High-quality hair samples allow us to identify both the species (e.g., black bear) and individual (e.g., black bear “A” versus black bear “B”) of origin. Once individuals have been identified via hair samples, the DNA of each individual can be further analyzed to provide detailed information about relatedness between individuals—a critical component of our landscape genetic study.
Our survey design is based on hexagonal sample units projected across the entire North Cascades Ecosystem. Each hexagon represents 2500 ha, an area slightly smaller than the average size of a female black bear home range in this region.
For bears, we optimally deploy two barbed-wire corrals within each sample unit surveyed, and space them as far apart as possible (e.g., ≥3 km) while maintaining a distance of ~1 km or more from the edge of the unit. Corrals comprise a single strand of barbed-wire stretched around four or more trees at a height of 45–50 cm, with woody debris piled in the center and treated with one liter of liquid scent lure (i.e., cattle blood and fish).
Corrals are revisited at ~14 days and (a) removed if a sufficient sample is present or (b) re-baited and left for another 14 days if no sample is present.
In the field, hair samples are immediately placed in small coin envelopes and stored in plastic containers with desiccant.
For martens, we deploy 3–5 tree-mounted hair snares within each sample unit surveyed, spacing devices at approximately 500 m and targeting suitable marten habitat (i.e., mature forest) whenever possible. Hair-snagging devices (i.e., gun-cleaning brushes) are attached to the tree-mounted enclosure, which is baited with chicken and scent lure.