from Bay Nature Jan-Mar 2010

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A N E X P L O R AT I O N O F N AT U R E I N T H E S A N F R A N C I S C O B AY A R E A

Beyond Jaws

Learning the Ways of the White Shark

From Bunkers to Parkland in Concord on the trail Climb to the Top at Castle Rock families afield What’s Under that Log? Public Transit and Other Endangered Species

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BEYOND There are many fish here — large fish, blue water fish, fish with true piscine gravitas: yellowfin tuna, mahimahi, Galapagos sharks. But the human visitors here at the Monterey Bay Aquarium’s one-million-gallon “pelagic” (open ocean) tank have big

Scot Anderson

eyes and slack jaws for one fish only: a female white shark.

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“We came all the way from Ventura for this,” says Michelle Smith, who is visiting with her husband, Noah. “And I have to say, it was really worth the drive.

You hear so much about them — it’s wonderful to actually see one.”

Not that the shark impresses with her size. At a few inches past five feet long, she’s a mere juvenile, not even the largest fish in the tank. But that singular blocky profile, the emblematic pattern of gray dorsal surface with white belly, the obsidian eyes that seem to suck light from the water: somehow they connect with the saurian part of the human brain, bypassing our typical aesthetic metrics. We can only be enthralled — and intimidated — by her transcendent predatory grace.

Interest in white sharks is nothing new; in Northern California they are an enduring obsession. Our coast is one of the few places on the planet where these apex marine predators remain relatively abundant — other regions include the waters off Australia and New Zealand, South Africa, and Mexico’s Guadalupe Island.

Spectacular white shark attacks on elephant seals and other pinnipeds (seals and sea lions) in our waters are logged each year at the Farallon Islands and Año Nuevo Island, and attacks on humans occur with some frequency.

Despite great popular interest in white sharks — an interest that has evolved over the years from the hyperbolically inaccurate clichés of Jaws to a more nuanced appreciation — little was known of these iconic predators until recently. About all we knew for sure was that they inhabited the waters off California, preyed heavily on pinnipeds, opportunistically scavenged whale carcasses, and sometimes bit surfers and divers, apparently mistaking them for seals or sea lions.

But we didn’t know if white sharks were wholly coastal animals or if they ranged well out to sea. We didn’t know where or when they breed, their rate of growth, their abundance. Now, thanks to sophisticated telemetry technology and an ambitious tracking program, some answers are starting to emerge.

Most of the new data is coming from Tagging of Pacific Predators (topp), a program that began in 2000 as a part of the international Census of Marine Life. During the past decade, topp has deployed sophisticated satellite archival tags and sonic tags on 4,000 individual Pacific predators, including blue whales, elephant seals, leatherback turtles, blackfooted albatrosses, bluefin tuna, and blue, white, mako, and salmon sharks.

Among the findings of this research: contrary to past assumptions, white sharks are not coastal homebodies. Early conclusions by topp scientists — published in 2002 — demonstrated that white sharks are wide-ranging, venturing far into the Pacific, with one individual traveling 3,800 kilometers in 40 days to the west coast of Kahoolawe Island in the Hawaiian archipelago. b ay n at u r e

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© Monterey Bay Aquarium/Randy Wilder

(above) A boy watches a juvenile white shark on exhibit in the Monterey Bay Aquarium’s Outer Bay tank. The tank holds more than 1 million gallons of water, but it can accommodate only young white sharks. This shark was placed on exhibit in late August and released in November 2009. (left) A white shark bites a seal-shaped decoy near the Farallon Islands, one of several areas where researchers tag sharks to learn more about their habits.

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Fathoming the Ways of the White Shark

And more recent research, detailed in The Proceedings of the Royal Society in fall 2009, indicates there is a method to their wanderings.

