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Volzke S, Cleeland JB, Hindell MA, Corney SP, Wotherspoon SJ, McMahon CR. Extreme polygyny results in intersex differences in age-dependent survival of a highly dimorphic marine mammal. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221635. [PMID: 36968236 PMCID: PMC10031410 DOI: 10.1098/rsos.221635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
Developmental differences in vital rates are especially profound in polygamous mating systems. Southern elephant seals (Mirounga leonina) are highly dimorphic and extremely polygynous marine mammals. A demographic model, supported by long-term capture-mark-recapture records, investigated the influence of sex and age on survival in this species. The study revealed clear differences between female and male age-dependent survival rates. Overall juvenile survival estimates were stable around 80-85% for both sexes. However, male survival estimates were 5-10% lower than females in the same age classes until 8 years of age. At this point, male survival decreased rapidly to 50% ± 10% while female estimates remained constant at 80% ± 5%. Different energetic requirements could underpin intersex differences in adult survival. However, the species' strong sexual dimorphism diverges during early juvenile development when sex-specific survival rates were less distinct. Maximizing growth is especially advantageous for males, with size being a major determinant of breeding probability. Maturing males may employ a high-risk high-reward foraging strategy to compensate for extensive sexual selection pressures and sex-specific energetic needs. Our findings suggest sex-specific adult survival is a result of in situ ecological interactions and evolutionary specialization associated with being a highly polygynous marine predator.
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Affiliation(s)
- Sophia Volzke
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
- Australian Antarctic Division, Department of Agriculture, Water and the Environment, Kingston, TAS 7050, Australia
| | - Jaimie B. Cleeland
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
- Australian Antarctic Division, Department of Agriculture, Water and the Environment, Kingston, TAS 7050, Australia
| | - Mark A. Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
| | - Stuart P. Corney
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
- Centre for Marine Socioecology, University of Tasmania, Hobart, TAS 7005, Australia
- Australian Antarctic Partnership Program, University of Tasmania, Hobart, TAS 7005, Australia
| | - Simon J. Wotherspoon
- Australian Antarctic Division, Department of Agriculture, Water and the Environment, Kingston, TAS 7050, Australia
| | - Clive R. McMahon
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
- IMOS Animal Tagging, Sydney Institute of Marine Science, Mosman, NSW 2088, Australia
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Green CP, Ratcliffe N, Mattern T, Thompson D, Lea MA, Wotherspoon S, Borboroglu PG, Ellenberg U, Morrison KW, Pütz K, Sagar PM, Seddon PJ, Torres LG, Hindell MA. The role of allochrony in influencing interspecific differences in foraging distribution during the non-breeding season between two congeneric crested penguin species. PLoS One 2022; 17:e0262901. [PMID: 35139102 PMCID: PMC8827451 DOI: 10.1371/journal.pone.0262901] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 01/09/2022] [Indexed: 01/28/2023] Open
Abstract
Mechanisms promoting coexistence between closely related species are fundamental for maintaining species diversity. Mechanisms of niche differentiation include allochrony which offsets the peak timing of resource utilisation between species. Many studies focus on spatial and temporal niche partitioning during the breeding season, few have investigated the role allochrony plays in influencing interspecific segregation of foraging distribution and ecology between congeneric species during the non-breeding season. We investigated the non-breeding migrations of Snares (Eudyptes robustus) and Fiordland penguins (Eudyptes pachyrhynchus), closely related species breeding between 100-350 km apart whose migration phenology differs by two months. Using light geolocation tracking, we examined the degree of overlap given the observed allochrony and a hypothetical scenario where the species commence migration simultaneously. We found that Fiordland penguins migrated to the Sub-Antarctic Frontal Zone and Polar Frontal Zone in the austral autumn whereas Snares penguins disperse westwards staying north of the Sub-Tropical Front in the austral winter. Our results suggest that allochrony is likely to be at the root of segregation because the relative profitability of the different water masses that the penguins forage in changes seasonally which results in the two species utilising different areas over their core non-breeding periods. Furthermore, allochrony reduces relatively higher levels of spatiotemporal overlap during the departure and arrival periods, when the close proximity of the two species' colonies would cause the birds to congregate in similar areas, resulting in high interspecific competition just before the breeding season. Available evidence from other studies suggests that the shift in phenology between these species has arisen from adaptive radiation and phenological matching to the seasonality of local resource availability during the breeding season and reduced competitive overlap over the non-breeding season is likely to be an incidental outcome.
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Affiliation(s)
- Cara-Paige Green
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | | | - Thomas Mattern
- New Zealand Penguin Initiative, Dunedin, New Zealand
- Department of Zoology, University of Otago, Dunedin, New Zealand
- Global Penguin Society, Puerto Madryn, Chubut, Argentina
| | - David Thompson
- National Institute of Water and Atmospheric Research Ltd., Hataitai, Wellington, New Zealand
| | - Mary-Anne Lea
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
- Australian Centre for Excellence in Antarctic Science, University of Tasmania, Hobart, Tasmania, Australia
| | - Simon Wotherspoon
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
- Australian Antarctic Division, Department of Agriculture, Water and the Environment, Kingston, Tasmania, Australia
| | - Pablo Garcia Borboroglu
- New Zealand Penguin Initiative, Dunedin, New Zealand
- Global Penguin Society, Puerto Madryn, Chubut, Argentina
- Centro para el Estudio de Sistemas Marinos (CESIMAR–CONICET), Puerto Madryn, Chubut, Argentina
| | - Ursula Ellenberg
- Global Penguin Society, Puerto Madryn, Chubut, Argentina
- Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Australia
| | - Kyle W. Morrison
- National Institute of Water and Atmospheric Research Ltd., Hataitai, Wellington, New Zealand
| | | | - Paul M. Sagar
- National Institute of Water and Atmospheric Research Ltd., Christchurch, New Zealand
| | - Philip J. Seddon
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Leigh G. Torres
- Department of Fisheries and Wildlife, Marine Mammal Institute, Oregon State University, Newport, Oregon, United States of America
| | - Mark A. Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
- Australian Centre for Excellence in Antarctic Science, University of Tasmania, Hobart, Tasmania, Australia
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Allegue H, Guinet C, Patrick SC, Hindell MA, McMahon CR, Réale D. Sex, body size, and boldness shape the seasonal foraging habitat selection in southern elephant seals. Ecol Evol 2022; 12:e8457. [PMID: 35127010 PMCID: PMC8796948 DOI: 10.1002/ece3.8457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/22/2021] [Accepted: 11/25/2021] [Indexed: 12/04/2022] Open
Abstract
Selecting foraging habitat is a fundamental behavior in the life of organisms as it directly links resource acquisition to fitness. Differences in habitat selection among individuals may arise from several intrinsic and extrinsic factors, and yet, their interaction has been given little attention in the study of wild populations. We combine sex, body size, and boldness to explain individual differences in the seasonal foraging habitat selection of southern elephant seals (Mirounga leonina) from the Kerguelen Archipelago. We hypothesize that habitat selection is linked to the trade-off between resource acquisition and risk, and that individuals differ in their position along this trade-off because of differences in reproductive strategies, life stages, and metabolic requirements. Before the post-molt foraging trip, we used a novel object approach test to quantify the boldness of 28 subadult and adult females and 42 subadult males and equipped them with data loggers to track their movements at sea. Subadult males selected neritic and oceanic habitats, whereas females mostly selected less productive oceanic habitats. Both sexes showed a seasonal shift from Antarctic habitats in the south in the summer to the free of ice subantarctic and subtropical habitats in the north in the winter. Males avoided oceanic habitats and selected more productive neritic and Antarctic habitats with body size mostly in the winter. Bolder males selected northern warmer waters in winter, while shyer ones selected the Kerguelen plateau and southern colder oceanic waters. Bolder females selected the Kerguelen plateau in the summer when prey profitability is assumed to be the highest. This study not only provides new insights into the spatiotemporal foraging ecology of elephant seals in relation to personality but also emphasizes the relevance of combining several intrinsic and extrinsic factors in understanding among-individual variation in space use essential in wildlife management and conservation.
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Affiliation(s)
- Hassen Allegue
- Département des Sciences BiologiquesUniversité du Québec à MontréalMontréalQCCanada
| | | | | | - Mark A. Hindell
- Institute for Marine and Antarctic StudiesBattery PointTASAustralia
- Antarctic Climate and Ecosystems Cooperative Research CentreUniversity of TasmaniaHobartTASAustralia
| | - Clive R. McMahon
- Institute for Marine and Antarctic StudiesBattery PointTASAustralia
- Sydney Institute of Marine ScienceSydneyNSWAustralia
- Department of Biological SciencesMacquarie UniversitySydneyNSWAustralia
| | - Denis Réale
- Département des Sciences BiologiquesUniversité du Québec à MontréalMontréalQCCanada
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Facka AN, Powell RA. Intraspecific Competition, Habitat Quality, Niche Partitioning, and Causes of Intrasexual Territoriality for a Reintroduced Carnivoran. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.734155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Animals exploring a new environment develop cognitive maps using diverse sensory input and, thereby, gain information needed to establish home ranges. Experiencing, and learning information about, resources should be advantageous to the resident of a home range while lack of such information should put invaders into the home range at a disadvantage. Conspecifics, especially, should avoid the home ranges of one another to ensure that they do not experience reduced resource availability caused by resource depression or depletion. Yet, encountering conspecific competitors of different sexes may elicit responses that can lead to spacing on a landscape that has different costs and benefits on males and females. We tested the hypothesis that female fishers (Pekania pennanti) avoid competition from both males and female conspecifics whereas male fishers avoid competition only from other males. We reintroduced fishers onto our study site in the presence or absence of competitors’ home ranges during late 2009 through 2011. Using satellite transmitters (Argos) and land-based (VHF) telemetry, we monitored fishers and estimated their locations, movements and use of the surrounding landscape during their first 500 days after release. All fishers settled in relatively high-quality habitat but females that encountered the home ranges of conspecifics moved farther, explored larger areas, and settled farther from their release locations than did females that did not encounter a conspecific’s home range. Male fishers exhibited diverse responses upon encountering the home ranges of conspecifics. Thus, female fishers avoid conspecific competition from all fishers, but males tolerate, or impose, competition with females, apparently to increase mating opportunities. These observations are consistent with the movements and strategies of other solitary carnivores.
