S.F. bullfrog with social media buzz can be big problem
A very big bullfrog photographed recently at Blue Heron Lake in San Francisco’s Golden Gate Park has been drawing a lot of attention on social media.
Bob Johansen, a Sunset resident, snapped a closeup of the bulging-eyed amphibian, its greenish skin casting an iridescent glow in the bright sunshine at the recently renamed lake and posted it on Feb. 1 to social media site Nextdoor.
“A new friend at Blue Heron Lake,” he wrote. “Huge. At least eight inches long.”
Johansen told the Chronicle he took and posted the photo after spotting a group of tourists peering into bushes near the boathouse at Blue Heron Lake, near where turtles hang out, and was surprised to see a frog.
“In my 15 years living in San Francisco and walking through Golden Gate Park and the Presidio,” he said, “I have never seen a toad or a frog.”
The amphibian was likely an American bullfrog — a species that, though nonnative in California, is actually quite common in much of the state, including in the Bay Area, according to several wildlife experts who spoke to the Chronicle.
The American bullfrog — or just plain bullfrog, as it’s commonly known — lives in freshwater ponds, lakes and marshes. It’s native to the Eastern and Southeastern United States and is known for the male bullfrog’s deep call, which some liken to the sound of a cow mooing. It ranges in size from around 3-8 inches.
Most American bullfrogs were introduced as a food source and for insect control, according to the California Department of Fish and Wildlife. The amphibians may have accidentally made their way into some waterways and wetlands during fish stocking, farming and when discarded by pet owners who no longer want them.
That may be the case with the big bullfrog Johansen photographed at Blue Heron Lake, according to spokespersons with San Francisco’s parks and animal control departments.
Many animals — dogs, cats, guinea pigs, goats and amphibians — are abandoned in the city’s parks, mainly Golden Gate Park, said Deb Campbell, a spokesperson for the San Francisco Department of Animal Care and Control.
City animal services officers will capture and take in former pets, she said, but deal with wild animals only when they’re injured, dead or dangerous to humans. The agency doesn’t get involved with culling wildlife populations or with invasive species, she said.
Campbell said animal services hasn’t received any calls or complaints about bullfrogs of any size, and officers haven’t reported any encounters with the big bullfrog in Blue Heron Lake.
But given how common American bullfrogs are in California, for one to show up in a lake — even in urban San Francisco — is not surprising, wildlife experts said.
“They’re literally everywhere,” said a representative of the California Fish and Game Commission.
Though widespread, they’re not popular with the California Department of Fish and Wildlife, which labels them one of California’s “invaders” on its website.
The frogs, it says, are an invasive species that “have voracious appetites and will eat anything they can fit into their mouths, including invertebrates, birds, bats, rodents, frogs, newts, lizards, snakes, and turtles.”
Their tadpoles mostly eat algae and other aquatic plant material, as well as invertebrates, but they will also eat the tadpoles of other frog species, the department says.
“As a result of these feeding behaviors, all lifestages of bullfrogs prey upon and are able to outcompete native frogs and other aquatic species.”
Bullfrogs also carry chytrid fungus, which causes chytridiomycosis — believed to be a leading cause of the decline of native amphibian populations all over the world and responsible for the extinction of over 100 species since the 1970s.
At the end of last year, the California Fish and Game Commission voted to begin the process of banning the importation and sale of live bullfrogs in the state, a move it had debated since 2012 when the city and county of Santa Cruz enacted prohibitions on the sale and possession of the amphibians.
The commission and state Department of Fish and Wildlife staff will work together to develop a list of proposed rules and regulations, a task that should take about two months. Then the proposal will go through a series of public hearings before it’s adopted, said a commission representative who spoke with the Chronicle. The full process could take as long as 11 months.
Commenters on Johansen’s post concurred that the large frog at Golden Gate Park is anything but a friend to the lake’s other inhabitants and the California ecology.
“They are an ecological disaster,” said Jose Garcia of San Francisco.
Ant Ko of San Francisco commented that the bullfrog is “probably a pet that no one wanted, or a bleeding heart bought live from a supermarket, and ‘freed’ into the lake not considering the detriment to the local species.
“Like Jose said, they are voracious and aggressive. They’ve probably eaten ducklings.”
She ended her post with a frowning-face emoji.