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Rojano-Doñate L, Teilmann J, Wisniewska DM, Jensen FH, Siebert U, McDonald BI, Elmegaard SL, Sveegaard S, Dietz R, Johnson M, Madsen PT. Low hunting costs in an expensive marine mammal predator. SCIENCE ADVANCES 2024; 10:eadj7132. [PMID: 38748803 PMCID: PMC11318689 DOI: 10.1126/sciadv.adj7132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 04/11/2024] [Indexed: 08/15/2024]
Abstract
Many large terrestrial mammalian predators use energy-intensive, high-risk, high-gain strategies to pursue large, high-quality prey. However, similar-sized marine mammal predators with even higher field metabolic rates (FMRs) consistently target prey three to six orders of magnitude smaller than themselves. Here, we address the question of how these active and expensive marine mammal predators can gain sufficient energy from consistently targeting small prey during breath-hold dives. Using harbor porpoises as model organisms, we show that hunting small aquatic prey is energetically cheap (<20% increase in FMR) for these marine predators, but it requires them to spend a large proportion (>60%) of time foraging. We conclude that this grazing foraging strategy on small prey is viable for marine mammal predators despite their high FMR because they can hunt near continuously at low marginal expense. Consequently, cessation of foraging due to human disturbance comes at a high cost, as porpoises must maintain their high thermoregulation costs with a reduced energy intake.
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Affiliation(s)
- Laia Rojano-Doñate
- Department of Biology, Aarhus University, Aarhus, Denmark
- Department of Ecoscience, Aarhus University, Roskilde, Denmark
| | - Jonas Teilmann
- Department of Ecoscience, Aarhus University, Roskilde, Denmark
| | | | - Frants H. Jensen
- Department of Ecoscience, Aarhus University, Roskilde, Denmark
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Biology Department, Syracuse University, Syracuse, NY, USA
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Hannover, Germany
| | | | - Siri L. Elmegaard
- Department of Biology, Aarhus University, Aarhus, Denmark
- Department of Ecoscience, Aarhus University, Roskilde, Denmark
| | - Signe Sveegaard
- Department of Ecoscience, Aarhus University, Roskilde, Denmark
| | - Rune Dietz
- Department of Ecoscience, Aarhus University, Roskilde, Denmark
| | - Mark Johnson
- Department of Biology, Aarhus University, Aarhus, Denmark
- Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark
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Optimal diving and oxygen use. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Fayet AL, Houston AI. A critical evaluation of the index of patch quality. Proc Biol Sci 2021; 288:20210459. [PMID: 34004133 PMCID: PMC8131121 DOI: 10.1098/rspb.2021.0459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The inverse optimality approach can allow us to learn about an animal's environment by assuming their behaviour is optimal. This approach has been applied to animals diving underwater for food to produce the index of patch quality (IPQ), which aims to provide a proxy for prey abundance or quality in a foraging patch based on the animal's diving behaviour. The IPQ has been used in several empirical studies but has never been evaluated theoretically. Here, we discuss the strengths and weaknesses of the IPQ approach from a theoretical angle and review the empirical evidence supporting its use. We highlight several potential issues, in particular with the gain function-the function describing the energetic gain of an animal during a dive-used to calculate the IPQ. We investigate an alternative gain function which is appropriate in some cases, provide a new model based on this function, and discuss differences between the IPQ model and ours. We also find that there is little supporting empirical evidence justifying the general use of the IPQ and suggest future empirical validation methods which could help strengthen the case for the IPQ. Our findings have implications for the field of diving ecology and habitat assessment.
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Affiliation(s)
- Annette L Fayet
- Department of Zoology, University of Oxford, Mansfield Road, Oxford OX1 3SZ, UK
| | - Alasdair I Houston
- School of Biological Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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Mallpress DEW. Some theoretical notes on spatial discounting. Behav Processes 2021; 186:104355. [PMID: 33571612 DOI: 10.1016/j.beproc.2021.104355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 10/22/2022]
Abstract
Spatial discounting is a largely underexplored area of decision-making research, both theoretically and empirically, especially when compared to intertemporal choice, which has received significant attention in psychology and animal behaviour. Spatial decision problems seem to share some of the same features of a temporal decision problem (namely, the risk of reward objects disappearing and the opportunity cost of waiting), but there are several additional factors that affect the appropriate discount function for distant rewards. These include more significant opportunity costs, changes in the distances to all the other available opportunities, the post-reward costs of getting back home, the complex energetics associated with locomotion and all the additional risks faced by travelling itself. This paper organises and explores these factors and suggests some normative models that should predict the adaptive behaviour of animals and humans.
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Affiliation(s)
- Dave E W Mallpress
- Institute of Psychology, Chinese Academy of Sciences, 16 Lincui Road, Chaoyang District, Beijing, 100101, China.
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Tyson R, Friedlaender A, Nowacek D. Does optimal foraging theory predict the foraging performance of a large air-breathing marine predator? Anim Behav 2016. [DOI: 10.1016/j.anbehav.2016.03.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Mahendiran M. Coexistence of three sympatric cormorants (Phalacrocorax spp.); partitioning of time as an ecological resource. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160175. [PMID: 27293799 PMCID: PMC4892461 DOI: 10.1098/rsos.160175] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 04/19/2016] [Indexed: 06/01/2023]
Abstract
Resource partitioning is well known along food and habitat for reducing competition among sympatric species, yet a study on temporal partitioning as a viable basis for reducing resource competition is not empirically investigated. Here, I attempt to identify the mechanism of temporal partitioning by intra- and interspecific diving analyses of three sympatric cormorant species at different freshwater wetlands around the Delhi region. Diving results indicated that cormorants opted for a shallow diving; consequently, they did not face any physiological stress. Moreover, diving durations were linked with seasons, foraging time and foraging habitats. Intraspecific comparison suggested that cormorants spent a longer time underwater in early hours of the day. Therefore, time spent for dive was higher in the forenoon than late afternoon, and the interspecific analysis also yielded a similar result. When Phalacrocorax niger and Phalacrocorax fuscicollis shared the same foraging habitat, they tended to differ in their foraging time (forenoon/afternoon). However, when P. niger and Phalacrocorax carbo shared the same foraging time, they tended to use different foraging habitats (lentic/lotic) leading to a mechanism of resource partitioning. Thus, sympatric cormorants effectively use time as a resource to exploit the food resources and successful coexistence.
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Chiaradia A, Ramírez F, Forero MG, Hobson KA. Stable Isotopes (δ13C, δ15N) Combined with Conventional Dietary Approaches Reveal Plasticity in Central-Place Foraging Behavior of Little Penguins Eudyptula minor. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2015.00154] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Jouma'a J, Le Bras Y, Richard G, Vacquié‐Garcia J, Picard B, El Ksabi N, Guinet C. Adjustment of diving behaviour with prey encounters and body condition in a deep diving predator: the Southern Elephant Seal. Funct Ecol 2015. [DOI: 10.1111/1365-2435.12514] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | - Yves Le Bras
- CEBC UMR 7372 ULR‐CNRS 79360 Villiers en Bois France
| | | | | | | | - Nory El Ksabi
- CEBC UMR 7372 ULR‐CNRS 79360 Villiers en Bois France
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Optimal diving: physiology is not the issue. Trends Ecol Evol 2011. [DOI: 10.1016/j.tree.2011.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Optimal diving models: their development and critique requires accurate physiological understanding. Trends Ecol Evol 2011; 26:437-8; author reply 438-9. [DOI: 10.1016/j.tree.2011.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 05/01/2011] [Indexed: 10/18/2022]
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