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Volzke S, McMahon CR, Hindell MA, Burton HR, Wotherspoon SJ. Climate influences on female survival in a declining population of southern elephant seals ( Mirounga leonina). Ecol Evol 2021; 11:11333-11344. [PMID: 34429922 PMCID: PMC8366891 DOI: 10.1002/ece3.7919] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 06/21/2021] [Accepted: 06/25/2021] [Indexed: 11/22/2022] Open
Abstract
The Southern Ocean has been disproportionately affected by climate change and is therefore an ideal place to study the influence of changing environmental conditions on ecosystems. Changes in the demography of predator populations are indicators of broader shifts in food web structure, but long-term data are required to study these effects. Southern elephant seals (Mirounga leonina) from Macquarie Island have consistently decreased in population size while all other major populations across the Southern Ocean have recently stabilized or are increasing. Two long-term mark-recapture studies (1956-1967 and 1993-2009) have monitored this population, which provides an opportunity to investigate demographic performance over a range of climatic conditions. Using a 9-state matrix population model, we estimated climate influences on female survival by incorporating two major climatic indices into our model: The Southern Annular Mode (SAM) and the Southern Oscillation Index (SOI). Our best model included a 1 year lagged effect of SAM and an unlagged SOI as covariates. A positive relationship with SAM1 (lagged) related the previous year's SAM with juvenile survival, potentially due to changes in local prey availability surrounding Macquarie Island. The unlagged SOI had a negative effect on both juvenile and adult seals, indicating that sea ice dynamics and access to foraging grounds on the East Antarctic continental shelf could explain the different contributions of ENSO events on the survival of females in this population.
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Affiliation(s)
- Sophia Volzke
- Institute for Marine & Antarctic StudiesUniversity of TasmaniaHobartTas.Australia
| | - Clive R. McMahon
- Institute for Marine & Antarctic StudiesUniversity of TasmaniaHobartTas.Australia
- IMOS Animal TaggingSydney Institute of Marine ScienceMosmanNSWAustralia
| | - Mark A. Hindell
- Institute for Marine & Antarctic StudiesUniversity of TasmaniaHobartTas.Australia
- Antarctic Climate and Ecosystems Cooperative Research CentreUniversity of TasmaniaHobartTas.Australia
| | - Harry R. Burton
- Australian Antarctic DivisionDepartment of Agriculture, Water and the EnvironmentKingstonTas.Australia
| | - Simon J. Wotherspoon
- Institute for Marine & Antarctic StudiesUniversity of TasmaniaHobartTas.Australia
- Australian Antarctic DivisionDepartment of Agriculture, Water and the EnvironmentKingstonTas.Australia
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Hindell MA, McMahon CR, Jonsen I, Harcourt R, Arce F, Guinet C. Inter- and intrasex habitat partitioning in the highly dimorphic southern elephant seal. Ecol Evol 2021; 11:1620-1633. [PMID: 33613994 PMCID: PMC7882946 DOI: 10.1002/ece3.7147] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/25/2020] [Accepted: 12/02/2020] [Indexed: 01/15/2023] Open
Abstract
Partitioning resources is a key mechanism for avoiding intraspecific competition and maximizing individual energy gain. However, in sexually dimorphic species it is difficult to discern if partitioning is due to competition or the different resource needs of morphologically distinct individuals. In the highly dimorphic southern elephant seal, there are intersexual differences in habitat use; at Iles Kerguelen, males predominantly use shelf waters, while females use deeper oceanic waters. There are equally marked intrasexual differences, with some males using the nearby Kerguelen Plateau, and others using the much more distant Antarctic continental shelf (~2,000 km away). We used this combination of inter and intrasexual behavior to test two hypotheses regarding habitat partitioning in highly dimorphic species. (a) that intersexual differences in habitat use will not appear until the seals diverge in body size and (b) that some habitats have higher rates of energy return than others. In particular, that the Antarctic shelf would provide higher energy returns than the Kerguelen Shelf, to offset the greater cost of travel. We quantified the habitat use of 187 southern elephant seals (102 adult females and 85 subadult males). The seals in the two groups were the same size (~2.4 m) removing the confounding effect of body size. We found that the intersexual differences in habitat use existed before the divergence in body size. Also, we found that the amount of energy gained was the same in all of the major habitats. This suggests that the use of shelf habitats by males is innate, and a trade-off between the need to access the large benthic prey available on shelf waters, against the higher risk of predation there. Intrasexual differences in habitat use are another trade-off; although there are fewer predators on the Antarctic shelf, it is subject to considerable interannual fluctuations in sea-ice extent. In contrast, the Kerguelen Plateau presents more consistent foraging opportunities, but contains higher levels of predation. Habitat partitioning in this highly dimorphic species is therefore the result of complex interplay of life history strategies, environmental conditions and predation pressure.
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Affiliation(s)
- Mark A. Hindell
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTasmaniaAustralia
| | - Clive R. McMahon
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTasmaniaAustralia
- IMOS Animal Tagging, Sydney Institute of Marine ScienceMosmanNew South WalesAustralia
- Department of Biological SciencesMacquarie UniversityNorth Ryde, SydneyNew South WalesAustralia
| | - Ian Jonsen
- Department of Biological SciencesMacquarie UniversityNorth Ryde, SydneyNew South WalesAustralia
| | - Robert Harcourt
- IMOS Animal Tagging, Sydney Institute of Marine ScienceMosmanNew South WalesAustralia
- Department of Biological SciencesMacquarie UniversityNorth Ryde, SydneyNew South WalesAustralia
| | - Fernando Arce
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTasmaniaAustralia
| | - Christophe Guinet
- Centre d’Etudes Biologiques de Chizé (CEBC)UMR 7372Université de la Rochelle‐CNRSVilliers en BoisFrance
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Bowden-Parry M, Postma E, Boogert NJ. Effects of food type and abundance on begging and sharing in Asian small-clawed otters ( Aonyx cinereus). PeerJ 2020; 8:e10369. [PMID: 33335807 PMCID: PMC7713600 DOI: 10.7717/peerj.10369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/25/2020] [Indexed: 11/23/2022] Open
Abstract
Begging for food, a conspicuous solicitation display, is common in a variety of taxa, and it has received extensive research attention in a parent-offspring context. Both theoretical models and empirical evidence suggest that offspring begging can be an honest signal of hunger or a mediator of competition between siblings. At a behavioural mechanistic level, begging for food can be a form of harassment aimed at persuading those in possession of food to share. Food sharing, defined as the transfer of a defendable food item from one individual to another, can vary considerably between species, age-classes and food type and abundance. We investigated the determinants of begging and food-sharing behaviours in Asian small-clawed otters (Aonyx cinereus), a group-living species that commonly exhibits begging in captivity. We presented two captive otter populations with three food types that varied in exploitation complexity, in three different abundances. We predicted that begging rates would be highest when food was in lowest abundance and hardest to exploit, and that increased begging would lead to increased food sharing. We found that, over time, increased begging rates were indeed correlated with increased food transfers, but neither food type complexity nor abundance affected begging or sharing rates. However, age category was significantly associated with begging and food sharing rates: juvenile otters begged more and shared less than adult otters. The results from this first experimental study on begging and food sharing within the Mustelid family begin to reveal some of the drivers of these behaviours.
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Affiliation(s)
- Madison Bowden-Parry
- Department of Biosciences, University of Exeter, Penryn, Cornwall, United Kingdom
| | - Erik Postma
- Department of Biosciences, University of Exeter, Penryn, Cornwall, United Kingdom
| | - Neeltje J. Boogert
- Department of Biosciences, University of Exeter, Penryn, Cornwall, United Kingdom
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Frankish CK, Phillips RA, Clay TA, Somveille M, Manica A. Environmental drivers of movement in a threatened seabird: insights from a mechanistic model and implications for conservation. DIVERS DISTRIB 2020. [DOI: 10.1111/ddi.13130] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- Caitlin K. Frankish
- British Antarctic Survey Cambridge UK
- Department of Zoology University of Cambridge Cambridge UK
| | | | - Thomas A. Clay
- School of Environmental Sciences University of Liverpool Liverpool UK
| | | | - Andrea Manica
- Department of Zoology University of Cambridge Cambridge UK
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Boucher NP, Derocher AE, Richardson ES. Spatial and temporal variability in ringed seal ( Pusa hispida) stable isotopes in the Beaufort Sea. Ecol Evol 2020; 10:4178-4192. [PMID: 32489588 PMCID: PMC7246210 DOI: 10.1002/ece3.6186] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 12/02/2022] Open
Abstract
Arctic ecosystem dynamics are shifting in response to warming temperatures and sea ice loss. Such ecosystems may be monitored by examining the diet of upper trophic level species, which varies with prey availability. To assess interannual variation in the Beaufort Sea ecosystem, we examined spatial and temporal trends in ringed seal (Pusa hispida) δ13C and δ15N in claw growth layers grown from 1964 to 2011. Stable isotopes were correlated with climate indices, environmental conditions, seal population productivity, and geographic location. Sex and age did not influence stable isotopes. Enriched 13C was linked to cyclonic circulation regimes, seal productivity, and westward sampling locations. Higher δ15N was linked to lower sea surface temperatures, a higher percentage of pups in the subsistence harvest, and sample locations that were eastward and further from shore. From the 1960s to 2000s, ringed seal niche width expanded, suggesting a diversification of diet due to expansion of prey and/or seal space use. Overall, trends in ringed seal stable isotopes indicate changes within the Beaufort Sea ecosystem affected by water temperatures and circulation regimes. We suggest that continued monitoring of upper trophic level species will yield insights into changing ecosystem structure with climate change.
