In the 2014 field season, over 250 hair snag sites were set up across the Yellowhead region, often in very remote areas. Snag sites consist of a scent lure (rancid cattle blood and oil poured on a pile of branches) enclosed by a strand of barbed wire. When curious bears come to investigate the smell, they leave clumps of hair on the barbs. The field crew return regularly to the hair snag sites to collect the hair, and DNA is extracted for analysis.
These DNA-based sampling techniques are a non-invasive adaptation of capture-mark-recapture (CMR) methods—the most frequently employed approach for estimating wildlife population size across a wide variety of wildlife species. A number of authors have concluded that noninvasive genetic sampling using hair is ideally suited for monitoring rare or hard-to-capture species like grizzly bears because the hair can be collected remotely without having to catch or disturb the animal. As a result, numerous projects outside of Alberta have also used this technique to estimate grizzly bear population size, including projects in British Columbia.
In 2014, we selected site locations based on the 180-cell 7 km x 7 km grid system applied to BMA 3 during the 2004 grizzly bear DNA inventory. One hair snag site was placed in each grid cell. By maintaining close consistency between the 2004 and 2014 study design and sampling strategies, we facilitated direct comparisons between these two datasets. We modified the 2014 grid, however, to better reflect core and secondary grizzly bear conservation areas, which had not been established or mapped before the 2004 DNA inventory.
Specifically, we placed additional cells within the Whitegoat Wilderness Area. Where possible, we placed sites at the same within-cell locations as in previous DNA surveys (2004, 2011, 2013). Where necessary, we generated new site locations in a geographic information system (GIS) prior to fieldwork using a grizzly bear RSF model, a model of buffaloberry abundance, aerial photographs, and expert opinion. Preference was given to areas of high RSF, high buffaloberry abundance, and reasonable access. In the field, we also targeted site locations near riparian areas, linear clearings, natural meadows, and cutblocks, based on research indicating site placement in these areas is important for maximizing detection at fixed hair snag sites. Sites were also placed at least 100 m from roads, trails, and facilities.
Samples were sent to Wildlife Genetics International for extraction and sequencing. 21 loci were sequenced to give each bear a unique ID and establish parent-offspring relationships.