Статті в журналах: "Otariid"

1

Boessenecker, Robert W., and Morgan Churchill. "The oldest known fur seal." Biology Letters 11, no. 2 (February 2015): 20140835. http://dx.doi.org/10.1098/rsbl.2014.0835.

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The poorly known fossil record of fur seals and sea lions (Otariidae) does not reflect their current diversity and widespread abundance. This limited fossil record contrasts with the more complete fossil records of other pinnipeds such as walruses (Odobenidae). The oldest known otariids appear 5–6 Ma after the earliest odobenids, and the remarkably derived craniodental morphology of otariids offers few clues to their early evolutionary history and phylogenetic affinities among pinnipeds. We report a new otariid, Eotaria crypta , from the lower middle Miocene ‘Topanga’ Formation (15–17.1 Ma) of southern California, represented by a partial mandible with well-preserved dentition. Eotaria crypta is geochronologically intermediate between ‘enaliarctine’ stem pinnipedimorphs (16.6–27 Ma) and previously described otariid fossils (7.3–12.5 Ma), as well as morphologically intermediate by retaining an M 2 and a reduced M 1 metaconid cusp and lacking P 2–4 metaconid cusps. Eotaria crypta eliminates the otariid ghost lineage and confirms that otariids evolved from an ‘enaliarctine’-like ancestor.

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2

Kovacs, Kit M., and D. M. Lavigne. "Maternal investment in otariid seals and walruses." Canadian Journal of Zoology 70, no. 10 (October 1, 1992): 1953–64. http://dx.doi.org/10.1139/z92-265.

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We examined neonatal size, growth rate during lactation, weaning mass, adult body mass, and the degree of polygyny among fur seals and sea lions (Otariidae) and walruses (Odobenidae). Observed patterns of maternal and sexual investment were compared with those reported for true seals (Phocidae) and for other mammals. There was a strong positive interspecific allometric relationship between mass at birth and maternal mass for otariid species (p < 0.001). The slope of this relationship was significantly different from that for phocid species (p < 0.001). All pinniped data were above the regression line for terrestrial mammals. Lactation was longer and growth rates were slower for otariid and odobenid species than for phocid species. The cyclic foraging pattern of lactating otariids allows for more flexibility in the duration of lactation than is possible in phocids. Such flexibility may serve as a buffer when food is scarce. The longer lactation period of otariids and walruses also permits offspring to develop swimming and foraging skills while still depending on their mothers for energy. The relationship of mass at weaning to maternal mass suggests a greater investment in each neonate in otariids and walruses than in phocids. The large body size and advanced state of development at weaning may be an adaptive response to predation pressure on otariids. Adult male otariids and walruses are larger than females and, in both families, the average birth mass, mass at weaning, and growth rate of male pups are greater than those of females. The ratio of body masses of male pups to female pups at birth and at weaning was not correlated with the degree of adult sexual dimorphism within species, despite a positive correlation between the ratio of body masses of adult males to adult females and the degree of polygyny across otariid species.

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3

Churchill, Morgan, and Robert W. Boessenecker. "Taxonomy and biogeography of the Pleistocene New Zealand sea lionNeophoca palatina(Carnivora: Otariidae)." Journal of Paleontology 90, no. 2 (March 2016): 375–88. http://dx.doi.org/10.1017/jpa.2016.15.

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AbstractThe Otariidae (fur seals and sea lions) are an important and highly visible component of Southern Hemisphere marine mammal faunas. However, fossil material of Southern Hemisphere otariids is comparatively rare and often fragmentary. One exception is the Pleistocene sea lionNeophoca palatinaKing, 1983a, which is known from a nearly complete skull from the North Island of New Zealand. However, the phylogenetic affinities of this taxon are poorly known, and comparisons with other taxa have been limited. We provide an extensive redescription ofNeophoca palatinaand diagnose this taxon using a morphometric approach. Twenty measurements of the skull were collected forN. palatina, as well as for all extant Australasian otariids and several fossilNeophoca cinereaPerón, 1816. Using principal component analysis, we were able to segregate taxa by genus, andN. palatinawas found to cluster withNeophocaaccording to overall size of the skull as well as increased width of the intertemporal constriction and interorbital region.N. palatinacan be distinguished from all other Australasian otariids by its unusually broad basisphenoid. Discriminant function analysis supported referral ofNeophoca palatinatoNeophocawith very high posterior probability. These results confirm the treatment ofNeophoca palatinaas a distinct species ofNeophocaand highlight the former broad distribution and greater tolerance for colder temperatures of this genus. These results also suggest that New Zealand may have played a pivotal role in the diversification of Southern Hemisphere otariid seals.

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4

Wierucka, Kaja, Benjamin J. Pitcher, Robert Harcourt, and Isabelle Charrier. "The role of visual cues in mother–pup reunions in a colonially breeding mammal." Biology Letters 13, no. 11 (November 2017): 20170444. http://dx.doi.org/10.1098/rsbl.2017.0444.

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Parental care is an important factor influencing offspring survival and adult reproductive success in many vertebrates. Parent–offspring recognition ensures care is only directed to filial young, avoiding the costs of misallocated resource transfer. It is essential in colonial mammal species, such as otariids (fur seals and sea lions), in which repeated mother–offspring separations increase the risk of misdirecting maternal effort. Identification of otariid pups by mothers is known to be multi-modal, yet the role of visual cues in this process remains uncertain. We used three-dimensional visual models to investigate the importance of visual cues in maternal recognition of pups in Australian sea lions ( Neophoca cinerea ). We showed that the colour pattern of pup pelage in the absence of any other sensory cues served to attract the attention of females and prompt investigation. Furthermore, females were capable of accurately distinguishing between models imitating the age-class of their own pup and those resembling older or younger age-classes. Our results suggest that visual cues facilitate age-class discrimination of pups by females and so are likely to play an important role in mother–pup reunions and recognition in otariid species.

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5

Neises, Victoria M., Shawna A. Karpovich, Mandy J. Keogh, and Stephen J. Trumble. "Examination of Blubber Fatty Acids in Pregnant and Lactating Alaskan Harbor Seals (Phoca vitulina)." Aquatic Mammals 48, no. 4 (July 15, 2022): 362–79. http://dx.doi.org/10.1578/am.48.4.2022.362.

