Why are coyotes swimming to Angel Island?

Coyote swims in the San Francisco Bay

SAN FRANCISCO – An unusual sighting was caught on video – a coyote swimming in the San Francisco Bay on its way to Angel Island.

The video has sparked questions and curiosity about the coyote population on the largest natural island in San Francisco Bay.

What we know:

California State Parks officials said the video was taken on Aug. 29, as the animal was swimming through what’s known as Raccoon Strait about a quarter of a mile from the shore of Angel Island. And they believe it was making its way back home from Tiburon.

“That’s like a one-mile distance, so that’s no small feat for any critter,” California State Parks environmental scientist Bill Miller told KTVU. “It was absolutely surprising. That was the first I had ever seen that in my, what, dozen years of working here,” the longtime parks official added.

Coyotes are good swimmers, Miller said, and the animal made its way safely to the shore.

Coyotes’ presence on the island is a relatively new one.

The backstory:

“You know, before eight years ago, there were no coyotes on Angel Island,” Miller explained. “We don’t have evidence of coyotes being on the island in the 10,000-year history that it’s been around,” he added.

So it was in 2017, the first coyote was spotted there and then, “One coyote became two and then there was a litter and then so now we have about, maybe 14 or 15, coyotes on the island,” the environmental scientist explained.

Park officials said the coyotes are all from the same family.

“The DNA was consistent with all of the individuals being descended from one female. And it seemed like three generations,” Miller said.

Experts believe the mother and grandmother of the family line have since died.

5-year study

The Angel Island coyotes are part of an ongoing five-year study, now in its second year, that was spearheaded by the California Department of Fish and Wildlife.

The study is looking into aspects like diet and other behavioral patterns, offering insight into how the coyotes on the island are related.

“So think of building a family tree for, you know, who’s related to who,” Miller said.

Researchers are using wildlife cameras as well as collecting scat from not only coyotes but also deer, in an effort to understand the dynamic between the two animals.

Coyotes, which are primarily carnivores, eat deer and other mammals.

Once numbering in the hundreds, back in the 1970s and 80s, the island faced an overpopulation of deer, prompting culling efforts to manage the herds. Today, there are about 43 deer, according to wildlife experts.

Researchers are also looking at how the coyotes are affecting populations of other Angel Island species.

“We also have a special mole on the Island called the Angel Island Mole, which is endemic to the island. So we’re interested in knowing if the coyotes are impacting those guys as well,” Miller said.

What you can do:

Evidence has shown that the coyotes have also gotten access to pig and chicken in their diet, which prompted parks officials to caution visitors to the island from leaving behind food and, most certainly, from feeding the coyotes.

“It’s through trash, or hopefully not, but deliberate feeding,” Miller said, adding, “It’s really the negative interactions with our wildlife that we want to avoid.”

And in the event of a coyote encounter, while many people have a tendency to first grab their phone to capture images of the wild animals, Miller advised they actually take measures to “haze” or scare the coyote, by speaking loudly, making a lot of noise, or making themselves large by waving their arms.

Mysterious intrigue

The video of the swimming coyote has triggered much intrigue into the unknowns related to the relatively new residents to the island.

“Why the first coyote came over to the island, I don’t know,” Miller said. “Probably thought it saw opportunity over there and decided to take a swim and somehow made it across.”

He speculated that after the first one arrived, it was her howling that brought others over.

“I can only imagine that maybe another one showed up because they heard her calling out there,” he conjectured. “Coyotes expand their territory and range as young ones grow up and are looking for new places. And the fact that it hasn’t really occurred in the 10,000 years of history on that island until now, speaks to that the initial colonization seems like it’s pretty rare. But we have no idea how often coyotes are actually coming on and off the island.”

And more questions, when it comes to the swimming coyote caught on video. Miller noted that Angel Island is only about one square mile and suggested the animal could have just been out looking for new territory.

But what is certain is that the Bay Area, as a whole, continues to be a space that is hospitable to wildlife.

“The Bay Area is still pretty wild. The fact that we’re actually able to support, you know, populations of coyotes and bear in the North Bay, it just speaks to the amount of open space and the quality of the habitat that we have,” Miller said, adding, “Now, obviously, we need to learn to live with them.”

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Why are coyotes swimming to Angel Island?

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