Читать книгу East Bay Trails - David Weintraub - Страница 18

◆ Martin Luther King, Jr. Regional Shoreline ◆

ARROWHEAD MARSH

Length: 3.7 miles

Time: 2 to 3 hours

Rating: Easy

Regulations: EBRPD; dogs on leash.

Facilities: Picnic tables, water, toilet, phone.

Directions: From Interstate 880 in Oakland, take the 66th Ave./Coliseum exit and go briefly west on Zhone Way to Oakport St. Turn left and go 0.6 mile to Hassler Way. Turn right and go 0.2 mile to Edgewater Dr. Turn right again and go 0.2 mile to the end of Edgewater Dr. Continue straight 0.1 mile on the entrance road to the Garretson Point parking area. The trailhead is at the southwest edge of parking area.

The San Leandro shoreline, in one of the East Bay’s busiest industrial corridors, hosts a wonderful array of waterbirds, from long-legged waders such as the great blue heron, to small shorebirds like the least sandpiper. This out-and-back trip follows a level, paved pathway that runs from Garretson Point to Swan Way, passing San Leandro Bay, Elmhurst Creek, San Leandro Creek, Arrowhead Marsh, and Airport Channel, all productive birding areas. Birds will be most numerous in fall through spring, because the San Francisco Bay, on the Pacific Flyway, attracts large numbers of migrating and wintering species, many of which are on northern breeding grounds during the late spring and early summer. Plan your visit for a rising or falling tide when the birds are active but not too far away to identify. Benches and picnic tables along the way provide plenty of opportunities to sit, watch birds, and enjoy the view.

With binoculars and a bird guide or note pad handy, walk toward the water from the parking area and turn left on the Garretson Point Trail, a paved pathway along the shoreline. In front of you is San Leandro Bay, nestled between Oakland International Airport and Alameda. To your left, jutting northwest into the bay, is Arrowhead Marsh, a wildlife sanctuary that attracts large numbers of coots, ducks, grebes, herons, egrets, gulls, terns, and shorebirds. Arrowhead Marsh is part of the Western Hemisphere Shorebird Reserve Network, a collection of sites identified as critical to shorebird survival. To your right is the much smaller Damon Marsh, also a wildlife sanctuary. In 1998, tidal flow was restored to 71 acres of previously filled tidal and seasonal wetlands, thanks to the efforts of EBRPD, the Port of Oakland, the Golden Gate Audubon Society, and numerous other groups.

Soon you reach Fred (Skip) Garretson Memorial Point, named for an Oakland Tribune reporter whose stories inspired shoreline conservation efforts. Here is a picnic area surrounded by white alder, western sycamore, eucalyptus, and acacia trees.

Although this park is situated in a heavily industrial area, it is one of the best places to observe birds in the East Bay. Looking south across the bay with binoculars or a spotting scope, you should be able, depending on the tide and time of year, to pick out a wide variety of birds, including common ducks such as American widgeons, mallards, northern pintails, ruddy ducks, scoters, and scaups, and shorebirds such as American avocets, dowitchers, and willets. Perhaps a great blue heron will pay you a visit, landing silently on a nearby rock.

Where there are ducks and shorebirds, especially in the fall, there may be falcons—merlin and peregrine—hunting them. Be alert for something “putting up” the birds: when panicked, great clouds of waterbirds will lift from the mud flats or water in a noisy attempt to evade and confuse their predators. Nothing sets a birder’s heart pounding like the glimpse of a dark shape, wings swept back, streaking seemingly out of nowhere in hot pursuit of a meal.

At about 0.7 mile, the paved path bends left, away from the water. Here a set of railroad tracks dead-end at an exercise station, and a small spit of land juts southwest into the water beside Elmhurst Creek. At high tide, look for large numbers of shorebirds roosting at the end of this spit. Species here may include American avocet, black-necked stilt, willet, marbled godwit, dowitcher, and small sandpipers. Roosting is a crucial part of a shorebird’s daily activity, when the rising tide covers feeding areas and forces the birds to seek out protected high ground. Disturbing roosting or feeding birds threatens their delicate, life-and-death struggle to balance energy, rest, and food requirements. It may be fun for kids or dogs to chase birds, but it is cruel sport.

