The estimation of grizzly bear density through hair‐snagging techniques above the tree line

• Published in: Wildlife Society Bulletin
• Main Authors: Mathieu Dumond, John Boulanger, David Paetkau
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Arctic; DENSITY; DNA degradation; hair‐snagging; mark–recapture; noninvasive; General. Including nature conservation; geographical distribution; QH1-199.5; Gulo gulo; Tundra; Ursus arctos
• Online Access: https://doi.org/10.1002/wsb.520; https://doaj.org/article/8a43e8f074424f5787e82e8ace54d13d

ABSTRACT Assessing grizzly bears' (Ursus arctos) abundance in the Arctic has been challenging because of the large scale of their movements and the remoteness of field locations. We modified a post sampling method used for wolverines (Gulo gulo) to allow collection of hair samples from grizzly bears in the Canadian tundra. We deployed 1 post/cell in a sampling grid of 393 10 × 10‐km cells sampled in 2008 and 2009 for two 14‐day sessions in July–August of both years. We then compared density estimates from mark–recapture estimators that used telemetry data from previous years with spatially explicit mark–recapture models that used only genetic detections. Over the 2 years of sampling, we detected 98 female and 81 male grizzly bears. We found that the DNA degradation rate was related to collection interval and the number of days between rainfall events and sample collection. Estimates of density were in the order of 5 bears/1,000 km2. The estimates from the 2 methods were statistically similar, but spatially explicit estimates were more precise than those using radiocollar data. Our results provide the first demonstration of the viability of posts as hair‐snagging stations to obtain DNA from grizzly bears, and of spatially explicit mark–recapture methods to estimate population size and density for grizzly bears above the tree line. © 2015 The Wildlife Society.