As the natural food sources for San Francisco’s coyotes decrease, these animals are altering their diet. A recent study sheds light on their current eating habits.
With the decline of their traditional food sources and the rising number of restaurants, homes, and sidewalks, the coyotes of San Francisco are changing their diet.
A team of researchers from the University of California, Davis, aimed to explore the eating habits of the city’s coyotes and how their diet is influenced by the ever-changing urban landscape.
Their research, published in the journal Ecosphere, discovered that the presence of restaurants and hard surfaces such as pavement greatly affected what coyotes consumed. The study found that the number of rats eaten by coyotes was highest in areas with many restaurants, while human food sources were most prevalent in the most concreted parts of the city.
The insights gained can aid in developing effective management strategies to safeguard native coyotes and lessen human-wildlife interactions.
What San Francisco’s coyotes are eating
So, what are the coyotes feasting on in San Francisco?
“ A significant portion of their diet consists of food provided by humans,” stated Tali Caspi, the lead author and a Ph.D. candidate in Environmental Science and Policy at UC Davis. “Chicken is a major component; we found it in 72% of the scat samples examined in the study.”
Next in popularity was pocket gophers, a natural prey source, which appeared in about 57% of the scat samples. Additionally, pig (human-sourced) and raccoon (natural) were also included. Although some people worry about coyotes consuming cats, the analysis found felines in only 4.5% of the samples.
Scat and DNA analysis
To arrive at their conclusions, the researchers collected over 700 scat samples from coyotes across San Francisco between September 2019 and April 2022. They then conducted laboratory analyses at UC Davis’s Mammalian Ecology and Conservation Unit, part of the Veterinary Genetics Laboratory. Techniques like genotyping matched the fecal samples to specific coyotes, while DNA metabarcoding helped assess diet composition.
Caspi points out that, while the analysis identifies food sources, it does not specify if the chicken came from a backyard, a takeout container in a dumpster, or pet food.
The research also indicated that coyotes residing in more urban areas, such as Telegraph Hill near Coit Tower or Bernal Hill, consumed more human-sourced food compared to their counterparts living in greener spaces like the Presidio or Golden Gate Park.
Furthermore, the diets within coyote families showed considerable variability, while individual family members shared similar dietary habits.
“This study emphasizes the broad dietary range and habitat preferences of coyotes as a species,” remarked senior author Ben Sacks, director of the Mammalian Ecology and Conservation Unit at UC Davis. “While they are known for their adaptability, our findings also indicate a tendency for individual coyotes to favor familiar food sources.”
Living among coyotes
Coyotes are originally from San Francisco. They were driven out in the early 1900s but made a comeback in the early 2000s, now cohabitating with over 870,000 people across 47 square miles—making it the second most densely populated major city in the U.S., with water surrounding it on three sides.
There are several ways for people to coexist peacefully with coyotes and minimize conflicts. Recommendations include keeping cats indoors, avoiding leaving pet food outside, securely disposing of food waste, and most importantly: “Don’t feed coyotes,” emphasized Caspi. “There is a common misconception that coyotes are starving and need our assistance finding food in San Francisco, but that is not the case.”
Coping with urban life
From song sparrows changing their song frequencies in Portland, Oregon, to cockatoos in Australia learning to open trash cans, this study adds to existing literature demonstrating behavioral differences among the same species in urban settings.
“Animals have various strategies to adapt to city living,” noted Caspi. “The range of coping mechanisms showcases the flexibility and resilience of these species.”
Additional coauthors include Monica Serrano and Stevi Vanderzwan from UC Davis, independent researcher Janet Kessler, and Christopher Schell of UC Berkeley.
This research was supported by a Christine Stevens Wildlife Award from the Animal Welfare Institute, the UC Davis Center for Community and Citizen Science, and further grants from UC Davis and UC Berkeley. Caspi also expressed gratitude for the assistance from community scientists via iNaturalist, which helped her find fresh scat samples and trace a rare fin whale DNA analysis in a coyote’s diet back to a nearby beaching recorded on the app.
