What wildlife scat can tell us about how to protect open space

A Santa Cruz study of carnivore diets reveals how animals respond to human disturbance.

 

In a cramped upstairs room on the University of California, Santa Cruz campus, Justine Smith hoists open the lid of a white chest freezer to show off her poop.

Smith, an Environmental Studies PhD student with a curtain of blond hair and a ready smile, rifles through a stack of chilled plastic bags. The bags contain samples of animal scat, each dollop unique as a snowflake: some gray and braided, others brown and lumpy, still others flecked with the teeth of luckless rodents. “This is not the most organized freezer right now,” Smith apologizes, holding aloft a smeary greenish specimen inscribed with the word Fox in permanent marker. 

Though it may be a touch haphazard, this freezer forms the heart of Conservation Scats, the citizen science project through which Smith is unveiling the secrets of Santa Cruz’s wildlife — and revealing how even our most benign activities affect our fellow creatures.

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Most people see a humble turd. Justine Smith sees a treasure trove of information.
Justine Smith

Conservation Scats’ origins lie in a complex question: How are Homo sapiens affecting carnivores in the Santa Cruz Mountains? When Smith launched the study in 2014, she suspected that human disturbances, from home-building to hiking, were forcing coyotes, bobcats and gray foxes to modify their lifestyles — to change how they hunted, perhaps, or to compete for certain prey. But how to figure out what the animals were eating?

The obvious solution was to examine scat. If you’ve ever dissected, say, an owl pellet, you know you can tell an awful lot about a predator’s habits from the hair, fur, bones and teeth embedded in its droppings. Still, even seasoned biologists are prone to excrement errors, and Smith needed certainty. To that end, she found a lab that would analyze the DNA in her scat samples. Not only could the lab reliably differentiate coyote from bobcat from fox, but it could tell her exactly what the carnivores had noshed on.

Though Conservation Scats’ aims are unique, it’s hardly the first wildlife project to go high-tech. While buckling radio-collars around furry necks still has its place, scientists are increasingly leaning on camera traps, hair snares, and Environmental DNA — techniques that don’t require laying a finger on fauna. Such non-invasive methods are not only cheaper, they also prevent animals from having to suffer through being captured, drugged, and saddled with gadgets. “This is the new wave,” Smith claims.

With one problem solved, Smith faced another challenge: How the heck was she going to collect several hundred samples of predator poop? For the dirty work, she turned to citizen scientists, the class of untrained but eager volunteers who have assisted other researchers in identifying phytoplankton, surveying spiders, and observing hummingbirds, among other efforts. Though picking up scat may not be quite as glamorous as, say, counting pikas in Glacier National Park, 27 enthusiastic civilians answered Smith’s call and collected a total of 293 samples.

“Some people talk about walking in labyrinths as a kind of spiritual journey,” says Kelly Runyon, a San Francisco-based environmental engineer who bagged around 20 samples at the 2,000-acre Skyline Ridge Open Space Preserve. “I wouldn’t call looking for poop a spiritual journey, exactly, but there was a contemplative yet focused aspect that I’d never experienced before.”

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Smith rifles through the scat motherlode.
Monte Kawahara

Though Smith hasn’t yet had her samples analyzed — each scat costs $60 to process, and she’s still raising the money — she hopes the results will aid conservation. A burgeoning body of literature suggests that recreation disrupts ecosystems more severely than well-intentioned outdoorsmen realize. One 2008 study, for instance, suggested that bobcats were five times scarcer in California reserves that allowed hiking. Smith’s research represents the next phase in understanding our own footprint: Not only does our presence alter the behavior of individual species, but it may profoundly influence interactions within entire ecological guilds — in this case, mid-sized carnivores.  

“People in the Bay Area want to protect these ecosystems, but they might not realize that a high-traffic preserve is not actually preserving all that much,” Smith says. “That knowledge could affect how we buy open space in the future, how we protect core areas, or where we put trails.” You could hardly ask more from a freezer full of dung.

Ben Goldfarb is a Seattle-based correspondent for High Country News. Homepage image of Skyline Ridge Open Space Preserve in the Santa Cruz Mountains, by Flickr user David Baron.