You don’t need bait to catch an Alameda whipsnake—just luck, and a low, fifty-foot-long fiberboard fence staked into the ground. If a snake encounters this fence, it will naturally respond by running alongside it, presumably with the logical intent of finding the end and going around. Instead, the snake is shunted through a wire-mesh funnel into a shady trap, with a wet sponge, a take-out soup cup filled with cotton balls, and a tomato, all of which are meant as creature comforts for any rodents or amphibians inadvertently detained. If you’re trapping whipsnakes, you tend to catch a lot of other things as well, and it’s better when everyone comes out alive. On the slopes of Mount Wanda, at the John Muir National Historic Site in Martinez, a small team of National Park Service researchers laid 28 traps this spring, and somebody was out there checking them every weekday for 11 weeks.
Tori Seher, an NPS biologist who has invited me out for a day of trapping, warns me that I’m unlikely to see a whipsnake. It’s a warm Friday in May, and her crew has only caught six so far this year—about average, despite all the effort.
But that elusiveness is what drew me to it. This true East Bay local is our very own mystery snake.
Though Alameda whipsnakes (Masticophis lateralis euryxanthus), a subspecies of the California whipsnake, patrol many of our most popular parks—from Tilden to Mount Diablo to Sunol Regional Wilderness—few humans ever lay eyes on one. Hemmed in by houses and highways, “they’re very wary of people and speed off very, very quickly,” says Jeff A. Alvarez, a wildlife biologist who has been studying Alameda whipsnakes since 1981. “An old professor of mine said, ‘If you thought you saw a snake, it was probably a whipsnake,’” Alvarez says.
Consequently, our whipsnake ignorance is fathomless: We know enough to say it’s rare and declare it threatened (it’s state and federally listed), but we can’t really say how rare. Alvarez says it’s pointless to even guess at the total population size. Nor do we know whether the population is increasing or decreasing. “This is a snake that has 10 million neighbors,”—us humans, that is—“and we essentially know nothing about it,” Alvarez says. “The snake doesn’t get the attention it needs, and because of that we’re not learning enough to publish anything that tells us a bigger story.”
To protect these whipsnakes, scientists must uncover their secrets, and the best way to do that is by trapping them. When limited funding has allowed, this has been done across their range, which is mostly in Alameda and Contra Costa counties. Some of the longest-running research takes place at Mount Wanda, where the NPS has been capturing whipsnakes every year since 2017. But the fact that Alameda whipsnakes live on Mount Wanda at all came as something of a surprise.
Snakes in unexpected places
“For years, we never saw them out here,” says Seher, who has since left the agency. It didn’t seem like their kind of country. People used to think Alameda whipsnakes were chaparral specialists, and chaparral grows on less than one out of Mount Wanda’s 326 acres. Yet since the NPS started trapping, whipsnakes have turned up not just in the chaparral but in an old olive orchard, oak woodlands and grasslands. Even at multi-year study sites like Mount Wanda, it’s unclear how many whipsnakes there are—the number trapped can vary significantly from year to year. “It may be attributed to population dynamics,” Alvarez says of the up-and-down numbers, “or it may be attributed to our trapping techniques.”
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One reason to think so is that all the traps are on the ground, which may not be a great strategy if the snakes themselves are in bushes or trees. Snake researchers a century ago described California whipsnakes as arboreal, an unusual niche among California snakes. But then there was a four-decade gap in published research, during which scientists seemed to forget this fact. Now it has been re-established (technically, they’re semi-arboreal). Alvarez and fellow wildlife biologist Amanda Colombo Murphy have urged their peers to test out arboreal trapping methods, such as a series of canopy-hung traps connected by a rope “upon which lizards or mice would have been kept for several days” as a scent trail—the rope functioning much like the fiberboard fence does in the ground traps to direct the snakes on where to go.
If you ever do see an Alameda whipsnake in a tree, it’s probably moving, because once it stops it is very hard to spot. You’d be looking for a slender snake, up to five feet long, with a black or dark-brown back, and long yellow lateral stripes like garter snakes but without the garter snake’s third yellow stripe down its back. When climbing, whipsnakes use their prehensile tails to grasp branches, and then freeze—thereby disappearing. “They don’t hang like a monkey,” says Murphy, who has been studying whipsnakes since 2001, but rather use their tails “like an anchor.” On the ground, they often slither along with their heads held high like cobras.
Alameda whipsnakes love dining on western fence lizards, though they also eat plenty of other small animals (and in turn are eaten by hawks, raccoons, foxes, and coyotes). Their relatively high body temperature facilitates speed and agility, and they have binocular vision. “They’re very active predators,” Murphy says. Lizard caught, a snake wraps its body around its prey to prevent it from escaping, then swallows it whole.
Whipsnakes are most active in spring, when they court and mate, and in late summer to mid-fall, when their young emerge, after about three months of incubation, from clutches of six to 11 eggs. Like other snakes, they have two sets of genitalia, though they only use one at a time. As was only recently discovered, female snakes have clitorises. In the winter whipsnakes mainly hide out in refugia, conserving energy until it warms up again.
Alvarez has come to suspect Alameda whipsnakes are smarter than your average snake. “As you hold them, they’re looking right into your eye, as opposed to a garter snake or a gopher snake, which are just looking to get away,” he says. “It’s as if they’re trying to create a plan.”
