Saturday, 23 September 2017

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

PeerJ. 2017 Aug 17;5:e3701. doi: 10.7717/peerj.3701. eCollection 2017. Bryce CM1,2, Wilmers CC3, Williams TM1. Author information 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. 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 [Formula: see text] 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. KEYWORDS: Accelerometer; Adaptive strategies; Energetics; GPS telemetry; Hunting modes; Large carnivore; Movement ecology; Performance; Physiology; Tradeoffs PMID: 28828280 PMCID: PMC5563439 DOI: 10.7717/peerj.3701 Free PMC Article