Moose response to high‐elevation forestry: Implications for apparent competition with endangered caribou

Abstract

Habitat disturbance threatens woodland caribou (Rangifer tarandus caribou) by altering intertropic relationships, which causes predation rates to increase. Of particular concern is the increase in early seral vegetation in high-elevation caribou summer habitat created by the recent expansion of logging into these forests. Deep snow confines the relatively abundant moose (Alces alces) population to valleys during winter, but in summer they can move up slope, where their spatial overlap with caribou increases. Wolves (Canis lupus) follow moose, their primary prey, up slope and occasionally encounter and kill caribou. We tested the hypothesis that early seral vegetation in high-elevation cutblocks (i.e., logged areas) attracts moose into mountain caribou summer habitat, and thereby increases the spatial overlap between caribou, moose, and wolves. To test our hypothesis, we examined how moose selection for early seral vegetation changed with elevation, how moose used undisturbed habitat, and how the proportion of early seral vegetation at high elevations in a moose home range was related to the amount of time moose spent at high elevations. Moose selection for cutblocks increased with elevation; however, when moose were at high elevations they spent the majority of their time in old-growth forest where they were likely browsing on understory shrubs, and the area of high-elevation cutblocks in moose home ranges did not affect the amount of time moose spent at high elevations. When we further explored the relationship between the amount of early seral vegetation at high elevations and the amount of time moose spent at high elevations, we found moose spent more time at high elevations when total early seral vegetation (from natural sources and cutblocks) increased, but there was little evidence that either type, on their own, influenced moose to use higher elevations. We conclude that although moose select cutblocks, the influence of high-elevation cutblocks on moose was minor in our study. Our results and those of other studies suggests low-elevation logging in moose winter ranges has led to an increased number of moose, and likely has a greater effect on moose distribution than logging at higher elevations. These insights can help guide management of apparent competition between moose and caribou.

Trophic consequences of terrestrial eutrophication for a threatened ungulate

“…This mechanism was also not supported in our study, even though moose have a higher intrinsic growth rate, with greater niche breadth [ 37 , 38 , 74 ]. Moose did not appear to exert competitive exclusion on caribou, probably because these species do not have a major overlap of needed resources [ 74 , 81 ].…”

Management‐mediated predation rate in the caribou–moose–wolf system: spatial configuration of logging activities matters

“…For the three seasons, a moose agent represented a single individual, whereas a wolf agent represented a wolf pack (i.e., meta-individual). In our simulations, we accounted for the typical numerical response of moose that follows timber harvesting (Potvin et al 2005, Anderson et al 2018) and the concurrent increase in wolf density. We thus adjusted the number of moose in a simulation to the total disturbance and then adjusted the number of wolf packs to moose density based on Messier (1994).…”

Spatializing oil and gas subsidies in endangered caribou habitat: Identifying political‐economic drivers of defaunation

“…Wolves use seismic lines as lines of sight to hunt caribou, and these lines facilitate quicker movement or scouting over a larger piece of land (Dickie et al, 2017), and increase wolf density in a particular area (Dickie et al, 2022). Cutting seismic lines and other linear features creates an “early successional” environment that generates favorable forage for moose and elk, and therefore drives up the primary prey source for wolves and other predators, a process known as “apparent competition” (Anderson et al, 2018). Seismic lines and other linear features associated with oil and gas development, such as access roads and trails, also increase opportunities for wolf encounters with caribou (Mumma et al, 2018; Whittington et al, 2011).…”