After crossing Elmhurst Creek on a bridge and scanning its banks for more birds—perhaps a greater yellowlegs—you reach a T-junction with the Elmhurst Creek Trail. Turn right and follow it back toward the marsh. Soon you reach another bridge, this one across the mouth of San Leandro Creek, here a wide channel. Just before the bridge, you pass a junction on your left with San Leandro Creek Trail East; just after the bridge is a junction with San Leandro Creek West. Once across the bridge, bear right on the Arrowhead Marsh Trail as it passes a large parking area, fishing pier, and picnic area. (Toilets and water are available here.)

Although your attention may be focused on birds, you may also notice large numbers of California ground squirrels, standing at attention by their burrows or scurrying through the grass in the open field, left. A squirrel hole is sometimes taken over by a pair of burrowing owls, so it is worth scanning with binoculars all squirrel colonies you come across. Ahead, past the fishing pier, is a boardwalk jutting a few hundred yards into the marsh. This is a great spot to scope the mud flats and pickleweed for ducks and shorebirds, but also look under the boardwalk for Virginia rails—dark brown, robin-sized waders that prowl the overgrown areas of the marsh. In addition to pickleweed, other common salt-marsh plants found here include cord grass and salt grass. Each of these plants is tolerant of salt water to a different degree, and this accounts for its distribution, relative to the high-tide line, in the marsh.

Arrowhead Marsh and the nearby mud flats that are exposed at low tide occupy a large part of San Leandro Bay. With the sun at your back, the boardwalk is a fine vantage point for viewing shorebirds. Because the tide dictates shorebird behavior, you should plan your viewing for a few hours before or after high tide. This will allow you to observe birds as they feed, while they are still close enough to identify. Once the tide goes all the way out, the birds disperse and are hard to see clearly. You may notice broken mussel shells near the end of the boardwalk; these are deposited by gulls, which drop them from the air in an attempt to crack them open.

You may see a white, heron-like bird feeding on fish in the shallows near the walkway, and then do a double-take when you notice one just like it, but almost twice as big. The smaller is called a snowy egret, and the larger is the great egret. Careful study reveals other differences besides size. The snowy has a black bill and golden feet, while the great has a yellow bill and black feet. Both are graceful fliers, and, with their cousin the great blue heron, add an exotic touch to marshes and wetlands of North America.

Southwest of Arrowhead Marsh are Airport Channel, Doolittle Dr., and the hangars of Oakland International Airport. Being in the midst of urban hustle and bustle gives you an appreciation for this 739-acre wildlife sanctuary, opened to the public in 1979 as the San Leandro Bay Regional Shoreline, and renamed in 1992 to honor the slain civil-rights leader. Along the southwest edge of Arrowhead Marsh is another good place to look for shorebirds, but you will probably need a spotting scope to identify individual species. Closer in, birds may be feeding along the near shoreline of Airport Channel.

Besides pickleweed and marsh grasses, you may notice tall, thick-leaved plants with bright yellow flowers, growing along the upper edge of the marsh. This is gumplant, which is named for the sticky resin that oozes from the daisy-like flower buds. These attractive plants bring color to marshes around San Francisco, San Pablo, and Suisun bays from late summer through fall. A dirt road, left, parallels your route from the Arrowhead Marsh parking area to another just off Swan Way, your turn-around point. A grassy field, home for ground squirrels and perhaps a pair of burrowing owls, lies between you and this road.

As you continue southeast on the Arrowhead Marsh Trail, other shorebirds to look for include dunlin, a chunky sandpiper with a long bill curved down at the tip; and black-necked stilt, a black-and-white wader with shocking pink legs. A bit farther along, as you near Swan Way, look for a large black pipe that runs under your path and into Airport Channel. On the mud flats, right, you may find least sandpipers, small brown and white birds with pale legs; on the pipe itself there may be black turnstones, pecking at barnacles. When you reach the parking area at Swan Way, which has water, a toilet, a picnic table, and a grove of trees planted to honor Dr. King, turn and retrace your route to the Garretson Point parking area.