Spatially explicit power analyses for occupancy-based monitoring of wolverine in the U.S. Rocky Mountains

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Dublin Core

Title

Spatially explicit power analyses for occupancy-based monitoring of wolverine in the U.S. Rocky Mountains

Description

Conservation scientists and resource managers often have to design monitoring programs for species that are rare or patchily distributed across large landscapes. Such programs are frequently expensive and seldom can be conducted by one entity. It is essential that a prospective power analysis be undertaken to ensure stated monitoring goals are feasible. We developed a spatially based simulation program that accounts for natural history, habitat use, and sampling scheme to investigate the power of monitoring protocols to detect trends in population abundance over time with occupancy-based methods. We analyzed monitoring schemes with different sampling efforts for wolverine (Gulo gulo) populations in 2 areas of the U.S. Rocky Mountains. The relation between occupancy and abundance was nonlinear and depended on landscape, population size, and movement parameters. With current estimates for population size and detection probability in the northern U.S. Rockies, most sampling schemes were only able to detect large declines in abundance in the simulations (i.e., 50% decline over 10 years). For small populations reestablishing in the Southern Rockies, occupancy-based methods had enough power to detect population trends only when populations were increasing dramatically (e.g., doubling or tripling in 10 years), regardless of sampling effort. In general, increasing the number of cells sampled or the per-visit detection probability had a much greater effect on power than the number of visits conducted during a survey. Although our results are specific to wolverines, this approach could easily be adapted to other territorial species.

Bibliographic Citation

Ellis, M. M., J. S. Ivan, and M. K. Schwartz. 2014. Spatially explicit power analyses for occupancy-based monitoring of wolverine in the U.S. Rocky Mountains. Conservation Biology 28:52–62. https://doi.org/10.1111/cobi.12139

Creator

Ellis, Martha M.
Ivan, Jacob S.
Schwartz, Michael K.

Subject

Detection probability
Occupancy
Population monitoring
Population trends
Sampling design

Extent

11 pages

Date Created

2013-09-03

Type

Article

Format

application/pdf

Language

English

Is Part Of

Conservation Biology

Collection

Citation

Ellis, Martha M., Ivan, Jacob S., and Schwartz, Michael K., “Spatially explicit power analyses for occupancy-based monitoring of wolverine in the U.S. Rocky Mountains,” CPW Digital Collections, accessed February 27, 2024, https://cpw.cvlcollections.org/items/show/279.