CORRELATION BETWEEN MALE SONG REPERTOIRE, EXTRA-PAIR PATERNITY AND OFFSPRING SURVIVAL IN THE GREAT REED WARBLER

IN many birds, females copulate with males other than their social mat e, resulting in extra-pair fertilizations (EPFs)(1-7). It is still unk nown, however, why females seek EPFs(7,8). In one study, males that ac counted for most EPFs had higher survival(6), but neither the characte ristics revealing male quality nor the benefits accruing to females se lecting attractive males were identified. Great reed warblers, Acrocep halus arundinaceus, are socially polygynous, and females base their ma te choice on territory quality(9) and song-repertoire size(10), both o f which predict harem size and reproductive success(11,12). By DNA fin gerprinting(13), we demonstrate that female great reed warblers obtain EPFs from neighbouring males with larger song repertoires than their social mate. In addition, the relative post-fledging survival of offsp ring was positively correlated with their genetical fathers' song repe rtoire size. These data support the hypothesis that females, by engagi ng in extra-pair fertilizations, seek genetic benefits for their offsp ring(7,8).