Sex recognition in brown skuas: do acoustic signals matter?
- 105 Downloads
Bird vocalisations are often essential for sex recognition, especially in species that show little morphological sex dimorphism. Brown skuas (Catharacta antarctica lonnbergi), which exhibit uniform plumage across both sexes, emit three main calls: the long call, the alarm call and the contact call. We tested the potential for sex recognition in brown skua calls of 42 genetically sexed individuals by analysing 8–12 acoustic parameters in the temporal and frequency domains of each call type. For every call type, we failed to find sex differences in any of the acoustic parameters measured. Stepwise discriminant function analysis (DFA) revealed that sexes cannot be unambiguously classified, with increasing uncertainty of correct classification from contact calls to long calls to alarm calls. Consequently, acoustic signalling is probably not the key mechanism for sex recognition in brown skuas.
KeywordsAcoustic signalling Catharacta antarctica lonnbergi Sex recognition Vocal sexual dimorphism
Two anonymous referees made useful suggestions that improved the manuscript. This study was partially supported by the German Research Council (DFG, PE 454/1ff.). All field work was done in accordance with permissions issued by the Federal Environment Agency of Germany.
- Ballintijn MR, ten Cate C (1997) Sex differences in the vocalizations and syrinx of the collared dove (Streptopelia decaocto). Auk 114:22–39Google Scholar
- Bradbury J, Vehrencamp SL (1998) Principles of animal communication. Sinauer, New YorkGoogle Scholar
- Furness RW (1996) Family Stercorariidae (skuas). In: del Hoyo J, Elliott A, Sargatal J (eds) Handbook of the birds of the world, vol 3. Lynx Edicions, Barcelona, pp 556–571Google Scholar
- Hahn S, Ritz M, Peter H-U (2003) Living in mixed pairs––better for fitness? A study on skuas. In: Huiskes AHL, Gieskes WWC, Rozema J, Schorno RML, van der Vies SM, Wolff WJ (eds) Antarctic biology in a global context. Backhuys, Leiden, pp 229–233Google Scholar
- James PC (1984) Sexual dimorphism in the voice of the British Storm Petrel Hydrobates pelagicus. Ibis 126:89–92Google Scholar
- Janicke T, Hahn S, Ritz M, Peter H-U (2007) Vocal performance reflects individual quality in a non-passerine. Anim Behav (in press)Google Scholar
- Massey BW (1976) Vocal differences between American least terns and European little tern. Auk 93:760–773Google Scholar
- Olsen KM, Larsson H (1997) Skuas and jaegers: a guide to the skuas and jaegers of the world. Pica, Mountfield, UKGoogle Scholar
- Suthers RA (2004) How birds sing and why it matters. In: Marler P, Slabbekoorn H (eds) Nature’s music: the science of bird song. Academic, New York, pp 272–295Google Scholar
- Taoka M, Sato T, Kamada T, Okumura H (1989) Sexual dimorphism of chatter-calls and vocal sex recognition in leach’s storm-petrels (Oceanodroma leucorhoa). Auk 106:498–501Google Scholar