Estimating Bobcat Abundance in Michigan

By Deb Martell, MS State University; Dr. Jerrold Belant, MS State University and Dr. Dean Beyer, MI DNR

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1. A bobcat (Lynx rufus) caught on camera at a hair snare site.

Estimating wildlife abundance is important for effective management and understanding species’ ecology, including predator-prey relationships.  Use of DNA-based identification of individuals from tissue samples such as hair, along with advances in capture-recapture techniques, has markedly improved our ability to estimate wildlife abundance.  Methods have now been developed which allow researchers to collect hair samples without capturing the animal, thus reducing stress on the individual.  The DNA extracted from hair follicles allows individual identification of animals, and biologists can use this information to estimate abundance and density of wildlife populations.

Bobcats are secretive and typically occur at low densities; therefore, few techniques are available to estimate their abundance.  In Michigan’s Upper Peninsula (UP), researchers with the Michigan Predator-Prey Project are using hair snares to collect hair samples from bobcats and estimate their abundance.  These hair snares work similarly to traditional snares, but barbs are created by clipping strands of wire from the braided snare cable to catch hair.  Also, the locking mechanisms used with traditional snares are replaced with paperclips, which allow the snares to break away after the animal pulls against the snare.  In addition to not restraining animals, the break-away modification ensures that hair from multiple individuals will not be mixed which would preclude our ability to identify individuals.

 M2E40L142-142R399B3102. An example of a bobcat hair snare site; notice the snares set in the openings of the “vegetation wall” and bait placed at the center tree.

This past winter researchers with Mississippi State University and the Michigan Department of Natural Resources established 64 hair snare sites throughout their study area in the central UP.  Commercial lures and bait (white-tailed deer or beaver carcasses) were placed at each site and surrounded by a “wall” of branches and vegetation containing several openings with hair snares, which encouraged animals to walk through snares to reach the bait.  Researchers also deployed trail cameras at each site to collect more data about which animals were visiting.

Researchers collected 160 hair samples of target and non-target species and obtained more than 500,000 camera images.  The images contain evidence of over 30 different species of birds and mammals that scavenged on bait piles.  Species included American martens, fishers, bald and golden eagles, woodpeckers, and flying squirrels.

The Michigan Predator-Prey Project is a multi-year study, which aims to assess baseline reproductive parameters and the magnitude of cause-specific mortality and survival of white-tailed deer.  Getting accurate population information for carnivores, such as bobcats, is integral to this research.  A more technical description of the methods used
to estimate bobcat abundance can be found in Stricker et al. (2012).

hair_sample3. A hair sample snagged on the barbs of a modified body snare.

3 Comments

  1. Thanks for sharing guys. I really enjoy getting the updates. I hope to get out with you next winter… of course I have said that for the last two winters as well.

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