Limited evidence for proactive and reactive spatial responses of prey to an active predator [article]

Jeremy Cusack, Michel T. Kohl, Matthew C. Metz, Tim Coulson, Daniel R. Stahler, Douglas W. Smith, Daniel R. MacNulty
2017 bioRxiv   pre-print
Predator-prey interactions are often assumed to result in spatial avoidance patterns whereby prey respond to the distribution and movement of predators, yet this assumption is rarely tested. We estimated spatial overlap between the winter trajectories of GPS-collared elk (Cervus elaphus) and the long-term utilisation distribution of GPS-collared grey wolf (Canis lupus) packs in northern Yellowstone, as well as evaluated encounter rates during a subset of winter months when the movement of both
more » ... pecies was tracked simultaneously. We carried out a null model analysis that randomised elk trajectories according to three different formulations (rotation, rotation and shift, and correlated random walk) to test whether observed values of spatial overlap and encounter rate were less than expected by chance. Our analysis revealed 1 in 5 elk winter trajectories had lower spatial overlap than expected by chance when the less restrictive null formulation was used. Although elk encountered wolves on average once every 8.5 days, encounter rate was no different to null expectations for all but two of the 120 tested trajectories. Our study suggests that predator-prey interactions may not always result in strong spatial patterns of avoidance, and that other behavioural mechanisms may be more important in shaping long and short-term prey responses.
doi:10.1101/215475 fatcat:6lhhmtkqwjhg7mhcgnevj24f3q