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McInnes JD, Lester KM, Dill LM, Mathieson CR, West-Stap PJ, Marcos SL, Trites AW. Foraging behaviour and ecology of transient killer whales within a deep submarine canyon system. PLoS One 2024; 19:e0299291. [PMID: 38507673 PMCID: PMC10954312 DOI: 10.1371/journal.pone.0299291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 02/08/2024] [Indexed: 03/22/2024] Open
Abstract
Transient killer whales have been documented hunting marine mammals across a variety of habitats. However, relatively little has been reported about their predatory behaviours near deep submarine canyons and oceanic environments. We used a long-term database of sightings and encounters with these predators in and around the Monterey Submarine Canyon, California to describe foraging behaviour, diet, seasonal occurrence, and habitat use patterns. Transient killer whales belonging to the outer coast subpopulation were observed within the study area 261 times from 2006-2021. Occurrences, behaviours, and group sizes all varied seasonally, with more encounters occurring in the spring as grey whales migrated northward from their breeding and calving lagoons in Mexico (March-May). Groups of killer whales foraged exclusively in open water, with individuals within the groups following the contours of the submarine canyon as they searched for prey. Focal follows revealed that killer whales spent 51% of their time searching for prey (26% of their time along the shelf-break and upper slope of the canyon, and 25% in open water). The remainder of their time was spent pursuing prey (10%), feeding (23%), travelling (9%), socializing (6%), and resting (1%). Prey species during 87 observed predation events included California sea lions, grey whale calves, northern elephant seals, minke whales, common dolphins, Pacific white-sided dolphins, Dall's porpoise, harbour porpoise, harbour seals, and sea birds. The calculated kill rates (based on 270 hours of observing 50 predation events) were 0.26 California sea lions per killer whale over 24 hours, 0.11 grey whale calves, and 0.15 for all remaining prey species combined. These behavioural observations provide insights into predator-prey interactions among apex predators over submarine canyons and deep pelagic environments.
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Affiliation(s)
- Josh D. McInnes
- Institute for the Oceans and Fisheries, Marine Mammal Research Unit, University of British Columbia, Vancouver, Canada
- Pacific WildLife Foundation, Port Moody, BC, Canada
- Oceanic Ecology Research Group, Monterey Bay, California, United States of America
| | - Kevin M. Lester
- Oceanic Ecology Research Group, Monterey Bay, California, United States of America
| | - Lawrence M. Dill
- Department of Biological Sciences, Evolutionary and Behavioural Ecology Research Group, Simon Fraser University, Burnaby, Canada
| | - Chelsea R. Mathieson
- Oceanic Ecology Research Group, Monterey Bay, California, United States of America
- School of Resource and Environmental Management, Simon Fraser University, Burnaby, Canada
| | | | | | - Andrew W. Trites
- Institute for the Oceans and Fisheries, Marine Mammal Research Unit, University of British Columbia, Vancouver, Canada
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Tombak KJ, Hex SBSW, Rubenstein DI. New estimates indicate that males are not larger than females in most mammal species. Nat Commun 2024; 15:1872. [PMID: 38472185 DOI: 10.1038/s41467-024-45739-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 02/02/2024] [Indexed: 03/14/2024] Open
Abstract
Sexual size dimorphism has motivated a large body of research on mammalian mating strategies and sexual selection. Despite some contrary evidence, the narrative that larger males are the norm in mammals-upheld since Darwin's Descent of Man-still dominates today, supported by meta-analyses that use coarse measures of dimorphism and taxonomically-biased sampling. With newly-available datasets and primary sources reporting sex-segregated means and variances in adult body mass, we estimate statistically-determined rates of sexual size dimorphism in mammals, sampling taxa by their species richness at the family level. Our analyses of wild, non-provisioned populations representing >400 species indicate that although males tend to be larger than females when dimorphism occurs, males are not larger in most mammal species, suggesting a need to revisit other assumptions in sexual selection research.
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Affiliation(s)
- Kaia J Tombak
- Department of Anthropology, Hunter College of the City University of New York, New York, NY, USA.
