Monday, March 11, 2024

New study reveals what urban coyotes are really eating in San Francisco

By Amanda Bartlett
March 10, 2024

On a foggy morning just after 7 a.m., Tali Caspi sat behind the wheel of a golf cart and drove across the manicured hills of the San Francisco Golf Club, searching for evidence.

Dew clung to the greenery, and save for a couple of red-tailed hawks soaring through the sky, there wasn’t a soul in sight. Armed with Google Maps and a fanny pack, the UC Davis Ph.D. student zoomed along the fairway until she found a thicket of bushes. She put the cart in park, stepped out and knelt down in the wet grass, scrutinizing the lumpy brown object that lay before her. It was exactly what she had been looking for: coyote poop.

She jotted down the information in her field notebook: where she had found the scat and what time of day it was. Then, she slid on a pair of white rubber gloves and retrieved a little tube filled with ethanol from her fanny pack, taking off a piece of the scat and shoving it into the tube with a wooden applicator stick to help preserve the DNA. She labeled and sealed it, and set off to find more.

Caspi’s notes from that day spare no detail. Some of the found samples were “full of cherry plum pits and berries” while others were “twisted in shape and full of hair.” One had just been deposited by a coyote she saw darting across the course and was mottled with tiny bones. There were traces of orange peel and aluminum foil, and one in particular was overflowing with peanuts.

Caspi has spent two years of her mornings like this, traversing over 621 miles throughout San Francisco — crisscrossing popular neighborhoods, scouring cemeteries and soccer fields, even breaking her foot during one hike up Bernal Hill — on her quest to find out what urban coyotes living in the city are actually eating.

“I feel like there’s not a park, not a trail that I haven’t been on,” Caspi, who conducts her research through UC Davis' mammalian ecology and conservation unit, told SFGATE. “I have them all memorized like the back of my hand at this point. And I can tell you, truly every green space that you can think of in the city has coyotes. San Francisco is totally saturated.”

The animals are native to California, and after years of no sightings, they recolonized San Francisco in the early 2000s, when they began building dens again after police ended the practice of killing them as they ventured into the city. Since then, their numbers have grown considerably. San Francisco Animal Care and Control estimates that there are about 100 individuals living in the city, with each mating pair establishing their own 1-to-2-square-mile territory, ranging from the Presidio and Golden Gate Park to Lands End, Coit Tower and McLaren Park. Some even took up residence at a solar panel project in the Sunset. “These are really adaptable creatures,” Caspi said.

Yet, as more and more sightings of coyotes were reported, concerns rose surrounding the animals and the potential threat they posed for young children and pets. Caspi, whose primary interest was in studying how people and urban wildlife coexist, happened to be in the right place at the right time when she reached out to the Presidio Trust and the San Francisco Recreation and Park Department regarding possible research for her Ph.D. in 2019.

“They were like, ‘Oh, we’ve been waiting for you,’” Caspi said. “‘We have growing issues with coyotes in the city.’ They had some data, but no one had the time or funds or ability to really analyze it.”

With help from Janet Kessler — also known as the “Coyote Lady,” who has been documenting the city’s coyote population for the last 16 years — she made it her mission to raise awareness about the often-misunderstood animals, studying their behavior and social dynamics but also learning more about their eating habits: how they vary by location and are influenced by an urban environment, as well as how those habits change for each individual animal over the course of its life.

Caspi’s been able to figure this out by not only gathering stool samples from live coyotes, but also collecting the tips of whiskers from roadkill specimens and sending them off to a lab for further analysis. More information regarding the precise breakdown won’t be available until later this year. But the findings she’s discovered so far are groundbreaking, and could even change the way people think about and study coyotes in the future.

One of the most surprising takeaways? The canines are scarfing down much more human food than previously thought.

“I’ve found a whole bunch of weird stuff,” Caspi said. “I’ve found chocolate. I’ve found mango. I’ve found grapes. But the biggest, most frequent offender is chicken.”

It’s worth noting the coyotes’ taste for poultry could be coming from a lot of different sources, like dog kibble, or discarded McNuggets that they’re fishing out of people’s garbage. The DNA metabarcoding process Caspi uses can only determine the type of food or prey remains that are present, not necessarily where they’re coming from. However, human handouts are a worsening issue that SFACC has been attempting to mitigate for years, and Caspi herself has witnessed people leaving out entire rotisserie chickens, tortillas and several pounds of ground meat for coyotes.

The motivation for this is unclear. When coyotes shed their coats in the summer, they can take on a scraggly appearance, causing many people to think they’re malnourished. Others want to “befriend” or take photos of them, and some even seem to hope that if they give them food, the coyotes won’t go after their pets, Deb Campbell, a spokesperson for SFACC, told SFGATE. You should never feed a coyote: It’s illegal and punishable by jail time or a fine of up to $1,000, and people are encouraged to call SFACC at 415-554-9400 if they see someone doing it, she said. It’s a problem that hurts everyone, especially the naturally skittish coyotes, which start to lose their fear of humans, become more emboldened to approach them and regularly visit neighborhoods they come to associate with treats.

“There’s a big misconception people have that if they see them wandering around the city, they must be starving and need our help,” Caspi said. “But they don’t — and trust me, they’re definitely not starving.”

Swaths of San Francisco residents are unintentionally catering to coyotes by feeding their pets outside and not removing uneaten traces of food, forgetting to secure their trash and recycling and not cleaning up the seed around bird feeders or fallen fruit from trees in their front yards, Campbell said.

And it shows in Caspi’s research, which has demonstrated that coyotes’ diets are rich in other foods like pork, fish and soybeans easily scavenged from a dense urban landscape. That’s not to say they’re not very capable hunters — coyotes also frequently seek out natural prey like squirrels, gophers and raccoons. Data collected by Caspi has also proven the animals are even willing to venture out to the coastline for a good meal, as was the case when several of them feasted upon a stranded fin whale that washed up on Fort Funston in 2021.

No comments: