MTPR

'Field Notes': Seeing The Stories In Scat

Jan 16, 2017

Some years ago, I worked at a science school near Yellowstone National Park. I taught kids ecology. My favorite day was the tracks and signs day where ten fifth-grade companions joined me for a hike along a river bottom to piece together recent animal activity. We rarely saw any animals, but the place throbbed with life. We were a team of detectives, opening our senses to all the clues we could find.

Prowling among cottonwoods on the way to the river’s edge, I’m in the lead, with a wake of ten-year-olds fanning out behind me. Our eyes survey the ground as if we expect it to come alive at any moment. Without a word, I pass a pile of droppings on my left side. "WAIT!" yells a small voice from behind.  The cry goes out and we circle up to examine the find.

Some animals just aren’t common, and if you want to learn about them, one of the best ways is through the field of scatology.

Now I’ve got ‘em; open young faces poised, all eyes fixed on a pile of animal feces. I reach down, pretend to pick up a couple pellets while palming a few chocolate candies, pause a split second for effect, toss them into my mouth and chew with a wine connoisseur’s expression on my face.

First thing to learn: size is important. Whether you’re a wildlife ecologist or a fifth graders, that’s the initial characteristic to note. Second to size is shape—lucky enough for field instructors, deer droppings have an amazing resemblance in both size and shape to Raisinettes. Keep that in mind the next time you’re at the theater.

Biologists often study scat to analyze the diet and seasonal diet changes of herbivores and carnivores. The idea is, if you know what comes out, you can know what goes in. By breaking apart and carefully analyzing scat, it is possible to determine the different prey items and relative amounts of these food sources. Studies are done throughout the year in order to quantify seasonal variation in diet. Carnivore scat may contain hair, bones, teeth, and feathers. Herbivore scat is analyzed for plant parts, often microscopic in size. Studies have been done with grizzly bears, dear, moose, and other animals. Scat analysis becomes especially important in identifying the dietary needs of elusive animals not often observed feeding in the wild. For forest managers concerned about preserving populations of rare animals, scatological studies are imperative.

With a gaggle of fifth-grade imaginations taking guesses at a scat’s origin, you’ll find yourself in a place filled with bears and wolves. But it doesn’t take much practice to learn the basics of scat ID. Rope-like pieces indicate carnivore scat such as wolves, weasels, and coyotes. Herbivore scat consists of roundish pellets. Any naturalist equipped with a small stick and a curious mind can often identify prey items in the field.

Elk scat.
Credit Josh Burnham

Using only slightly more advanced tools, biologists use scat analysis to determine resource partitioning. The diets of coyotes, foxes, and bobcats consist of the same items, which might lead us to believe that they compete with each other for available food. Biologists have shown through scat analysis how these three animals use different proportions of food items to reduce competition among each other. Coyotes and bobcats eat more meat, while foxes eat more insects. And both the coyotes and foxes eat a considerable amount of vegetation. Results from studies like this vary depending on the location of the study and the food available in that area, but they always help us to define complex relationships within a food web.

At the end of our day, my fifth-grade class and I find our own place in the food web as we munch our lunch and chat about scat while sitting in the grass among the big cottonwoods.

Broadcast: "Fieldnotes," 12/06/16. You can hear the program on the radio Sundays at 12:55 p.m., Tuesdays at 4:54 p.m., and Fridays at 4:54 p.m., or listen via podcast.