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.
| | - Severine B S W Hex
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Daniel I Rubenstein
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
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3
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Ouled-Cheikh J, March D, Borras-Chavez R, Drago M, Goebel ME, Fariña JM, Gazo M, Coll M, Cardona L. Future climate-induced distribution shifts in a sexually dimorphic key predator of the Southern Ocean. GLOBAL CHANGE BIOLOGY 2024; 30:e17191. [PMID: 38433338 DOI: 10.1111/gcb.17191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 03/05/2024]
Abstract
The response to climate change in highly dimorphic species can be hindered by differences between sexes in habitat preferences and movement patterns. The Antarctic fur seal, Arctocephalus gazella, is the most abundant pinniped in the Southern Hemisphere, and one of the main consumers of Antarctic krill, Euphausia superba, in the Southern Ocean. However, the populations breeding in the Atlantic Southern Ocean are decreasing, partly due to global warming. Male and female Antarctic fur seals differ greatly in body size and foraging ecology, and little is known about their sex-specific responses to climate change. We used satellite tracking data and Earth System Models to predict changes in habitat suitability for male and female Antarctic fur seals from the Western Antarctic Peninsula under different climate change scenarios. Under the most extreme scenario (SSP5-8.5; global average temperature +4.4°C projected by 2100), suitable habitat patches will shift southward during the non-breeding season, leading to a minor overall habitat loss. The impact will be more pronounced for females than for males. The reduction of winter foraging grounds might decrease the survival of post-weaned females, reducing recruitment and jeopardizing population viability. During the breeding season, when males fast on land, suitable foraging grounds for females off the South Shetland Islands will remain largely unmodified, and new ones will emerge in the Bellingshausen Sea. As Antarctic fur seals are income breeders, the foraging grounds of females should be reasonably close to the breeding colony. As a result, the new suitable foraging grounds will be useful for females only if nearby beaches currently covered by sea ice emerge by the end of the century. Furthermore, the colonization of these new, ice-free breeding locations might be limited by strong female philopatry. These results should be considered when managing the fisheries of Antarctic krill in the Southern Ocean.
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Affiliation(s)
- Jazel Ouled-Cheikh
- Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
- iMARES group, Departament de Recursos Marins Renovables, Institut de Ciències del Mar (ICM-CSIC), Barcelona, Spain
| | - David March
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Paterna, València, Spain
- Centre for Ecology and Conservation, College of Life and Environmental Science, University of Exeter, Penryn, Cornwall, UK
| | - Renato Borras-Chavez
- Center of Applied Ecology and Sustainability (CAPES), Pontificia Universidad Católica de Chile, Santiago, Chile
- Department of Biology, Baylor University, Waco, Texas, USA
| | - Massimiliano Drago
- Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Michael E Goebel
- Institute of Marine Sciences, University of California Santa Cruz (UCSC), Santa Cruz, California, USA
- Antarctic Ecosystem Research Division, SWFSC, NMFS, NOAA, La Jolla, California, USA
| | - José M Fariña
- Center of Applied Ecology and Sustainability (CAPES), Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Manel Gazo
- Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Marta Coll
- iMARES group, Departament de Recursos Marins Renovables, Institut de Ciències del Mar (ICM-CSIC), Barcelona, Spain
- Ecopath International Initiative (EII), Barcelona, Spain
| | - Luis Cardona
- Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
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4
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Thibault M, Letourneur Y, Cleguer C, Bonneville C, Briand MJ, Derville S, Bustamante P, Garrigue C. C and N stable isotopes enlighten the trophic behaviour of the dugong (Dugong dugon). Sci Rep 2024; 14:896. [PMID: 38195771 PMCID: PMC10776846 DOI: 10.1038/s41598-023-50578-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/21/2023] [Indexed: 01/11/2024] Open
Abstract
The dugong (Dugong dugon), a large marine mammal herbivore of the Indo-Pacific, is vulnerable to extinction at a global scale due to a combination of human-related threats including habitat degradation. The species forages on seagrass habitats (marine phanerogams) and plays a key role in the functioning and sensitivity of these declining coastal ecosystems. The trophic behaviour and plasticity of dugong populations in response to extrinsic and intrinsic factors are therefore crucial features to both dugong and seagrass conservation. Yet, this knowledge remains limited to few visual observations and analyses of mouth, stomach or faecal contents of stranded individuals. We take advantage of a long-term monitoring of stranded individuals from the endangered New Caledonian population to depict features of dugongs' trophic ecology from Carbon and Nitrogen stable isotopes. A total of 59 dugong skin samples were used to portrait the stable isotope niche of dugongs according to their sex and maturity. In light of previous work conducted in New Caledonia, a subset of these samples was used to model the trophic mix of dugong males and females. Our stable isotope mixing models used C and N isotope values of 10 taxa bbelonging to five divisions of metazoans, plants, and chromists. Our results represent the first estimate of the species dietary niche in the isotopic space. They suggest that the diet of dugong calves overlaps more with that of adult females (δ13C: - 6.38 ± 1.13 ‰; δ15N: 2.49 ± 1.10 ‰) than males (δ13C: - 5.92 ± 1.10 ‰; δ15N: 3.69 ± 1.28 ‰). Further, we highlight differences in the expected trophic mix of dugong adult males and females. From these, we formulate a sex-specific foraging behaviour hypothesis in dugongs, whereby lactating females could forage over smaller spatial ranges but more diverse food sources thanmales. The study emphasizes the importance of long-term stranding monitoring programs to study the ecology of marine mammals.. Finally, it depicts an ecological feature that may contribute to the sensitivity of vulnerable dugongs to ongoing changes on tropical coastal ecosystems.
