Evaluating the influence of anthropogenic landscape change on wolf distribution: implications for woodland caribou

Abstract

Abstract. Across much of the range of woodland caribou (Rangifer tarandus caribou), predator-prey dynamics have changed as a result of large-scale industrial development. Land clearing and associated early-successional forests have resulted in a greater density and distribution of moose (Alces alces), deer (Odocoileus spp.), and their associated predators. This process of apparent competition has resulted in increased predation on woodland caribou. We employed a combination of field and statistical methods to better understand the distribution and interactions of wolves (Canis lupus) and caribou across a region with high levels of industrial development. We used count models to investigate the frequency of wolf occurrence relative to landcover types, disturbance features, and caribou habitat. As predicted, the co-occurrence between caribou and wolves was rare. Similarly, the remains of caribou were identified at a small proportion of the sites where wolves killed large prey. Caribou occurred at low densities across the study area, and thus, wolves likely pursued other more abundant deer species. Encounters between wolves and caribou habitat was most likely to occur in the low-elevation boreal forest and areas closer to and with higher densities of forestry cutblocks. Our results highlight the importance of understanding the spatial dynamics of multi-species interactions when developing recovery strategies for threatened and endangered species.

Lost in translation? Insights into caribou habitat selection from forest inventory data

“…During winter, in accordance with previous research, we found that caribou generally selected older and moderate to open canopy cover stands, and they avoided mixed stands and early seral habitat (e.g., Fortin et al 2008;Leblond et al 2011;DeCesare et al 2012;Losier et al 2015), likely to reduce their predation risk (Courbin et al 2009;Ehlers et al 2016) and maximize their access to terrestrial and arboreal lichens, important winter forage (Vitt et al 1988;Coxson and Marsh 2001;Szkorupa and Schmiegelow 2003). However, we also found caribou selected pine stands regardless of stand age or canopy cover.…”

Fall supplemental feeding increases population growth rate of an endangered caribou herd

“…Although the results were consistent with our hypothesis that summer nutrition may limit population growth, they do not explain why nutrition appeared to be inadequate. Our reasoning remains tenable that at the landscape scale, caribou reduced predation risk by remaining on their high elevation winter ranges rather than risk foraging in spring at lower elevations with nutritious greening-up vegetation and high wolf densities ( Bergerud & Page, 1987 ; Gustine et al, 2006a ; Jones et al, 2007 ; Ehlers, Johnson & Seip, 2016 ). At the foraging site scale, caribou appeared to reduce predation risk by foraging primarily during the day, a time when wolves are least active ( Fig.…”

“…Here, we considered the possibility that summer food may be limiting. Caribou, like many other mountain ungulates ( Hebblewhite & Merrill, 2007 ) are generally predator sensitive foragers ( Lima, 1998 ), trading off high quality foraging opportunities as vegetation greens up at lower elevations in order to reduce predation risk ( Bergerud, Butler & Miller, 1984 ; Bergerud & Page, 1987 ; Poole, Heard & Mowat, 2000 ; Johnson et al, 2002 ; Gustine et al, 2006a ; Gustine et al, 2006b ; Jones et al, 2007 ; Ehlers, Johnson & Seip, 2016 ) at a time their nutritional demands are greatest and body condition is lowest ( Heard, Williams & Melton, 1996 ; Gerhart et al, 1996 ; Parker, Barboza & Gillingham, 2009 ). We hypothesized that if summer nutrition was inadequate, then fall supplemental feeding (hereafter ‘feeding’) could at least partially compensate for that limitation, contributing to population growth by improving caribou’s body condition going into winter, increasing winter survival and leading to larger more viable calves the following spring ( Veiberg et al., 2016 ; Gustine et al, 2017 ).…”

The density of anthropogenic features explains seasonal and behaviour-based functional responses in selection of linear features by a social predator

“…Our study is unique because although the cumulative effects of industrial activity have been investigated previously for wolves (e.g. 23 , 24 ), our study is the first to specifically observe evidence of (1) behaviour-specific (i.e., resting-feeding vs. travelling) responses to variation in vegetation height on seismic lines, and (2) year-round landscape-scale functional response in habitat selection in response to variation in vegetation height on seismic lines. In two distinct landscapes with largely dissimilar densities of anthropogenic features, we found that wolves consistently selected for seismic lines with relatively low vegetation height when in areas of low densities of anthropogenic features.…”

“…Industrial activities can alter the spatial composition and arrangement of diverse landscape features (i.e. landscape heterogeneity), have compounding effects on the way that wildlife perceive disturbance features, can occur at multiple scales, and can influence the functional response in habitat selection 23 , 24 . Typical habitat selection models make the implicit assumption that selection stays constant as availability changes.…”