How competition dynamics drive access to shared scavenging opportunities amongst a group of mesocarnivores in the Rocky Mountains of Alberta

• Main Author: Bell, Elicia
• Other Authors: Bone, Christopher
• Format: Thesis
• Language: English
• Published: 2021
• Subjects: wildlife ecology; mustelids; camera traps; scavenging ecology; American marten; Gulo gulo; Martes americana
• Online Access: http://hdl.handle.net/1828/13363

Mesocarnivores occupy critical functional roles in regulating ecosystems and maintaining biodiversity. In the Canadian Rocky Mountains, mustelid species depend heavily on carrion as an important dietary contribution, particularly in winter when resources are scarce. In diverse mesocarnivore communities such as this, sympatric species must balance energetic resource acquisitions through scavenging with avoidance of costly competition dynamics, in a manner that optimizes energetic gain through risk aversion. We examined the nature of spatial-temporal interactions between wolverine (Gulo gulo), American marten (Martes Americana), and short-tailed weasel (Mustela erminea) in the Willmore Wilderness Park in western Alberta. Data were collected from camera traps (n = 59) baited with a simulated scavenging opportunity during winter months between 2006 to 2008. The spatial-temporal dimensions of intraguild competition were evaluated using a multi-model approach. Zero-inflated negative binomial (ZINB) or zero-inflated Poisson (ZIP) regression models were used to identify the competitive and environmental factors that affected (1) species presence/absence and (2) how intensely a species would spatiotemporally optimize a carrion site. A time-to-event analysis was used to quantify the directionality of fine-scale (hourly) reactionary behavioural responses of species to potential sources of competition. An extension of this group of models, the Cox proportional hazard (CPH) model was used to further reveal the relative influence of external environmental variables (i.e. diel period, landcover, and snow depth) on temporal spacing. Pairing CPH and ZINB/ZIP models enables us to recognize the relative contribution of fine-scale spatial and temporal behavioural responses to competitors in shaping coexistence strategies. Our results suggest that facultative scavengers adopt different coexistence mechanisms based on the interspecific competitor and environmental conditions they encounter at carrion sites. We found that carrion use ...