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Affiliation(s)
- Martin Thibault
- Centre d'Écologie et des Sciences de la Conservation (CESCO), Muséum National d'Histoire Naturelle, Station de Biologie Marine, 1 Place de la Croix, 29900, Concarneau, France.
- UMR ENTROPIE (UR-IRD-IFREMER-CNRS-UNC), Labex-CORAIL, 98800, Nouméa, New Caledonia.
| | - Yves Letourneur
- UMR ENTROPIE (UR-IRD-IFREMER-CNRS-UNC), Labex-CORAIL, 98800, Nouméa, New Caledonia
| | - Christophe Cleguer
- Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), James Cook University, Townsville, Australia
| | - Claire Bonneville
- UMR ENTROPIE (UR-IRD-IFREMER-CNRS-UNC), Labex-CORAIL, 98800, Nouméa, New Caledonia
| | - Marine J Briand
- CRIOBE, USR 3278 EPHE-CNRS-UPVD, LabEx « Corail », PSL Research University, Université de Perpignan, Avenue Paul Alduy, 66860, Perpignan Cedex, France
| | - Solène Derville
- UMR ENTROPIE (UR-IRD-IFREMER-CNRS-UNC), Labex-CORAIL, 98800, Nouméa, New Caledonia
- Opération Cétacés, BP 12827, 98802, Nouméa, New Caledonia
| | - Paco Bustamante
- Littoral Environnement Et Sociétés (LIENSs), UMR 7266, CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, 17000, La Rochelle, France
| | - Claire Garrigue
- UMR ENTROPIE (UR-IRD-IFREMER-CNRS-UNC), Labex-CORAIL, 98800, Nouméa, New Caledonia
- Opération Cétacés, BP 12827, 98802, Nouméa, New Caledonia
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Costa DP, Favilla AB. Field physiology in the aquatic realm: ecological energetics and diving behavior provide context for elucidating patterns and deviations. J Exp Biol 2023; 226:jeb245832. [PMID: 37843467 DOI: 10.1242/jeb.245832] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
Comparative physiology has developed a rich understanding of the physiological adaptations of organisms, from microbes to megafauna. Despite extreme differences in size and a diversity of habitats, general patterns are observed in their physiological adaptations. Yet, many organisms deviate from the general patterns, providing an opportunity to understand the importance of ecology in determining the evolution of unusual adaptations. Aquatic air-breathing vertebrates provide unique study systems in which the interplay between ecology, physiology and behavior is most evident. They must perform breath-hold dives to obtain food underwater, which imposes a physiological constraint on their foraging time as they must resurface to breathe. This separation of two critical resources has led researchers to investigate these organisms' physiological adaptations and trade-offs. Addressing such questions on large marine animals is best done in the field, given the difficulty of replicating the environment of these animals in the lab. This Review examines the long history of research on diving physiology and behavior. We show how innovative technology and the careful selection of research animals have provided a holistic understanding of diving mammals' physiology, behavior and ecology. We explore the role of the aerobic diving limit, body size, oxygen stores, prey distribution and metabolism. We then identify gaps in our knowledge and suggest areas for future research, pointing out how this research will help conserve these unique animals.