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Pregnancy and lactation are energetically expensive for female mammals and greatly influence the evolution of species-specific reproductive strategies. Phocid (“true” seals) lactation is generally short in duration and relies heavily on stored energy, whereas otariid (sea lions and fur seals) lactation is generally much longer, and energy is supplemented by foraging. While a phocid, the smaller body size of the harbor seal (Phoca vitulina) is assumed to preclude the maintenance of lactation solely from stored energy. For this reason, their lactation strategy is believed intermediate to that of otariids and phocids. The purpose of this study was to characterize blubber fatty acids (FAs) of pregnant and lactating harbor seals and determine if lactating blubber FA profiles more closely resemble phocids or otariids. Blubber FA differences between female reproductive states (lactating, n = 18; pregnant, n = 7; non-lactating–non-pregnant, n = 17), mother–pup pairs (n = 6), and families (otariid, n = 3; phocid, n = 3) were evaluated using permutation analysis of variance (PERMANOVA). Compared to lactating females, pregnant harbor seals had elevated polyunsaturated FAs (PUFAs) and decreased monounsaturated FAs (MUFAs) in their blubber, suggesting pregnant harbor seals may prioritize PUFA storage in the blubber. Additionally, when compared to their pregnant counterparts, lactating harbor seals had lower PUFA, as well as saturated FAs (SFAs) and MUFA ≤ 16C, suggesting lactating harbor seals may utilize blubber FAs similar to other phocids. Lastly, while blubber SFA and MUFA concentrations may be conserved among pinniped families, PUFA concentrations among lactating phocids and otariids appear to be similar, suggesting lactating species may selectively mobilize PUFA from the blubber in a similar way despite family or lactation strategy. Understanding how family and body size influence the lactation strategy of a species provides greater insight into the physiological and behavioral limitations a species may have to both internal and external forces during such a critical time in its life history.

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6

Bastida, Ricardo, Viviana Quse, María Paz Martinoli, and Atilio Francisco Zangrando. "First record of tuberculosis lesions in zooarchaeological samples of otariid pinnipeds. New aspects of the pre-european origin of human tuberculosis in South America and dissemination mechanisms of Mycobacterium pinnipedii in the Southern Hemisphere." Comechingonia. Revista de Arqueología 24, no. 3 (November 30, 2020): 227–53. http://dx.doi.org/10.37603/2250.7728.v24.n3.28917.

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In 2003 Mycobacterium pinnipedii was described as responsible for producing tuberculosis (TB) in living otariid pinnipeds from Argentina and Australia. It is the only member of marine origin within the Mycobacterium tuberculosis Complex (MTBC), which also affects other domestic and wild mammals, and humans. Based on several pre-Columbian records of human tuberculosis in South America, in 2010-2011 a new hypothesis about the origin of this zoonosis through otariid pinnipeds arose. In 2014, this hypothesis was confirmed based on the study of ancient DNA from three mummies (700-1,000 years BP) of the Chiribaya culture (Peru). Since there were no records of TB bone lesions in zooarchaeological samples of otariid pinnipeds from South America and the rest of the world, our study aimed at examining zooarchaeological samples of pinnipeds from coastal sites of the Beagle Channel (Tierra del Fuego, Argentina), being the oldest Túnel I (6,400-4,300 years BP). A total of 4,138 vertebrae were analyzed, of which 0.46 % showed lesions compatible with TB. In addition, we propose a new hypothesis on possible mechanisms of Mycobacterium pinnipedii dissemination that would explain the transmission routes to the different otariid pinniped species of the Southern Hemisphere. Mycobacterium pinnipedii is one of the most aggressive mycobacteria of the MTBC and of high risk for humans.

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7

Brunner, Sylvia, Michael M. Bryden, and Peter D. Shaughnessy. "Cranial ontogeny of otariid seals." Systematics and Biodiversity 2, no. 1 (August 2004): 83–110. http://dx.doi.org/10.1017/s1477200004001367.

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8

Dellinger, T., and F. Trillmich. "Estimating diet composition from scat analysis in otariid seals (Otariidae): is it reliable?" Canadian Journal of Zoology 66, no. 8 (August 1, 1988): 1865–70. http://dx.doi.org/10.1139/z88-269.

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Analysis of teleost sagittal otoliths contained in scats has been widely used to determine the diet of seals. This method is based on the assumption that relative frequencies of otoliths in scats faithfully reflect those offish in the diet. This assumption has rarely been tested experimentally. We compared the ratios of herring (Clupea harengus) to sprat (Sprattus sprattus) otoliths in faeces (output) of captive California sea lions (Zalophus californianus) and South American fur seals (Arctocephalus australis) with the ratios at feeding (input). Sea lions and fur seals showed no consistent differences in recovery rates and partial digestion of otoliths. Output ratios deviated only slightly from input ratios, the smaller sprat otoliths being underrepresented in the output by 8%. Only about 40% of the otoliths fed to the seals were found in the scats. For both species partial digestion of otoliths led to a 16% underestimation of fish length and a 35% underestimation of fish mass.

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9

Velez-Juarbe, Jorge. "Eotaria citrica, sp. nov., a new stem otariid from the “Topanga” formation of Southern California." PeerJ 5 (February 23, 2017): e3022. http://dx.doi.org/10.7717/peerj.3022.

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A new taxon of stem otariid,Eotaria citricasp. nov., is described from the upper Burdigalian to lower Langhian “Topanga” formation of Orange County, California. The new species is described from mandibular and dental remains that show a unique combination of plesiomorphic and derived characters. Specifically, it is characterized by having trenchant and prominent paraconid cusps in p3–m1, lingual cingula of p2–4 with faint crenulations, premolars and molars with vestigial metaconid, bilobed root of m2 and a genial tuberosity located under p3. Furthermore, additional material of the contemporaneousEotaria cryptais described, providing new information on the morphology of this taxon. Both species ofEotariarepresent the earliest stem otariids, reinforcing the hypothesis that the group originated in the north Eastern Pacific Region. At present, the “Topanga” Fm. pinniped fauna includesEotaria citrica,Eotaria crypta, the desmatophocidAllodesmussp., the odobenidsNeotheriumsp.,Pelagiarctossp. and includes the oldest records of crown pinnipeds in California. Overall this pinniped fauna is similar to the nearly contemporaneous Sharktooth Hill bonebed. However, unambiguous records ofEotariaare still missing from Sharktooth Hill. This absence may be due to taphonomic or paleoenvironmental factors. The new “Topanga” record presented here was integrated into an overview of the late Oligocene through early Pleistocene pinniped faunas of Southern California. The results show an overall increase in body size over time until the Pleistocene. Furthermore, desmatophocids were the largest pinnipeds during the middle Miocene, but were extinct by the beginning of the late Miocene. Odobenids diversified and became the dominant pinnipeds in late Miocene through Pleistocene assemblages, usually approaching or exceeding 3 m in body length, while otariids remained as the smallest taxa. This pattern contrasts with modern assemblages, in which the phocidMirounga angustirostrisis the largest pinniped taxon in the region, odobenids are extinct and medium and small size ranges are occupied by otariids or other phocids.

