Coyote Yipps

Traditionally, ecologists study diet either by directly observing what animals are eating, or by dissecting animal scat and looking for prey remains. However, these methods have some challenges and limitations. For one, it takes a lot of time and effort to observe wild animals, and though we may be able to observe them foraging, it can be hard to see everything they eat and estimate the relative amounts of different foods consumed by different individuals. Regarding dissection, this method relies on there being undigested parts in the scat left behind – for example fur or bones which are used to identify the species consumed. However, in cities, animals have access to a lot of foods that may not leave anything visual behind in the scat for us to identify. For example, a chicken nugget won’t leave any chicken bones or feathers behind! However, it will leave some chicken DNA behind. This is where a more recent technology for studying diet, known as DNA metabarcoding, is very useful. This method allows scientists to quantify and characterize the diet of animals by first amplifying the DNA present in the scat and then identifying which species that DNA belongs to.

As part of my dissertation research for my PhD in ecology at UC Davis, I am using DNA metabarcoding to identify the species that coyotes in San Francisco consume, estimate which food items are the most frequently eaten, and consider how the diets of coyotes differ depending on where in the city they live. I’m still completing my data analysis, but I have some tidbits to share!

First, coyotes in San Francisco eat a lot of food provided by people, such as domestic chicken and pig – this could be coming from pet foods, garbage, or meat people intentionally put out for coyotes. As Janet has described in her blog many times, this isn’t good. Not only can these foods lack the nutritional content that coyotes need to thrive, but the presence of these foods brings coyotes into closer contact with people, which can lead to interactions between people and coyotes that are undesirable. Securing garbage, not leaving out attractants like fallen fruit and pet food, and making sure to never feed wildlife help decrease the quantity of these foods in coyote diets.

Second, coyotes in San Francisco eat a lot of pocket gophers—they are experts at hunting gophers, which are present throughout most of the city. Other frequently consumed natural prey includes raccoons, voles, and rats.

Finally, although coyotes in San Francisco do eat domestic cats, it’s not as common as many people think: I’m only detecting cats in <5% of the scats I’ve collected. Still, from the standpoint of cat welfare, it’s always a good idea to keep pet cats indoors. Not only does this keep your cats safer, but it protects wildlife and is better for human health and the environment. More to come!