It’s just past noon on a Tuesday in April, and I’m bottle-feeding a seven-day-old black-tailed deer fawn on top of Potrero Hill. Energetic young squirrels perform gymnastics in a cage; a 60-year-old tortoise slowly makes his way through the backyard of a small house on 25th Street, where animal babies are kept until they can be released back into the wild.
My search for wildlife in the area has led me to Yggdrasil, a wildlife rescue organization started in 2001 and directed by Lila Travis, a squirrel behaviorist, wildlife rehabilitation specialist, and overall friend to animals.
“Back in our youth, when my husband and I founded this organization, we were fascinated by this Norse myth,” said Travis. “The universe is supported in the branches of a tree. The tree’s name is Yggdrasil. Up and down travels Ratatosk the squirrel, and Ratatosk delivers messages between the snake coiled at the roots, and the eagle at the top, and the deer in the branches. It’s a beautiful story”, she laughed, “and for some reason we decided to name our organization Yggdrasil, so nobody can pronounce it.”
The squirrels typically found in the Bay Area are Eastern grays, introduced a century ago by California Fish and Wildlife to provide sport for hunters. The Western gray squirrel tends to stay in forested areas. According to Travis, squirrels spend a long time with their mothers. “They have to completely take care of these helpless creatures for months in an environment that’s not easy to live in. Because of this, mom nature has activated in their brains a serious emotional complexity,” she explained.
“Our job is to raise orphan wildlife with the express purpose of releasing them back into the wild, to give them a second chance, and to mitigate the human impact on the environment,” Travis said.
Yggdrasil regularly receives calls from San Franciscans concerned about squirrels damaging gardens and fruit. “People call and say ‘this squirrel is taking one bite out all my apples and dropping them on the ground’. Well, they’re supposed to do that, because mom nature programmed them to trigger germination,” Travis said.
Travis also gets calls to extricate pigeons from human hair, which, when discarded outdoors, gets tangled up in the birds’ feet.
With a small budget, Yggdrasil relies on Travis and other volunteers to maintain its operations. “I did have a formative experience in my childhood,” Travis confided. “When I was six, I had this magical summer. My best friend, who was three, was named Thelma. We would run around and play, and down by the ocean there were these pines, where we could climb and play hide-and-seek. We wrestled, ate lunch, and took naps together. And every day, I would go home, and Thelma would return to her cage at the San Francisco Zoo.”
Thelma was a baby orangutan. Travis’s mother volunteered at the Zoo, and befriended the primate keeper, John Alcaraz, who had previously worked with Marlon Perkins in Chicago. Alcaraz was a free spirit; it’s doubtful that any child today would be allowed to romp at the seaside with one of the Zoo’s orangutans. Alcaraz, now in his nineties, serves on Yggdrasil’s board.
According to Travis, the timing of landscape maintenance can impact local wildlife. “When you go out in your yard, and say, let’s prune, let’s clean everything up, think of what time of year you’re doing it. Don’t do it in the spring, because you’ll be cutting down nests,” she explained.
As I descended the hill to Dogpatch and walked through the Potrero Annex-Terrace housing project, childhood home to OJ Simpson, I spotted an Anna’s hummingbird. With nests the size of a walnut, these hummingbirds can fly up to 40 miles an hour. They feed on flower nectar, favoring plants such as Hummingbird Sage, Salvia, gooseberry, Western Columbine, and Red-flowering currant, as well as Eucalyptus trees.
On Potrero Hill’s eastern slope, near the Caltrain tracks, there’s a small population of Pacific tree frogs. These amphibians are capable of rapid color change, and thrive in a variety of habitats, from sea level to 10,000 feet altitude. They’re attracted to backyard ponds, capable of eating insects their own size. The nocturnal tree frogs are difficult to spot, hiding under logs and leaf litter. They’re eaten by snakes, raccoons, herons, and salamanders.
Salamanders and newts are widespread in the Bay Area, found under garbage cans, in streams and seepages. One man I met walking his dog on Potrero Hill told me he finds newts under stones in his backyard. He was concerned that he’d get into trouble with wildlife officials; since he wasn’t planning on destroying any newt habitat, he needn’t have worried.
Warm Water Cove, at Dogpatch’s eastern edge, is home to pelicans, Western gulls, and the occasional heron. The California brown pelican is a large-beaked bird, with a wingspan of up to seven feet, that’s been brought back from the brink of extinction several times. In the 19th Century the birds were prized for their plumage; demand for their feathers substantially reduced their population. In the 1960s the animals were again threatened by widespread DDT use. After a ban on that insecticide the species made a partial recovery, with roughly ten thousand breeding pairs now in the state.
The Double-crested cormorant, which can be seen at Heron’s Head Park, south of Warm Water Cove, surface-dives for fish, with feathers that require drying between plunges. The cormorant, also once threatened by DDT and other human-induced pressures, has recently thrived, possibly due to the proliferation of aquaculture facilities, where the birds find easy pickings.
While cormorants and pelicans are still relatively rare, the Western gull is plentiful. Excellent fliers, these birds will gladly give up their usual food sources of marine invertebrates and fish, as well as other fowls’ eggs, in favor of human fare. At AT&T Park, flocks are known to gather towards the end of baseball games, to await the bounty left behind by departing San Francisco Giants fans. These gulls nest exclusively on the Pacific Coast in colonies, in small shallow depressions in the ground.
Further inland, the Western Tiger Swallowtail butterfly spends its caterpillar stage in London planetrees on Market Street. The butterflies are well camouflaged; for further protection they have a malodorous organ behind their head called an “osmeterium” to discourage predators. When newly emergent, the Swallowtail resembles a bird dropping. Market Street simulates a river canyon for these colorful insects; urban nature advocates, such as Nature in the City, have fought to protect the planetrees from being displaced by development.
In recent years, crow populations have increased substantially in the Bay Area. These birds favor open spaces, and enjoy discarded fast food. Highly intelligent, crows are also rather social; adolescents of the species will hang out in large numbers on power lines or roosts. Crows are known to mob predators like hawks, and will use specific vocal signals to warn other crows of the presence of predators.
Another Corvidae, the California scrub jay, is always alert to potential observers when burying acorns caches. A scrub jay can keep track of two hundred food stores at a time and is considered one of the most intelligent animals. Some of the acorns must be lost, however, as scrub jays, along with squirrels, are credited with planting most of the oak trees in the West.
In the absence of a higher predator, mesopredators – raccoons, skunks, and opossums – flourish. Opossums, the only marsupials in North America, have a prodigious memory, like scrub jays. Resembling a large furry rat, opossums perform a valuable service, removing carrion, eating insects, rodents, even snakes. The animals are excellent climbers, using their tales to wrap around branches. Opossums carry their young in pouches, much like kangaroos. Marsupials are thought to have originally evolved in North America; the opossum’s ancestor went extinct here 20 million years ago, eventually returning from South America.
Skunks eat grubs and caterpillars, as well as rodents. They live in dens, and avoid human contact.
Raccoons enjoy the bounty provided by humans, such as pet food left outdoors; they also eat rodents.
Jamie Ray, who runs the San Francisco Rescued Orphan Mammal Program, in the Richmond District, started her organization because in the past mesopredators were routinely euthanized. She considers skunks, opossums, and raccoons to be beneficial animals, due to their taste for rodents. San Francisco lacks a facility to handle wild animals; with a small budget and a tight group of volunteers Ray fields calls from San Francisco Animal Care and Control and helps return orphaned animals to the wild.