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10

Hernández-Orts, J. S., F. E. Montero, A. Juan- García, N. A. García, E. A. Crespo, J. A. Raga, and F. J. Aznar. "Intestinal helminth fauna of the South American sea lion Otaria flavescens and fur seal Arctocephalus australis from northern Patagonia, Argentina." Journal of Helminthology 87, no. 3 (September 12, 2012): 336–47. http://dx.doi.org/10.1017/s0022149x12000454.

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AbstractWe report on the intestinal helminth fauna of 56 South American sea lions, Otaria flavescens, and 5 South American fur seals, Arctocephalus australis, from northern Patagonia, Argentina. A total of 97,325 helminth specimens were collected from sea lions. Gravid individuals were represented by 6 species of parasites: 1 digenean (Ascocotyle (Ascocotyle) patagoniensis), 1 cestode (Diphyllobothrium spp.), 3 nematodes (Uncinaria hamiltoni, Contracaecum ogmorhini s.s., Pseudoterranova cattani) and 1 acanthocephalan (Corynosoma australe). In addition, third-stage larvae of 2 nematodes (Contracaecum sp. and Anisakis sp. type I) and 3 juvenile acanthocephalans (Andracantha sp., Profilicollis chasmagnathi and Corynosoma cetaceum) were also collected. Andracantha sp., C. ogmorhini s.s. and P.chasmagnathi represent new host records. A total of 1516 helminth specimens were collected from fur seals. Gravid individuals were represented by three species of parasites, namely, Diphyllobothrium spp., C. ogmorhini s.s. and C. australe. In addition, larvae of Contracaecum sp. and P. cattani, juveniles of C. cetaceum and immature cestodes (Tetrabothriidae gen. sp.) were also collected. Corynosoma australe was the most prevalent and abundant parasite in both hosts, accounting for >90% of all specimens. Sea lions and furs seals from northern Patagonia harbour the intestinal helminth communities that could be predicted for otariids, i.e. the combination of species of the genera Corynosoma, Diphyllobothrium, Pseudoterranova, Contracaecum and, in pups, Uncinaria. Additionally, both species of otariid are apparently unsuitable hosts (i.e. non-hosts) for as many as five parasite taxa. The inclusion or exclusion of these species affects estimation of species richness at both component community (11 versus 6 species in sea lions; 7 versus 3 species in fur seals) and infracommunity (mean: 3.1 versus 2.6 in sea lions; 2.2 versus 1.7 species) levels. Information about the reproductive status of helminth species is often lacking in parasitological surveys on otariids and other marine vertebrates, but it is of significance to improve precision in parascript studies or ecological meta-analyses.

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11

Hooker, Sascha K., Russel D. Andrews, John P. Y. Arnould, Marthán N. Bester, Randall W. Davis, Stephen J. Insley, Nick J. Gales, Simon D. Goldsworthy, and J. Chris McKnight. "Fur seals do, but sea lions don't — cross taxa insights into exhalation during ascent from dives." Philosophical Transactions of the Royal Society B: Biological Sciences 376, no. 1830 (June 14, 2021): 20200219. http://dx.doi.org/10.1098/rstb.2020.0219.

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Management of gases during diving is not well understood across marine mammal species. Prior to diving, phocid (true) seals generally exhale, a behaviour thought to assist with the prevention of decompression sickness. Otariid seals (fur seals and sea lions) have a greater reliance on their lung oxygen stores, and inhale prior to diving. One otariid, the Antarctic fur seal ( Arctocephalus gazella ), then exhales during the final 50–85% of the return to the surface, which may prevent another gas management issue: shallow-water blackout. Here, we compare data collected from animal-attached tags (video cameras, hydrophones and conductivity sensors) deployed on a suite of otariid seal species to examine the ubiquity of ascent exhalations for this group. We find evidence for ascent exhalations across four fur seal species, but that such exhalations are absent for three sea lion species. Fur seals and sea lions are no longer genetically separated into distinct subfamilies, but are morphologically distinguished by the thick underfur layer of fur seals. Together with their smaller size and energetic dives, we suggest their air-filled fur might underlie the need to perform these exhalations, although whether to reduce buoyancy and ascent speed, for the avoidance of shallow-water blackout or to prevent other cardiovascular management issues in their diving remains unclear. This article is part of the theme issue ‘Measuring physiology in free-living animals (Part I)’.

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12

Kretzmann, Maria B., Daniel P. Costa, Lesley V. Higgins, and D. J. Needham. "Milk composition of Australian sea lions, Neophoca cinerea: variability in lipid content." Canadian Journal of Zoology 69, no. 10 (October 1, 1991): 2556–61. http://dx.doi.org/10.1139/z91-360.

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Thirty-eight milk samples collected over three seasons from 23 individual Australian sea lions (Neophoca cinerea) were analyzed. Mean milk composition was 25.4% lipid (± 9.3% SD), 62.4% water (± 8.1%), 10.5% protein (± 2.2%), and 0.9% ash (± 0.2%). Milk composition appeared to vary considerably among females, and occasionally between successive samples from the same individual. Milk fat content was not correlated with pup age (stage of lactation), female mass, length of the preceding foraging trip, or time onshore prior to milk collection. The relatively low lipid content of Australian sea lion milk compared with that of some other otariid seals is consistent with the hypothesis that otariid females making relatively short trips to sea produce milk with lower fat content than those species which make foraging trips of longer duration.

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13

Gentry, Roger L., and Vivian R. Casanas. "A NEW METHOD FOR IMMOBILIZING OTARIID NEONATES." Marine Mammal Science 13, no. 1 (January 1997): 155–57. http://dx.doi.org/10.1111/j.1748-7692.1997.tb00621.x.

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14

Savelle, James M., Max T. Friesen, and Lee R. Lyman. "Derivation and Application of an Otariid Utility Index." Journal of Archaeological Science 23, no. 5 (September 1996): 705–12. http://dx.doi.org/10.1006/jasc.1996.0066.

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15

Berta, Annalisa, Morgan Churchill, and Robert W. Boessenecker. "The Origin and Evolutionary Biology of Pinnipeds: Seals, Sea Lions, and Walruses." Annual Review of Earth and Planetary Sciences 46, no. 1 (May 30, 2018): 203–28. http://dx.doi.org/10.1146/annurev-earth-082517-010009.