These studies, which involved more than 100 white sharks fitted with satellite tags, showed that white sharks from the California Coast and Mexico’s Guadalupe Island region converge each winter on a million-square-kilometer chunk of the Pacific, roughly equidistant from Hawaii and the continental United States, that researchers have dubbed the “White Shark Café.”

It’s not completely clear what they’re doing out there, says

Barbara Block, a professor of marine science at Stanford University and coauthor of the recent Royal Society paper — but researchers have some ideas.

“The males that we’ve tracked seem fairly localized in the café region, while the females are more broadly distributed,” says Block.

“There could be — with the emphasis on could — periods of overlapping between males and females that might be related to mating.”

Block noted the telemetry data logged in the pop-up tags also recorded unusual dive behavior among the sharks that might j a n ua ry – m a rc h 2 0 1 0

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A

rtist Todd Gilens seeks to

turn a ubiquitous distraction of city life—advertising on buses—into something much more: mobile street art that gives voice simultaneously to people and to wildlife. The idea is so simple: buses transformed into migrating calling cards for imperiled local species like the salt marsh harvest mouse or brown pelican.

Butterflies fluttering up Van Ness, salmon swimming down Sansome, snakes stopping in the

Look, a flock of pelicans among the taxis! A garter snake caught in traffic! An express mouse disappearing just as you reach the stop . . .

Presidio—all of these represent a chance to acknowledge the habitats that were here not so long ago and the species that still hang on at the margins of our metropolis.

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t and photomontages by Todd Gilens Transit and good city planning are part of the solution to habitat loss, and the buses will display a web link to more information.

But that’s not the only point.

“We’re so used to being assaulted by advertising,” says Gilens, “that it’s rare just to enjoy something.

When you see these images along with everything else on the street, your senses are heightened, and from there you might start to ask, ‘How can our environment be more lively, more nourishing, more humane?’ ” Gilens hopes to get his project rolling in 2010. Learn more, or contribute, at baynature.org/ endangeredtransit.

Dan Rademacher

a project of Community Initiatives, with support from Adobe Foundation, rero Nuevo Fund of Tides Foundation, San Francisco Art Commission, the tion, and Zellerbach Family Foundation.

Vertigo can be marvelous rather than malignant, gracious instead of manipulative.

A bus goes by—or was it a butterfly?

Clockwise from upper left: Brown pelicans, Todd Gilens; San Francisco garter snake, John Sullivan/ Ribbit Photography; Mission blue butterfly, Thomas Wang/ missionblueterritory.com; Salt marsh harvest mouse, B. Moose Peterson/WRP

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development would hug the existing North Concord bart station. To the south and east a great regional park would protect the base and slopes of the Los Medanos Hills.

After years of controversy, the City of Concord has moved some distance toward this concept, adopting what it calls the Clustered Villages Plan. State and federal environmental reviews are currently under way. If the planned time line holds, the final release of the land could come as early as January 2011. There is debate still to come about the final scope of development, but the creation of a major park on more than half of the site is widely supported. The East Bay Regional Park District’s 2008 Measure WW earmarked $16 million for the acquisition, restoration, and development of this property specifically.

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of overlapping alluvial fans; and at the bottom of the slope the course of Mount Diablo Creek, tree-lined but usually dry. A little rise in elevation is enough to show you much of central Contra Costa County, from Diablo to tidewater. As in the desert, simple forms and lack of concealment cause you to underestimate distances — or perhaps to see them more realistically than we do when nearer patterns complicate the view. At some 2,500 acres, the proposed

t h e place The first thing that impresses you, out on the site, is the military imprint: the vast number and extent of ammunition bunkers, train tracks, and roads. The second is the land’s sheer openness. The terrain is simple: the hills, a ridgeline growing gradually higher toward the south; little oak-lined drainages coming down; a broad apron or bajada

(left) A California tiger salamander, a federally threatened species, up the hill from Cistern Pond. (above) Jackrabbits are plentiful here, and so are the coyotes that hunt them. Rabbits and numerous rodents also attract raptors to John Keibel, behindthebarbedwire.com

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the weapons station’s wide-open grasslands.

is Cistern Pond north of Bailey Road. Judging by rock fragments from toolmaking, the site was used by Chupcan Indians, a tribelet of the Coast Miwok. Later it was tapped for a dairy ranch; an old windmill and the namesake cistern remain. It was here that the Department of Fish and Game planted red-legged frog tadpoles in 1982. Alone of the station’s waters, Cistern also supports the western pond turtle, a species of state concern.

