6% forskel i deres mtDNA (Helbig et al.1995). Af de 14 godkendte fund af Bjergløvsanger i Danmark (ni fanget af ringmærkere, fem observeret i felten) er fem bestemt til Vestlig Bjergløvsanger på basis af vingelængden (fi re ringmærkede fugle) eller kontakt- og alarmkald (en han set og hørt Dollerup Bakker 23/5-5/6 1990). Blodprøver fra to fugle fanget på Christiansø hhv. 25/8 1990 og 17/10 1991 har gjort det muligt at sekventere en del af deres mtDNA, og en sam-menligning med sekvenser i Genbank har bekræftet den oprindelige bestemmelse af begge fuglene som Vestlig Bjergløvsanger. Til dato foreligger der ingen godkendte fund af Østlig Bjergløvsanger i Danmark.ReferencesBOU 1997: Records Committee: Twenty-third Report (July 1996). – Ibis 139: 197-201.Hagemeijer, E.J.M. & M.J. Blair 1997: The EBCC At-las of European breeding birds. – T & A D Poyser, London.Helbig, A.J., I. Seibold, J. Martens & M. Wink 1995: Ge-netic differentiation and phylogenetic relationships of Bonelli's Warbler Phylloscopus bonelli and Green Warbler P. nitidus. - J. Avian Biol. 26: 139–153.Helb, H-W., H-H. Bergmann & J. Martens 1982: Acous-tic differences between populations of western and eastern Bonelli's Warblers (Phylloscopus bonelli, Sylviidae). – Cellular and Molecular Life Sciences 38: 356-357. Occhiato, D. 2007: Western and Eastern Bonelli's War-blers in the fi eld. – Birding World 20: 303-308.Svensson, L. 1992: Identifi cation guide to European passerines. 4th ed. – Stockholm.Snow, D.W. & C.M. Perrins 1998: The birds of the west-ern Palearctic, Concise Edition. – Oxford University Press.Kasper Thorup (kthorup@snm.ku.dk), Troels Eske Ortvad & Knud A. Jønsson Zoological Museum, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark.Fig. 1. Western Bonelli's Warbler Phylloscopus bonelli, Christiansø 17/10 1991. Photo: Per Kjær.Vestlig Bjergløvsanger, Christiansø 17/10 1991.

Two Western Bonelli's Warblers <em>Phylloscopus bonelli </em>from Christiansø, Denmark, confirmed by DNA

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Two Western Bonelli's Warblers <em>Phylloscopus bonelli </em>from Christiansø, Denmark, confirmed by DNA

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