Patterns in the vocalizations of male harbor seals (original) (raw)
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Interspecific differences in male vocalizations of three sympatric fur seals (Arctocephalus spp.)
Journal of Zoology, 2002
This study investigated species recognition based on bark calls and full threat calls (FTCs) in three fur seal species, Antarctic Arctocephalus gazella, subantarctic A. tropicalis and New Zealand A. forsteri, that breed sympatrically and hybridize at subantarctic Macquarie Island. Bark calls, which are produced by males in male±female interactions, were more species-speci®c than their full threat calls, suggesting that bark calls could be used in species recognition and female mate choice. Further, the bark calls of A. tropicalis were more species-speci®c than those of A. gazella and A. forsteri, suggesting that divergence of calls between species is a consequence of phylogenetic distance, or has resulted from sexual selection through female mate choice. We believe the latter is more probable as we did not observe similar divergence in the FTCs of males. As such, the highly divergent bark calls of A. tropicalis may have resulted from sexual selection that has promoted pre-mating isolation via the process of reinforcement.
Vocal traits of hybrid fur seals: intermediate to their parental species
Animal Behaviour, 2001
Vocal communication is important for species recognition in colonial breeding species such as fur seals, especially where closely related species that can hybridize breed sympatrically. This is the first study to describe the calls of hybrid fur seals. We investigated whether these vocalizations are intermediate to those of their parental species (Antarctic, Arctocephalus gazella, subantarctic, A. tropicalis, and New Zealand, A. forsteri) and discuss the evolutionary implications of hybrids having intermediate vocal traits. Hybrid males' bark calls were intermediate between two distinct groups formed by A. tropicalis and A. gazella/A. forsteri. Patterns of intermediate call characteristics were also discernible for pup attraction calls (given by females) but not for full threat calls (given by males), nor female attraction calls (given by pups); however, for all call types hybrid calls were distinct from those of their parental species. The pattern of hybrid calls being intermediate is consistent with the expectation that call traits are genetically inherited.
Journal of Zoology, 1999
We compared the underwater vocalizations of harp seals Pagophilus groenlandicus Erxleben, 1777 recorded during the breeding season at three locations: Jan Mayen Island (north of Iceland); Gulf of St Lawrence; and the 'Front' ice east of Labrador. The three herds shared 17 call types. The Jan Mayen herd had one call type not found in the Gulf or Front. One of the Gulf and Front call types was not found at Jan Mayen. Based on ANO VA post hoc pairwise comparisons between locations, the three herds exhibited a similar number of within-call type differences in duration, number of elements, start pitch and end pitch. There were no differences in proportional usage of call types between the Gulf and Front herds but both differed in a similar manner from those of the Jan Mayen herd. These Undings support tagging studies that indicate that the Gulf and Front herds may be interbreeding and both are reproductively isolated from the Jan Mayen herd. We found no evidence of acoustic adaptation to the site-specific ice and environmental conditions associated with the three study locations.
In-air and underwater vocalizations of eastern Canadian harbour seals, Phoca vitulina
Canadian Journal of Zoology, 2002
Harbour seals, Phoca vitulina, have long been thought to be one of the least vocal pinniped species both in air and under water. However, recent studies have shown that males use underwater vocalizations intensively during the mating season. In air, harbour seals are still thought to be relatively silent. In this study we describe the vocal repertoire of Eastern Canadian harbour seals during the breeding season. Harbour seals from this area produced seven vocalization types in air and one vocalization type under water. In-air vocalizations are predominantly used by adult males during agonistic interactions. Other sex and age classes also vocalize, but less frequently. Nearest neighbour responses to in-air vocalizations were primarily agonistic when any age or sex class vocalized. In this study, seals produced an underwater roar vocalization closely resembling that produced by adult males during the mating season at other sites. Eastern Canadian harbour seals appear to be considerabl...
Geographic variation of Weddell seal (Leptonychotes weddellii) airborne mother–pup vocalisations
Polar Biology, 2007
Geographic variation of vocal behaviour may be reXective of genetic, cultural and ecological diVerences between locations. Such diVerences have been previously reported in six pinnipeds, including Weddell seals (Leptonychotes weddellii). This study investigated whether the acoustic characteristics of airborne Weddell seal mother and pup 'contact' calls vary geographically between the Vestfold Hills and McMurdo Sound. From each location, 72 mother and 120 pup calls were analysed, with 11 acoustic characteristics measured. MANOVA and Discriminant function analysis (DFA) identiWed signiWcant diVerences in several fundamental frequency characteristics. The crossvalidated DFA classiWed greater than 60% of mother and pup vocalisations to the correct location. For novel calls, the probabilities of correctly classifying these percentages by chance are low. Additionally, ordinal logistic regression identiWed signiWcant diVerences in the maximum energy distribution of mother and pup vocalisations. For pups, this variation is likely the result of genetic diVerences between the two populations. Nevertheless, results support suggestions that, when compared with underwater repertoire diVerences, airborne within-call diVerences are less eYcient at identifying Weddell seal breeding populations.