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The oldest definitive pinniped fossils date from approximately 30.6–23 million years ago (Ma) in the North Pacific. Pinniped monophyly is consistently supported; the group shares a common ancestry with arctoid carnivorans, either ursids or musteloids. Crown pinnipeds comprise the Otariidae (fur seals and sea lions), Odobenidae (walruses), and Phocidae (seals), with paraphyletic “enaliarctines” falling outside the crown group. The position of extinct Desmatophocidae is debated; they are considered to be closely related to both otariids and odobenids or, alternatively, to phocids. Both otariids and odobenids are known from the North Pacific, diverging approximately 19 Ma, with phocids originating in the North Atlantic or Paratethys region 19–14 Ma. Our understanding of pinniped paleobiology has been enriched by studies that incorporate anatomical and behavioral data into a phylogenetic framework. There is now evidence for sexual dimorphism in the earliest pinnipeds, heralding polygynous breeding systems, followed by increased body sizes, diving capabilities, and diverse feeding strategies in later-diverging phocid and otarioid lineages.

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16

Lunn, N. J. "Fostering behaviour and milk stealing in Antarctic fur seals." Canadian Journal of Zoology 70, no. 4 (April 1, 1992): 837–39. http://dx.doi.org/10.1139/z92-119.

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During the lactation period, female otariid seals alternate trips at sea to feed with visits ashore to nurse their pups. A female returning ashore must be able to recognize her own pup, and it is generally agreed that this is facilitated by auditory and olfactory cues. Instances of fostering behaviour (females nursing nonfilial pups) and milk stealing are reportedly rare among the otariids. In the austral summer of 1989, I observed eight and two instances of fostering behaviour and milk stealing, respectively, by Antarctic fur seals at Bird Island, South Georgia. The following summer, 26 cases of fostering behaviour and 71 cases of milk stealing were documented. In 1990, females appeared to have difficulty acquiring sufficient resources to feed their pups, so nutritional stress was probably responsible for the increase in milk stealing. The occurrence of fostering behaviour suggests that mothers were unable to recognize their own pups, although in the above cases the cause was not clear; neither human disturbance nor density appeared to be the primary factor. Maternal experience may have been a factor in 1990, as 10 of 14 females fostering pups were 5 years of age or less and had given birth to either their first or second pup.

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17

Brunner, S., P. D. Shaughnessy, and M. M. Bryden. "Geographic variation in skull characters of fur seals and sea lions (family Otariidae)." Australian Journal of Zoology 50, no. 4 (2002): 415. http://dx.doi.org/10.1071/zo01056.

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Geographic variation was observed in skulls of several otariid species, with a general change in size corresponding with a change in latitude and primary productivity. The largest specimens were from cool temperate localities, conforming mostly to Rensch's rule. Skulls of Australian sea lions from Western Australia were generally smaller in condylobasal length, but were more robust than those from South Australia. The subantarctic fur seal did not conform to Bergmann's rule: skulls from Amsterdam Island (37�55´S) were largest, those from Gough Island (40�20´S) intermediate and those from Marion Island (46�55´S) the smallest. For both sexes, skulls of southern sea lions from the Falkland Islands were smaller than their equivalents from mainland South America. Similarly, skulls of South African fur seals from south-east South Africa appeared smaller than those from the west coast of South Africa and Namibia; skulls from Namibia grouped separately from those of south-east and west coast, South Africa. We postulate that the Otariidae are in the process of species divergence, much of which may be driven by local factors, particularly latitude and resources.

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18

Boness, Daryl J., and John M. Francis. "The Effect of Thermoregulatory Behaviour On the Mating System of the Juan Fernández Fur Seal, Arctocephalus Philippii." Behaviour 119, no. 1-2 (1991): 104–26. http://dx.doi.org/10.1163/156853991x00391.

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AbstractRecent studies of fur seals and sea lions (Otariids) which are cold water adapted, indicate that social behaviour in hotter climes is constrained by the form and availability of cool substrate provided by the rookery environment. This first study of the behaviour of the Juan Fernández fur seal provides new evidence of this relationship and the extent to which thermoregultory requirements can affect social behaviour in pinnipeds. Females of this species on Alejandro Selkirk Island made daily movements from inland pupping and rest sites to the shoreline and into the water in response to rapid increases in solar radiation to levels exceeding 1.3 cal/cm2/min. Thirty percent of these females floated and groomed offshore in the afternoon in areas protected from the surf by offshore islets and rocky reefs. Males held territories on land either along the shoreline (39%) or in land-locked areas (45%) as is typical of fur seals, or held completely aquatic territories (16%) that encompassed the site where females floated. The average aquatic male, present on territory primarily during the afternoon hours when females floated offshore, achieved as many copulations as did the average land-locked or shoreline male. Land-locked males often abandoned their territories for short periods (45 minutes on average) in response to increasing solar radiation in the afternoon and at a time when female numbers on land were low. The existence of aquatic territoriality as a successful mating strategy has not yet been documented for any other otariid. The occurrence of this behavioural strategy is likely a product of the interaction of thermoregulatory constraints and topographical features which together promote predictable aggregations of females offshore. This study further substantiates that constraints on female aggregation appear to dictate the range and mode of male mating strategies in otariids.

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19

Fiorito, C., J. Marfil, E. Falzoni, M. Martínez Vivot, M. Zumárraga, D. Lombardo, and S. Barandiaran. "Tuberculosis in wild South American sea lions Otaria flavescens stranded in Chubut, Argentina." Diseases of Aquatic Organisms 142 (November 19, 2020): 33–40. http://dx.doi.org/10.3354/dao03520.

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Pinniped tuberculosis, commonly caused by Mycobacterium pinnipedii, is a zoonotic disease reported in free-living and captive otariid species of the southern hemisphere. Currently, data concerning pinniped tuberculosis in South America are scarce, reinforcing the need for further studies of the disease in free-ranging pinnipeds. In this study, we investigated the presence of tuberculosis in South American sea lions Otaria flavescens (SASLs) stranded along the Chubut coastline (Argentina). Necropsies were performed in 9 SASLs, and tissue samples were collected for histopathology, bacteriology, and molecular diagnosis. Four SASLs showed enlarged tracheobronchial lymph nodes (TBLNs) with multifocal to coalescing granulomas. In these animals, a direct IS6110-PCR amplification confirmed the presence of a Mycobacterium tuberculosis complex member in TBLNs (n = 4) and lungs (n = 2), but the agent could not be further identified. In one SASL, Mycobacterium murale was isolated from lungs without lesions. This study confirms the presence of tuberculosis in SASLs from Chubut, where tourist activities promote close interaction with the animals, generating a potential risk to human health. Further research is currently focusing on addressing the prevalence of tuberculosis in wild SASLs, to assess the risk for public health and develop management strategies to avoid human infection.

