Exploring Nature in the San Francisco Bay Area
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Clear Skies Ahead

Dig out the binoculars; it’s clear skies ahead.

In the Bay Area, the winter months are your best bet for a clear view of, well, anything you’re trying to spy–be it bird, Big Dipper or sweeping vista.

A year lived in the region (let alone two or three or a lifetime) will tell you as much. But observance of the trend leaves its cause a curiosity. Why are winter skies the least hazy?

Distribution of pollutants in the atmosphere is the primary factor determining how obscured your view will be. In the winter, winds tend to be stronger. This mixes the air of the Bay Area more thoroughly, and consequently disperses pollution that would otherwise stagnate. The air sweeping down from Canada following a cold front also tends to contain less salt and pollution.

The lower angle of the sun in winter also contributes to greater visibility. It prevents a significant buildup of photochemical pollutants, to which the region’s inland valleys are prone. It’s a combination of sunlight and warm temperatures (both, of course, harder to come by this time of year) that cause hydrocarbons and oxides of nitrogen to react, forming secondary photochemical pollutants like ozone.

In sum: it’s the right time to bundle up and make the trek you’ve been contemplating. The view from the summit should be at its best.

On the Rocks, with a Pup

If you’re looking for northern elephant seals, there is no place better to visit than Ano Nuevo State Reserve, home to the world’s largest mainland breeding colony. The seals return to this seemingly barren, rocky, windswept point each December to birth their young and mate. The largest of the pinnipeds (seals, sea lions, walruses), elephant seals are a real spectacle: Males reach 2.5 tons and grow to be 16 feet long (though the females are smaller by about 6 feet and several thousand pounds).

The prelude to breeding begins late in December, when males battle for dominance. These battles, though dramatic, rarely result in serious injuries. Soon after the males arrive, the females come ashore. Within days they give birth (typically each to a single pup, conceived the year before, who will nurse for 25 to 28 days). About 24 days after birthing, the seals mate. Shortly thereafter, they return to the sea, weaning their pubs abruptly–by abandoning them. Adult seals are largely gone by the end of February. Their pups, called “weaners,” remain through the following month.

Docent-led tours are held daily at the reserve, December through March, allowing visitors a view of the seals in action. The fame of the Ano Nuevo colony is considerable; thousands of people make the pilgrimage to catch a glimpse of the seals. So tour reservations are a must. Sign up at the California State Parks website. There’s no public access to Ano Nuevo Island, just off shore.

Though Ano Nuevo is the larger and more renowned local rookery, Point Reyes also boasts an elephant seal population. Basking or in action on the beach, they can be glimpsed from the aptly named Elephant Seal Overlook, though the view is rather distant without good binoculars or a spotting scope. In January and February, rangers lead viewing expeditions for sixth through eighth graders.

In late spring and summer, elephant seals return briefly to land in order to molt before heading back out to sea.

It’s Raining…Rain Beetles?

As April showers are to May flowers in other parts of the country, so are autumn rains to the rain beetle here in the Bay Area. The rainy season’s first soaking precipitation (an inch or more) beckons forth this remarkable insect.

After ten to twelve years underground–and up to a month of this time spent as adults–the beetles emerge to mate. The winged male of the species has enough energy for about two hours of flight, which he spends searching for a flightless partner, who waits for his arrival at the entrance of her burrow. Keeping low to the ground, the male–aided by a pair of large antennae–follows the scent of the female’s pheromone.

Once she’s found, the pair mate. The female then closes off the entrance to her burrow and tunnels down to lay her eggs. Adult Rain Beetles have neither functional mouths nor digestive tracts. They have one purpose only–to reproduce–and their anatomy reflects the fact. For the female, this means a larger body with powerful legs and a rigid digging device (called a clypeus) at the end of her head, designed for expedient excavation. Tunnel complete, she lays her eggs in a spiral at its base. They mature the following spring.

If you’re hoping to glimpse these ephemeral insects, try Berkeley’s Tilden Park the morning after the first fall rain. At dusk, or on a drizzly day, you’ll also have a good chance of catching the critters out. Be on the lookout for roughly quarter-sized emergence holes and the males, in fast flight, following their antennae.

The Sandhill Homecoming

It’s a short trip east to Lodi to see the sandhill cranes. Each autumn the birds return, several thousand of them, to overwinter in the Central Valley. They’re a rare treat worth the pilgrimage. Sandhills are one of only 15 species of crane in the world, and of these only whooping cranes also inhabit North America. Fossils dating back 6 million years make sandhills the oldest known species of bird still living.

The sandhills’ dramatic appearance seems fitting for such ancient avians. Large and a little bit gangly, with long bills, long legs, and long necks, they’re most distinguished by their bright red crowns. Given their appearance, you can imagine what a spectacle these birds make when they begin their characteristic courtship dance. In pairs (the birds mate for life), they move about, bowing and hopping with exuberance, arching their necks and sometimes lifting their bills to call out in unison.

In the first weekend of November, by way of welcome, the Lodi Chamber of Commerce hosts the Sandhill Crane Festival, complete with lectures, crane-inspired poetry, and guided tours of the Isenberg Crane Reserve. This is not the only time to spot the cranes, though. From October through the end of February, the Department of Fish and Game offers tours at the Reserve. You can also drive to the nearby Cosumnes River Preserve–host to as many as 4,000 cranes each winter–or west, down Woodbridge Road, to spy the delicate birds dancing and feasting on rice, corn stubble, and small animals in the farm fields.

The cranes begin to depart in late February, bound for their breeding grounds in Canada, Alaska and Siberia, though some remain as late as April.

Tarantula Trekking

Whether you’re cautiously curious or already avid, autumn is the time to go tarantula-spotting in the Bay Area. It’s mating season for the hairy critters, and, accordingly, the males are venturing forth from the ground in search of potential partners, who coyly await their suitors on their burrows’ “doorsteps,” and try to eat them after the fact.

Tarantulas, contrary to common portrayal, are rather fragile beasts: easily trodden upon, possessing poor eyesight, and liable to loose a leg if they fall too great a distance. Their bite isn’t even as bad as you might think: enough to kill a cricket, but you’d feel it on the magnitude of a bee sting. Because they are so vulnerable, the arachnids are nocturnal and spend most of their time underground, just popping to the surface to grab a meal.

In autumn, however, tarantulas are more easily spotted as they forsake caution in the name of procreation. In the East Bay, you can find them at Las Trampas, Sunol, Del Valle, and Pleasanton Ridge Regional Parks. Mount Diablo is also prime tarantula territory, and both the State Park and the Lindsay Museum typically offer guided tarantula walks along its slopes. In the South Bay, try Coyote Reservoir, Joseph D. Grant County Park, and Henry W. Coe State Park. Henry Coe hosts their annual Tarantula Festival and Fall Barbecue each October. It’s a fun, educational affair that attracts in the order of 400 attendees with the aim of dispelling the long-standing monster myth. Check out info on the 2008 event here.