Characterization of Australian fur seal vocalizations during the breeding season
Marine mammal …, 2008
The vocal repertoire, structure, and behavioral context of airborne vocalizations produced by Australian fur seals (Arctocephalus pusillus doriferus) are described using recordings made at a breeding colony on Kanowna Island, Bass Strait, Australia. The study identified six different call types: three produced by males (bark, guttural threat, and submissive call); five produced by females (bark, guttural threat, submissive call, growl, and pup attraction call) and the female attraction call produced by pups and yearlings. Vocalizations were compared according to age and sex classes. The overall structure and function of the pup attraction and female attraction call produced by females, yearlings, and pups, was similar. However, while similar in their overall appearance, certain call types have a lower fundamental frequency when compared with other fur seals. In addition, the male bark call alters in rate of production according to the context used, where calls are slower when males are stationary and advertising their territorial status and faster when males are involved in confrontations with other males or actively herding females. Further research is required to investigate changes in environmental conditions and 913 914 MARINE MAMMAL SCIENCE, VOL. 24, NO. 4, 2008 their effects on shaping the call structure and communication in Australian fur seals.
Individuality in harp seal, Phoca groenlandica, pup vocalizations
Animal Behaviour, 2004
In gregarious breeders, parents often use individually stereotyped vocalizations as a cue to relocate offspring. Harp seals aggregate in large colonies on pack ice during the whelping season. During the 11-day lactation period, females alternate between periods at sea and attending their pup. If they use vocal cues in the relocation process, individual variation in pup vocalizations would be expected. We recorded vocalizations, sex and age class for 91 individuals at whelping patches in the Greenland Sea. Pups produced three call types: tonal, pulsed and a combination of the two. Only tonal vocalizations were used for analyses. To explore individual variation in measured vocal parameters, we used classification trees: 43% of 4075 vocalizations were classified correctly according to individual. The first split was driven by the third peak frequency, splitting male pups from females. For females total duration produced most further splits, whereas the maximum frequency of the lower harmonic, the maximum frequency of the second harmonic and total duration caused splits between males. We correctly identified 55% of 42 female pups and 8% of 49 male pups based on vocal parameters. Calls were misclassified according to individual but never according to sex. Repeated measures of eight individuals over several age classes showed that 82% of 869 calls were correctly classified regardless of age. Alongside vision and smell, acoustic cues appear to be important in relocating offspring. Differences in vocal variability between sexes may reflect different selection pressures working on males and females.
Aquatic Mammals, 2005
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 ("attending females") 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 ("foraging females"), 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 "foraging-females" 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, "foraging-females" 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.
Age-related differences in the acoustic characteristics of male leopard seals, Hydrurga leptonyx
The Journal of the Acoustical Society of America, 2007
During the breeding season, the underwater vocalizations and calling rates of adult male leopard seals are highly stereotyped. In contrast, sub-adult males have more variable acoustic behavior. Although adult males produce only five stereotyped broadcast calls as part of their long-range underwater breeding displays the sub-adults have a greater repertoire including the adult-like broadcast calls, as well as variants of these. Whether this extended repertoire has a social function is unknown due to the paucity of behavioral data for this species. The broadcast calls of the sub-adults are less stereotyped in their acoustic characteristics and they have a more variable calling rate. These age-related differences have major implications for geographic variation studies, where the acoustic behavior of different populations are compared, as well as for acoustic surveying studies, where numbers of calls are used to indicate numbers of individuals present. Sampling regimes which unknowingly include recordings from sub-adult animals will artificially exaggerate differences between populations and numbers of calling animals. The acoustic behavior of sub-adult and adult male leopard seals were significantly different and although this study does not show evidence that these differences reflect vocal learning in the male leopard seal it does suggest that contextual learning may be present.
Behavioral Ecology and Sociobiology, 2021
The ability to recognize the identity of conspecifics is a key component for survival of many animal species and is fundamental to social interactions such as parental care, intra-sexual competition or mate recognition. In group-living species, the simultaneous coexistence of many individuals increases the number of interactions and reinforces the need for individual recognition. Acoustic signals are widely used by birds and mammals to communicate and to convey information about identity, but their use in very dense colonies becomes challenging due to the high level of background noise and the high risk of confusion among individuals. The Cape fur seal (CFS) is the most colonial pinniped species and one of the most colonial mammals in the world, with colonies of up to 210,000 individuals during the breeding season. Here, we investigated the individual stereotypy in vocalizations produced by pups, females and male CFS using Random Forests and index of vocal stereotypy (IVS). We thus compared IVS values of CFS to other pinniped species. Within CFS we identified individuality in all call types but the degree of individual stereotypy varies in regards to their social function: affiliative calls produced in a mother-pup reunion context and territorial calls produced by mature bulls holding harem were more individualized than vocalizations involved in agonistic interactions. Our inter-species comparisons among pinnipeds showed that CFS affiliative and territorial calls displayed higher degrees of individuality compared to other species with similar or lower ecological constraints (colony density and social structure).