As restaurants, homes and pavements replace natural landscapes, San Francisco’s coyotes are adapting their eating habits to suit their changing environment.
But what exactly are these urban coyotes consuming and how is their diet influenced by the city's layout, which can change significantly from one neighbourhood to another?
That's exactly what researchers from the University of California, Davis (UC Davies) set out to investigate. Their study, published recently in the journal Ecosphere, found that the number of restaurants and the amount of paved surfaces in an area have a strong impact on what coyotes consume. They also discovered that the animals eat more rats in areas with a high density of restaurants, while in highly urbanised areas with lots of pavement, they rely more on human food waste.
The scientists say their findings could help city officials and wildlife managers develop better strategies to protect native coyote populations while minimising conflicts between people and wildlife.
What's on the menu?
Coyotes are native to San Francisco. After disappearing from the city in the early 1900s, they made a comeback in the early 2000s and now share 47 square miles with over 870,000 people, surrounded by water on three sides. Living so closely alongside humans means they have had to adapt their diet. But what exactly is on the menu for San Francisco’s coyotes?
“A lot of human-provided food,” says lead author of the study Tali Caspi, a PhD candidate at UC Davies. "Chicken is a really big diet item; we found it in 72% of the scat samples analysed in the study.”
Despite this, some natural prey remains important. Pocket gophers were the second-most common food source, found in 57% of samples, followed by pig (from human sources) and raccoon (natural prey). The study found that cats were also present, but only in 4.5% of samples.
A deeper dive
To conduct their research, the scientists collected over 700 coyote scat samples from urban green spaces – including parks, golf courses and gardens – from across San Francisco between September 2019 and April 2022. The samples were then analysed at UC Davis, where DNA metabarcoding helped identify what the coyotes had eaten.
Although the study confirms what coyotes eat, it doesn’t distinguish between different sources of food – such as whether chicken came from a backyard coop, restaurant waste or pet food. However, the research did reveal that coyotes in more built-up areas, such Telegraph Hill and Bernal Hill, eat more human food than those in greener areas, such as the Presidio or Golden Gate Park.
The study also found that while different coyote families had distinct diets, individuals within the same family ate similar foods.
"This study highlights the huge range of dietary and habitat affinities of coyotes as a species,” says senior author Ben Sacks, director of the Mammalian Ecology and Conservation Unit at UC Davis. "That is a trait for which they are already well-known, but the study also joins a growing body of evidence pointing to relatively narrow proclivities of coyotes as individuals. They tend to stick with what they know.”
Living alongside urban coyotes
There are simple ways for residents to coexist with these adaptable animals and reduce potential conflicts. First and foremost, “don’t feed coyotes,” Caspi says. "There’s a misconception that coyotes are starving and need our help finding food in San Francisco, and clearly they don’t.”
Residents can also help by keeping cats indoors wherever possible, not leaving pet food outside, and securely disposing of food waste, add the authors.
Find out more about the study: Impervious surface cover and number of restaurants shape diet variation in an urban carnivore
Main image: Urban coyote/Getty
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