Modeling influences on winter distribution of caribou in northwestern Alaska through use of satellite telemetry

Abstract

I hypothesize that the distribution of barren-ground caribou (Rangifer tarandus granti) is affected by multiple, interrelated factors. These factors include, but are not limited to, terrain and snow characteristics as well as predation pressure and habitat. To test this hypothesis, I attributed caribou locations derived from satellite telemetry over a 6 year period with terrain (elevation, slope, aspect, and ruggedness), habitat characteristics, and moose density -potentially an index of wolf predation pressure. These locations were compared to random locations, attributed using the same data layers, using logistic regression techniques to develop resource selection functions (RSFs). I found that caribou moved significantly less during mid-winter than early-or late-winter and that cows moved significantly more in April than bulls due to their earlier departure on their spring migration. Distribution was different between cows and bulls. Terrain variables were important factors but were scale-dependent. Cows avoided forested areas, highlighting the importance of tundra habitats, and selected for dwarf shrub, with relatively high lichen cover, and sedge habitat types. Bulls selected for dryas, coniferous forest and dwarf shrub habitats but against lowland sedge, upland shrub and burned tundra. Cow distribution was negatively correlated with moose density at the scale of the Seward Peninsula. My results support the hypothesis that caribou distribution during winter in northwest Alaska is affected by multiple, interrelated factors. These results may be useful for researchers to track and/or model changes in future patterns of range use over winter.

Evaluating Potential Effects of an Industrial Road on Winter Habitat of Caribou in North-Central Alaska

“…Indeed, roads have been proposed from Ambler to Nome, Kotzebue, and other locations in western Alaska that are currently roadless (DOWL HKM, 2011). Westward expansion of roads beyond Ambler has the potential to affect Western Arctic caribou and a greater portion of the herd's winter and other seasonal ranges (Joly, 2011).…”

“…During September of each year (2009-12), we captured adult female caribou (39 in 2009, 15 in 2010, 14 in 2011, and 12 in 2012) as they swam across the Kobuk River at Onion Portage and instrumented each with a global positioning system satellite telemetry collar (Telonics TGW-4680, Mesa, Arizona, USA) (Joly, 2011). We programmed collars to acquire locations every eight hours.…”

“…We also included a variety of topographic variables into the set available for model selection, given their previously documented importance in other resource selection studies for caribou (Gustine et al, 2006;Joly et al, 2011). We used a digital elevation model (60 m; Gesch, 2007) to obtain elevation data.…”

Simulating the effects of climate change on fire regimes in Arctic biomes: implications for caribou and moose habitat

“…Similarly, we calculated the areal extent of habitat in (1) deciduous stands 10-30 years old and (2) tundra and spruce forest 50 years old. WAH caribou utilize both tundra and boreal forest habitats during winter (Joly et al 2007a, Joly 2011. We also calculated these extents for just the herd's core winter range (Fig.…”

“…Similarly, greater burn severity in the boreal forest could alter the black spruce (Picea mariana) self-replacement trajectory by consuming semi-serotinous seeds and reducing organic layers which results in an early successional deciduous phase (Johnstone et al 2010). This would also be disadvantageous for overwintering caribou as they avoid these habitat types (Joly et al 2010, Collins et al 2011, Joly 2011. Likewise, additional shrub cover, such as Salix spp., could attract herbivores associated with boreal forests, such as moose (Alces alces; Bryant andReichardt 1992, Joly et al 2010).…”