Examining spatial patterns of selection and use for an altered predator guild

Abstract

Anthropogenic disturbances have altered species' distributions potentially impacting interspecific interactions. Interference competition is when one species denies a competing species access to a resource. One mechanism of interference competition is aggression, which can result in altered space-use of a subordinate species due to the threat of harm, otherwise known as a 'landscape of fear'. Alternatively, subordinates might outcompete dominant species in resource-poor environments via a superior ability to extract resources. Our goal was to evaluate spatial predictions of the 'landscape of fear' hypothesis for a carnivore guild in Newfoundland, Canada, where coyotes recently immigrated. Native Newfoundland carnivores include red foxes, Canada lynx, and black bears. We predicted foxes and lynx would avoid coyotes because of their larger size and similar dietary niches. We used scat-detecting dogs and genetic techniques to locate and identify predator scats. We then built resource selection functions and tested for avoidance by incorporating predicted values of selection for the alternative species into the best supported models of each species. We found multiple negative relationships, but notably did not find avoidance by foxes of areas selected by coyotes. While we did find that lynx avoided coyotes, we also found a reciprocal relationship. The observed patterns suggest spatial partitioning and not coyote avoidance, although avoidance could still be occurring at different spatial or temporal scales. Furthermore, Newfoundland's harsh climate and poor soils may swing the pendulum of interspecific interactions from interference competition to exploitative competition, where subordinates outcompete dominant competitors through a superior ability to extract resources.

Predicting multi-predator risk to elk (Cervus canadensis) using scats: Are migrant elk exposed to different predation risk?

“…Scat contents reflective a predation event and the scat location indicates the broad-scale spatial overlap of predators and prey. A scat-based approach may be advantageous over telemetry-based kill sites because scats can be less invasive and more cost efficient when using scat-detection dogs (Wasser et al, 2004;Mumma et al, 2017), particularly in multi-predator communities. In this paper, we compare a scat-based approach to quantifying spatial predation risk from bears (Ursus arctos/U.…”

Cats and dogs: A mesopredator navigating risk and reward provisioned by an apex predator

“…Confounding effects can make it difficult to determine if selection for a habitat feature is a true response to its presence on the landscape (Northrup et al, 2012 ; Roever et al, 2010 ). Similarly, avoidance of the habitat selected by another species is not necessarily avoidance of that species; instead, it may simply be a reflection of differing habitat niches (Mumma, Holbrook, et al, 2017 ). Habitat selection does not directly communicate the particular cues an animal uses to navigate its environment and does not necessarily indicate that the pattern in habitat selection is a direct result of the habitat feature tested.…”

Beyond the encounter: Predicting multi‐predator risk to elk (Cervus canadensis) in summer using predator scats

“…We found DNA analysis detected elk present in 88% of the scats where we detected elk macroscopically. It is likely that the 12% of hairs where elk was detected macroscopically but not through DNA analysis is a result of false negatives because of PCR inconsistency (see Mumma et al, 2017 ). Wildlife Genetics International (Nelson, Canada) performed DNA analyses.…”

“…The 50‐m width reflected the estimated distance of scat detection by dogs. We sampled 10 random (available) points within the buffer around each scat location for a density of ~0.8 random points per km 2 , which is just under the 1 random point/km not uncommonly used in telemetry‐based selection studies at the home‐range scale (Hebblewhite and Merrill, 2008 ; Mumma et al, 2017 ). We used an exponential RSF model deriving parameters using logistic regression (Johnson et al, 2006 ).…”

“…Where scat contents reflect primarily predation rather than scavenging events, the location of scat that contains prey reflects the area where a prey encountered a predator and was killed similar to kill sites. In this case, a scat‐based approach to quantifying predation risk may be advantageous over telemetry‐based kill sites because scat surveys are less invasive and may be more cost‐efficient in multi‐predator communities especially when using scat‐detection dogs (Mumma et al, 2017 ; Wasser et al, 2004 ). In this paper, we present an approach to quantifying spatial predation risk from bears ( Ursus arctos / U .…”