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Affiliation(s)
- Nicole P. Boucher
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada
| | | | - Evan S. Richardson
- Wildlife Research Division, Science and Technology BranchEnvironment and Climate Change CanadaWinnipegMBCanada
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Thomas JL, Parrott ML, Handasyde KA, Temple-Smith P. Burrow use by juvenile platypuses (Ornithorhynchus anatinus) in their natal home range. J Mammal 2019. [DOI: 10.1093/jmammal/gyz078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AbstractWe determined patterns of burrow use by juvenile platypuses (Ornithorhynchus anatinus) in their natal home range, and evaluated associations between burrows and vegetation. Between March 2015 and March 2017, we captured seven juvenile platypuses along a 3-km stretch of Badger Creek, Victoria and fitted them with radiotransmitters. We recorded the locations of animals in their burrows daily while transmitters were attached (range: 14–132 days). Juveniles used 74 different burrows, with each using 11 ± 2 burrows. Overall, 65% of burrows (48) were used once, 22% (16) were used between 2 and 9 times (moderate-use), and 13% (10) were used frequently (> 10 times). No juveniles dispersed during the monitoring period (14–132 days). Although some association was observed between burrow use and particular vegetation communities, vegetation was not a strong factor driving site selection of burrows. Use of multiple burrows may allow juveniles to avoid competition with conspecifics, reduce exposure to ectoparasites, and develop shelter-seeking behavior. Juvenile platypuses remained in their natal home range, where conditions are likely to be good because they supported recent breeding, while completing their growth and development prior to dispersal.
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Affiliation(s)
- Jessica L Thomas
- Healesville Sanctuary, Healesville, Victoria, Australia
- School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Marissa L Parrott
- Wildlife Conservation and Science, Zoos Victoria, Parkville, Victoria, Australia
| | - Kathrine A Handasyde
- School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Peter Temple-Smith
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
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11
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A quantitative, hierarchical approach for detecting drift dives and tracking buoyancy changes in southern elephant seals. Sci Rep 2019; 9:8936. [PMID: 31222003 PMCID: PMC6586652 DOI: 10.1038/s41598-019-44970-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 05/29/2019] [Indexed: 11/08/2022] Open
Abstract
Foraging behaviour of marine predators inferred from the analysis of horizontal or vertical movements commonly lack quantitative information about foraging success. Several marine mammal species are known to perform dives where they passively drift in the water column, termed “drift” dives. The drift rate is determined by the animal’s buoyancy, which can be used to make inference regarding body condition. Long term dive records retrieved via satellite uplink are often summarized before transmission. This loss of resolution hampers identification of drift dives. Here, we develop a flexible, hierarchically structured approach to identify drift dives and estimate the drift rate from the summarized time-depth profiles that are increasingly available to the global research community. Based on high-resolution dive data from southern elephant seals, we classify dives as drift/non-drift and apply a summarization algorithm. We then (i) automatically generate dive groups based on inflection point ordering using a ‘Reverse’ Broken-Stick Algorithm, (ii) develop a set of threshold criteria to apply across groups, ensuring non-drift dives are most efficiently rejected, and (iii) finally implement a custom Kalman filter to retain the remaining dives that are within the seals estimated drifting time series. Validation with independent data sets shows our method retains approximately 3% of all dives, of which 88% are true drift dives. The drift rate estimates are unbiased, with the upper 95% quantile of the mean squared error between the daily averaged summarized profiles using our method (SDDR) and the observed daily averaged drift rate (ODDR) being only 0.0015. The trend of the drifting time-series match expectations for capital breeders, showing the lowest body condition commencing foraging trips and a progressive improvement as they remain at sea. Our method offers sufficient resolution to track small changes in body condition at a fine temporal scale. This approach overcomes a long-term challenge for large existing and ongoing data collections, with potential application across other drift diving species. Enabling robust identification of foraging success at sea offers a rare and valuable opportunity for monitoring marine ecosystem productivity in space and time by tracking the success of a top predator.
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Siegelman L, O'Toole M, Flexas M, Rivière P, Klein P. Submesoscale ocean fronts act as biological hotspot for southern elephant seal. Sci Rep 2019; 9:5588. [PMID: 30944405 PMCID: PMC6447572 DOI: 10.1038/s41598-019-42117-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 03/25/2019] [Indexed: 01/22/2023] Open
Abstract
The area west of the Kerguelen Islands (20-70°E/45-60°S) is characterized by a weak mesoscale activity except for a standing meander region of the Antarctic Circumpolar Current (ACC) localized between 20 and 40°E. A unique bio-physical dataset at high-resolution collected by a southern elephant seal (Mirounga leonina) reveals a conspicuous increase in foraging activity at the standing meander site up to 5 times larger than during the rest of her three-month trip west of the Kerguelen Islands. Here, we propose a physical explanation for such high biological activity based on the study of small-scale fronts with scales of 5 to 20 km, also called submesoscales. The standing meander is associated with intensified frontal dynamics at submesoscale, not observed in the rest of the region. Results shed new light on the spatial distribution of submesoscale fronts in the under-sampled area west of the Kerguelen plateau and emphasize their importance for upper trophic levels. Despite that most elephant seals target foraging grounds east of the Kerguelen Plateau, our findings suggest that excursions to the west are not accidental, and may be explained by the recurrently elevated physical and biological activity of the site. As such, other standing meanders of the ACC may also act as biological hotspots where trophic interactions are stimulated by submesoscale turbulence.
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Affiliation(s)
- Lia Siegelman
- Univ. Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France. .,California Institute of Technology, Pasadena, CA, USA. .,Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.
| | - Malcolm O'Toole
- UWA Oceans Institute, Indian Ocean Marine Research Centre, University of Western Australia, Crawley, WA, 6009, Australia
| | - Mar Flexas
- California Institute of Technology, Pasadena, CA, USA
| | - Pascal Rivière
- Univ. Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France
| | - Patrice Klein
- California Institute of Technology, Pasadena, CA, USA.,Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
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Orgeret F, Cox SL, Weimerskirch H, Guinet C. Body condition influences ontogeny of foraging behavior in juvenile southern elephant seals. Ecol Evol 2019; 9:223-236. [PMID: 30680109 PMCID: PMC6341977 DOI: 10.1002/ece3.4717] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/12/2018] [Accepted: 10/26/2018] [Indexed: 11/21/2022] Open
Abstract
Ontogeny of diving and foraging behavior in marine top predators is poorly understood despite its importance in population recruitment. This lack of knowledge is partly due to the difficulties of monitoring juveniles in the wild, which is linked to high mortality early in life. Pinnipeds are good models for studying the development of foraging behaviors because juveniles are large enough to robustly carry tracking devices for many months. Moreover, parental assistance is absent after a juvenile departs for its first foraging trip, minimizing confounding effects of parental input on the development of foraging skills. In this study, we tracked 20 newly weaned juvenile southern elephant seals from Kerguelen Islands for up to 338 days during their first trip at sea following weaning. We used a new generation of satellite relay tags, which allow for the transmission of dive, accelerometer, and location data. We also monitored, at the same time, nine adult females from the colony during their post-breeding trips, in order to compare diving and foraging behaviors. Juveniles showed a gradual improvement through time in their foraging skills. Like adults females, they remarkably adjusted their swimming effort according to temporal changes in buoyancy (i.e., a proxy of their body condition). They also did not appear to exceed their aerobic physiological diving limits, although dives were constrained by their smaller size compared to adults. Changes in buoyancy appeared to also influence their decision to either keep foraging or return to land, alongside the duration of their haul outs and choice of foraging habitat (oceanic vs. plateau). Further studies are thus needed to better understand how patterns in juveniles survival, and therefore elephant seal populations, might be affected by their changes in foraging skills and changes in their environmental conditions.
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Affiliation(s)
- Florian Orgeret
- Centre d’Etudes Biologique de ChizéUMR 7372 ‐ CNRS & Université de La RochelleVilliers‐en‐BoisFrance
| | - Sam L. Cox
- Centre d’Etudes Biologique de ChizéUMR 7372 ‐ CNRS & Université de La RochelleVilliers‐en‐BoisFrance
- Centre National d'Études Spatiales (CNES)18 Avenue Edouard Belin31400 ToulouseFrance
- MARBEC (Institut de Recherche pour le Developpemente; IRD)Station Ifremer de Sete, Avenue Jean Monnet, CS 30171, 34203SèteFrance
| | - Henri Weimerskirch
- Centre d’Etudes Biologique de ChizéUMR 7372 ‐ CNRS & Université de La RochelleVilliers‐en‐BoisFrance
| | - Christophe Guinet
- Centre d’Etudes Biologique de ChizéUMR 7372 ‐ CNRS & Université de La RochelleVilliers‐en‐BoisFrance
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Mendez L, Prudor A, Weimerskirch H. Ontogeny of foraging behaviour in juvenile red-footed boobies (Sula sula). Sci Rep 2017; 7:13886. [PMID: 29066750 PMCID: PMC5654766 DOI: 10.1038/s41598-017-14478-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 10/11/2017] [Indexed: 11/13/2022] Open
Abstract
The early life stages represent a crucial period that can strongly influence population dynamics. We studied the development of foraging behaviour in the red-footed booby, a tropical seabird with an extensive post-fledging care period (3 to 6 months). Adults and juveniles were observed from shore and tracked at sea using GPS loggers over 3 consecutive 12-day periods. Juveniles initially made a majority of flights inland, likely to practice flying, and formed groups of up to 10 juveniles before making short trips at sea. They left the island later and returned earlier than the adults, allowing them to be fed on the nest. Over time, juveniles left the colony alone more frequently and increased the range of their trips while remaining significantly closer to the colony than the adults. They spent more time intensively foraging (slow and sinuous trajectory) than adults, which could reflect attempts to capture prey. Juveniles foraged independently of their parents but associated frequently with congeners, particularly during area-restricted search (ARS) behaviour. The extensive post-fledging care period observed may be explained by the need to develop proper foraging skills adapted to tropical waters, where resources are particularly scarce and unpredictable.