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20

Inoshima, Yasuo, Tomoaki Murakami, Naotaka Ishiguro, Kazuhiro Hasegawa, and Masahiko Kasamatsu. "An outbreak of lethal adenovirus infection among different otariid species." Veterinary Microbiology 165, no. 3-4 (August 2013): 455–59. http://dx.doi.org/10.1016/j.vetmic.2013.04.013.

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21

Neises, V., J. Zeligs, B. Harris, and L. Cornick. "Examining the metabolic cost of otariid foraging under varying conditions." Journal of Experimental Marine Biology and Ecology 486 (January 2017): 352–57. http://dx.doi.org/10.1016/j.jembe.2016.11.001.

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22

Lyons, E. T., R. L. DeLong, T. R. Spraker, S. R. Melin, and S. C. Tolliver. "Observations in 2001 on hookworms (Uncinaria spp.) in otariid pinnipeds." Parasitology Research 89, no. 6 (December 19, 2002): 503–5. http://dx.doi.org/10.1007/s00436-002-0784-3.

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23

Ball, Mark D., Christopher P. Nizzi, Harold C. Furr, James A. Olson, and Olav T. Oftedal. "Fatty-acyl esters of retinol (vitamin A) in the liver of the harp seal (Phoca groenlandica), hooded seal (Cystophora cristata), and California sea lion (Zalophus californianus)." Biochemistry and Cell Biology 70, no. 9 (September 1, 1992): 809–13. http://dx.doi.org/10.1139/o92-123.

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The fatty-acid composition of retinyl esters in the livers of two species of phocid seal, the harp seal (Phoca groenlandica, n = 20) and the hooded seal (Cystophora cristata, n = 15), and one species of otariid seal, the California sea lion (Zalophus californianus, n = 6), was determined. Vitamin A ranged in concentration from 4 to 1024 nmol retinol/g liver for the phocids and from 381 to 979 nmol/g liver for the otariids. In most of the livers, retinyl palmitate was not the principal ester, and the palmitate + stearate + oleate trio of retinyl esters represented less than 50% of the total. In all samples, the retinyl esters contained 20:1, 20:4, 20:5, and 22:6 in unusually large amounts. Retinyl esters tended to be richer than whole-liver lipids in 20:5 + 22:6, whereas whole-liver lipids were richer in 18:0 and 18:2. Therefore, the pool of acyl donors used for the esterification of retinol may be distinct from that used for other lipids. Birth-to-weaning changes were seen only in the harp seals. In the pups, the hepatic vitamin-A concentration increased 454%, while the proportion of 18:0 and 20:1 in the retinyl esters rose and that of 14:0 + 16:1 and 20:4 fell. Concomitantly, in their mothers, the proportion of 20:4 increased but that of 16:0 and 18:0 decreased.Key words: fatty-acid composition, pinniped liver, retinyl esters, vitamin A.

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24

Ponganis, Paul J., Edward P. Ponganis, Katherine V. Ponganis, Gerald L. Kooyman, Roger L. Gentry, and Fritz Trillmich. "Swimming velocities in otariids." Canadian Journal of Zoology 68, no. 10 (October 1, 1990): 2105–12. http://dx.doi.org/10.1139/z90-293.

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Velocities during surface swimming and diving were measured with microprocessor recorders in four otariid species: northern fur seals (Callorhinus ursinus), Galapagos sea lions (Zalophus californianus wollebaeki), Galapagos fur seals (Arctocephalus galapagoensis), and Hooker's sea lions (Phocarctos hookeri). Mean surface swimming velocities ranged from 0.6 to 1.9 m/s. Transit distances to feeding sites (1.2–90 km) were calculated using these velocities. Dive velocities, recorded every 15 s, ranged from 0.9 to 1.9 m/s. These velocities were consistent with calculated minimal cost of transport velocities in the smaller species. Using time partitioning, the metabolic cost of a northern fur seal foraging trip is estimated on the basis of recorded velocities and their calculated energy costs. This value is within 6% of that previously made with doubly labeled water techniques.

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25

CLARK, P., WS BOARDMAN, and PJ DUIGNAN. "Cytology of haematological cells of otariid seals indigenous to Australasian waters." Australian Veterinary Journal 80, no. 3 (March 2002): 161–64. http://dx.doi.org/10.1111/j.1751-0813.2002.tb11383.x.

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26

Franco-Trecu, Valentina, Massimiliano Drago, Helena Katz, Emanuel Machín, and Yamandú Marín. "With the noose around the neck: Marine debris entangling otariid species." Environmental Pollution 220 (January 2017): 985–89. http://dx.doi.org/10.1016/j.envpol.2016.11.057.

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27

Franco-Trecu, Valentina, Mateo D. García-Olazábal, Bettina Tassino, and Jorge Acevedo. "Parturition process in an amphibian mammal species: new evidences in South American fur seal (Arctocephalus australis)." Animal Biology 66, no. 1 (2016): 21–29. http://dx.doi.org/10.1163/15707563-00002484.

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In mammals, the transition from a terrestrial to an aquatic environment has implied a great number of adaptations. While in terrestrial mammals the presentation of the foetus at birth is typically cephalic, in strictly aquatic mammals as cetaceans and sirenians the presentation of the foetus is mainly breech. The order Pinnipedia is the most recently evolved group of marine mammals and has an amphibian lifestyle. We document, for the first time, the parturition process in the largest breeding colony of the South American fur seal Arctocephalus australis in Uruguay and compare our results with the scarce information available for other species. The analysis of the parturition processes shows that the cephalic/breech birth ratio was 1. In this species, the presentation of the foetus did not affect the total duration of the parturition process, but the cephalic presentation implied a significantly lower duration of the stage 1 of birth, a trend that is also observed in other Otariid species. Phylogenetic reconstructions suggest that O. flavescens and E. jubatus are older than the Arctocephalus genus, having their most recent common ancestor dated between 5-5.8 mybp. Within the Arctocephalus genus, A. australis would be the most recent species (0.7 mybp). In this light, the skewed ratios of breech presentation in older otariids species may suggest a convergent adaptation toward the aquatic life. We hope this finding will promote an increase of studies aiming for a more detailed examination on the adaptive processes involved in the selection of both types of fetal presentations, and their potential effect on the survival of the pup.

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28

Reisfeld, L., NCCA Fernandes, A. Sarmiento, P. Canedo, F. Salvagni, AC Ewbank, T. Zecchini Barrese, et al. "Myeloid and histiocytic sarcomas in subantarctic fur seals Arctocephalus tropicalis, Brazil." Diseases of Aquatic Organisms 148 (February 10, 2022): 13–18. http://dx.doi.org/10.3354/dao03642.