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Affiliation(s)
- Daniel P Costa
- Institute of Marine Sciences, Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95060, USA
| | - Arina B Favilla
- Institute of Marine Sciences, Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95060, USA
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6
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Poulin MP, Cherry SG, Merkle JA. Dynamic balancing of risks and rewards in a large herbivore: Further extending predator-prey concepts to road ecology. J Anim Ecol 2023; 92:1954-1965. [PMID: 37462330 DOI: 10.1111/1365-2656.13985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 06/21/2023] [Indexed: 10/05/2023]
Abstract
Animal behaviour is shaped by the ability to identify risks and profitably balance the levels of risks encountered with the payoffs experienced. Anthropogenic disturbances like roads generate novel risks and opportunities that wildlife must accurately perceive and respond to. Basic concepts in predator-prey ecology are often used to understand responses of animals to roads (e.g. increased vigilance, selection for cover in their vicinity). However, prey often display complex behaviours such as modulating space use given varying risks and rewards, and it is unclear if such dynamic balancing is used by animals in the context of road crossings. We tested whether animals dynamically balance risks and rewards relative to roads using extensive field-based and GPS collar data from elk in Yoho National Park (British Columbia, Canada), where a major highway completely bisects their range during most of the year. We analysed elk behaviour by combining hidden Markov movement models with a step-selection function framework. Rewards were indexed by a dynamic map of available forage biomass, and risks were indexed by road crossings and traffic volumes. We found that elk generally selected intermediate and high forage biomass, and avoided crossing the road. Most of the time, elk modulated their behaviour given varying risks and rewards. When crossing the highway compared with not crossing, elk selected for greater forage biomass and this selection was stronger as the number of highway crossings increased. However, with traffic volume, elk only balanced foraging rewards when they crossed a single time during a travel sequence. Using a road ecology system, we empirically tested an important component of predator-prey ecology-the ability to dynamically modulate behaviour in response to varying levels of risks and rewards. Such a test articulates how decision-making processes that consider the spatiotemporal variation in risks and rewards allow animals to successfully and profitably navigate busy roads. Applying well-developed concepts in predator-prey theory helps understand how animals respond to anthropogenic disturbances and anticipate the adaptive capacity for individuals and populations to adjust to rapidly changing environments.
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Affiliation(s)
- Marie-Pier Poulin
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, USA
| | - Seth G Cherry
- Parks Canada Agency, Radium Hot Springs, British Columbia, Canada
| | - Jerod A Merkle
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, USA
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7
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Holser RR, Crocker DE, Favilla AR, Adachi T, Keates TR, Naito Y, Costa DP. Effects of disease on foraging behaviour and success in an individual free-ranging northern elephant seal. CONSERVATION PHYSIOLOGY 2023; 11:coad034. [PMID: 37250476 PMCID: PMC10214463 DOI: 10.1093/conphys/coad034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 04/14/2023] [Accepted: 05/17/2023] [Indexed: 05/31/2023]
Abstract
Evaluating consequences of stressors on vital rates in marine mammals is of considerable interest to scientific and regulatory bodies. Many of these species face numerous anthropogenic and environmental disturbances. Despite its importance as a critical form of mortality, little is known about disease progression in air-breathing marine megafauna at sea. We examined the movement, diving, foraging behaviour and physiological state of an adult female northern elephant seal (Mirounga angustirostris) who suffered from an infection while at sea. Comparing her to healthy individuals, we identified abnormal behavioural patterns from high-resolution biologging instruments that are likely indicators of diseased and deteriorating condition. We observed continuous extended (3-30 minutes) surface intervals coinciding with almost no foraging attempts (jaw motion) during 2 weeks of acute illness early in her post-breeding foraging trip. Elephant seals typically spend ~ 2 minutes at the surface. There were less frequent but highly extended (30-200 minutes) surface periods across the remainder of the trip. Dive duration declined throughout the trip rather than increasing. This seal returned in the poorest body condition recorded for an adult female elephant seal (18.3% adipose tissue; post-breeding trip average is 30.4%). She was immunocompromised at the end of her foraging trip and has not been seen since that moulting season. The timing and severity of the illness, which began during the end of the energy-intensive lactation fast, forced this animal over a tipping point from which she could not recover. Additional physiological constraints to foraging, including thermoregulation and oxygen consumption, likely exacerbated her already poor condition. These findings improve our understanding of illness in free-ranging air-breathing marine megafauna, demonstrate the vulnerability of individuals at critical points in their life history, highlight the importance of considering individual health when interpreting biologging data and could help differentiate between malnutrition and other causes of at-sea mortality from transmitted data.
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Affiliation(s)
- Rachel R Holser
- Corresponding author: Institute of Marine Sciences, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA. Tel.: +1 253-514-0110.