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Affiliation(s)
- Loriane Mendez
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR7372 CNRS, Université de La Rochelle, 79360, Villiers-en-Bois, France.
| | - Aurélien Prudor
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR7372 CNRS, Université de La Rochelle, 79360, Villiers-en-Bois, France
| | - Henri Weimerskirch
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR7372 CNRS, Université de La Rochelle, 79360, Villiers-en-Bois, France
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Clausius E, McMahon CR, Hindell MA. Five decades on: Use of historical weaning size data reveals that a decrease in maternal foraging success underpins the long-term decline in population of southern elephant seals (Mirounga leonina). PLoS One 2017; 12:e0173427. [PMID: 28301546 PMCID: PMC5354283 DOI: 10.1371/journal.pone.0173427] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 02/19/2017] [Indexed: 01/31/2023] Open
Abstract
The population of Southern elephant seals (Mirounga leonina) at Macquarie Island has declined since the 1960s, and is thought to be due to changing oceanic conditions leading to reductions in the foraging success of Macquarie Island breeding females. To test this hypothesis, we used a 55-year-old data set on weaning size of southern elephant seals to quantify a decrease in weaning size from a period of population stability in 1950s to its present state of on-going decline. Being capital breeders, the size of elephant seal pups at weaning is a direct consequence of maternal foraging success in the preceding year. During the 1940-1950s, the mean of female pups at weaning was similar between the Heard and Macquarie Island populations, while the snout-tail-length length of male weaners from Heard Island were longer than their conspecifics at Macquarie Island. Additionally, the snout-tail-length of pups at weaning decreased by 3cm between the 1950s and 1990s in the Macquarie Island population, concurrent with the observed population decline. Given the importance of weaning size in determining first-year survival and recruitment rates, the decline in the size at weaning suggests that the decline in the Macquarie Island population has, to some extent, been driven by reduced maternal foraging success, consequent declines in the size of pups at weaning, leading to reduced first-year survival rates and recruitment of breeding females into the population 3 to 4 years later.
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Affiliation(s)
- Ella Clausius
- Centre for Ecology and Biodiversity, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | - Clive R. McMahon
- Sydney Institute of Marine Science, Mosman, New South Wales, Australia
| | - Mark A. Hindell
- Centre for Ecology and Biodiversity, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
- Antarctic Climate and Ecosystems CRC, University of Tasmania, Hobart, Tasmania, Australia
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16
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Rees ALF, Carreras C, Broderick AC, Margaritoulis D, Stringell TB, Godley BJ. Linking loggerhead locations: using multiple methods to determine the origin of sea turtles in feeding grounds. MARINE BIOLOGY 2017; 164:30. [PMID: 28133395 PMCID: PMC5236075 DOI: 10.1007/s00227-016-3055-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 12/05/2016] [Indexed: 06/06/2023]
Abstract
Many marine megavertebrate taxa, including sea turtles, disperse widely from their hatching or birthing locations but display natal homing as adults. We used flipper tagging, satellite tracking and genetics to identify the origin of loggerhead turtles living in Amvrakikos Gulf, Greece. This location has been identified as hosting regionally important numbers of large-juvenile to adult sized turtles that display long-term residency and/or association to the area, and also presents a male biased sex ratio for adults. A total of 20 individuals were linked to nesting areas in Greece through flipper tagging and satellite telemetry, with the majority (16) associated with Zakynthos Island. One additional female was tracked from Amvrakikos Gulf to Turkey where she likely nested. Mitochondrial DNA mixed stock analyses of turtles captured in Amvrakikos Gulf (n = 95) indicated 82% of individuals originated from Greek nesting stocks, mainly from Zakynthos Island (63%), with lesser contributions from central Turkey, Cyprus and Libya. These results suggest that the male-biased sex ratio found in Amvrakikos Gulf may be driven by the fact that males breed twice as frequently on Zakynthos, resulting in their using foraging grounds of greater proximity to the breeding site. Conservation measures in localised foraging habitats for the protection of marine vertebrates, such as sea turtles, may have positive impacts on several disparate breeding stocks and the use of multiple methods to determine source populations can indicate the relative effectiveness of these measures.
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Affiliation(s)
- ALan F. Rees
- ARCHELON, the Sea Turtle Protection Society of Greece, Solomou 57, 104 32 Athens, Greece
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
| | - Carlos Carreras
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
- Department of Genetics, Microbiology and Statistics and IRBio, University of Barcelona, Av.Diagonal 643, 08028 Barcelona, Spain
| | - Annette C. Broderick
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
| | - Dimitris Margaritoulis
- ARCHELON, the Sea Turtle Protection Society of Greece, Solomou 57, 104 32 Athens, Greece
| | - Thomas B. Stringell
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
| | - Brendan J. Godley
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
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Habitat modelling of crabeater seals (Lobodon carcinophaga) in the Weddell Sea using the multivariate approach Maxent. Polar Biol 2016. [DOI: 10.1007/s00300-016-2020-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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18
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de Grissac S, Börger L, Guitteaud A, Weimerskirch H. Contrasting movement strategies among juvenile albatrosses and petrels. Sci Rep 2016; 6:26103. [PMID: 27189182 PMCID: PMC4870643 DOI: 10.1038/srep26103] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 04/26/2016] [Indexed: 11/29/2022] Open
Abstract
Animal movement is a fundamental eco-evolutionary process yet the behaviour of juvenile animals is largely unknown for many species, especially for soaring seabirds which can range widely over the oceans at low cost. We present an unprecedented dataset of 98 juvenile albatrosses and petrels (nine species), tracked for the first three months after independence. There was a startling diversity within and among species in the type and scale of post-natal movement strategies, ranging from area-restricted to nomadic patterns. Spatial scales were clustered in three groups that ranged from <3000 km to >6000 km from the natal nest. In seven of the nine species, the orientation of flight paths and other movement statistics showed strong similarities between juveniles and adults, providing evidence for innate orientation abilities. Our results have implications for understanding the development of foraging behaviour in naïve individuals and the evolution of life history traits such as survival, lifespan and breeding strategy.
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Affiliation(s)
- Sophie de Grissac
- Centre d’Etudes Biologiques de Chizé, UMR 7372 CNRS & Université de La Rochelle, Villiers en Bois, France
- UMR 9220 CNRS IRD ENTROPIE, Université de la Réunion, Saint Denis, France
| | - Luca Börger
- Department of Biosciences, College of Science, University of Swansea, Swansea, UK
| | - Audrey Guitteaud
- Centre d’Etudes Biologiques de Chizé, UMR 7372 CNRS & Université de La Rochelle, Villiers en Bois, France
| | - Henri Weimerskirch
- Centre d’Etudes Biologiques de Chizé, UMR 7372 CNRS & Université de La Rochelle, Villiers en Bois, France
- UMR 9220 CNRS IRD ENTROPIE, Université de la Réunion, Saint Denis, France
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19
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Lower foraging efficiency in immatures drives spatial segregation with breeding adults in a long-lived pelagic seabird. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2015.09.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Thometz NM, Murray MJ, Williams TM. Ontogeny of Oxygen Storage Capacity and Diving Ability in the Southern Sea Otter (Enhydra lutris nereis): Costs and Benefits of Large Lungs. Physiol Biochem Zool 2015; 88:311-27. [DOI: 10.1086/681019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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21
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Arthur B, Hindell M, Bester M, Trathan P, Jonsen I, Staniland I, Oosthuizen WC, Wege M, Lea MA. Return customers: foraging site fidelity and the effect of environmental variability in wide-ranging antarctic fur seals. PLoS One 2015; 10:e0120888. [PMID: 25807082 PMCID: PMC4373865 DOI: 10.1371/journal.pone.0120888] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 01/26/2015] [Indexed: 11/19/2022] Open
Abstract
Strategies employed by wide-ranging foraging animals involve consideration of habitat quality and predictability and should maximise net energy gain. Fidelity to foraging sites is common in areas of high resource availability or where predictable changes in resource availability occur. However, if resource availability is heterogeneous or unpredictable, as it often is in marine environments, then habitat familiarity may also present ecological benefits to individuals. We examined the winter foraging distribution of female Antarctic fur seals, Arctocephalus gazelle, over four years to assess the degree of foraging site fidelity at two scales; within and between years. On average, between-year fidelity was strong, with most individuals utilising more than half of their annual foraging home range over multiple years. However, fidelity was a bimodal strategy among individuals, with five out of eight animals recording between-year overlap values of greater than 50%, while three animals recorded values of less than 5%. High long-term variance in sea surface temperature, a potential proxy for elevated long-term productivity and prey availability, typified areas of overlap. Within-year foraging site fidelity was weak, indicating that successive trips over the winter target different geographic areas. We suggest that over a season, changes in prey availability are predictable enough for individuals to shift foraging area in response, with limited associated energetic costs. Conversely, over multiple years, the availability of prey resources is less spatially and temporally predictable, increasing the potential costs of shifting foraging area and favouring long-term site fidelity. In a dynamic and patchy environment, multi-year foraging site fidelity may confer a long-term energetic advantage to the individual. Such behaviours that operate at the individual level have evolutionary and ecological implications and are potential drivers of niche specialization and modifiers of intra-specific competition.
