Translator Disclaimer
1 July 2004 SAMPLING DESIGN AND BIAS IN DNA-BASED CAPTURE–MARK–RECAPTURE POPULATION AND DENSITY ESTIMATES OF GRIZZLY BEARS
Author Affiliations +
Abstract

Over a 3-year period, we assessed 2 sampling designs for estimating grizzly bear (Ursus arctos) population size using DNA capture–mark–recapture methods on a population of bears that included radiomarked individuals. We compared a large-scale design (with 8 × 8-km grid cells and sites moved for 4 sessions) and a small-scale design (5 × 5-km grid cells with sites not moved for 5 sessions) for closure violation, capture-probability variation, and estimate precision. We used joint telemetry/capture–mark–recapture (JTMR) analysis and traditional closure tests to analyze the capture–mark–recapture data with each design. A simulation study compared the performance of each design for robustness to heterogeneity bias caused by reduced capture probabilities of cubs. Our results suggested that the 5 × 5-km grid cell design was more precise and more robust to potential sample biases, but the risk of closure violation due to smaller overall grid size was greater. No design exhibited complete closure as estimated by JTMR. The results of simulation studies suggested that CAPTURE heterogeneity models are relatively robust to probable forms of capture-probability variation when capture probabilities are >0.2. Only the 5 × 5-km designs exhibited this capture-probability level, suggesting that this design is preferred to ensure estimator robustness when population size is <100. The power of the CAPTURE model selection routine to detect capture probability variation was low regardless of sampling design used. Our study illustrated the trade-off between intensive sampling to ensure robustness and adequate precision of estimators while being extensive enough to avoid closure violation bias.

JOHN BOULANGER, BRUCE N. MCLELLAN, JOHN G. WOODS, MICHAEL F. PROCTOR, and CURTIS STROBECK "SAMPLING DESIGN AND BIAS IN DNA-BASED CAPTURE–MARK–RECAPTURE POPULATION AND DENSITY ESTIMATES OF GRIZZLY BEARS," Journal of Wildlife Management 68(3), 457-469, (1 July 2004). https://doi.org/10.2193/0022-541X(2004)068[0457:SDABID]2.0.CO;2
Received: 26 November 2002; Accepted: 9 March 2004; Published: 1 July 2004
JOURNAL ARTICLE
13 PAGES

This article is only available to subscribers.
It is not available for individual sale.
+ SAVE TO MY LIBRARY

SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top