East Bay Trails. David Weintraub

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.

      ◆Hayward Regional Shoreline ◆

      COGSWELL MARSH

      Length: Approximately 3.3 miles

      Time: 2 to 3 hours

      Rating: Easy

      Regulations: EBRPD; no dogs.

      Facilities: A small visitor center, open only on weekends, 10 A.M. to 5 P.M., with toilets, water, books, maps, exhibits, and information.

      Directions: From Highway 92 eastbound at the east end of the San Mateo Bridge in Hayward, take the Clawiter Road/Eden Landing Road exit. At a four-way stop, turn left onto Clawiter Road, cross over the highway, and at the next four-way stop turn left onto Breakwater Ave. Almost immediately, Breakwater Ave. turns left, then veers right and heads west, parallel to Highway 92. Follow Breakwater Ave. to the Hayward Shoreline Interpretive Center, about 1 mile from Clawiter Road. Park on the right side of the road. The trailhead is behind the visitor center.

      From Highway 92 westbound at the east end of the San Mateo Bridge in Hayward, take the Clawiter Road/Eden Landing Road exit, and from the four-way stop at the end of the exit ramp go directly across Clawiter Road onto Breakwater Ave., then follow the directions above.

      Hayward Shoreline Interpretive Center, located on Breakwater Ave., just north of Highway 92. The Hayward shoreline is a good place to see shorebirds, ducks, geese, gulls, herons, and egrets. It is also home to the endangered salt marsh harvest mouse.

      The Hayward Regional Shoreline is one of the best places in the East Bay to view shorebirds. The trails are easy and bring you close to the water. The birds are used to people and will generally stay put. This semi-loop route goes through a restored marsh—a great example of how nature, with a little help, can reclaim areas previously altered by human intervention. The area gets windy in the afternoon, especially during spring and summer.

      From just behind the visitor center, operated by the Hayward Area Recreation and Park District, take a moment to look out over the system of marshes around you. To your left are the Oliver Ponds, remnants of a vast salt-harvesting industry that began during the mid-19th century in San Francisco Bay and still exists today in limited areas of the Bay. Four generations of the Oliver family farmed salt on the Hayward shoreline, and the Hayward Area Recreation and Park District (HARD) purchased the ponds from the Oliver estate in the mid-1990s. The area directly in front of you is the HARD Marsh, former salt ponds restored to tidal action in 1986. Beyond lies the fresh and brackish water Hayward Marsh, an EBRPD project created in 1988 to naturally cleanse and release into the Bay some one million gallons per day of secondary treated sewage discharge water. To your right is habitat managed for the endangered salt marsh harvest mouse.

      Turn left and begin walking west on a wide, hard-packed dirt path; your route will be along the levees that crisscross this area. The 1-mile trail from the visitor center to the Bay honors Arthur Emmes, a prominent Castro Valley optometrist and member of the Hayward Area Shoreline Planning Agency’s citizen advisory committee, who championed acquisition and development of trails along the shoreline. After reaching the Bay, this trail joins EBRPD’s trail system, which continues north about 7 miles to the San Leandro Marina.

      As you walk toward San Francisco Bay, following a slough on your left, scan the marsh to your right for shorebirds, a tribe that includes oystercatchers, avocets,