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Affiliation(s)
- Benjamin Arthur
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | - Mark Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | - Marthan Bester
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Phil Trathan
- British Antarctic Survey, Cambridge, United Kingdom
| | - Ian Jonsen
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | | | - W. Chris Oosthuizen
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Mia Wege
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Mary-Anne Lea
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
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22
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Burdman L, Daneri GA, Negrete J, Mennucci JA, Marquez MEI. Cephalopoda as prey of juvenile Southern elephant seals at Isla 25 de Mayo/King George, South Shetland Islands. IHERINGIA. SERIE ZOOLOGIA 2015. [DOI: 10.1590/1678-4766201510511219] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of the present study was to enhance the knowledge of the feeding habits of the juvenile component of the population of Southern elephant seals [Mirounga leonina (Linnaeus, 1758)] from Isla 25 de Mayo, South Shetland Islands, age class whose diet information is scarce. A total of 60 individuals were stomach lavaged in the spring - summer seasons of three consecutive years (2003, 2004 and 2005) of which 53.3 % (n = 32) presented food remnants. The Antarctic glacial squid Psychroteuthis glacialis Thiele, 1921 was the dominant prey taxon in terms of frequency of occurrence (68.7%), numerical abundance (60.1%) and biomass (51.5%), contributing 84.1% to the total relative importance index. Other squid prey species of importance were Slosarczykovia circumantartica Lipinski, 2001 in terms of occurrence (37.5%) and numerical abundance (14%) and Moroteuthis knipovitchi Filippova, 1972 in terms of biomass (16%). All identified cephalopod prey taxa are distributed south of the Antarctic Polar Front, except for the squid Martialia hyadesi Rochebrune & Mabille, 1889 which has a circumpolar distribution associated to the Polar Frontal Zone. No significant differences in the sizes of P. glacialis preyed upon by elephant seals were found between sexes and years. However, significant interannual differences were found in the taxonomical composition of their diet. This would be associated with temporal changes in food availability at the foraging areas of seals, which in turn may have been influenced by changes in oceanographic conditions as a result of the El Niño Southern Oscillation (ENSO) phenomenon that occurred during part of the study period. Furthermore, a differential response of males and females to this temporal variation was observed, with the former being also associated to a predation on octopods. This would suggest a sexual segregation in foraging habits of this species from the early stages of its life cycle.
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Affiliation(s)
- Luciana Burdman
- Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Argentina
| | - Gustavo A. Daneri
- Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Argentina
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23
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The feeding habits of the Southern elephant seal, Mirounga leonina, at Isla 25 de Mayo/King George Island, South Shetland Islands. Polar Biol 2014. [DOI: 10.1007/s00300-014-1629-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Pütz K, Trathan PN, Pedrana J, Collins MA, Poncet S, Lüthi B. Post-fledging dispersal of king penguins (Aptenodytes patagonicus) from two breeding sites in the South Atlantic. PLoS One 2014; 9:e97164. [PMID: 24828545 PMCID: PMC4020799 DOI: 10.1371/journal.pone.0097164] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 04/15/2014] [Indexed: 11/24/2022] Open
Abstract
Most studies concerning the foraging ecology of marine vertebrates are limited to breeding adults, although other life history stages might comprise half the total population. For penguins, little is known about juvenile dispersal, a period when individuals may be susceptible to increased mortality given their naïve foraging behaviour. Therefore, we used satellite telemetry to study king penguin fledglings (n = 18) from two sites in the Southwest Atlantic in December 2007. The two sites differed with respect to climate and proximity to the Antarctic Polar Front (APF), a key oceanographic feature generally thought to be important for king penguin foraging success. Accordingly, birds from both sites foraged predominantly in the vicinity of the APF. Eight king penguins were tracked for periods greater than 120 days; seven of these (three from the Falkland Islands and four from South Georgia) migrated into the Pacific. Only one bird from the Falkland Islands moved into the Indian Ocean, visiting the northern limit of the winter pack-ice. Three others from the Falkland Islands migrated to the eastern coast of Tierra del Fuego before travelling south. Derived tracking parameters describing their migratory behaviour showed no significant differences between sites. Nevertheless, generalized linear habitat modelling revealed that juveniles from the Falkland Islands spent more time in comparatively shallow waters with low sea surface temperature, sea surface height and chlorophyll variability. Birds from South Georgia spent more time in deeper waters with low sea surface temperature and sea surface height, but high concentrations of chlorophyll. Our results indicate that inexperienced king penguins, irrespective of the location of their natal site in relation to the position of the APF, develop their foraging skills progressively over time, including specific adaptations to the environment around their prospective breeding site.
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Affiliation(s)
- Klemens Pütz
- Antarctic Research Trust, Bremervörde, Germany
- * E-mail:
| | - Phil N. Trathan
- British Antarctic Survey, Natural Environment Research Council, High Cross, Cambridge, United Kingdom
| | - Julieta Pedrana
- Recursos Naturales y Gestión Ambiental, CONICET - INTA, Balcarce, Argentina
| | - Martin A. Collins
- British Antarctic Survey, Natural Environment Research Council, High Cross, Cambridge, United Kingdom
- Government of South Georgia & South Sandwich Islands, Stanley FIQQ 1ZZ, Falkland Islands, South Atlantic
| | - Sally Poncet
- Antarctic Research Trust, Stanley, Falkland Islands, South Atlantic
- South Georgia Surveys, Stanley, Falkland Islands, South Atlantic
| | - Benno Lüthi
- Antarctic Research Trust (Switzerland), Forch, Switzerland
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25
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van den Hoff J, McMahon CR, Simpkins GR, Hindell MA, Alderman R, Burton HR. Bottom-up regulation of a pole-ward migratory predator population. Proc Biol Sci 2014; 281:20132842. [PMID: 24619437 DOI: 10.1098/rspb.2013.2842] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
As the effects of regional climate change are most pronounced at polar latitudes, we might expect polar-ward migratory populations to respond as habitat suitability changes. The southern elephant seal (Mirounga leonina L.) is a pole-ward migratory species whose populations have mostly stabilized or increased in the past decade, the one exception being the Macquarie Island population which has decreased continuously over the past 50 years. To explore probable causes of this anomalous trend, we counted breeding female seals annually between 1988 and 2011 in order to relate annual rates of population change (r) to foraging habitat changes that have known connections with atmospheric variability. We found r (i) varied annually from -0.016 to 0.021 over the study period, (ii) was most effected by anomalous atmospheric variability after a 3 year time lag was introduced (R = 0.51) and (iii) was associated with sea-ice duration (SID) within the seals' foraging range at the same temporal lag. Negative r years may be extrapolated to explain, at least partially, the overall trend in seal abundance at Macquarie Island; specifically, increasing SID within the seals foraging range has a negative influence on their abundance at the island. Evidence is accruing that suggests southern elephant seal populations may respond positively to a reduced sea-ice field.
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Affiliation(s)
- John van den Hoff
- Australian Antarctic Division, , 203 Channel Highway, Kingston, Tasmania 7050, Australia, Institute for Marine and Antarctic Studies, University of Tasmania, , Hobart, Tasmania 7001, Australia, Climate Change Research Centre, University of New South Wales, , Sydney, New South Wales 2052, Australia, Department of Primary Industries, Parks, Water and Environment, , 134 Macquarie Street, Hobart, Tasmania 7000, Australia
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26
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Walters A, Lea MA, van den Hoff J, Field IC, Virtue P, Sokolov S, Pinkerton MH, Hindell MA. Spatially explicit estimates of prey consumption reveal a new krill predator in the Southern Ocean. PLoS One 2014; 9:e86452. [PMID: 24516515 PMCID: PMC3905967 DOI: 10.1371/journal.pone.0086452] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 12/15/2013] [Indexed: 02/05/2023] Open
Abstract
Development in foraging behaviour and dietary intake of many vertebrates are age-structured.
Differences in feeding ecology may correlate with ontogenetic shifts in dispersal patterns, and
therefore affect foraging habitat and resource utilization. Such life-history traits have important
implications in interpreting tropho-dynamic linkages. Stable isotope ratios in the whiskers of
sub-yearling southern elephant seals (Mirounga leonina;
n = 12) were used, in conjunction with satellite telemetry and environmental
data, to examine their foraging habitat and diet during their first foraging migration. The trophic
position of seals from Macquarie Island (54°30′S, 158°57′E) was estimated using
stable carbon (δ13C) and nitrogen (δ15N) ratios along the
length of the whisker, which provided a temporal record of prey intake. Satellite-relayed data
loggers provided details on seal movement patterns, which were related to isotopic concentrations
along the whisker. Animals fed in waters south of the Polar Front (>60°S) or within
Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) Statistical Subareas
88.1 and 88.2, as indicated by both their depleted δ13C
(<−20‰) values, and tracking data. They predominantly exploited varying proportions
of mesopelagic fish and squid, and crustaceans, such as euphausiids, which have not been reported as
a prey item for this species. Comparison of isotopic data between sub-yearlings, and 1, 2 and 3 yr
olds indicated that sub-yearlings, limited by their size, dive capabilities and prey capture skills
to feeding higher in the water column, fed at a lower trophic level than older seals. This is
consistent with the consumption of euphausiids and most probably, Antarctic krill (Euphausia
superba), which constitute an abundant, easily accessible source of prey in water masses
used by this age class of seals. Isotopic assessment and concurrent tracking of seals are
successfully used here to identify ontogenetic shifts in broad-scale foraging habitat use and diet
preferences in a highly migratory predator.
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Affiliation(s)
- Andrea Walters
- Institute for Marine and Antarctic Studies, University of
Tasmania, Hobart, Tasmania, Australia
- Antarctic Climate and Ecosystems Cooperative Research
Centre, Hobart, Tasmania, Australia
- * E-mail:
| | - Mary-Anne Lea
- Institute for Marine and Antarctic Studies, University of
Tasmania, Hobart, Tasmania, Australia
| | | | - Iain C. Field
- Marine Mammal Research Group, Department of Environment
and Geography, Macquarie University, Sydney, New South Wales, Australia
| | - Patti Virtue
- Institute for Marine and Antarctic Studies, University of
Tasmania, Hobart, Tasmania, Australia
- Antarctic Climate and Ecosystems Cooperative Research
Centre, Hobart, Tasmania, Australia
| | - Sergei Sokolov
- Commonwealth Scientific and Industrial Research
Organisation Marine and Atmospheric Research, Hobart, Tasmania, Australia
| | - Matt H. Pinkerton
- National Institute of Water and Atmospheric Research Ltd,
Kilbernie, Wellington, New Zealand
| | - Mark A. Hindell
- Institute for Marine and Antarctic Studies, University of
Tasmania, Hobart, Tasmania, Australia
- Antarctic Climate and Ecosystems Cooperative Research
Centre, Hobart, Tasmania, Australia
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Ratcliffe N, Takahashi A, O'Sullivan C, Adlard S, Trathan PN, Harris MP, Wanless S. The roles of sex, mass and individual specialisation in partitioning foraging-depth niches of a pursuit-diving predator. PLoS One 2013; 8:e79107. [PMID: 24205368 PMCID: PMC3804524 DOI: 10.1371/journal.pone.0079107] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 09/18/2013] [Indexed: 11/30/2022] Open
Abstract
Intra-specific foraging niche partitioning can arise due to gender differences or individual specialisation in behaviour or prey selection. These may in turn be related to sexual size dimorphism or individual variation in body size through allometry. These variables are often inter-related and challenging to separate statistically. We present a case study in which the effects of sex, body mass and individual specialisation on the dive depths of the South Georgia shag on Bird Island, South Georgia are investigated simultaneously using a linear mixed model. The nested random effects of trip within individual explained a highly significant amount of the variance. The effects of sex and body mass were both significant independently but could not be separated statistically owing to them being strongly interrelated. Variance components analysis revealed that 45.5% of the variation occurred among individuals, 22.6% among trips and 31.8% among Dives, while R2 approximations showed gender explained 31.4% and body mass 55.9% of the variation among individuals. Male dive depths were more variable than those of females at the levels of individual, trip and dive. The effect of body mass on individual dive depths was only marginally significant within sexes. The percentage of individual variation in dive depths explained by mass was trivial in males (0.8%) but substantial in females (24.1%), suggesting that differences in dive depths among males was largely due to them adopting different behavioural strategies whereas in females allometry played an additional role. Niche partitioning in the study population therefore appears to be achieved through the interactive effects of individual specialisation and gender upon vertical foraging patch selection, and has the potential to interact in complex ways with other axes of the niche hypervolume such as foraging locations, timing of foraging and diet.