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Histopathological and immunohistochemical methods were used to diagnose round cell tumors in 2 subantarctic fur seals Arctocephalus tropicalis with marked anemia. Although wild-born, both individuals were placed under human care while juveniles in a Brazilian aquarium. Both pinnipeds were PCR tested for herpesvirus, and 1 was infected with otariid gammaherpesvirus 5 (OtHV-5), previously described in a subantarctic fur seal stranded in Brazil. Although some gammaherpesviruses can cause sarcomas and other neoplasms, it was not possible to definitively associate OtHV-5 with the neoplasm. To our knowledge, these are the first neoplasm records in subantarctic fur seals.

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29

Mulsow, Jason, and James J. Finneran. "New approaches for studying the perception of vocal signals in otariid pinnipeds." Journal of the Acoustical Society of America 129, no. 4 (April 2011): 2504. http://dx.doi.org/10.1121/1.3588271.

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30

Kastelein, Ronald A., Lean Helder-Hoek, Linde N. Defillet, Femke Kuiphof, Léonie A. E. Huijser, and John M. Terhune. "Temporary Hearing Threshold Shift in California Sea Lions (Zalophus californianus) Due to One-Sixth-Octave Noise Bands Centered at 8 and 16 kHz: Effect of Duty Cycle and Testing the Equal-Energy Hypothesis." Aquatic Mammals 48, no. 1 (January 15, 2022): 36–58. http://dx.doi.org/10.1578/am.48.1.2022.36.

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To determine the frequency-dependent susceptibility of California sea lions (Zalophus californianus) to noise-induced temporary hearing threshold shift (TTS), two subjects were exposed for 60 min to two fatiguing sounds: continuous one-sixth-octave noise bands (NBs) centered at 8 kHz (at sound exposure levels [SELs] of 166 to 190 dB re 1 µPa2s) and at 16 kHz (at SELs of 183 to 207 dB re 1 µPa2s). Using a psychoacoustic technique, TTSs were quantified at 8, 11.3, 16, 22.4, and 32 kHz (at the center frequency of each NB, half an octave higher, and one octave higher). For both NBs, higher SELs resulted in greater TTSs. In the SEL ranges that were tested, the largest TTSs occurred when the hearing test frequency was half an octave higher than the frequency of the fatiguing sound. When their hearing was tested at the same time after the fatiguing sounds stopped, initial TTSs and hearing recovery patterns were similar in both sea lions. The effect of fatiguing sound duty cycle on TTS was investigated with the 8 kHz NB, using 1,600 ms signals at a mean sound pressure level (SPL) of 154 dB re 1 µPa. Duty cycle reduction from 100 to 90% resulted in a large decrease in TTS; no TTS was observed at duty cycles ≤ 30%. The equal-energy hypothesis was tested with the 8 kHz NB and found to hold true: five combinations of SPL and exposure duration all resulting in a 182 dB SEL produced similar initial TTSs in both sea lions. These findings will contribute to the protection of otariid hearing from anthropogenic noise by facilitating the development of evidence-based underwater sound weighting functions. Our results also show that the introduction of short inter-pulse intervals to underwater sounds aids in the protection of otariid hearing by allowing recovery to take place.

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31

Liggins, Graham C., John T. France, Robert C. Schneider, Bruce S. Knox, and Warren M. Zapol. "Concentrations, metabolic clearance rates, production rates and plasma binding of cortisol in Antarctic phocid seals." Acta Endocrinologica 129, no. 4 (October 1993): 356–59. http://dx.doi.org/10.1530/acta.0.1290356.

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We have reported previously that plasma of the Weddell seal, a member of the phocid family, contains a very high concentration of cortisol. The present study was undertaken to determine whether high cortisol levels were common to seals in the Antarctic environment, or to other phocidae, and to determine the mechanism of the hypercortisolaemia. High levels of cortisol (0.82–2.38 μmol/l) were found in 4 phocidae (Weddell, crabeater, leopard and Southern elephant seals), whereas levels in a member of the otariid family (Antarctic fur seal) were similar to human values. Metabolic clearance rates (MCR) and production rates (PR) of cortisol were determined in the field in Weddell (N = 1), crabeater (N= 3) and leopard (N= 3) seals following bolus injections of [3H] cortisol. The MCR and PR did not differ between the three phocids, but whereas the MCR of 410–590 1/day was twice that of human values, the PR of 460–1180 μmol·m−2·d−1 was up to 40-fold greater. The binding capacity of corticosteroid-binding globulin (CBG) was equal to or greater than the plasma concentrations of cortisol, resulting in relatively low concentrations of free cortisol. We conclude that hypercortisolaemia is maintained in phocid seals mainly by a high production rate—the highest (corrected for surface area) reported in any species. The relatively low cortisol levels in otariid seals studied in the same environment suggest that the high PR in phocidae is unrelated to the harsh climatic conditions, but may be part of their adaptation for diving to extreme depths. The phocid seals and New World primates have similarly high levels of cortisol and a high PR but CBG in the primates has low binding capacity and affinity and cortisol is mainly free.

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32

Nummela, Sirpa, Simo Hemilä, Annalisa Berta, and Tom Reuter. "Inertial and cochlear constraints for high‐frequency hearing in phocid and otariid pinnipeds." Journal of the Acoustical Society of America 123, no. 5 (May 2008): 3508. http://dx.doi.org/10.1121/1.2934403.

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33

Lyons, E. T., and R. L. DeLong. "Photomicrographic images of some features of Uncinaria spp (Nematoda: Ancylostomatidae) from otariid pinnipeds." Parasitology Research 95, no. 5 (February 18, 2005): 346–52. http://dx.doi.org/10.1007/s00436-005-1308-8.

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34

Boessenecker, Robert W. "New records of the fur sealCallorhinus(Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution." Journal of Vertebrate Paleontology 31, no. 2 (March 17, 2011): 454–67. http://dx.doi.org/10.1080/02724634.2011.550362.

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35

Cárdenas-Alayza, Susana, Dimitri Gutiérrez, and Yann Tremblay. "Trends in sympatric otariid populations suggest resource limitations in the Peruvian Humboldt Current System." Marine Environmental Research 169 (July 2021): 105349. http://dx.doi.org/10.1016/j.marenvres.2021.105349.

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36

Lowther, Andrew D., and Simon D. Goldsworthy. "Maternal strategies of the Australian sea lion (Neophoca cinerea) at Dangerous Reef, South Australia." Australian Journal of Zoology 59, no. 1 (2011): 54. http://dx.doi.org/10.1071/zo11025.

