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UBC Theses and Dissertations

Assessing passive recording of howls to measure wolf (Canis lupus) occupancy in the East Kootenays, British Columbia Gauthier, Danielle


Wolves (Canis lupus) population management is a priority for conservationists, wildlife managers, hunters, trappers, cattle producers, and First Nations. Ideally, a survey technique should allow individual identification to increase managers’ ability to precisely and accurately estimate population trends in abundance, distribution, density and pack structure. However, wolf monitoring is notoriously difficult because of the species’ low density and elusive nature. Furthermore, lowering operating costs is a priority for wildlife agencies. In some cases, non-invasive survey techniques have lower monitoring costs relative to more invasive approaches like capture and tagging. There have been very promising developments in bioacoustics that could answer these questions. Morphological differences in the vocal tract of wolves mean that individuals have measurably distinct vocalizations. Minimum counts, age class, and individual identification have been achieved in previous studies, yet these methods remain to be proven in the field where little or no information about wolves or packs is available. The goal of this study was to assess bioacoustics for monitoring wolf occupancy by deploying autonomous recording units (ARU) in southeastern British Columbia. We hypothesized that deploying ARUs at wolf rendezvous sites would yield the best number and quality of recordings. To do so, we created a predictive map of rendezvous sites, and used it in an attempt to find rendezvous sites through grounds searches and elicited howling surveys. We paired ARUs with cameras traps to compare detection probability, overlap, and environmental covariates through single and multiple-method occupancy models. We also compared costs for equipment, deployment, and analysis. Finally, howling phenology was investigated to detect trends that could be used to refine recording schedules and reduce requirements for field data. ARUs proved more efficient at detecting wolves than camera traps paired at the same location, however the former method is costlier and time consuming in the field and the lab. No temporal trends were found in howling phenology to potentially refine recording schedules. Additional effort to target rendezvous sites mostly proved futile as only one site was found. Although bioacoustics is a promising method for wolf monitoring, further research is needed before becoming a practical technique for wildlife managers.

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