Whipsnake problems
We may not know much about the Alameda whipsnake, but we know it has problems, mostly of our making. It has been listed as threatened under the federal Endangered Species Act since 1997, by which time surveys had concluded that it had disappeared from 35 of 60 known East Bay haunts. Overgrazing, fire suppression, and predation from non-native species, like feral pigs, dogs, and cats, are all believed to have taken a toll. Most of all, though, the snake has suffered from urban sprawl. (Even the Oakland Zoo recently expanded into whipsnake territory.) In addition to directly destroying habitat, the East Bay’s innumerable houses, roads, and strip malls have isolated Alameda whipsnakes into five distinct populations that have little to no contact with each other. A Mount Wanda whipsnake, for example, might be able to reach Briones Regional Park if it’s looking for food or a mate. But no snake is likely getting across State Route 4 to the north, I-680 to the east, or State Route 24 to the south. Smaller roads can be deadly as well; Alvarez says whipsnakes are regularly crushed on the road up Mount Diablo.
Several wildlife crossings have been proposed for the Bay Area. But Alvarez is skeptical that whipsnakes would traverse a long, dark tunnel. Wildlife officials could trap whipsnakes and transfer them between the isolated population groups to help them interbreed. “That would not take very much effort,” Alvarez says. It’s not unprecedented: people truck salmon around dams, for example. But such translocations are uncommon for less famous animals, or purely to facilitate genetic diversity. “We tend to not want to meddle with things, despite the fact that our mere existence meddles with things,” he says.
A relatively new threat is the pathogen causing snake fungal disease, which first appeared in California in 2019. Statewide, it has infected at least 13 different species so far, and has reached the Alameda whipsnake’s range. So far, no Alameda whipsnakes have tested positive, but state scientists are monitoring the situation.
The Alameda whipsnake is not the only East Bay snake worse off than it used to be, Alvarez says. “When I was a kid [in Hayward], you could walk along a creek and see a dozen garter snakes in a single day,” he says. “But that’s not happening anymore.”
Lucky breaks for snakes
The Alameda whipsnake does have some things going for it. Much of the snake’s core territory—some 154,834 acres—is protected as critical habitat (though this Bush administration designation was smaller than originally proposed). “Our public lands are so important for this species,” Seher says. Even on private land, some landowners have entered into easements to conserve whipsnake territory. Moreover, the snake prefers hills, rocky outcroppings, and other areas that are harder to put buildings on, in contrast to, say, the California tiger salamander, whose vernal pool habitat “is just completely nuked,” as Murphy says.
As mega-fires have ravaged California in recent years, the Alameda whipsnake is one among many animals potentially caught in the crosshairs. Yet it has proven to be able to survive even the biggest burns. Murphy once re-trapped a snake that showed no damage from the 2020 SCU Lightning Complex fires, which scorched nearly 400,000 acres in the Diablo Range. “It shows that these snakes have evolved with fire and know how to get out of harm’s way,” Murphy says.
It’s also possible that the Alameda whipsnake’s range isn’t so restricted after all. Using tissue samples obtained from trapped whipsnakes, Jonathan Richmond, a geneticist at the U.S. Geological Survey, and several colleagues published a 2016 study demonstrating that, though some whipsnakes in southern Alameda County and northern Santa Clara County look more like chaparral whipsnakes—the far more common subspecies of California whipsnake—they’re genetically closer to Alameda whipsnakes.
Whether those whipsnakes should be treated as Alamedas or chaparrals or something else entirely remains unresolved. Richmond points out that DNA sequencing technology has become cheaper and more advanced over the past decade or so. He advocates for follow-up research to examine the full genomes of California whipsnakes across their range, from “pure” Alameda whipsnakes to “pure” chaparral whipsnakes and everything in between. “It’s incredibly complicated,” Richmond says. “There are definitely a lot of open-ended questions.” By trapping the snakes year after year, NPS researchers hope to unravel some of these unknowns.
Out on Mount Wanda, it’s a peaceful day. A blue-gray gnatcatcher chatters incessantly. Turkey vultures soar overhead and perch on dead snags. The chamise, buckeyes and sticky monkeyflowers are all blooming as Seher, natural resource intern Mikayla Gregory, biological science technician Hannah Blank, and I travel between the traps. In them we find western fence lizards, false tarantulas, a western skink, and a beetle. Wearing masks and gloves to protect themselves and the animals, the researchers release their temporary captives, then disinfect each trap.
Then, at one trap, we see wriggling. Seher tells me it’s my lucky day. She pulls out a whipsnake and hands it over. I can feel its muscles pulsing in my gloved hands. Though scarcely thicker than a rock-climbing rope, this three-foot-long reptile is strapping. Remarkably calm, it wraps its tail, colored bubble gum pink on the underside, around my wrist.
I pass it back, and the researchers all take a turn holding it. Smiles abound as they weigh it, measure it, and photograph the spots on its chin—which, like stripes on a zebra, distinguish it from other individuals. Finally, they mark its side with a water-based pen. Though this splotch of green will soon wear off, it alerts them if they recapture the same snake in the near future. I can’t help but wonder what the snake is thinking as it waits us out, making little effort to flee or fight. “I definitely feel the weight of responsibility of protecting them after holding them,” Seher says. Once free, the whipsnake glides into a nearby poison oak bush. It blends in so well that, even from a few feet away, I can barely see it.
