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A family of coyotes may disturb a delicate ecosystem on Angel Island · Best of: Features

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A family of coyotes may disturb a delicate ecosystem on Angel Island.
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Written by Amanda Bartlett. This article is being read by an automated
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voice, generated by Everlet. I'm was standing in a remote clearing just
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a few miles outside of San Francisco, my hiking boot perchaled precariously
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on the base of a steep ridge covered in poison oak. It's
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a foggy Tuesday morning in August, and I'm starting to wonder what
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I've gotten myself into, but I remember I'm with a trio of
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wildlife experts for whom this is a routine occurrence. We're following a
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trail of orange flags that mark a path up and through the
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thick brush on Angel Island, in search of an unusual harvest, deer
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and coyote poop. Eucalyptus leaves crunching beneath our feet. We stop every
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few moments to take in the sweeping vista of the bay on
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the horizon. Janelle Dorsey Ponce, an environmental scientist for the California Department
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of Fish and Wildlife, captures photos of the surrounding vegetation, a crucial
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detail to compare with what scientists know the unseen creatures lurking around
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us are eating. I'm fairly sure no one has ever found a
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rattlesnake on the island. Bill Miller, an environmental scientist with California State
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Parks, quips at one point, reassuringly. Too little vegetation could be a
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sign of a plummeting source. But too much could also make it
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challenging for us to find the evidence we've taken a ferry ride
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here in search of. Within moments, however, Dorsey Ponce kneels to the
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ground, keenly inspecting a few pellets. Deer poop, the scientist confirms. She
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collects the samples, jamming them into a test tube with the help
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of a stick and zipping the away in her fanny pack. She
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pulls out her iPhone, opening a special field maps app to input
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the data, selecting between several descriptive categories such as wet, shiny, and
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no cracks or pits, the fresher the samples are, the better. I
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remark on how quickly she spotted them, and Dorsey Pont smiles, grabbing
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two more from beneath a tuft of grass. If you do this
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a long time, you'll start seeing them in your dreams, she says,
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before kicking dirt over the remaining waste to prevent other scientists from
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recollecting it. There's no way to romanticize the ritual, which helps the
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team of wildlife officials who have the rare opportunity to study the
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predatory prey dynamic between coyotes and deer coexisting in this seven hundred
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forty acre habitat completely surrounded by water. Neither species is native to
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Angel Island, with Columbian black tailed deer being transported over by the
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US Army for hunting in nineteen fifteen, and coyotes swimming over themselves
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nearly a decade ago from nearby Tiburon. The coyote family group, which
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has grown to roughly fourteen individuals, has long mystified scientists, but drew
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renewed interest in May when a coyote that in January had been
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recorded swimming to Alcatraz for the first time ever was proven to
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be from Angel Island rather than San Francisco. The DNA evidence confirming
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the family lineage was provided by the type of scat collection survey
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we were taking part in. Because the coyote, nicknamed Floyd by fans,
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was never seen again, this new research could determine whether he ever
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swam back home to Angel Island. A one in a million discovery.
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When I first heard about it, I thought it was a deep
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fake. Brett Furnace, a research affiliate with the California Department of Fish
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and Wildlife, said over the phone a couple of months before our
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early morning trek. Seeing that coyote struggling from the cold, people said
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it had definitely come from San Francisco. But I was skeptical. Those
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were some strong currents. Earlier this year, Fish and Wildlife, which has
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been monitoring the deer on the island, partnered with UC Davis Mammalian
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Ecology and Conservation Unit, to investigate further, collecting seven or eight scat
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samples the coyote left behind on Alcatraz, and sending the off to
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the college's veterinary genetics laboratory. There, a team led by adjunct professor
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and unit director Ben Sachs analyzed the DNA cells on the surface
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of each SCAT sample, tracing The back to just one individual. It
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was just like comparing a classic fingerprint in a computer database, Sax
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told SF Gate over the phone, noting They university has an extensive
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archive of samples from coyotes living all over the Bay Area, including
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San Francisco, Napa, Sonoma, and Santa Clara, but I wasn't expecting to
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get an exact match. The probability of that happening is somewhere around
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one in a million. Experts sampled the individual, which they labelled M
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twenty four eight, on several occasions starting in twenty twenty four. They
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knew he had eight siblings, all originating from the same pregnant female
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that swam over to Angel Island in twenty seventeen, and suspected he
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was the coyote that was previously spotted paddling from Angel Island before
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turning back last September. It didn't work then, but this time it
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did, Sax said. Coyotes are territorial, so it would make sense that
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they want to disperse. I suspect it was trying to swim closer
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to Marin, but got swirled around in the currents, and was plain
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lucky it got to Alcatraz. It's not clear why some coyotes swim
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and others don't. Sachs has been studying the adaptable carnivores since the
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nineteen nineties. Not long before they had reemerged in Marin County and
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in two thousand two the first would be documented crossing into San
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Francisco for the first time in nearly a century, after ranchers had
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wiped them out. He theorized that it could be a learned behavior.
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Coyotes like to take forays, leaving their territories and roaming around to
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get the lay of the land Before targeting a new area, to
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disperse to once they're old enough to leave the den. Because they're
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on an island, the foray has to be in the water, he
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suggested. At the time, National Park Service officials were concerned about how
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the coyote that wound up on Alcatraz could affect its local biodiversity.
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The rock hosts some of the large nesting populations of Brant's Cormorants
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and Western Gulls in the Bay Area. Before they could follow through
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on plans to remove the animal, however, he was either swept away
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or left of his own accord. As scientists continue to study the
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family of coyotes on Angel Island, they're two years into a five
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year study. Though Furness hopes it will extend longer, they're also considering
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the relatively new predator's impact on another source of prey, the deer.
