Source level of male vocalisations in the genus Mirounga: repeatability and correlates

S. Sanvito & F. Galimberti (2003). Source level of male vocalisations in the genus Mirounga: repeatability and correlates. Bioacoustics, Volume 14 (1): 47 -59

Male vocalisations have an important role in mating tactics, breeding strategies and sexual selection. Most studies of vocalisations are concentrated on the time and frequency domains, while the intensity of sound, an important acoustic parameter that should be related to body size, is almost completely ignored as a possible honest signal of resource holding potential (RHP) and cue for mate choice. In this paper, we analyse the repeatability, the correlations with age and size, and the relationship with breeding status of source level (SL) of male vocalisations in the two species of elephant seals (Mirounga leonina and M. angustirostris). We found a high repeatability of SL, equal or higher than the repeatability of frequency domain parameters estimated in a previous study. Southern elephant seal males were significantly larger and produce significantly more powerful vocalisations than northern males. Moreover, in each species SL was related to age, body size, and breeding status of males, but relationships were weak and accounted for just a small proportion of SL variance. We conclude that, although SL may be an honest signal of gross differences of RHP, it is not, by itself, a good candidate for the transmission of high-resolution information on individual phenotype. A combination of SL and frequency components could be, on the contrary, an effective way to communicate RHP.


male vocalisations, source level, honest signals, elephant seals, Mirounga