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Maternal strategies of otariid seals reflect the optimisation between resource exploitation and offspring provisioning driven across spatially separated foraging and nursing grounds. Intercolony variation in the expression of maternal strategies may represent temporal and spatial differences in resource availability, intraspecies competition or differences in life-history traits. The current study describes maternal strategies of the Australian sea lion at the largest breeding colony of the species (Dangerous Reef) and a comparative analysis was performed with data collected 16 years earlier at Seal Bay (Kangaroo Island). Significant differences in maternal strategies were characterised by lower milk lipid content (21.0 versus 28.9%), abbreviated periods onshore (0.93 versus 1.63 days) and slower pup growth rates (0.09–0.12 kg day–1) at Dangerous Reef. These data suggest flexibility in the expression of maternal investment between breeding sites and support the hypothesis of localised adaptation

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37

Foster, G., JL Baily, F. Howie, AC Brownlow, JA Wagenaar, MJ Gilbert, WG Miller, et al. "Campylobacter pinnipediorum subsp. caledonicus and C. pinnipediorum subsp. pinnipediorum recovered from abscesses in pinnipeds." Diseases of Aquatic Organisms 142 (November 19, 2020): 41–46. http://dx.doi.org/10.3354/dao03544.

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Campylobacter pinnipediorum was described recently for isolates recovered from pinnipeds. The novel species was further split into 2 subspecies based on host and geography, with C. pinnipediorum subsp. pinnipediorum recovered from otariid seals in California (USA) and C. pinnipediorum subsp. caledonicus recovered from phocid seals in Scotland. We report details of the infections of 7 pinnipeds from which C. pinnipediorum was isolated: C. pinnipediorum subsp. caledonicus was isolated from 2 harbour seals Phoca vitulina and a single grey seal Halichoerus grypus, and C. pinnipediorum subsp. pinnipediorum was isolated from California sea lions Zalophus californianus. Six of the isolates were recovered from samples collected at post-mortem investigation. In 2 of the Scottish seals and in 3 of the California seals, C. pinnipediorum was the sole bacterial isolate recovered from abscesses present and suggests they may have resulted from conspecific or intraspecific bite wounds.

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38

Barnes, Lawrence G., and Kiyoharu Hirota. "Miocene pinnipeds of the otariid subfamily Allodesminae in the North Pacific Ocean: Systematics and relationships." Island Arc 3, no. 4 (December 1994): 329–60. http://dx.doi.org/10.1111/j.1440-1738.1994.tb00119.x.

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39

Williams, Terrie M., M. Rutishauser, B. Long, T. Fink, J. Gafney, H. Mostman‐Liwanag, and D. Casper. "Seasonal Variability in Otariid Energetics: Implications for the Effects of Predators on Localized Prey Resources." Physiological and Biochemical Zoology 80, no. 4 (July 2007): 433–43. http://dx.doi.org/10.1086/518346.

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40

Ladds, Monique A., Adam P. Thompson, David J. Slip, David P. Hocking, and Robert G. Harcourt. "Seeing It All: Evaluating Supervised Machine Learning Methods for the Classification of Diverse Otariid Behaviours." PLOS ONE 11, no. 12 (December 21, 2016): e0166898. http://dx.doi.org/10.1371/journal.pone.0166898.

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41

Lowther, A. D., R. G. Harcourt, and S. D. Goldsworthy. "Regional variation in trophic ecology of adult female Australian sea lions inferred from stable isotopes in whiskers." Wildlife Research 40, no. 4 (2013): 303. http://dx.doi.org/10.1071/wr12181.

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Context The primary selective forces responsible for shaping life-history traits come from the physical and biological environment in which a species resides. Consequently, the limits of a species range may provide a useful measure of adaptive potential to environmental change. The proximity of foraging grounds to terrestrial nursing habitat constrains central-place foragers such as otariid seals in selecting breeding locations. The Australian sea lion (Neophoca cinerea) is an endangered otariid endemic to Australia, whose northern-range extent occurs at a temperate–tropical transition zone on the western coast of Western Australia (WA). Aims Currently, there is a complete absence of data on the foraging ecology of Australian sea lions in WA. We sought to address this critical knowledge gap and provide data on the foraging ecology of adult female Australian sea lions at three isolated breeding colonies in western WA. Methods We used stable-isotope ratios of carbon (δ13C) and nitrogen (δ15N) in the whiskers of pups as proxies to characterise feeding behaviour of 10–28% of all adult female Australian sea lions at each colony. We then compared these geographic data to (1) conspecifics at similar latitude in South Australia (SA) and (2) isotopic data collated from other studies on seabirds that inhabit the region, to place foraging behaviour of adult female Australian sea lions into context. Key results At the southernmost colonies in WA, individual animals were members of one of two distinct isotopic clusters that could be described by differences in δ15N and δ13C values. Individuals at the northernmost colony displayed δ15N values similar to those of seabirds in the same region. Across the study, isotope ratios of adult female Australian sea lions in western WA were between 3‰ and 5‰ lower than those observed at a colony at similar latitude in SA. Conclusions Gross differences in the physical oceanography between WA and SA may in part explain the differences in isotope ratios of individuals between the regions, with lower δ15N and δ13C values in WA probably reflecting the relatively depauperate conditions of the Leeuwin Current. Implications Potential regional differences in trophic structure should be considered when developing appropriate management plans for Australian sea lions and regional variation in the diet of Australian sea lion warrants further investigation.

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42

Reisfeld, Laura, Carlos Sacristán, Angélica María Sánchez-Sarmiento, Samira Costa-Silva, Josué Díaz-Delgado, Kátia Regina Groch, Juliana Marigo, et al. "Fatal pulmonary parafilaroidiasis in a free-ranging subantarctic fur seal (Arctocephalus tropicalis) coinfected with two gammaherpesviruses and Sarcocystis sp." Revista Brasileira de Parasitologia Veterinária 28, no. 3 (July 2019): 499–503. http://dx.doi.org/10.1590/s1984-29612019029.

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Abstract A juvenile subantarctic fur seal (Arctocephalus tropicalis) found dead in Santa Catarina state, southern Brazil, presented with disseminated verminous pneumonia due to Parafilaroides sp. A concomitant infection with two different gammaherpesviruses was identified by PCR in different tissues; one of them possibly a novel species (tentatively named Otariid herpesvirus 7). Sarcocystis sp. DNA was identified molecularly in skeletal muscle samples with intrasarcoplasmic bradyzoites and no apparent tissue response. All analyzed samples (mandibular, laryngeal, tracheal, and mesenteric lymph nodes, and lung) were PCR-negative for Brucella spp. The most likely cause of death was severe pulmonary parafilaroidiasis. The pathogenic role of the gammaherpesviruses in several of the tissues was not evident. This study describes the pathogenicity of Parafilaroides sp. in a subantarctic fur seal, widens the host range of herpesvirus in pinnipeds, and reports the first molecular identification of Sarcocystis sp. in this species.

