Abstract 183 – Effectiveness of different methods for non-invasive monitoring of grizzly bears

Darío Fernández-Bellon, Cameron McClelland, Gordon Stenhouse

Non-invasive sampling methods have long been a preferred approach for bear population
monitoring and conservation programs across the world. Despite their widespread use, limited
evidence is available on the effectiveness of different methodological approaches. In North
America, hair snag corrals baited with cow blood as a non-reward attractant have been widely
used as a means of non-invasive sampling for grizzly bears Ursus arctos. This method has
proved successful for developing population estimates, but some challenges remain: snag
effectiveness has not been quantified, the use of cow blood raises safety and logistic
difficulties, and determining whether samples correspond to single or multiple individuals is
challenging. Here we analyse data from two seasons (2023 and 2024) at 80 hair snag sites
(monitored by trail cameras) distributed over an area of 18,000 km2 in the foothills of the
Canadian Rocky Mountains. We tested (i) different hair snag site configurations, (ii) alternative
non-reward attractants, and (iii) different sampling periods and assessed their effectiveness for
both grizzly bears and black bears Ursus americanus. We found corral hair snag sites to have
high effectiveness compared to other methods (e.g., rub trees). Of 6 alternative attractants
tested, anise-based lures showed similar effectiveness to blood for attracting grizzly bears,
while fish fertilizer was the most effective attractant for black bears. Trail cameras indicated
that behaviours at the site also varied between species and across attractants. Temporal
variability in detections may reflect seasonal activity which can help inform optimal sampling
periods. Overall, these results can help optimize cost-effectiveness of ongoing and future
monitoring efforts.