Scoop on Poop: Virginia’s Dominant Predators

After I wrapped up my undergraduate career, I landed a job at Virginia Tech as a full time scatologist. As I explained in my last post, I got my start in research at the North Carolina Museum of Natural Sciences sorting coyote scat samples for a research project. With my new job, I earned the added responsibilities of washing and identifying coyote, black bear, and bobcat scat contents for a new project.

The three dominant predators in western Virginia are coyotes, bobcats, and black bears. (Image credit: coyote and bear/Virginia Tech and Virginia Department of Game and Inland Fisheries; bobcat/Dana Morin)

The three dominant predators in western Virginia are coyotes, bobcats, and black bears. (Image credit: coyote and bear/Virginia Tech and Virginia Department of Game and Inland Fisheries; bobcat/Dana Morin)

The goals of this study were similar to the North Carolina project. We wanted to determine diet for coyotes, black bears, and bobcats, the three dominant predators in western Virginia. Because this study included three predators, we could take it a step further than the North Carolina study and actually compare the predator diets. This comparison allows us to get a sense of how the three predators are interacting on the landscape.

The first step in this project was to determine whether our samples belonged to a coyote, a bobcat, or a bear. We used size, shape, odor, and associated tracks to identify samples in the field, and then corroborated those identifications using a species identification multiplex in the lab. That’s fancy terminology that really just means we used the DNA left behind by the predator on the outside of the scat to determine which predator pooped the sample.

After we verified our identifications, we washed, sorted, and identified the scat contents. We used species-specific patterns on hairs and teeth to confidently identify mammalian prey. For example, deer hairs have a honeycomb pattern, vole hairs have rows of dark ovals, and rabbit hairs resemble corn-on-the-cob. A reference bank of seeds helped us identify fruits and we left some categories like insects and birds broad.

Mammalian prey hairs are identifiable because of the unique patterns called medulla patterns that are visible under a microscope.

Mammalian prey hairs are identifiable because of the unique patterns called medulla patterns that are visible under a microscope.

It’s fascinating to think that these predators might be influencing diet options for the others. We have the raw data collected from this study and are working on organizing and publishing it. I will follow-up on this post when those publications are out. In the meantime, stick around to learn more about why researchers collect so much scat and check out some of my favorite finds from the Virginia study in the photo gallery below!

This slideshow requires JavaScript.

Advertisements

Scoop on Poop: Coyotes at Ft. Bragg

At the beginning of my junior year at NC State, I caught a city bus downtown to the North Carolina Museum of Natural Sciences. I had a meeting with Biodiversity Lab Director Roland Kays to discuss undergraduate research opportunities. I had no idea what “undergraduate research” meant.

After a brief discussion in which Dr. Kays learned that I hadn’t a clue what I wanted to study, he said, “Can you start today?”

Pie chart representing red fox diet in the 1944 paper “The ecological relationship of red fox food in eastern New York” by David B. Cook and W. J. Hamilton, Jr. published in the journal Ecology.

Pie chart representing red fox diet in the 1944 paper “The ecological relationship of red fox food in eastern New York” by David B. Cook and W. J. Hamilton, Jr. published in the journal Ecology.

The Biodiversity Lab has one entire wall, which is in fact a window allowing the public to view the lab goings-on as they stroll through the museum. I sat down that day in front of said window with a plate of scat. A plate of poop. Coyote poop, to be exact.

For the rest of the semester, I held a volunteer position in the lab sorting coyote scat. The poop sorting was part of an NC State research project to study food habits of coyotes at Fort Bragg Military Installation in the southeastern part of the state. Scat is a relatively common method used to determine the diets of predator species and we’ve been using that reliable method for a long time.

Do you remember dissecting owl pellets in grade school? They were filled with hair and bones—the bits of prey that owls can’t digest. Owls spit out those indigestible pieces, but coyotes let the digestive system take care of them. Coyotes swallow their entire food item and anything that can’t be digested is pushed through the digestive tract and out the other end. Some of those leftover bits turn out to be identifiable teeth, fur, feathers, insects, and seeds. That’s what scatologists are after.

pellet vs scat

An owl pellet (left) with small mammal bones and a mammalian predator scat (right) with deer fawn hooves.

Getting to those identifiable items is actually quite simple. In this study, researchers collected coyote scat by gathering up samples they spotted along roads at the study site. Back at the lab, they rinsed the samples through mesh sieves, which collected the large, important parts of the scat, like clumps of hair and bones, and allowed the rest of the sample to wash away.

Then came the sorting (i.e., the reason I came to the lab each week). I picked apart samples and created like piles of diet items. Some samples consisted strictly of hair and bones while others were made up primarily of seeds. I even found garbage like candy wrappers and paracord (remember the study was conducted on Fort Bragg) in some samples.

The next and final step is identifying all of those piles of diet items. Researchers used species-specific patterns visible in prey hairs under a microscope to identify the hair masses found in scats. Likewise, mammal teeth were identifiable with a trusty guidebook. Researchers also identified plant seeds to species and insects to order when possible and created more general categories in the data for items like garbage and birds.

A coyote captured on a camera trap at Fort Bragg Military Installation.

A coyote captured on a camera trap at Fort Bragg Military Installation.

The final data set paints a picture of what coyotes at Fort Bragg are eating. One scat can’t tell the whole story; scientists must go through the finding, washing, sorting, and identifying process for many samples to discover what coyotes are really eating out there.

As it turns out, coyotes at Fort Bragg commonly consumed fruits, mammals, and insects. Diet shifted depending on season, which reflects a shift in food availabilities. Coyotes took advantage of plentiful persimmon fruits in fall and insects in spring when warmer weather triggers young grasshoppers, crickets, and other insects to emerge from their eggs. White-tailed deer were the most commonly depredated mammal. NC State master’s student Morgan Swingen summarizes the data in a science paper published in the journal Southeastern Naturalist.

I am glad I sat down in front of that window-wall with a plate of scat back in undergrad. That volunteer position in the lab led to some other exciting scat research down the road. Stay tuned to my Scoop on Poop series for more on how researchers are using scat to learn about our wildlife!