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The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Naturalist's Almanac What to look for this Winter January
Sometime this winter-no one knows exactly when-there will be an incredible pulse of activity in the food web as countless Pacific herring surge into San Francisco Bay. They congregate just outside the Golden Gate until triggered by an unknown signal-thought by some to be a sudden increase in plankton numbers. Adults may enter the bay any time between November and March, but their peak activity generally occurs during January. This underwater spectacle is surprisingly obvious to landlubbers; just look for the frenzied groups of gulls, cormorants, scoters, and sea lions boiling the surface of the water. In areas like Richardson Bay in Marin County, where herring gather to lay their gelatinous eggs on rocks, it's possible to find several hundred thousand birds feeding at once. This is an important time of the year for these predators-it helps them build up fat reserves in preparation for their own courting and egg laying.
Walk into a grove of coast live oaks in late January or early February and you are sure to unleash a confetti-like swarm of small dusky moths called oak winter highfliers. Camouflaged to look like shards of lichen-encrusted bark, highfliers disappear as soon as they land, creating a brief sense of confusion as they flush like pheasants, then instantly wink from sight. This is their breeding season, with good reason. These moths would feed a lot of hungry mouths if they hesitated any longer-famished migratory songbirds start arriving in a couple of months. By swarming in huge numbers, highfliers are able to quickly mate and lay eggs on oak branches before dying. These creatures are one of nature's geometers. As caterpillars they loop along as if measuring the length of a branch; hence the nickname "inchworm." Though cryptically colored like tiny leaf buds, inchworms must sometimes fall from the canopy to the ground to escape capture from the same ravenous birds their parents avoided.
One of the prettiest of the early blooming shrubs on the north coast of California has been co-opted by European gardeners. It is said that the sponsors of botanist David Douglas' 1825 expedition to the Pacific Northwest recouped all of their costs from this one plant alone. Long after it became an esteemed ornamental in Europe, the red-flowering currant was then 'reintroduced' to American gardeners-as if the plant wasn't here the whole time. Laden with showy sprays of pink or red flowers, this currant is often the first hint of color at the drab tail end of winter and is a sure sign that spring is on the way. However, the plant is less interested in beautifying gardens than in attracting early pollinators who have few other flowers to distract their attention. A currant in full flower may buzz with activity ranging from eager bees to jostling hummingbirds.
Though March 19 is the legendary day the swallows
return to San Juan Capistrano, observant naturalists will notice the arrival
of cliff swallows and their relatives as early as mid-February. Contrary
to popular opinion, however, predicting swallow arrival is not a perfect
science. The northward push of these birds into California is actually
linked to weather systems that affect the presence of insect prey. Several
weeks may elapse between the date they cross the Mexican border en route
from their wintering grounds, and their landing in northern California.
These birds must balance pushing north to claim lucrative breeding territories
and risking the possibility of a late winter storm. There are many accounts
of courageous but starving swallows stranded by sudden ice storms. At
the other end of the scale, this gamble pays off in an unseasonably warm
spring. With a warming global climate, we can expect to see more and more
early-arriving swallows. March
In early spring, western gray squirrels do the craziest things. Supercharged with hormones, three to four males at a time will chase females in noisy bouts that can last for hours. Racing round and round tree trunks and up and down branches, they send bits of bark flying and leaves tumbling to the ground. The point is to sort out which male is the most nimble or aggressive. By March, females retreat to cozy oak cavities throughout California to give birth to two to five young. While raising young, squirrels couldn't act more different. All of a sudden, parents turn stealthy and silent, refusing to draw attention to themselves. But keep your eyes open; one day in June you'll be rewarded with the first glimpse of youngsters tumbling from their nest.
For a spring wildflower spectacle, as well as dramatic scenery, you can't go wrong with a visit to Pinnacles National Monument. Among the mysterious spires, caves, and gorges of spectacularly eroded volcanic rock, hikers can amble along slopes vibrating with colorful wildflowers. On Pinnacles' High Peaks Trail or Condor Gulch Trail, you could expect to meet up with Indian paintbrush, Indian warrior, manzanita, nightshade, California poppies, buttercups, milk maids, shooting stars, sticky monkeyflower, bush lupine, goldfields, fiesta flower, mariposa lily, scarlet bugler, Chinese lanterns, baby blue eyes, owl's clover, and Johnny jump-ups. These are just a few of the species on full display starting this month. And if that isn't testament enough, talk to some true flower experts. They'll tell you the park also hosts over 400 species of bees-the most diverse collection in the world. 831-389-4485 x 0
David Lukas leads natural history tours and programs in the Bay Area. He can be reached at davidlukas@earthlink.net |
