Above: a Bobcat (Lynx rufus) from the upper penninsula of Michigan.
Photo courtesy of Stantec, Inc.
There's no reason to expect I shouldn't find wild felines at several of my study sites. These sites consist of rather large, undisturbed blocks of woodland....some of which have stands of older trees (not old-growth, but still old)....most have stream corridors running through them....and all have very little human activity.
In short, the sites have everything I imagined would be conducive to bobcats.
But, bobcats can be a tricky lot. They are sometimes elusive and usually not crazy about showing themselves. They also do not exist in very high densities here. As solitary animals (like most wild felines, with the expection of African Lions), there are not the numbers of bobcats per given area as there are deer, raccoon, or even coyotes. Therefore, assuming they are even present at a given site, the odds that one will happen to pass by a camera trap are pretty low.
Needless to say, I wasn't having any luck catching them.
This was not for lack of trying. I felt like I was pulling out all the stops to draw them into my camera traps. I was using scent lures (catnip, spearmint, coyote urine, bobcat urine, gland-based lures, etc.)....I tried bait (squirrel carcasses, mouse carcasses, etc.) and I found what appeared to be outstanding locations for carnivores. I didn't try visual attractants, which are supposed to be good for bobcats. For example, ribbons tied to a tree branch, bird feathers tied to a tree branch, etc. The reason I didn't do this is because visual attractants also attract curious Homo sapiens. I didn't want to cue a potential thief in to where my cameras were!
But, at two of the sites that I thought had good bobcat potential.....after almost a year......there still has been not a single Bobcat appearance.
My bad luck with cats changed this March, however. I initiated a new camera trap project with an undergraduate researcher at a completely new site (see The Anatomy of a Camera Trapping Project posted on March 22, 2011).
The cameras for this project were deployed in mid-February, 2011, within a large tract of forest associated with a river. We've found some interesting stuff to-date. I'm still not ready to tell you all what the goal of the project is, but I can share some of the neat stuff we've caught on the cameras (see also Do Angry Raccoons Make Precarious Lovers? posted on March 12, 2011)...including my first Bobcat since moving to the southeastern US.
Dave (the undergraduate conducting the research) and I swapped the memory cards on these cameras for the first time in early March, 2011. We brought the cards back, plugged them into a computer and started clicking through the images....hopeful of what we might find. Within minutes, both of us let out a whoop of excitement!
Melting out of the darkness, came the cat.....who proceeded to walk directly in front of our camera!
An important point about the pictures above....take note and remember the small notch out of the cat's right ear.
So....needless to say, we were happy. This was not the last camera that had produced pictures for us to scroll through on this day! So we started pouring through the rest of the pictures and were excited to see yet another bobcat.
Captured on the same day, and roughly an hour before the first set of pictures we viewed.
The cat comes into view facing away from the camera.......
But something just doesn't feel right, I guess, and the cat swivels its head around to face the camera.....take alook at that right ear.
This is one of my favorite pictures that I've ever captured on a camera trap!
He doesn't bolt...but he is wary enough to give the camera a bit of scrutiny......
And then he's off......
It's also worth noting that there were no lures or baits used in front of these cameras.
We earned these photos, if you ask me!
Notes on Bobcat Densities
Density estimates of bobcats vary considerably.
Examples from the Midwest:
- Minnesota: 4-6 individuals / 100 km-sq (Berg, 1979)
- Missouri: 6-10 individuals /100 km-sq (Hamilton 1982)
- Arkansas: roughly 10 / 100 km-sqr (Rucker et al. 1989)
Examples from the Southeast. Roberts and Crimmins (2010) indicate that bobcat population estimates in our general neck of the woods vary, or are incomplete.
- North Carolina harvest analysis yielded an estimate of 90,115 bobcats in a 126,161 km-sq area of suitable habitat in the state.
- South Carolina, harvest analysis and scent station analysis led to an estimated population ranging from 40,552-94,622 bobcats in 56,773 km-sq of suitable habitat.
- Virginia populatioin estimates were "uknown"
- Tennessee population estimates were "unknown"
Examples from the West:
- Nevada: 20 / 100 km-sq (Golden 1982)
- Arizona: 24-28 / 100 km-sq (Jones and Smith, 1979)
- Oregon: 77 / 100 km-sq (Witmer and DeCalesta, 1986)
- California: 115-153 / 100 km-sq (Lembeck and Gould 1979)
Bobcat popultions are currently believed to be on the increase. A large-scale analysis by Roberts and Crimmins (2010) that included harvest data from 47 US states, Mexico and 7 Canadian provinces from 1996-2008 supports this. They found that 31 of the jurisdictions reporting (64.6%) indicated an increase in bobcat populations, 15 (31.3%) have reported stable populations, and only one (Florida) reported decreasing populations.
Reletively recent studies have been published using camera traps to estimate bobcat populations and densities (Larrucea et al., 2007). So the precedent to use cameras for more than inventory work is there. While cameras have limitations for estimating populations of some animals...it is posssible with bobcats because individuals can be recognized by physical characteristics, such as spot patterns (Larrucea et al. 2007).
Berg, W.E. 1979. Ecology of bobcats in northern Minnesota. Pages 55-61 In P.C. Escherich and L. Blum (eds.). Proceedings of the 1979. bobcat research conference (Science and Technology Series 6). National Wildlife Federation, Washington, DC.
Hamilton, D.A. 1982. Ecology of the bobcat in Missouri. MS Thesis., University of Missouri, Columbia (note: I have not actually read this thesis, I am citing this based on information in Feldhammer et al. 2003 second edition of Wild Mammals of North America).
Golden, H. 1982. Bobcat populations and environmental relationships in northwestern Nevada. MS Thesis, University of Nevada, Reno.(note: I have not actually read this thesis, I am citing this based on information in Feldhammer et al. 2003 second edition of Wild Mammals of North America).
Jones, J.H., and N.S. Smith. 1979. Bobcat density and prey selection in central Arizona. Journal of Wildlife Management 43:666-672.
Lembeck, M. and G.I. Gould, Jr. 1979. Dynamics of a harvested and unharvested bobcat populations in California. Pages 53-54 In P.C. Escherich and L. Blum (eds.). Proceedings of the 1979. bobcat research conference (Science and Technology Series 6). National Wildlife Federation, Washington, DC.
Larrucea, E.S., G. Serra, M.M. Jaeger, and R.H. Barrett. 2007. Censusing bobcats using remote cameras. Western North American Naturalist 67:538-548.
Roberts, N.M. and S.M. Crimmins. 2010. Bobcat population status and management in North America: evidence of large-scale population increase. Journal of Fish and Wildlife Management 1:169-174.
Rucker, R.A., M.L. Kennedy, G.A. Heidt, and M.J. Harvey. 1989. Population density, movements and habitat use of bobcats in Arkansas. The Southeastern Naturalist 34:101-108.
Whitemer, G.W. and D.S. DeCalesta. 1986. Resource use by unexploited symbatric bobcats and coyotes in Oregon. Canadian Journal of Zoology 64:2333-2338.