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      Energetics and evasion dynamics of large predators and prey: pumas vs. hounds

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          Abstract

          Quantification of fine-scale movement, performance, and energetics of hunting by large carnivores is critical for understanding the physiological underpinnings of trophic interactions. This is particularly challenging for wide-ranging terrestrial canid and felid predators, which can each affect ecosystem structure through distinct hunting modes. To compare free-ranging pursuit and escape performance from group-hunting and solitary predators in unprecedented detail, we calibrated and deployed accelerometer-GPS collars during predator-prey chase sequences using packs of hound dogs ( Canis lupus familiaris, 26 kg, n = 4–5 per chase) pursuing simultaneously instrumented solitary pumas ( Puma concolor, 60 kg, n = 2). We then reconstructed chase paths, speed and turning angle profiles, and energy demands for hounds and pumas to examine performance and physiological constraints associated with cursorial and cryptic hunting modes, respectively. Interaction dynamics revealed how pumas successfully utilized terrain (e.g., fleeing up steep, wooded hillsides) as well as evasive maneuvers (e.g., jumping into trees, running in figure-8 patterns) to increase their escape distance from the overall faster hounds (avg. 2.3× faster). These adaptive strategies were essential to evasion in light of the mean 1.6× higher mass-specific energetic costs of the chase for pumas compared to hounds (mean: 0.76 vs. 1.29 kJ kg −1 min −1, respectively). On an instantaneous basis, escapes were more costly for pumas, requiring exercise at ≥90% of predicted and consuming as much energy per minute as approximately 5 min of active hunting. Our results demonstrate the marked investment of energy for evasion by a large, solitary carnivore and the advantage of dynamic maneuvers to postpone being overtaken by group-hunting canids.

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          Arms Races between and within Species

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            Conservation physiology.

            Conservation biologists increasingly face the need to provide legislators, courts and conservation managers with data on causal mechanisms underlying conservation problems such as species decline. To develop and monitor solutions, conservation biologists are progressively using more techniques that are physiological. Here, we review the emerging discipline of conservation physiology and suggest that, for conservation strategies to be successful, it is important to understand the physiological responses of organisms to their changed environment. New physiological techniques can enable a rapid assessment of the causes of conservation problems and the consequences of conservation actions.
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              Moving towards acceleration for estimates of activity-specific metabolic rate in free-living animals: the case of the cormorant.

              1. Time and energy are key currencies in animal ecology, and judicious management of these is a primary focus for natural selection. At present, however, there are only two main methods for estimation of rate of energy expenditure in the field, heart rate and doubly labelled water, both of which have been used with success; but both also have their limitations. 2. The deployment of data loggers that measure acceleration is emerging as a powerful tool for quantifying the behaviour of free-living animals. Given that animal movement requires the use of energy, the accelerometry technique potentially has application in the quantification of rate of energy expenditure during activity. 3. In the present study, we test the hypothesis that acceleration can serve as a proxy for rate of energy expenditure in free-living animals. We measured rate of energy expenditure as rates of O2 consumption (VO2) and CO2 production (VCO2) in great cormorants (Phalacrocorax carbo) at rest and during pedestrian exercise. VO2 and VCO2 were then related to overall dynamic body acceleration (ODBA) measured with an externally attached three-axis accelerometer. 4. Both VO2 and VCO2 were significantly positively associated with ODBA in great cormorants. This suggests that accelerometric measurements of ODBA can be used to estimate VO2 and VCO2 and, with some additional assumptions regarding metabolic substrate use and the energy equivalence of O2 and CO2, that ODBA can be used to estimate the activity specific rate of energy expenditure of free-living cormorants. 5. To verify that the approach identifies expected trends in from situations with variable power requirements, we measured ODBA in free-living imperial cormorants (Phalacrocorax atriceps) during foraging trips. We compared ODBA during return and outward foraging flights, when birds are expected to be laden and not laden with captured fish, respectively. We also examined changes in ODBA during the descent phase of diving, when power requirements are predicted to decrease with depth due to changes in buoyancy associated with compression of plumage and respiratory air. 6. In free-living imperial cormorants, ODBA, and hence estimated VO2, was higher during the return flight of a foraging bout, and decreased with depth during the descent phase of a dive, supporting the use of accelerometry for the determination of activity-specific rate of energy expenditure.
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                Author and article information

                Contributors
                Journal
                PeerJ
                PeerJ
                peerj
                peerj
                PeerJ
                PeerJ Inc. (San Francisco, USA )
                2167-8359
                17 August 2017
                2017
                : 5
                : e3701
                Affiliations
                [1 ]Department of Ecology & Evolutionary Biology, University of California, Santa Cruz , CA, United States of America
                [2 ]Botswana Predator Conservation Trust , Maun, Botswana
                [3 ]Center for Integrated Spatial Research, Environmental Studies Department, University of California, Santa Cruz , CA, United States of America
                Article
                3701
                10.7717/peerj.3701
                5563439
                28828280
                6936c038-af65-46f4-b944-045e2fd680fa
                ©2017 Bryce et al.

                This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.

                History
                : 5 June 2017
                : 26 July 2017
                Funding
                Funded by: National Science Foundation
                Award ID: DBI-0963022
                Award ID: DBI-1255913
                Award ID: GK-12 DGE-0947923
                Funded by: Gordon and Betty Moore Foundation
                Funded by: UCSC Science Internship Program (SIP)
                Funded by: Mazamas
                Funded by: ARCS Foundation
                Funded by: Ecology and Evolutionary Biology (EEB)
                Support was provided by the National Science Foundation (DBI-0963022, DBI-1255913, and GK-12 DGE-0947923) and the Gordon and Betty Moore Foundation. Additional support came to CMB from the UCSC Science Internship Program (SIP), Mazamas, the ARCS Foundation, and the Ecology and Evolutionary Biology (EEB) Department at UC Santa Cruz. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
                Categories
                Animal Behavior
                Conservation Biology
                Ecology
                Environmental Sciences
                Zoology

                large carnivore,physiology,movement ecology,tradeoffs,performance,adaptive strategies,accelerometer,gps telemetry,hunting modes,energetics

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