Abstract 300 – American Black Bears in Lowland Desert: Assessing Habitat Use with Hydrogen Isotopes

Sydney Stephens, Christy J. Mancuso, Austin M. Green, Cagan H. Sekercioglu

American black bears typically rely on forested land cover and are not expected to spend
prolonged periods of time in shrub-dominated arid lands like the red rock deserts of
southeastern Utah. While arid lands are known to be used as corridors between
metapopulations (i.e. the La Sal Mountains, Tavaputs Plateau, Uncompahgre Forest), these
areas are considered unsuitable for anything more than short-term occupation during dispersal.
However, increases in the number of bear encounters near the Rio Mesa Field Station north of
Castle Valley and Moab suggest bears may spend more time in arid systems than previously
known. Camera traps and hair snares were used to investigate the residency of frequently
visiting bears. Additionally, we received hair samples from bears in the La Sal (n=11) and San
Juan (n=4) mountains from the Utah Division of Natural Resources. We measured hydrogen
stable isotopes to examine bear land use at different elevations and to assess occupancy after
short-scale dispersal events. While our hair snare samples were all gathered from only one
individual at the low elevation area, the differences in their hydrogen values were still
significantly different from higher elevation bears (p=0.03). Our findings suggest that bears
were occupying these low-elevation deserts for time periods beyond temporary transit paths.
Continued use of this area by other bears has been confirmed with camera trap and visual
sightings. This case study provides preliminary evidence of desert habitat use being greater
than previously thought, and shows the potential for using this O/H stable isotopes to assess
similar situations as a more affordable, non-invasive, and random sampling technique than
other current options.