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Breed GA, Don Bowen W, Leonard ML. Behavioral signature of intraspecific competition and density dependence in colony-breeding marine predators. Ecol Evol 2013; 3:3838-54. [PMID: 24198943 PMCID: PMC3810878 DOI: 10.1002/ece3.754] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 07/26/2013] [Accepted: 08/12/2013] [Indexed: 11/09/2022] Open
Abstract
In populations of colony-breeding marine animals, foraging around colonies can lead to intraspecific competition. This competition affects individual foraging behavior and can cause density-dependent population growth. Where behavioral data are available, it may be possible to infer the mechanism of intraspecific competition. If these mechanics are understood, they can be used to predict the population-level functional response resulting from the competition. Using satellite relocation and dive data, we studied the use of space and foraging behavior of juvenile and adult gray seals (Halichoerus grypus) from a large (over 200,000) and growing population breeding at Sable Island, Nova Scotia (44.0 oN 60.0 oW). These data were first analyzed using a behaviorally switching state-space model to infer foraging areas followed by randomization analysis of foraging region overlap of competing age classes. Patterns of habitat use and behavioral time budgets indicate that young-of-year juveniles (YOY) were likely displaced from foraging areas near (<10 km) the breeding colony by adult females. This displacement was most pronounced in the summer. Additionally, our data suggest that YOY are less capable divers than adults and this limits the habitat available to them. However, other segregating mechanisms cannot be ruled out, and we discuss several alternate hypotheses. Mark–resight data indicate juveniles born between 1998 and 2002 have much reduced survivorship compared with cohorts born in the late 1980s, while adult survivorship has remained steady. Combined with behavioral observations, our data suggest YOY are losing an intraspecific competition between adults and juveniles, resulting in the currently observed decelerating logistic population growth. Competition theory predicts that intraspecific competition resulting in a clear losing competitor should cause compensatory population regulation. This functional response produces a smooth logistic growth curve as carrying capacity is approached, and is consistent with census data collected from this population over the past 50 years. The competitive mechanism causing compensatory regulation likely stems from the capital-breeding life-history strategy employed by gray seals. This strategy decouples reproductive success from resources available around breeding colonies and prevents females from competing with each other while young are dependent.
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Affiliation(s)
- Greg A Breed
- Department of Biology, Dalhousie University 1355 Oxford Street, Halifax, Nova Scotia, B3H 4J1, Canada
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Tracking through life stages: adult, immature and juvenile autumn migration in a long-lived seabird. PLoS One 2013; 8:e72713. [PMID: 23977344 PMCID: PMC3745401 DOI: 10.1371/journal.pone.0072713] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 07/15/2013] [Indexed: 11/19/2022] Open
Abstract
Seasonal long-distance migration is likely to be experienced in a contrasted manner by juvenile, immature and adult birds, leading to variations in migratory routes, timing and behaviour. We provide the first analysis of late summer movements and autumn migration in these three life stages, which were tracked concurrently using satellite tags, geolocators or GPS recorders in a long-ranging migratory seabird, the Scopoli's shearwater (formerly named Cory's shearwater, Calonectrisdiomedea) breeding on two French Mediterranean islands. During the late breeding season, immatures foraged around their colony like breeding adults, but they were the only group showing potential prospecting movements around non-natal colonies. Global migration routes were broadly comparable between the two populations and the three life stages, with all individuals heading towards the Atlantic Ocean through the strait of Gibraltar and travelling along the West African coast, up to 8000 km from their colony. However, detailed comparison of timing, trajectory and oceanographic conditions experienced by the birds revealed remarkable age-related differences. Compared to adults and immatures, juveniles made a longer stop-over in the Balearic Sea (10 days vs 4 days in average), showed lower synchrony in crossing the Gibraltar strait, had more sinuous pathways and covered longer daily distances (240 km.d(-1) vs 170 km.d(-1)). Analysis of oceanographic habitats along migratory routes revealed funnelling selection of habitat towards coastal and more productive waters with increasing age. Younger birds may have reduced navigational ability and learn progressively fine-scale migration routes towards the more profitable travelling and wintering areas. Our study demonstrates the importance of tracking long-lived species through the stages, to better understand migratory behavior and assess differential exposure to at-sea threats. Shared distribution between life stages and populations make Scopoli's shearwaters particularly vulnerable to extreme mortality events in autumn and winter. Such knowledge is key for the conservation of critical marine habitats.
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Riotte-Lambert L, Weimerskirch H. Do naive juvenile seabirds forage differently from adults? Proc Biol Sci 2013; 280:20131434. [PMID: 23926153 DOI: 10.1098/rspb.2013.1434] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Foraging skills of young individuals are assumed to be inferior to those of adults. The reduced efficiency of naive individuals may be the primary cause of the high juvenile mortality and explain the deferment of maturity in long-lived species. However, the study of juvenile and immature foraging behaviour has been limited so far. We used satellite telemetry to compare the foraging movements of juveniles, immatures and breeding adult wandering albatrosses Diomedea exulans, a species where foraging success is positively influenced by the distance covered daily. We showed that juveniles are able to use favourable winds as soon as the first month of independence, but cover shorter distances daily and spend more time sitting on water than adults during the first two months after fledging. These reduced movement capacities do not seem to be the cause of higher juvenile mortality. Moreover, juveniles almost never restrict their movement to specific areas, as adults and immatures frequently do over shelf edges or oceanic zones, which suggest that the location of appropriate areas is learned through experience. Immatures and adults have equivalent movement capacities, but when they are central place foragers, i.e. when adults breed or immatures come to the colony to display and pair, immatures make shorter trips than adults. The long duration of immaturity in this species seems to be related to a long period of learning to integrate the foraging constraints associated with reproduction and central place foraging. Our results indicate that foraging behaviour of young albatrosses is partly innate and partly learned progressively over immaturity. The first months of learning appear critical in terms of survival, whereas the long period of immaturity is necessary for young birds to attain the skills necessary for efficient breeding without fitness costs.
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Affiliation(s)
- Louise Riotte-Lambert
- Centre d'Etudes Biologiques de Chizé, Centre National de Recherche Scientifique, 79360 Villiers en Bois, France
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Spatial segregation among age classes in cave salamanders: habitat selection or social interactions? POPUL ECOL 2012. [DOI: 10.1007/s10144-012-0350-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Waite J, Burkanov V, Andrews R. Prey competition between sympatric Steller sea lions (Eumetopias jubatus) and northern fur seals (Callorhinus ursinus) on Lovushki Island, Russia. CAN J ZOOL 2012. [DOI: 10.1139/z11-117] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Approximately 1 000 Steller sea lions ( Eumetopias jubatus (Schreber, 1776); SSL) and 14 000 northern fur seals ( Callorhinus ursinus (L., 1758); NFS) breed sympatrically on Lovushki Island in the Russian Far East, creating the potential for interspecific competition for prey. An additional 13 000 – 14 000 juvenile NFS are present during the breeding season. The diets of breeding SSL and both breeding and juvenile NFS were examined through analysis of scats and spews collected during the breeding seasons of 2003, 2005, and 2007–2008. There were significant overlaps in the prey species and size selection of SSL and juvenile NFS. There were significant differences between the diets of SSL and breeding NFS. SSL and juvenile NFS fed primarily on Atka mackerel ( Pleurogrammus monopterygius (Pallas, 1810)), while breeding NFS fed on cephalopods, salmon (genus Oncorhynchus Suckley, 1861), Atka mackerel, and northern smoothtongue ( Leuroglossus schmidti Rass, 1955). The partitioning of resources between breeding animals has allowed both species to coexist within the same region and likely reflected differences in foraging abilities and provisioning strategies of the adults and the fasting abilities of their pups. However, continued growth of the NFS population may lead to the exclusion of SSL owing to interspecific competition for prey.
