California Wild Fall 2003 - Naturalist's Almanac

An animal with green blood and more teeth than a shark is lurking in your yard. It comes out at night, bent on sating a ravenous appetite. But only plants should fear the stirring of garden slugs. Because they are tiny, these slimy creatures seldom move more than forty feet in a single night, and their dietary preferences lean towards soft plants, fungi, and carrion. Slugs make lots of enemies, however. They consume several times their body weight in food each night, and leave gardeners irate at the loss of favorite plants. Introduced slugs are nearly always the ones devouring our non-native home and garden plants—native slugs prefer native plants. Slugs have a voracious appetite for sex as well as for food. Amorous pairs will circle each other energetically for hours, waving long penises that may reach half their body length. (Each slug is an hermaphrodite that lays eggs and has a penis, but can’t fertilize itself.) In one species, pairs hang from a long mucus thread and copulate in midair. A couple may become so entwined that they must apophallate—or gnaw off one another’s penis—in order to separate. A foray with flashlight on a rainy night might reveal sluggish orgies in your own yard.

Out at the Farallon Islands, 27 miles west of San Francisco, humpbacks and blue whales, plus the occasional orca, gray whale, elephant seal, dolphin, and great white shark come to feed on the riches from the upwelling current—and on each other. The Oceanic Society runs trips to the islands every weekend through the end of November. Call (415) 474-3385.

Within a week of strong winter rains arriving at the Jepson Prairie Preserve south of Davis, half-inch Conservancy fairy shrimp hatch from cysts that have lain dormant on dry mudflats since the previous spring. These primitive crustaceans are found at fewer than half a dozen vernal pool sites in the Central Valley, where many pools have fallen victim to the plow and the spread of concrete. Living up to four months, fairy shrimp look like small lobsters that swim on their backs with frilly legs held aloft. Scientists have described the life histories of only about ten of the world’s 260 fairy shrimp species in detail. They begin life as one of up to 1,500 eggs deposited by a female on the bottom of her home pool. Known as cysts, they are really shelled embryos that have the capacity to survive almost indefinitely in a state of suspended development. Cysts can remain viable after being frozen for long periods, or being subjected to near-boiling temperatures. Some cysts carbon-dated at 10,000 years old hatched as soon as they were placed in water. Once rain falls, they hatch by the score. Information about the Jepson Prairie Preserve is available through the Solano Land Trust, (707) 432-0150.

Although they may be raiding your bird feeders with audacity, this is a fine time of year to admire tree squirrels. Native western gray squirrels are only found in relatively undisturbed areas. Around city parks and urban areas, introduced eastern fox squirrels and eastern gray squirrels are usually more abundant. During the cold winter months, tree squirrels feed heavily on seeds rich in oil and carbohydrates. They readily make the switch from wild foods to seeds offered at backyard bird feeders. On such a diet, tree squirrels become plump and grow thick, luxuriant winter coats. Hair from a western gray squirrel has five bands of alternating silvery grays, browns, and whites-together, they give the squirrel a shimmering, grizzled appearance. If you find one carrying a mouthful of seeds, you may observe it scampering off to its nest. Large balls of leaves tucked among tree branches or in tree hollows, squirrel nests keep their owners cozy against the winter chill.

Visit the shoreline this month and discover some of the best tidepooling of the year. Low, low tides give beachcombers access to zones that are home to stunning fluorescent sea slugs such as the opalescent nudibranch, the football-sized gumboot chiton, and colorful variations of seastars. Retreating waves always reveal new surprises. This month’s lucky tidepoolers may even get a rare glimpse of the giant Pacific octopus. In the Bay Area, premier tidepool viewing is available at Duxbury Reef on the south end of the Point Reyes National Seashore. Check tide tables or call (415) 464-5100.

To view mistletoe in the wild, head out to Sunol Regional Park, (925) 862-2244 near Fremont. A hike along Canyon View Trail will take you past oaks draped in mistletoe, and out to waterfalls in Little Yosemite. The small clumps of green you see in the otherwise bare branches are the kissing plant. Unlike many parasites, oak mistletoe is able to photosynthesize its own food, but taps into its host for water and minerals. Its seeds are spread by birds, who are fond of the clear white berries.

David Lukas leads natural history tours and programs in the Bay Area. He can be reached at davidlukas@earthlink.net