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43

Cárdenas-Alayza, Susana, Michael J. Adkesson, Mickie R. Edwards, Amy C. Hirons, Dimitri Gutiérrez, Yann Tremblay, and Valentina Franco-Trecu. "Sympatric otariids increase trophic segregation in response to warming ocean conditions in Peruvian Humboldt Current System." PLOS ONE 17, no. 8 (August 11, 2022): e0272348. http://dx.doi.org/10.1371/journal.pone.0272348.

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Determining trophic habits of predator communities is essential to measure interspecific interactions and response to environmental fluctuations. South American fur seals, Arctocephalus australis (SAFS) and sea lions Otaria byronia (SASL), coexist along the coasts of Peru. Recently, ocean warming events (2014–2017) that can decrease and impoverish prey biomass have occurred in the Peruvian Humboldt Current System. In this context, our aim was to assess the effect of warming events on long-term inter- and intra-specific niche segregation. We collected whisker from SAFS (55 females and 21 males) and SASL (14 females and 22 males) in Punta San Juan, Peru. We used δ13C and δ15N values serially archived in otariid whiskers to construct a monthly time series for 2005–2019. From the same period we used sea level anomaly records to determine shifts in the predominant oceanographic conditions using a change point analysis. Ellipse areas (SIBER) estimated niche width of species-sex groups and their overlap. We detected a shift in the environmental conditions marking two distinct periods (P1: January 2005—October 2013; P2: November 2013—December 2019). Reduction in δ15N in all groups during P2 suggests impoverished baseline values with bottom-up effects, a shift towards consuming lower trophic level prey, or both. Reduced overlap between all groups in P2 lends support of a more redundant assemblage during the colder P1 to a more trophically segregated assemblage during warmer P2. SASL females show the largest variation in response to the warming scenario (P2), reducing both ellipse area and δ15N mean values. Plasticity to adapt to changing environments and feeding on a more available food source without fishing pressure can be more advantageous for female SASL, albeit temporary trophic bottom-up effects. This helps explain larger population size of SASL in Peru, in contrast to the smaller and declining SAFS population.

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44

Avery, Graham, and Richard G. Klein. "Review of fossil phocid and otariid seals from the southern and western coasts of South Africa." Transactions of the Royal Society of South Africa 66, no. 1 (February 2011): 14–24. http://dx.doi.org/10.1080/0035919x.2011.564490.

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45

Miller, Edward H., Kenneth W. Pitcher, and Thomas R. Loughlin. "BACULAR SIZE, GROWTH, AND ALLOMETRY IN THE LARGEST EXTANT OTARIID, THE STELLER SEA LION(EUMETOPIAS JUBATUS)." Journal of Mammalogy 81, no. 1 (February 2000): 134–44. http://dx.doi.org/10.1644/1545-1542(2000)081<0134:bsgaai>2.0.co;2.

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46

Miller, E. H., K. W. Pitcher, and T. R. Loughlin. "Bacular Size, Growth, and Allometry in the Largest Extant Otariid, the Steller Sea Lion (Eumetopias jubatus)." Journal of Mammalogy 81, no. 1 (February 17, 2000): 134–44. http://dx.doi.org/10.1093/jmammal/81.1.134.

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47

Hemilä, Simo, Sirpa Nummela, Annalisa Berta, and Tom Reuter. "High-frequency hearing in phocid and otariid pinnipeds: An interpretation based on inertial and cochlear constraints." Journal of the Acoustical Society of America 120, no. 6 (December 2006): 3463–66. http://dx.doi.org/10.1121/1.2372712.

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48

Page, Brad, Jane McKenzie, Mark A. Hindell, and Simon D. Goldsworthy. "Drift dives by male New Zealand fur seals (Arctocephalus forsteri)." Canadian Journal of Zoology 83, no. 2 (February 1, 2005): 293–300. http://dx.doi.org/10.1139/z05-013.

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Some phocid seal diving-behaviour studies have identified dives characterised by a period of passive drifting through the water column, rather than active locomotion. During these "drift dives" seals are thought to preferentially direct energy towards processing of food, lactate, or renal metabolites rather than to active propulsion. We describe the first drift dives reported in an otariid, the New Zealand fur seal (Arctocephalus forsteri (Lesson, 1828)), studied at Kangaroo Island in South Australia. Not all males in the study undertook drift dives and those that did were significantly heavier than those that did not, suggesting that body size may influence the propensity to drift dive in New Zealand fur seals. Drift dives lasted 6.0 ± 1.78 min and had passive drift segments of 3.5 ± 1.5 min, during which seals showed a negative change in depth (i.e., sinking) of 0.14 ± 0.05 m/s. Drift dives occurred at night and were possibly undertaken to avoid near-surface predators and to process food, lactate, or renal metabolites while resting.

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49

Hood, Wendy R., and Kathryn A. Ono. "Variation in maternal attendance patterns and pup behaviour in a declining population of Steller sea lions (Eumetopias jubatus)." Canadian Journal of Zoology 75, no. 8 (August 1, 1997): 1241–46. http://dx.doi.org/10.1139/z97-146.

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Maternal attendance patterns of lactating female Steller sea lions (Eumetopias jubatus) and the activity budgets of pups on Año Nuevo Island, California, were compared between the 1973 and 1992 breeding seasons to investigate temporal changes in behaviour that may be associated with population decline. Females were absent from the breeding area longer in 1992, which may reflect increased foraging effort. Pups also spent significantly less time sucking and more time swimming in 1992. Suckling time is correlated with milk intake in some otariid species, thus the decreased amount of time 1992 pups spent sucking could reflect a reduction in the total volume of milk produced by females. Pups in 1992 are likely to have spent more time swimming than pups in 1973 because high tide covered a greater proportion of the study site in 1992 than in 1973. An increase in time females spent at sea and a decrease in time pups spent sucking are consistent with behavioural changes associated with reduced prey availability.

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50

Barnes, Lawrence G., and Rodney E. Raschke. "Gomphotaria pugnax, a new genus and species of Late Miocene dusignathine otariid pinniped (Mammalia: Carnivora) from California." Contributions in science 426 (April 12, 1991): 1–16. http://dx.doi.org/10.5962/p.208154.

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Статті в журналах з теми "Otariid"

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