J. Omithol. 139, 287-296 (1998) © Deutsche Ornithologen-Gesellschaft/BlackwellWissensehafts-Verlag, Berlin ISSN 0021-8375 Song structure in the Hoopoe (Upupa epops) - Strophe length reflects male condition Manuel Martin-Vivaldi, Jos6 Javier Palomino and Manuel Soler Departamento de Biologfa Animal y Ecologfa, Facultad de Ciencias, Universidad de Granada, E-18071 Granada, Spain (e-mall: MVIVALDI@GOLIAT.UGR.ES) Summary The structure of Hoopoe (Upupa epops) song is analysed in a colour ringed population in southern Spain. The song of males in this species is very simple, with a repertoire size of one. The strophes of a male only differ in the number of elements that they include (strophe length), and strophe length is the main song feature differing between males. Daring the prelaying period each individual used mainly strophes of only two lengths, between 2 and 6 elements per strophe, and mean strophe length of males during this period was highly repeatable. However, some males changed the range of strophe types produced and decreased their mean strophe length after unsuccessful breeding or spending long periods of time singing (unpaired males). These changes show that strophe length is phenotypically plastic, and suggest that singing long strophes is energetically more costly than singing short ones. The significantrelationship between strophe length and body condition, and the fact that long strophes were associated with longer previous pauses than short strophes, also suggest that increasing strophe length is costly. All these findings are in accordance with the hypothesis that strophe length reflects male condition in the Hoopoe, although it is not clear what the actual cost of singing long strophes is. Key words: Sexual selection, honest signalling, non-passerines Zusammenfassung Struktur des Gesangs des Wiedehopfs (Upupa epops) - Strophenl~inge reflektiert M[innchen-Qualit~it Die Stmkmr des Gesangs des Wiedehopfs wurde in einer farbberingten stidspanischen Population untersucht. Der Gesang des Mfinnchens ist sehr einfach und umfaBt nur ein Repertoire. Die Strophen eines Mfinnchens differieren nur in der Anzahl Elemente (Strophenlange), und die Mannchen unter- scheiden sich vor allem in der Strophenl~nge voneinander. In der Vorbmtphase verwendeten die Mfinnchen meist nur zwei verschieden lange Strophen, bestehend aus 2 und 6 Elementen je Strophe, und die durchschnittliche Strophenl/inge war in dieser Phase sehr konstant. Nach Bmtverlust oder bei kontinuierlich singenden, ledigen MS_nnchen kam es zu einer Verkiirzung der mittleren Strophenl/m- ge. Die Strophenl~ge ist ph~notypisch plastisch, und lange Strophen zu singen scheint energetisch anfwendiger als kurze Strophen. Der enge Zusammenhang zwischen Strophenl/inge und m~nnlicher Konstitution einerseits und die Beobachtung, dab lange Strophen mit langen Pausen korrelieren andererseits, zeigen ebenfalls, dab lhngere Strophen energetisch aufwendiger sind. Die wirklichen Kosten daftir sind jedoch noch nicht bekannt. Introduction In most bird species several song features have been shown to function both in intersexual and intrasexual communication ("dual function" hypothesis, Albrecht & Oring 1995, Hassel- quist 1990, McDonald 1989, Searcy 1988), in- dicating that they provide information useful for both sexes. For instance, male quality, in particular male condition, is worth knowing for U.S. Copyright Clearance Center Code Statement: 0021-8375/98/13903-0287 $ 11.00/0