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, California, 94928, USA
| | - Arina R Favilla
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, 95064 USA
| | - Taiki Adachi
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, 95064 USA
- National Institute of Polar Research, Tachikawa, Tokyo, Japan
| | - Theresa R Keates
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, California, 95064, USA
| | - Yasuhiko Naito
- National Institute of Polar Research, Tachikawa, Tokyo, Japan
| | - Daniel P Costa
- Institute of Marine Sciences, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, 95064 USA
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Kendall-Bar JM, Williams TM, Mukherji R, Lozano DA, Pitman JK, Holser RR, Keates T, Beltran RS, Robinson PW, Crocker DE, Adachi T, Lyamin OI, Vyssotski AL, Costa DP. Brain activity of diving seals reveals short sleep cycles at depth. Science 2023; 380:260-265. [PMID: 37079694 DOI: 10.1126/science.adf0566] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Sleep is a crucial part of the daily activity patterns of mammals. However, in marine species that spend months or entire lifetimes at sea, the location, timing, and duration of sleep may be constrained. To understand how marine mammals satisfy their daily sleep requirements while at sea, we monitored electroencephalographic activity in wild northern elephant seals (Mirounga angustirostris) diving in Monterey Bay, California. Brain-wave patterns showed that seals took short (less than 20 minutes) naps while diving (maximum depth 377 meters; 104 sleeping dives). Linking these patterns to accelerometry and the time-depth profiles of 334 free-ranging seals (514,406 sleeping dives) revealed a North Pacific sleepscape in which seals averaged only 2 hours of sleep per day for 7 months, rivaling the record for the least sleep among all mammals, which is currently held by the African elephant (about 2 hours per day).
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Affiliation(s)
- Jessica M Kendall-Bar
- Scripps Institution of Oceanography, University of California San Diego, San Diego, CA, USA
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Terrie M Williams
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Ritika Mukherji
- Department of Neuroscience, University of Oxford, Oxford, UK
| | - Daniel A Lozano
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
| | | | - Rachel R Holser
- Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Theresa Keates
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Roxanne S Beltran
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Patrick W Robinson
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
| | - Taiki Adachi
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Oleg I Lyamin
- Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
- A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia
| | - Alexei L Vyssotski
- Institute of Neuroinformatics, University of Zurich and Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Daniel P Costa
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
- Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, CA, USA
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9
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Beltran RS, Hernandez KM, Condit R, Robinson PW, Crocker DE, Goetsch C, Kilpatrick AM, Costa DP. Physiological tipping points in the relationship between foraging success and lifetime fitness of a long-lived mammal. Ecol Lett 2023; 26:706-716. [PMID: 36888564 DOI: 10.1111/ele.14193] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/23/2023] [Accepted: 01/25/2023] [Indexed: 03/09/2023]
Abstract
Although anthropogenic change is often gradual, the impacts on animal populations may be precipitous if physiological processes create tipping points between energy gain, reproduction or survival. We use 25 years of behavioural, diet and demographic data from elephant seals to characterise their relationships with lifetime fitness. Survival and reproduction increased with mass gain during long foraging trips preceding the pupping seasons, and there was a threshold where individuals that gained an additional 4.8% of their body mass (26 kg, from 206 to 232 kg) increased lifetime reproductive success three-fold (from 1.8 to 4.9 pups). This was due to a two-fold increase in pupping probability (30% to 76%) and a 7% increase in reproductive lifespan (6.0 to 6.4 years). The sharp threshold between mass gain and reproduction may explain reproductive failure observed in many species and demonstrates how small, gradual reductions in prey from anthropogenic disturbance could have profound implications for animal populations.
