Environmental Monitoring and Research

Woodland Caribou Winter Range Selection in the Central Mackenzie Valley, Sahtú

Thursday, November 21, 2019 - 11:00am to 11:20am Theatre Two


J. Tigner (Presenting)

Boreal woodland caribou are a culturally important and politically charged species across Canada.  Despite strict legislated requirements and strong societal desire to protect caribou habitat, little detailed information is available in the Central Mackenzie Valley about local caribou distribution or habitat use patterns.  This knowledge gap means that management efforts cannot target areas of high habitat quality or high caribou use, but instead must be applied more broadly to prevent new disturbance even in locations of low habitat quality, where caribou do not occur, or where caribou are unlikely to occur.

In winter 2012-2013 caribou cratering locations and moose and wolf use data were collected along a network of aerial survey transects between the Mackenzie, Carcajou, and Little Bear Rivers and the Canol Trail to identify caribou winter range and determine the characteristics of winter range.  Kernel density estimates were used to identify caribou winter range and moose distribution within the study area.  Caribou winter range and moose use showed very little spatial overlap within the study area.  Next, a zero-inflated negative binomial modelling framework was used to test a series of hypotheses based on predation risk, escape terrain, habitat disturbance (natural and anthropogenic), and land cover to explain winter range selection patterns at two spatial and two temporal scales.  Spatial scales were based on the Oil and Gas Leasing Grid Sections and Units to understand caribou decision making at scales that are immediately related to scales at which oil and gas exploration and development decisions are made.  Sections and units also generally equate to first (274 ha; orientation on a landscape) and third (20 ha; food searching) order habitat selection for caribou.  Temporal scales were used to assess whether dramatic shifts in winter range locations or characteristics occur over a winter season.  At the broad scale caribou selected for winter range away from areas of high moose use and away from burns, regardless of burn age.  At the fine scale caribou selected for winter range with a high proportion of lichen landcover.  No temporal variation in selection patterns were observed.  Thus, caribou are selecting for winter range at two spatial scales, simultaneously.  At a broad scale caribou are selecting for locations with less alternate prey use (i.e., the spatial separation hypothesis to minimize predation risk) and at the fine scale caribou are selecting for locations with more food.  Finally, caribou habitat selection patterns were used to show how to predict habitat quality outside of the immediate study area in a spatially explicit way.  The predictive mapping shows where high-quality habitats may occur elsewhere and how such information may be used to inform management decisions around where and how industrial land uses occur more broadly within woodland caribou habitats in the Central Mackenzie Valley.