From Green to Gold

Each April, when the green hills begin to lose their color, I grieve a little. Green grass speaks of freshness, new growth, and the annual renewal that comes with the winter rains. But for those of us who have lived in California for a while, the fading of green into gold seems as inevitable as the lengthening days.  By the end of April you come to anticipate the change, relinquishing the green and when the hills take on the warm tones of sunshine, it looks right somehow. By mid-May, the transition is mostly complete except for those grassy areas beneath trees where fog drip keeps grass green well into the summer.

The hills turning brown are confusing to those who come from climates where winters are cold and summers have rain. But in coastal California, rains stop in the spring and won’t resume until fall. Spring wildflowers bloom, cast out seeds, and disappear. Grasses, like the wild oats which clothe the California hills, persist as straw, pale and almost transparent. The afternoon wind hisses through the dry stalks and the empty seed cases.

Our two seasons–the dry season and the wet season–are determined by the annual shifting of the Pacific High, a vast area of high pressure that presses down on the eastern Pacific. In the fall, the Pacific High and the high-altitude jet stream, following the sun, shift to the south, allowing the storms–generated mostly in the Gulf of Alaska–to reach our coast bringing their gift of rain. Some years, the Pacific High stays stubbornly in place and we have a dry winter. A dry winter means drought, the ultimate anxiety especially for those of us living in the West.

Though the rains end in late spring, our adobe soil retains moisture long after the rains have stopped. And the coastal fogs that arrive with the Pacific High positioning itself off our coast bring important moisture. Most folks consider fog a gray and gloomy business shutting out the sun for days at a time along the coastline, but the fog delivers needed moisture to a dry land. Rain gauges placed along the ridge tops above Berkeley have measured 10” of fog drip under the trees–or almost half our total rainfall for the year.

The prevailing wind along the coast in the summer blows from the northwest. The strong winds disturb the ocean surface allowing colder water to rise to the surface. The warmer air passing over the cold, upwelled water condenses into fog which rises as a fog bank over the coastal hills, spilling in cascades down the leeward slopes. Fog fingers inland through the gaps in the hills and flows as a rich river of vapor through the Golden Gate, the only complete break in the coastal hills.

While annual grasses and wildflowers dry up, native trees and shrubs have developed their own strategies for getting through the long rainless season. Trees like the California live oak have small, thick leaves which resist desiccation. Other plants have hairs on their leaves or a moisture-sealing layer of wax. One species of manzanita, the largest family of California native shrubs, turns its leaves edgewise to the sun. Some trees like the California buckeye with broad, thin leaves drop them in late summer, in a process called estivation (or “summer sleep"). These same trees and shrubs produce new growth and flowers during the rainy season, leaving their acorns, nuts, berries, and seeds to ripen under the summer sun.

Where water is available, mostly in the stream canyons, vegetation crowds together, often ascending the north-facing slopes. Below LHS, fragrant bay trees along with live oaks fill the steep canyon which contains the north branch of Strawberry Creek. Under the sheltering canopy of trees grow ferns, currants, hazel and a whole host of shade-loving plants. The green vegetation in the canyons contrasts with the dry hills–a familiar summertime pattern throughout coastal California.

Lethal Beauty

You can’t miss the lacy stands of poison hemlock (Conium maculatum) blooming along the roadways this time of year. There’s a nice stand on the left side of the road going down Centennial Drive.

The blooms are held aloft in flat-topped clusters of small white flowers. The flowers and lacy foliage identify them as members of the parsley family–but beware, these are the poisonous members. The plant is toxic in all its parts–roots, foliage, flowers, and especially the seeds–luring the uninformed to sample them with most-often deadly results.

The poison is a neurotoxin, a pyridine-type alkaloid that causes paralysis and finally respiratory failure. In ancient Greece, poison hemlock was used for executions. After Socrates was accused of “impiety” in 399 BC, he was given a deadly infusion of hemlock.

Poison hemlock, a European native, has spread world-wide. and is considered a noxious weed dangerous to livestock. It favors moist areas, the edges of pastures, or the disturbed areas along roads and paths.

The Irish call it “Devil’s Porridge.” Enjoy it for its grace, the way it sways in the breeze, but snack elsewhere.

An Early Summer Surprise

The first week of June, two regular walkers along the Ridge Trail above Claremont Canyon, made an exciting discovery. John Colbert and Erica Rutherford tell the story in an email: “We had just finished talking about not having seen a Lazuli Bunting lately when Erica followed an unusual song–and there was the Indigo Bunting.” (Though common in Eastern and Southern U.S., the Indigo Bunting is rare in the West).

