| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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NATURALIST'S ALMANAC What to Look For This Summer David Lukas July
One midsummer evening, when you least expect it, you might be treated to a rare sight. After two months of nurturing her litter of four to seven pups in secret under a log or in an underground chamber, a mother striped skunk is finally ready to lead them out on their first foray into the larger world. She takes the lead as her bumbling youngsters line up in single file behind her. In the dusky glow after sunset, they trail ghost-like through the dry grasses in search of insects, mice, berries, or bulbs. A whole family flashing a bold black and white warning pattern is a wonderful sight. Male skunks warily avoid each other by sticking to fairly discrete territories. But females and their youngsters wander at will. Faced with a female’s strong protective maternal instinct, virtually all wise intruders will back down.
As high Sierra Nevada meadows bloom with an astonishing array of flowers, southward-migrating rufous hummingbirds arrive in full force to take advantage of abundant nectar. Upon landing, these aggressive, dominant birds will commandeer every productive patch of flowers and breeding calliope hummingbirds quickly clear out of the area. During the July peak, so many rufous hummers take over that some meadows fairly zing with their hyperactive wings. The glittering cinnamon-red males arrive first, creating a particularly impressive spectacle in July. By the end of the month, when these jewels with wings begin heading south to wintering grounds in Mexico, their ranks are replaced by females and juveniles in plainer attire. August
For many people, few summertime traditions are as cherished as the annual harvest of scrumptiously good Himalayan blackberries for jams and pies. Introduced from India by Luther Burbank in 1885, these prolific berry producers quickly spread to moist lowland areas throughout California because they are loved by birds as well as people. Blackberry seeds sprout as soon as they have passed through a bird’s gut, and flying birds readily transport them to new sites. Once established, these plants utterly dominate their new homes through extensive vegetative shooting. The flowers don’t even need to be pollinated before producing fruit, saving the plant precious energy. The mass of a fully developed thicket—also known as a bramble—can exceed twelve tons per acre and form a towering wall of impenetrable thorns. Laden with succulent fruit, the blackberry gives fresh meaning to the term “sorely tempting.” Who hasn’t suffered countless pricks picking their fill?
Those master aerialists—the six species of swallows common in California—launch a spectacular if little recognized migration each summer. Completely dependent on small flying insects for food, swallows seem to realize before other animals do that summer’s bounty is coming to an end. This month, they swoop up into massive flocks around fields in moist valley bottoms. These congregations can reach impressive proportions. Scant published records cite 100,000 tree and cliff swallows at the south end of the Salton Sea, a number likely exceeded by gatherings in the Central Valley. Once massed, these huge flocks quickly work their way over the southern horizon with different species wintering from Mexico to Tierra del Fuego. But an annual gathering in Oregon’s Willamette Valley that exceeds 500,000 barn swallows apparently dwarfs our state’s record. It would be exciting to better document California’s swallow migration and see how high our own numbers soar. September
Temporarily drawn into warmer waters around Catalina Island to lay their eggs in dense kelp beds, the rarely seen flying fish of the open ocean can be readily observed through September. Though retreating into deeper waters by day, these sleek, 20-inch-long fish rise to the surface at night. Attracted to the lights of boats, they occasionally land on decks, but more commonly will fly into the beams of spotlights. These fish actually glide on long, winglike pectoral fins. They put on quite a show for folks on popular “flying fish boat tours.” While the exact reason for their leaping behavior is not understood, it is known that flying fish can hit speeds of 20 mph and soar above the surface of the water for distances of 200 feet. By stringing together several quick glides, a flying fish may stay aloft for more than 30 seconds.
“Leaves of three, let them be, Poison oak is the bane of countless outdoor enthusiasts in the West. To protect itself, the plant secretes phenolic compounds known as resorcinols and catechols. If touched or inhaled as smoke, these chemicals can land some people in hospital. Along the coast, local poison oak strains will raise terrible skin rashes on those who touch the oily leaves. Milder forms grow in the Sierra Nevada. The familiar three-leaved shape of poison oak rouses only horror in the viewer’s eye, although the leaves turn a gorgeous deep red color before they are shed. Like an autumn display in the understory, these fiery colors add a lively touch to an otherwise dry, dusty landscape. Once the leaves drop, the plant’s small whitish fruit becomes much more noticeable. Thrushes, wrentits, towhees, and other small birds will feed on the berries all winter. Though this plant gets little appreciation from humans, it is an important component of the ecosystems where it grows.
David Lukas leads natural history tours and programs in the Bay Area. davidlukas@earthlink.net |