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As a wildlife ecologist for the California Department of Fish and Wildlife,
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Furness's job is to count the animals, how many there are, where
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they are, if their numbers are increasing or decreasing, and what factors
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could be driving that. It's not like doing the census. You can't
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knock on their door, he said. Instead they use other means, such
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as trail cameras, to estimate how many are missing, how much territory
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they're covering, and their age, but our main method is basically picking
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up poop. Experts are conducting surveys of deer populations all over the
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state of California. More recently, they discovered a unique opportunity to do
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the research on Angel Island, where coyotes are now the lone apex
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predator to a population of roughly fifty to sixty deer. There are
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no bobcats, foxes, or mountain lions, and even raccoons seem to be
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showing up less and less, Miller said, though traces of their paw
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prints were visible on dumpsters near the ferry docks on our visit.
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It's what we call a natural experiment, Furna said. He noted it
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could help expert understand predator prey interactions in other parts of the
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state, but also the rate at which coyotes are able to reproduce
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and survive. When you have an island that's a controlled laboratory like
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this that removes a lot of other factors, it allows us to
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look at these population dynamics in a new way. After the U.S.
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Army left Angel Island and the land was taken over by California
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State Parks, in the nineteen sixties, the deer population exploded. With no
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hunters around to control their numbers, it reached its peak in the
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nineteen eighties at around three hundred deer, according to Miller, about one
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hundred deer per square kilometer, which is the highest documented density of
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deer ever recorded in California. There was a lot of concern that
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the deer were impacting the vegetation on the island, but also What
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they were starving and didn't look like they were in good condition,
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he said. One of the first environmental impact reports in California was
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born out of wildlife officials considering ways to manage the herd. Miller
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said, Contraception and relocation were among the options when one professor at
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UC Berkeley, Dale McCullough, suggested introducing coyotes as a way of controlling
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the population. It wasn't very well received, Miller
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said. People were envisioning like coyote tearing apart fawns while people were
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picnicking. Ultimately, State Park officials went with a culling programme for a
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number of years. What they didn't expect was that the coyotes would
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swim over on their down They're here and they're howling. Back in
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twenty seventeen, a ranger in her first year living on Angel Island
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claimed she had spotted a coyote through the window of her residence.
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Her colleagues didn't believe her until a couple of months later, when
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another employee said he had seen one crossing a fire road. Eventually,
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a third staffer captured proof on camera. They could hear it at
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night calling, Miller said. It wasn't long after that one coyote became
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Tuo, and then more. Since then there have been three or four
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anecdotal reports of coyotes swimming in the strait. Miller said he saw
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one with his own eyes nearly five years ago. He was down
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on the beach early one morning, and came across the animal with
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its paws in the water, looking out toward the bay. Now that
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they're here, there's some pressure to get off, Miller said. Why that
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first one came over, we'll never really know. What the do know
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for certain is that They coyotes have developed quite the diverse diet
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on Angel Island. About eighty percent of their tested scat contain California
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Vole, a small short tailed rodent, and thirty six percent contain black
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rat, an invasive species. Deer were found in only about thirteen percent
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of the samples. Miller once found a hoof. But scientists have also
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detected pig, likely from human sourced foods such as hot dogs, as
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well as seabirds like Brant's cormorants. It's actually the most common seabird
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that was eaten by the coyotes here, about eight percent, Furna said.
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So they're spending a lot of time down there in the water.
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On Angel Island, scientists are closely monitoring effects of coyote predation on
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the Angel Island mole, which is endemic there. The also eat vegetation
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like poison oak and blackberries, suggesting The
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don't necessarily need to rely upon the deer, but might still have
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an effect on their numbers, Furnace said. Does the population blip out?
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He asked aloud. Or do other coyotes start swimming over? They're here,
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and they're howling. Will that attract others? Future research. Around
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noon, mist rolls over the hills as we meet up with the
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team of researchers from UC Davis, who are tasked with focusing on
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the coyote surveys. Stevie Vanderzwan, an associate specialist from the lab, tells
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us they just spotted one of the canines while they were searching
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for their scat. Grace Bottomley, an undergraduate lab intern, shows us a
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deer vertebrae the found on the trail along the way. As we
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walk through the coyote transect, we pass the feathery remains of a
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dead cormorant. The way the research is done could soon be rendered
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obsolete. Furnace said. Fish and Wildlife is looking at more efficient methods
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that would be less time consuming for staff, such as deploying fixed
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wing aircraft that would monitor the animals using infrared cameras at night,
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which the agency has been testing in the Sierras over the past
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year. Telltale coyote scat typically contains hair or is mottled with seeds
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from blackberries. Collecting the samples can be challenging work, particularly when navigating
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rough terrain on hot days or having to stop due to wildfire
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smoke, and DNA is sensitive. Strong UV rays or rain can wipe
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the cells from the outer layer of the scat. Once the samples
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are sent to the lab, the rate of successfully genotyping the DNA
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can vary. But when we do get to go out, it's very
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cool to find yourself in places that oftentimes nobody else really goes
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to, Dorsey Pont said. Every year we've done this, we've had at
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least one story of someone looking for deerscat, and you look up
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and then there's a couple o does staring back at you. I
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don't see a coyote on my visit, but as we prepare to
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board the ferry and leave Angel Island, I spot a lone deer
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lapping at the water. Nearby, traces of paw prints linger in the
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sand.