John continues: "The female, in typical bunting fashion, stayed quite hidden–popping up briefly to follow the male, and then dropping down into the tall grass and shrubs. I think the likelihood of the female being a Laz (Lazuli) Bunting is greater than its being an Indigo. The chance of both a male and a female Indigo being in the same area at the same time and finding each other and going through courtship, etc. is vanishingly small!”

Most birdwatchers being “twitchers” at heart (the British word for those who pursue rare birds), many of our clan ascended the steep road up Panoramic Hill over the next few days. Most of us were lucky enough to get at least a glimpse, and a few had time to take photos. The male was often seen singing from the top of a small wind-pruned bay or from a similar-sized live oak nearby. The song is sweet, tinkling, and each note is repeated twice.

Indigo Bunting or not, the Ridge Trail that runs along the saddle between Strawberry Canyon and next door Claremont Canyon is an exciting piece of landscape–perhaps one of the wildest places in the East Bay. The hills drop away beneath you in a vertiginous swoop. The south-facing slope supports a fine assemblage of ‘soft ’chaparral plants which often grow on the steeper slopes near the coast. They include certain sages, sticky monkey, and coyote brush, all knit together to provide inviolate habitat for rabbits, wrentits, and California Thrashers.

You expect to see Lazuli Buntings in grassy, shrubby areas in the hills this time of year. They can often be heard singing their sweet bunting song on the slope across from LHS below the Space Sciences Building. But the Indigo is another story, rarely seen in these parts. In the mid-west where their ranges often overlap, they commonly hybridize which explains why the bunting accompanying the Indigo may well have been a Lazuli.

The blue of both birds is glorious–lapis lazuli, indeed, with the blue brightened by a touch of turquoise. Of course, there is no such thing a member of the bird kingdom with blue-pigmented feathers. They’re black ("blackbird of happiness" doesn’t sound quite right). It’s all a matter of reflection. Light striking the smooth, black feathers of the buntings is partly absorbed and partly reflected. The reflected part is seen by our eyes as blue and the message is sent for confirmation on to our brain.

Some birds–think of the throats of certain hummingbirds–have grooved feathers. The light is reflected in a different way and what we see is described as iridescence.

Finding a rare bird is a special event, one sure to lift you out of the summer doldrums, while keeping alive the possibility of unexpected gifts.

Note: News about the Indigo Bunting was passed on by Kay Loughman, an expert birder and photographer who lives in Claremont Canyon. She is documenting the natural history of our sister canyon. Check out the website: “Wildlife in the North Hills" www.nhwildlife.net.

White-throated Swifts at LHS

Two weeks ago I discovered an active White-throated Swift's nest up in a recessed ceiling light outside the building near the Discovery Corner gift shop.  Because swifts are regularly seen flying about the Hall, the discovery was not unexpected.  What was unexpected is that this appears to be the only nest.  White-throated Swifts are usually a communal species, nesting and roosting in groups.  (As of July 6, adults continue to come and go to noisy greetings from the nestlings).

Swifts are remarkable birds purported to be the fastest fliers among North American birds.  Though they resemble swallows, they are related instead to hummingbirds, sharing common ancestors.  The family name for the swift is Apodidae, in Greek meaning "without feet," referring to swifts' inability to perch.  But their feet are superbly adapted for clinging to vertical surfaces such as cliffs and, increasingly, to building walls where they nest in crevices.

Truly a creature of the air, White-throated Swifts have the generic name -- Aeronautes or "sky sailor.  They harvest insects in flight, mouth widen open.  They collect nesting material by snapping off small twigs while in flight which they stick together with glue-like saliva to form a simple cup.  Swifts even mate in flight.  Seeing the "Courtship Fall" is a memorable experience, one never to be forgotten.  Two birds clinging together, pinwheel downward, releasing just above the ground.

Almost everywhere over Western North America, the little black and white torpedoes with swept-backed wings hurtle across the sky while emitting piercing staccato cries.  Dashing through the air, they can abruptly change direction by making split-second adjustments of tail and wings.

Though they are a species hard to ignore, little is known of their life history.  When populations of insects decline with the approach of winter, White-throated Swifts move south, though enough remain in the Bay Area to be counted during the annual Audubon Christmas count.

We at Lawrence Hall of Science are lucky, indeed, to share our building with these remarkable birds.

–Phila Rogers