SHORT NOTE Sex recognition in brown skuas: do acoustic signals matter?

• Main Author: Hans-ulrich Peter
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Brown Skua
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.629.3890; http://evolution.unibas.ch/scharer/research/publications/janicke_et_al_2007.pdf

Abstract Bird vocalisations are often essential for sex recognition, especially in species that show little morpho-logical sex dimorphism. Brown skuas (Catharacta ant-arctica 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.