Proceedings of the Ninth Mountain Lion Workshop - Carnivore ...

Evaluation of Cougar Population Estimators in Utah
David M. Choate, 1 Department of Wildland Resources and Ecology Center, Utah State
University, Logan, UT 84322-5230, USA, dchoate@nd.edu
Michael L. Wolfe, Department of Wildland Resources, Utah State University, Logan, UT
84322-5230, USA, michael.wolfe@usu.edu
David C. Stoner, Department of Wildland Resources, Utah State University, Logan, UT
84322-5230, USA, david.stoner@usu.edu
ABSTRACT Numerous techniques have been proposed to estimate or index cougar
(Puma concolor) populations, but few have been applied simultaneously to populations
with reliable estimates of population size. Between 1996 and 2003, we evaluated the
relative efficacy and accuracy of multiple estimation and index techniques for
populations at 2 locations in Utah, Monroe Mountain and the Oquirrh Mountains. We
used radio-tagging followed by intensive monitoring and repeated capture efforts to
approach a complete enumeration of the populations. We used these benchmarks to
evaluate other population estimates (Lincoln-Petersen mark–recapture, helicopter-survey
probability sampling, catch-per-unit-effort) and indices (scent-station visits, track counts,
hunter harvest). Monitoring over 600 scent-station-nights using different attractants,
June–September in 1996 and 1997, yielded a single cougar visit. Summer track-based
indices reflected a 54–69% reduction in population size on the Monroe site and a
numerically stable population on the Oquirrhs, but relationships between indices and the
benchmark population estimates varied among techniques. Population estimates derived
from helicopter-survey probability sampling exceeded reference population estimates by
120–284%, and bootstrapped estimates of standard error encompassed 25–55% of the
population estimates (e.g., 5.6 ± 1.4 cougars/100 km 2 ). Despite poor performance in
predicting cougar population sizes, track-based estimates may provide better indices for
monitoring large changes in population trends (i.e., with low precision). However, we
recommend using multiple indices after determination of a more rigorous initial
population estimate for managing populations of conservation concern and when
considering connectivity to determine potential refuge sites for regional management
(e.g., management by zones).
1 Present address: Department of Biological Sciences, University of Notre Dame, Notre
Dame, IN 46556 USA.
Proceedings of the Ninth Mountain Lion Workshop
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