While the ponds are safely in the regional park zone, some other wetlands lie in the path of development. The most interesting of these is at the extreme western corner of the site, where lingering small ponds and marshes mark a past course of Mount Diablo Creek. The soils in the northern third of the site lend themselves also to formation of seasonal wetlands of the kind where tiger salamanders breed, though those amphibians have not been observed here.

Mount Diablo Creek is a lifeline of the station, less for the water it seasonally carries than for the trees it supports. A ragged but recovering riparian forest of willows, cotton-

ends abruptly at the edge of the shuttered navy base. The thin green band of Mount Diablo Creek lies inside the boundary of the proposed new regional park here. (below right) Mount Diablo Creek’s riparian woodlands are very limited, but they provide

new park would be larger than Tilden Regional Park in the Berkeley Hills, yet it seems curiously small.

The third thing you notice is grass, lots of it. This is indeed a piece of “golden” California, the color and texture of the land determined by the annual grasses that set seed early and die.

Annual grassland covers over 80 percent of the site, though patches of the native perennial species — purple needlegrass, California fescue, and others — hang on in folds of the hills.

Whatever its composition, undeveloped grassland is a rarity in this part of the world, and it provides a lot of habitat. Out in the fields you can’t miss the western fence lizard and the blacktailed jackrabbit. Stay a little longer and you are likely to see a rattlesnake, gopher snake, king snake, or all three. California ground squirrels burrow throughout the area, and many other species borrow these tunnels for shelter. The California vole, western harvest mouse, and Botta’s pocket gopher thrive here, as do the coyotes that eat them all. Western meadowlarks, horned larks, killdeer, and mourning doves nest in the grassland. There are at least a few pairs of burrowing owls, a California “species of special concern.” Hawks, kestrels, and falcons by day and owls by night patrol for their mostly rodent prey.

Much of the wildlife action on the station either occurs in, or depends on, the 9 percent of the land that is something other than grassland (or developed ground): seasonal and permanent ponds and wetlands, stream courses, and trees.

In the south half of the station, in and along the hills, are some 20 stock ponds, watering holes, and seepage pools. These are breeding grounds for the California red-legged frog and California tiger salamander, both threatened species, as well as for western toads and Pacific chorus frogs.

The largest pool, and the only one to retain water year-round,

Scott Hein, heinphoto.com

Bob Ecker

critical wildlife habitat, especially for nesting and roosting birds.

John Keibel, behindthebarbedwire.com

(below left) Mount Diablo looms over central Contra Costa County’s suburban sprawl, which

woods, oaks, and ashes draws many nesters, including hawks, kestrels, owls, downy woodpeckers, Anna’s hummingbirds, and Pacific-slope flycatchers. Arboreal salamanders live in the streamside strip and bats may roost there.

In a landscape of grass, the taller tree is an event. Valley oaks appear mostly to the south of the site, spaced out in the formation known as oak savanna, rarely found intact these days because the gentle ground it occupies is so easy to build on. Up in the canyons, buckeyes and blue and coast live oaks make pockets of woodland.

Another small portion of the site is covered in groves of eucalyptus and Coulter pine, most planted in the 1960s and 1970s as a forestry experiment. The taller eucalyptus trees draw nesting red-tailed and red-shouldered hawks, great horned owls, and golden eagles. Owls roost in the pines. Old walnut trees, j a n ua ry – m a rc h 2 0 1 0

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