Abstract: Phocid life history and vocal repertoire size data gathered from the literature were examined with independent contrasts analyses to assess whether there is a significant relationship between sexual selection and vocal repertoire size. Investigations showed that the degree of polygyny does not influence vocal repertoire size of males, but was strongly influenced by the strategy of maternal care adopted by females. Species where females remain with their pups while nursing ("stay-at-home mums") have males with simple crude vocal repertoires used in male-male agonistic interactions. In these species, male elephant (Mirounga sp.), grey (Halichoerus grypus), crabeater (Lobodon carcinophagus), and hooded (Cystophora cristata) seals generally have greater access to estrus females while they are still hauled out ashore. In species where females continue to go to sea while raising their pups ("working mums"), males have broader advertising vocal repertoires. The stability of the haul-out platform during breeding used by the females makes a further impact, however. Where "working-mums" breed in unstable pack ice, males have little chance of predictably locating routes used by estrus females while traveling to and from feeding grounds. These species, the leopard (Hydrurga leptonyx), Ross (Ommatophoca rossii), bearded (Erignathus barbatus), and ribbon (Histriophoca fasciata) seals, have intermediate- sized repertoires used in long-range underwater acoustic displays (scattergun advertising). The third group, the Weddell (Leptonychotes weddellii), harp (Pagophilus groenlandicus), harbour (Phoca vitulina), and ringed (Pusa hispida) seals, have the largest vocal repertoires. In these species, "working-mums" breed in stable environments, so males perform underwater acoustic advertisement displays (local advertising) in the vicinity of predictable feeding routes used by estrus females. Because these signals are not constrained by propagation, a large array of sound types have developed.

Key Words: PHOCIDS; VOCAL REPERTOIRE SIZE; MATERNAL CARE; COMPARATIVE ANALYSES; PUPPING; HABITAT

Document Type: Research article

DOI: 10.1578/AM.31.1.2005.96

Page Numbers: 96 - 103

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