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Affiliation(s)
- J.N. Waite
- School of Fisheries and Ocean Sciences, University of Alaska, 905 North Koyukuk Drive, 245 O’Neill Building, Fairbanks, AK 99775, USA
- Alaska SeaLife Center, P.O. Box 1329, 301 Railway Avenue, Seward, AK 99664, USA
| | - V.N. Burkanov
- National Marine Mammal Laboratory, National Oceanic and Atmospheric Administration (NOAA), 7600 Sand Point Way NE, Seattle, WA 98115, USA
- Kamchatka Branch of the Pacific Institute of Geography, Far East Branch of Russian Academy of Sciences, 6 Partizanskaya Street, Petropavlovsk-Kamchatsky, 683000, Russia
| | - R.D. Andrews
- School of Fisheries and Ocean Sciences, University of Alaska, 905 North Koyukuk Drive, 245 O’Neill Building, Fairbanks, AK 99775, USA
- Alaska SeaLife Center, P.O. Box 1329, 301 Railway Avenue, Seward, AK 99664, USA
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OOSTHUIZEN WCHRIS, DE BRUYN PJNICO, BESTER MARTHÁNN. Unmarked individuals in mark-recapture studies: Comparisons of marked and unmarked southern elephant seals at Marion Island. AUSTRAL ECOL 2011. [DOI: 10.1111/j.1442-9993.2011.02316.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Crawford JA, Frost KJ, Quakenbush LT, Whiting A. Different habitat use strategies by subadult and adult ringed seals (Phoca hispida) in the Bering and Chukchi seas. Polar Biol 2011. [DOI: 10.1007/s00300-011-1067-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Eder EB, Lewis MN, Marín MR, Campagna C. On- and off-shelf diving effort of juvenile elephant seals from Península Valdés determined by light loggers. J Mammal 2011. [DOI: 10.1644/10-mamm-a-292.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Biuw M, Nøst OA, Stien A, Zhou Q, Lydersen C, Kovacs KM. Effects of hydrographic variability on the spatial, seasonal and diel diving patterns of southern elephant seals in the eastern Weddell Sea. PLoS One 2010; 5:e13816. [PMID: 21072199 PMCID: PMC2972216 DOI: 10.1371/journal.pone.0013816] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 10/01/2010] [Indexed: 11/23/2022] Open
Abstract
Weddell Sea hydrography and circulation is driven by influx of Circumpolar Deep Water (CDW) from the Antarctic Circumpolar Current (ACC) at its eastern margin. Entrainment and upwelling of this high-nutrient, oxygen-depleted water mass within the Weddell Gyre also supports the mesopelagic ecosystem within the gyre and the rich benthic community along the Antarctic shelf. We used Conductivity-Temperature-Depth Satellite Relay Data Loggers (CTD-SRDLs) to examine the importance of hydrographic variability, ice cover and season on the movements and diving behavior of southern elephant seals in the eastern Weddell Sea region during their overwinter feeding trips from Bouvetøya. We developed a model describing diving depth as a function of local time of day to account for diel variation in diving behavior. Seals feeding in pelagic ice-free waters during the summer months displayed clear diel variation, with daytime dives reaching 500-1500 m and night-time targeting of the subsurface temperature and salinity maxima characteristic of CDW around 150–300 meters. This pattern was especially clear in the Weddell Cold and Warm Regimes within the gyre, occurred in the ACC, but was absent at the Dronning Maud Land shelf region where seals fed benthically. Diel variation was almost absent in pelagic feeding areas covered by winter sea ice, where seals targeted deep layers around 500–700 meters. Thus, elephant seals appear to switch between feeding strategies when moving between oceanic regimes or in response to seasonal environmental conditions. While they are on the shelf, they exploit the locally-rich benthic ecosystem, while diel patterns in pelagic waters in summer are probably a response to strong vertical migration patterns within the copepod-based pelagic food web. Behavioral flexibility that permits such switching between different feeding strategies may have important consequences regarding the potential for southern elephant seals to adapt to variability or systematic changes in their environment resulting from climate change.
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Affiliation(s)
- Martin Biuw
- Norwegian Polar Institute, Polar Environmental Centre, Tromsø, Norway.
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EINODER LD, PAGE B, GOLDSWORTHY SD, DE LITTLE SC, BRADSHAW CJA. Exploitation of distant Antarctic waters and close neritic waters by short-tailed shearwaters breeding in South Australia. AUSTRAL ECOL 2010. [DOI: 10.1111/j.1442-9993.2010.02176.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Tucker S, Bowen WD, Iverson SJ, Stenson GB. Intrinsic and extrinsic sources of variation in the diets of harp and hooded seals revealed by fatty acid profiles. CAN J ZOOL 2009. [DOI: 10.1139/z08-145] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Individuals of different age, sex, and morphology are expected to exhibit differences in dietary niches largely owing to sexual dimorphism, ontogenetic niche shifts, and resource polymorphism. Harp ( Pagophilus groenlandicus (Erxleben, 1777)) and hooded ( Cystophora cristata (Erxleben, 1777)) seals are geographically overlapping and highly migratory predators in the North Atlantic Ocean. These species differ in their diving behaviour, with hooded seals diving deeper, longer, and more associated with the continental shelf edge and deep ocean than harp seals. We examined blubber fatty acid (FA) composition (N = 37; 93% of total FA by mass) of harp (adults N = 294; juveniles N = 232) and hooded (adults N = 118; juveniles N = 38) seals to test hypotheses about sources of intrinsic (age and sex) and extrinsic (geographic location, season, year) variations in diets. A significant difference in FA profiles suggested dietary segregation between species. We found significant effects of sex and age class on FA profiles, with these being more pronounced in the highly size-dimorphic hooded seals than in harp seals. FA profiles of both species also varied between inshore and offshore sampling locations and between prebreeding and postbreeding periods. Finally, FA profiles of harp seals differed among years, which was coincident with large changes in prey distribution and availability in the mid-1990s.
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Affiliation(s)
- Strahan Tucker
- Department of Biology, Dalhousie University, 355 Oxford Street, Halifax, NS B3H 4J1, Canada
- Population Ecology Division, Bedford Institute of Oceanography, Fisheries and Oceans Canada, 1 Challenger Drive, Dartmouth, NS B2Y 4A2, Canada
- Marine Mammal Section, Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, P.O. Box 5667, St John’s, NL A1C 5X1, Canada
| | - W. Don Bowen
- Department of Biology, Dalhousie University, 355 Oxford Street, Halifax, NS B3H 4J1, Canada
- Population Ecology Division, Bedford Institute of Oceanography, Fisheries and Oceans Canada, 1 Challenger Drive, Dartmouth, NS B2Y 4A2, Canada
- Marine Mammal Section, Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, P.O. Box 5667, St John’s, NL A1C 5X1, Canada
| | - Sara J. Iverson
- Department of Biology, Dalhousie University, 355 Oxford Street, Halifax, NS B3H 4J1, Canada
- Population Ecology Division, Bedford Institute of Oceanography, Fisheries and Oceans Canada, 1 Challenger Drive, Dartmouth, NS B2Y 4A2, Canada
- Marine Mammal Section, Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, P.O. Box 5667, St John’s, NL A1C 5X1, Canada
| | - Garry B. Stenson
- Department of Biology, Dalhousie University, 355 Oxford Street, Halifax, NS B3H 4J1, Canada
- Population Ecology Division, Bedford Institute of Oceanography, Fisheries and Oceans Canada, 1 Challenger Drive, Dartmouth, NS B2Y 4A2, Canada
- Marine Mammal Section, Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, P.O. Box 5667, St John’s, NL A1C 5X1, Canada
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Field IC, Meekan MG, Buckworth RC, Bradshaw CJA. Chapter 4. Susceptibility of sharks, rays and chimaeras to global extinction. ADVANCES IN MARINE BIOLOGY 2009; 56:275-363. [PMID: 19895977 DOI: 10.1016/s0065-2881(09)56004-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Marine biodiversity worldwide is under increasing threat, primarily as a result of over-harvesting, pollution and climate change. Chondrichthyan fishes (sharks, rays and chimaeras) have a perceived higher intrinsic risk of extinction compared to other fish. Direct fishing mortality has driven many declines, even though some smaller fisheries persist without associated declines. Mixed-species fisheries are of particular concern, as is illegal, unreported and unregulated (IUU) fishing. The lack of specific management and reporting mechanisms for the latter means that many chondrichthyans might already be susceptible to extinction from stochastic processes entirely unrelated to fishing pressure itself. Chondrichthyans might also suffer relatively more than other marine taxa from the effects of fishing and habitat loss and degradation given coastal habitat use for specific life stages. The effects of invasive species and pollution are as yet too poorly understood to predict their long-term role in affecting chondrichthyan population sizes. The spatial distribution of threatened chondrichthyan species under World Conservation Union (IUCN) Red List criteria are clustered mainly in (1) south-eastern South America; (2) western Europe and the Mediterranean; (3) western Africa; (4) South China Sea and Southeast Asia and (5) south-eastern Australia. To determine which ecological and life history traits predispose chondrichthyans to being IUCN Red-Listed, and to examine the role of particular human activities in exacerbating threat risk, we correlated extant marine species' Red List categorisation with available ecological (habitat type, temperature preference), life history (body length, range size) and human-relationship (whether commercially or game-fished, considered dangerous to humans) variables. Threat risk correlations were constructed using generalised linear mixed-effect models to account for phylogenetic relatedness. We also contrasted results for chondrichthyans to marine teleosts to test explicitly whether the former group is intrinsically more susceptible to extinction than fishes in general. Around 52% of chondrichthyans have been Red-Listed compared to only 8% of all marine teleosts; however, listed teleosts were in general placed more frequently into the higher-risk categories relative to chondrichthyans. IUCN threat risk in both taxa was positively correlated with body size and negatively correlated albeit weakly, with geographic range size. Even after accounting for the positive influence of size, Red-Listed teleosts were still more likely than chondrichthyans to be classified as threatened. We suggest that while sharks might not have necessarily experienced the same magnitude of deterministic decline as Red-Listed teleosts, their larger size and lower fecundity (not included in the analysis) predispose chondrichthyans to a higher risk of extinction overall. Removal of these large predators can elicit trophic cascades and destabilise the relative abundance of smaller species. Predator depletions can lead to permanent shifts in marine communities and alternate equilibrium states. Climate change might influence the phenology and physiology of some species, with the most probable response being changes in the timing of migrations and shifts in distribution. The synergistic effects among harvesting, habitat changes and climate-induced forcings are greatest for coastal chondrichthyans with specific habitat requirements and these are currently the most likely candidates for extinction. Management of shark populations must take into account the rate at which drivers of decline affect specific species. Only through the detailed collection of data describing demographic rates, habitat affinities, trophic linkages and geographic ranges, and how environmental stressors modify these, can extinction risk be more precisely estimated and reduced. The estimation of minimum viable population sizes, below which rapid extinction is more likely due to stochastic processes, is an important component of this endeavour and should accompany many of the current approaches used in shark management worldwide.