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Affiliation(s)
- Roxanne S Beltran
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Keith M Hernandez
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA.,Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, California, USA
| | - Richard Condit
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Patrick W Robinson
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, California, USA
| | - Chandra Goetsch
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - A Marm Kilpatrick
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA.,Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, California, USA
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10
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Booth CG, Guilpin M, Darias-O’Hara AK, Ransijn JM, Ryder M, Rosen D, Pirotta E, Smout S, McHuron EA, Nabe-Nielsen J, Costa DP. Estimating energetic intake for marine mammal bioenergetic models. CONSERVATION PHYSIOLOGY 2023; 11:coac083. [PMID: 36756464 PMCID: PMC9900471 DOI: 10.1093/conphys/coac083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 11/08/2022] [Accepted: 12/21/2022] [Indexed: 06/18/2023]
Abstract
Bioenergetics is the study of how animals achieve energetic balance. Energetic balance results from the energetic expenditure of an individual and the energy they extract from their environment. Ingested energy depends on several extrinsic (e.g prey species, nutritional value and composition, prey density and availability) and intrinsic factors (e.g. foraging effort, success at catching prey, digestive processes and associated energy losses, and digestive capacity). While the focus in bioenergetic modelling is often on the energetic costs an animal incurs, the robust estimation of an individual's energy intake is equally critical for producing meaningful predictions. Here, we review the components and processes that affect energy intake from ingested gross energy to biologically useful net energy (NE). The current state of knowledge of each parameter is reviewed, shedding light on research gaps to advance this field. The review highlighted that the foraging behaviour of many marine mammals is relatively well studied via biologging tags, with estimates of success rate typically assumed for most species. However, actual prey capture success rates are often only assumed, although we note studies that provide approaches for its estimation using current techniques. A comprehensive collation of the nutritional content of marine mammal prey species revealed a robust foundation from which prey quality (comprising prey species, size and energy density) can be assessed, though data remain unavailable for many prey species. Empirical information on various energy losses following ingestion of prey was unbalanced among marine mammal species, with considerably more literature available for pinnipeds. An increased understanding and accurate estimate of each of the components that comprise a species NE intake are an integral part of bioenergetics. Such models provide a key tool to investigate the effects of disturbance on marine mammals at an individual and population level and to support effective conservation and management.
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Affiliation(s)
- Cormac G Booth
- Corresponding author: SMRU Consulting, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, KY16 8LB, UK.
| | | | - Aimee-Kate Darias-O’Hara
- SMRU Consulting, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, KY16 8LB, UK
| | - Janneke M Ransijn
- Sea Mammal Research Unit, Scottish Oceans Institute, East Sands, University of St. Andrews, St. Andrews, KY16 8LB, UK
| | - Megan Ryder
- SMRU Consulting, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, KY16 8LB, UK
| | - Dave Rosen
- Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall,
Vancouver, BC V6T 1Z4, Canada
| | - Enrico Pirotta
- Centre for Research into Ecological and Environmental Modelling,
The Observatory, Buchanan
Gardens, University of St. Andrews, St. Andrews,
KY16 9LZ, UK
| | - Sophie Smout
- Sea Mammal Research Unit, Scottish Oceans Institute, East Sands, University of St. Andrews, St. Andrews, KY16 8LB, UK
| | - Elizabeth A McHuron
- Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, 3737 Brooklyn Ave NE, Seattle, WA, 98105, USA
| | - Jacob Nabe-Nielsen
- Marine Mammal Research, Department of Ecoscience, Aarhus University, Aarhus, DK-4000
Roskilde, Denmark
| | - Daniel P Costa
- Ecology and Evolutionary Biology Department, University of California Santa Cruz, 130
McAlister Way, Santa Cruz, CA, 95064, USA
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11
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Ogilvy C, Constantine R, Bury SJ, Carroll EL. Diet variation in a critically endangered marine predator revealed with stable isotope analysis. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220470. [PMID: 35991335 PMCID: PMC9382206 DOI: 10.1098/rsos.220470] [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: 04/19/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
Understanding the foraging ecology of animals gives insights into their trophic relationships and habitat use. We used stable isotope analysis to understand the foraging ecology of a critically endangered marine predator, the Māui dolphin. We analysed carbon and nitrogen isotope ratios of skin samples (n = 101) collected from 1993 to 2021 to investigate temporal changes in diet and niche space. Genetic monitoring associated each sample with a DNA profile which allowed us to assess individual and population level changes in diet. Potential prey and trophic level indicator samples were also collected (n = 166; 15 species) and incorporated in Bayesian mixing models to estimate importance of prey types to Māui dolphin diet. We found isotopic niche space had decreased over time, particularly since the 2008 implementation of a Marine Mammal Sanctuary. We observed a decreasing trend in ∂13C and ∂15N values, but this was not linear and several fluctuations in isotope values occurred over time. The largest variation in isotope values occurred during an El Niño event, suggesting that prey is influenced by climate-driven oceanographic variables. Mixing models indicated relative importance of prey remained constant since 2008. The isotopic variability observed here is not consistent with individual specialization, rather it occurs at the population level.
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Affiliation(s)
- Courtney Ogilvy
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Rochelle Constantine
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
- Institute of Marine Science, University of Auckland, Auckland 1010, New Zealand
| | - Sarah J. Bury
- National Institute of Water and Atmospheric Research, Greta Point, Wellington 6021, New Zealand
| | - Emma L. Carroll
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
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