Abstract
We evaluated three methods of estimating population size of woodland caribou (boreal ecotype) on the Slate Islands in northern Ontario. Located on the north shore of Lake Superior, the Slate Islands provide a protected and closed population with very limited predator influence that is ideal for a comparison of survey methods. Our objective was to determine the costs and benefits of three population estimation techniques: (1) forward looking infrared (FLIR) technology to count the number of caribou on regular-spaced transects flown by fixed-wing aircraft; (2) observers to count the number of caribou seen or heard while walking random transects in the spring; and, (3) mark-recapture sampling of caribou pellets using DNA analysis. FLIR and the genetics 3-window approach gave much tighter confidence intervals but similar population estimates were found from all three techniques based on their overlapping confidence intervals. There are various costs and benefits to each technique that are discussed further. Understanding the costs and benefits of different population estimation techniques is necessary to develop cost-effective programs for inventorying and monitoring this threatened species not only on the Slate Islands but for other populations as well.
Highlights
The forest-dwelling ecotype of woodland caribou (Rangifer tarandus caribou) is listed as a threatened species in Canada
Our objective was to determine the costs and benefits of three population estimation techniques: (1) forward looking infrared (FLIR) technology to count the number of caribou on regular-spaced transects flown by fixed-wing aircraft; (2) observers to count the number of caribou seen or heard while walking random transects in the spring; and, (3) mark-recapture sampling of caribou pellets using DNA analysis
Forward looking infrared (FLIR) The FLIR survey of the Slate Islands was completed in 5.3 hours of flying over two days
Summary
The forest-dwelling ecotype of woodland caribou (Rangifer tarandus caribou) is listed as a threatened species in Canada. Special Issue No 20, 2012 techniques, aerial surveys, are hampered by the size of areas to be surveyed and difficulties in observing animals due to dense vegetation, as well as logistics and costs (McDonald 2004; Pollock et al 2004). These problems are exacerbated for species such as caribou that are sometimes sparsely distributed and difficult to detect. Non-invasive sampling methods such as genetic analyses of faecal or hair samples and thermal infrared imaging in aerial surveys, have increased in popularity and use for estimating abundance of rare or elusive species (Thompson, 2004)
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