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Affiliation(s)
- Iain C Field
- School for Environmental Research, Institute of Advanced Studies, Charles Darwin University, Darwin, Northern Territory 0909, Australia
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Pistorius PA, Bester MN, Hofmeyr GJG, Kirkman SP, Taylor FE. Seasonal survival and the relative cost of first reproduction in adult female southern elephant seals. J Mammal 2008. [DOI: 10.1644/07-mamm-a-219r.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Staniland IJ, Robinson SL. Segregation between the sexes: Antarctic fur seals, Arctocephalus gazella, foraging at South Georgia. Anim Behav 2008. [DOI: 10.1016/j.anbehav.2007.10.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Scaling laws of marine predator search behaviour. Nature 2008; 451:1098-102. [PMID: 18305542 DOI: 10.1038/nature06518] [Citation(s) in RCA: 458] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Accepted: 11/29/2007] [Indexed: 11/08/2022]
Abstract
Many free-ranging predators have to make foraging decisions with little, if any, knowledge of present resource distribution and availability. The optimal search strategy they should use to maximize encounter rates with prey in heterogeneous natural environments remains a largely unresolved issue in ecology. Lévy walks are specialized random walks giving rise to fractal movement trajectories that may represent an optimal solution for searching complex landscapes. However, the adaptive significance of this putative strategy in response to natural prey distributions remains untested. Here we analyse over a million movement displacements recorded from animal-attached electronic tags to show that diverse marine predators-sharks, bony fishes, sea turtles and penguins-exhibit Lévy-walk-like behaviour close to a theoretical optimum. Prey density distributions also display Lévy-like fractal patterns, suggesting response movements by predators to prey distributions. Simulations show that predators have higher encounter rates when adopting Lévy-type foraging in natural-like prey fields compared with purely random landscapes. This is consistent with the hypothesis that observed search patterns are adapted to observed statistical patterns of the landscape. This may explain why Lévy-like behaviour seems to be widespread among diverse organisms, from microbes to humans, as a 'rule' that evolved in response to patchy resource distributions.
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Zeno RL, Crocker DE, Hassrick JL, Allen SG, Costa DP. Development of foraging behavior in juvenile northern elephant seals. J Zool (1987) 2008. [DOI: 10.1111/j.1469-7998.2007.00371.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Wearmouth VJ, Sims DW. Sexual segregation in marine fish, reptiles, birds and mammals behaviour patterns, mechanisms and conservation implications. ADVANCES IN MARINE BIOLOGY 2008; 54:107-170. [PMID: 18929064 DOI: 10.1016/s0065-2881(08)00002-3] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Sexual segregation occurs when members of a species separate such that the sexes live apart, either singly or in single-sex groups. It can be broadly categorised into two types: habitat segregation and social segregation. Sexual segregation is a behavioural phenomenon that is widespread in the animal kingdom yet the underlying causes remain poorly understood. Sexual segregation has been widely studied among terrestrial mammals such as ungulates, but it has been less well documented in the marine environment. This chapter clarifies terms and concepts which have emerged from the investigation of sexual segregation in terrestrial ecology and examines how a similar methodological approach may be complicated by differences of marine species. Here we discuss the behavioural patterns of sexual segregation among marine fish, reptile, bird and mammal species. Five hypotheses have been forwarded to account for sexual segregation, largely emerging from investigation of sexual segregation in terrestrial ungulates: the predation risk, forage selection, activity budget, thermal niche-fecundity and social factors hypotheses. These mechanisms are reviewed following careful assessment of their applicability to marine vertebrate species and case studies of marine vertebrates which support each mechanism recounted. Rigorous testing of all hypotheses is lacking from both the terrestrial and marine vertebrate literature and those analyses which have been attempted are often confounded by factors such as sexual body-size dimorphism. In this context, we indicate the value of studying model species which are monomorphic with respect to body size and discuss possible underlying causes for sexual segregation in this species. We also discuss why it is important to understand sexual segregation, for example, by illustrating how differential exploitation of the sexes by humans can lead to population decline.
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Affiliation(s)
- Victoria J Wearmouth
- Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, United Kingdom
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Beck CA, Iverson SJ, Bowen WD, Blanchard W. Sex differences in grey seal diet reflect seasonal variation in foraging behaviour and reproductive expenditure: evidence from quantitative fatty acid signature analysis. J Anim Ecol 2007; 76:490-502. [PMID: 17439466 DOI: 10.1111/j.1365-2656.2007.01215.x] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. Intraspecific variation in diet can be an important component of a species niche breadth. We tested the hypothesis that sex differences in seasonal foraging behaviour and energy storage of sexually size dimorphic grey seals Halichoerus grypus (Fabrisius 1971) are reflected in differences in the diet and niche breadth. Diet composition was estimated for 496 adult (226 males, 270 females) and 91 juvenile (46 males/45 females; all 6 months old) grey seals sampled between 1993 and 2000 using quantitative fatty acid signature analysis. Niche breadth and overlap were estimated using the Shannon-Weaver diversity index (H') and the Morisita-Horn index (C(H)), respectively. 2. Sand lance Ammodytes dubius (Reinhardt 1837) and redfish Sebastes sp. (Cuvier 1829) accounted for a high proportion of the diet in both sexes and age groups. However, the diets of adult males were significantly more diverse across all seasons (H': males 0.36 +/- 0.007 vs. females 0.28 +/- 0.007) and less energy dense in spring (male 5.3 +/- 0.07 kJ g(-1) vs. females 5.6 +/- 0.09 kJ g(-1)) than those of adult females. 3. Season and sex explained most of the observed variation in adult diets, but there were significant sex-season interactions. These differences were most evident during the post-breeding (spring) foraging period when energy acquisition is important to female recovery of nutrient stores needed to support pregnancy. Females selected fewer and higher quality prey species in spring than males. 4. There were no sex differences in the diets of juvenile grey seals. Although many of the species overlapped with those eaten by adults, juvenile niche breadth (H': 0.41 +/- 0.014, n = 91) was significantly broader than that of adults (H': 0.30 +/- 0.011, n = 115). Juvenile diets were also of lower energy density (5.3 +/- 0.04 kJ g(-1)) than those of adults (5.6 +/- 0.09 kJ g(-1)), suggesting less selectivity in these young and relatively naïve predators. 5. Sex-specific seasonal changes in diet correspond to seasonal changes in diving behaviour and rate of body energy accumulation of adult males and females. Sex-specific reproductive requirements appear to be a primary factor generating the intraspecific variation in the seasonal foraging ecology of this large marine carnivore. However, sex differences in the breadth and energy content of diets also suggest the influence of body-size dimorphism as a factor shaping the diet of this species.
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Affiliation(s)
- Carrie A Beck
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
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Complex interplay between intrinsic and extrinsic drivers of long-term survival trends in southern elephant seals. BMC Ecol 2007; 7:3. [PMID: 17389038 PMCID: PMC1855316 DOI: 10.1186/1472-6785-7-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Accepted: 03/27/2007] [Indexed: 11/10/2022] Open
Abstract
Background Determining the relative contribution of intrinsic and extrinsic factors to fluctuations in population size, trends and demographic composition is analytically complex. It is often only possible to examine the combined effects of these factors through measurements made over long periods, spanning an array of population densities or levels of food availability. Using age-structured mark-recapture models and datasets spanning five decades (1950–1999), and two periods of differing relative population density, we estimated age-specific probabilities of survival and examined the combined effects of population density and environmental conditions on juvenile survival of southern elephant seals at Macquarie Island. Results First-year survival decreased with density during the period of highest population size, and survival increased during years when the Southern Oscillation Index (SOI) anomaly (deviation from a 50-year mean) during the mother's previous foraging trip to sea was positive (i.e., El Niño). However, when environmental stochasticity and density were considered together, the effect of density on first-year survival effectively disappeared. Ignoring density effects also leads to models placing too much emphasis on the environmental conditions prevailing during the naïve pup's first year at sea. Conclusion Our analyses revealed that both the state of the environment and population density combine to modify juvenile survival, but that the degree to which these processes contributed to the variation observed was interactive and complex. This underlines the importance of evaluating the relative contribution of both the intrinsic and extrinsic factors that regulate animal populations because false conclusions regarding the importance of population regulation may be reached if they are examined in isolation.
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Zeppelin TK, Ream RR. Foraging habitats based on the diet of female northern fur seals (Callorhinus ursinus) on the Pribilof Islands, Alaska. J Zool (1987) 2006. [DOI: 10.1111/j.1469-7998.2006.00122.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Field IC, Bradshaw CJA, Burton HR, Hindell MA. Juvenile Southern Elephant Seals Exhibit Seasonal Differences in Energetic Requirements and Use of Lipids and Protein Stores. Physiol Biochem Zool 2005; 78:491-504. [PMID: 15957104 DOI: 10.1086/430227] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2004] [Indexed: 11/03/2022]
Abstract
Growing juvenile animals undergo many morphological, physiological, and behavioural changes that influence their energetic requirements, patterns of energy use, and ultimately, their survival and reproductive success. We examined changes in mass loss and body composition of juvenile southern elephant seals (1- and 2-yr-olds) during their two annual haul-outs. At the start and end of the midyear and molt haul-outs, we caught, weighed, and measured 41 and 14 seals, respectively. We measured blubber depth using ultrasound to estimate body composition (lean and adipose tissue mass). Using energy densities of the adipose and lean tissue, we calculated total, lean, and adipose mass changes and energy expenditure. While molting, juvenile seals used more energy than during the midyear, which is related to the increased use of lean tissue for hair and skin regeneration. The amount of energy used increases with mass as individuals mature. We found sexual differences in energy use where females retained greater fat reserves than males by utilizing more lean tissue. These differences are most likely related to haul-out function and behavior, growth, and earlier development of females toward sexual maturity.
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Affiliation(s)
- Iain C Field
- Antarctic Wildlife Research Unit, School of Zoology, University of Tasmania, Private Bag 05, Hobart, Tasmania 7001, Australia.
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