Thursday, August 11, 2016

Bobcat Population Tracking

Yesterday I got to ride along in a truck with my friend and colleague Heather Shaw for a few hours.  Heather is the wildlife biologist for the Saginaw Chippewa Indian Tribe and she is currently working on a survey of Bobcat (Lynx rufus) populations in Isabella County.  A graduate of Central Michigan University, Heather has previously worked as a wildlife technician for the the Wyoming Department of Fish and Game and as a biologist for Ducks Unlimited in both Michigan and North Dakota.  In addition to working for the Saginaw Chippewa Tribe, she is also completing work on her masters thesis at CMU (expected defense coming up this fall).

Heather Shaw, wildlife biologist for the Saginaw Chippewa Indian Tribe, fills out a bobcat survey data sheet

Why monitor bobcat populations?

Bobcats are notoriously secretive and often have widely dispersed territories.  I have seen several road-killed Bobcats, but have never seen a live one in the wild.  Even wildlife biologists rarely see them except by chance.  It is very difficult to know exactly how many bobcat can be found living in a given area.

So how do you monitor a population like that?

Heather is using a series of scent stations situated along roadside transects in likely bobcat habitat.  What this means, is that along a selected path (a transect) she was setting up a bed of sand to record footprints and baiting it with a scent tablet to attract bobcat (and other predators).  When an animal investigated the scent tablet, their footprints would recorded in the sand, enabling Heather to build a picture of the locations where bobcats can be found.
This map shows the location of the bobcat survey transects in Isabella County (and penciled in near the corner, the location of an Amish bakery - biologists love baked goods)

The locations of these transects has been chosen by the Michigan Department of Natural Resources (DNR) based on models that predict possible bobcat habitat.  Each transect is three miles long and has a scent station located every 1/3 mile along the transect.  This is the second year that Heather has been conducting this survey in Isabella County - she also has one transect located in Midland County (the next county to the east).

One of ten scent stations located along Rolland Road

Why is this monitoring effort important?

Heather is not the only person setting up these stations and recording data.  Other biologists around the state are recording the same type of information.  This information is used by the Michigan DNR to set seasons and bag limits for bobcat hunting and trapping.  Bobcat hunting and trapping are currently allowed in the Upper Peninsula and northern Lower Peninsula, with Isabella County included in the the hunting/trapping zone.  Isabella County is one of the most southern Michigan counties where bobcat hunting and trapping are allowed.

What did we find?

We followed two of the transects that Heather had set up earlier in the week.  Both of these transects were located in the southwest corner of Isabella County.  The first transect was located on a gravel road that sees very little traffic.  The second transect was located on a relatively busy paved road.  These transects are set up along roadsides so they are easy to check.  In addition, many animals including bobcats will use roads as travel corridors, to these stations were likely to be found by any bobcat traveling through the vicinity.

This station along Gilmore Road had several tracks, but none belonged to a bobcat

Many of the scent stations that we visited were completely undisturbed, but we did find tracks from domestic dogs, house cats, raccoon, coyote, fox (possible), white-tailed deer, and birds.  At a station established where Rolland Road crosses the Pine River, we found a set of bobcat tracks.

This station along Rolland Road finally yielded a bobcat track

At each station, Heather measured and recorded any bobcat tracks and recorded all of the other tracks that we discovered.  Then, if necessary, she "reset" the station by smoothing out the sand and replacing the scent tablet if needed.

Heather photographing a bobcat track

Heather measures a bobcat track

Heather "resets" a scent station by smoothing the surface

This survey is almost done for the year.  In addition to the scent stations, Heather set up several trail cameras along the transects.  Her next step will be to sort through all of the trail cam photos - she expects a lot of car pictures.  I can't wait to see if any bobcats were "captured".

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