Abstract 326 – A more complete view: understanding black bear and grizzly bear spatial and temporal niche partitioning in two contrasting Yukon landscapes

Jodie Pongracz, Kai Breithaupt, Patrick Gibeau

Grizzly bear (Ursus arctos) and black bear (Ursus americanus) distributions overlap in much of
the Yukon Territory, however, little is known regarding how these sympatric species coexist at
the northern edge of their ranges. Black bears and grizzly bears have strong diet overlap, and
similar life histories. Understanding how these species interact in space and time is essential to
understanding how they coexist or potentially influence each other’s existence.
We used detections of black bears and grizzly bears at two contrasting remote Yukon
landscapes to better understand patterns of use. The Ogilvie Mountains study area contains
pristine habitat, encompasses a territorial protected area, and is comprised of large U-shaped
valleys and bare mountain ridges shaped by multiple glaciations. In contrast, the Klondike
Plateau study area was unglaciated, is centralized on a quartz mine exploration complex, and is
comprised of V-shaped valleys and upland areas of smooth topped ridges and boulder fields.
Remote cameras were positioned at scent-lured hair snag stations positioned in a gridded
arrangement across the two study areas. Camera traps in the Klondike Plateau (n=150) were
active between 18 June and 14 August 2022; those in the Ogilvie Mountains (n=154) were
active between 20 June – 19 September 2023. We use photo detections of black bears and
grizzly bears to 1) examine the level of spatial overlap and quantify how this relates to habitat
variables, and 2) examine the temporal overlap at differing temporal scales (daily and berry
season (pre-berry/berry/post-berry)).