East Bay Trails. David Weintraub

Park, where the 12-mile Alameda Creek Regional Trail—actually two trails, one on each side of the channel—connects to the Coyote Hills trail system.

      As you reach a short, steep pitch just below the summit of Red Hill, you may see California poppy, blue bush lupine, wild radish, and wild mustard in bloom, their bright colors contrasting with the red dirt underfoot. The only trees up here are acacias, imports from Australia. The summit itself is studded with rock outcrops of Franciscan chert, giving you a pleasant perch from which to take in the 360-degree view. To the northwest is the faint outline of San Francisco, with the dark hulk of Mt. Tamalpais looming behind. Oakland is also in view, beyond Hayward, San Leandro, and Alameda, and just north of this park vast tracts of new housing push almost to the shoreline. To the south, the vista extends past the Dumbarton Bridge and the Don Edwards San Francisco Bay National Wildlife Refuge, all the way to the Santa Cruz Mountains.

      Red Hill is an easy destination for hikers and runners, and offers spectacular views

      While on Red Hill, you may find yourself distracted from the view by the flutter of large yellow and black butterflies. These are swallowtails; there are several species, including one associated exclusively with fennel. Only hardy plants take root on this windy site, where California sagebrush and poison oak sprout from the red, rocky soil. After crossing the level summit, you descend steeply to a saddle between Red Hill and Glider Hill, the next rise south. Just as the route begins to climb once more, you arrive at a four-way junction. From here, single-track trails go left and right (but only the left-hand one, the Glider Hill Trail, is shown on the EBRPD map). Continuing your climb over moderate and then steep ground, you soon reach the top of Glider Hill, where the views equal those from Red Hill. The open, grassy summit even has a convenient picnic table; from here another unsigned single-track trail heads left.

      Now a short, steep descent brings you to another saddle and a four-way junction. At this point, the Red Hill Trail, which continues straight, is crossed by the Soaproot Trail, a dirt road. Turn left and begin a gentle descent. From here, the paved Bayview Trail, Dairy Glen picnic area, and South Marsh are all in view. Heading southeast, the Bayview Trail becomes Apay Way, which climbs over South Red Hill and continues to the San Francisco Bay National Wildlife Refuge.

      Your route zigzags moderately downhill. At a bend are several unofficial trails heading north. Pass these by and continue descending to a junction with the Bayview and Quail trails. Turn left onto the Quail Trail, a wide dirt-and-gravel road that climbs north. Just after the road crosses a rise, a single-track trail, right, offers you an easy side trip to Castle Rock, a jumble of pinnacles made from the same red chert as Red Hill.

      Following the Quail Trail downhill, you may see and hear its namesake, the California quail. On your way, you pass the Hoot Hollow Trail, left, and the Hoot Hollow picnic area, with its beautiful assortment of trees and shrubs, including acacia, coast live oak, madrone, toyon, and California buckeye. Late spring bloomers, buckeyes in flower resemble fireworks, with exploding white blossoms tinged pink and beige against bright green leaves.

      Beyond the picnic area, you pass an unsigned path heading left up some wooden steps, and a paved path, right, that leads to the visitor center. About 200 feet downhill from these paths you reach a gate and the entrance to the parking area.

      ◆ Don Edwards San Francisco Bay ◆

      National Wildlife Refuge

TIDELANDS TRAIL

      Length: 1.3 miles

      Time: 1 to 2 hours

      Rating: Easy

      Regulations: Pets are permitted only on the Tidelands Trail and must be leashed at all times. Pets are prohibited inside the visitor center and elsewhere on the refuge.

      Facilities: Visitor center with helpful staff, interpretive displays, books, maps, and information about guided nature walks and other programs; picnic tables, water, toilet, phone.

      Directions: From Highway 84 at the east end of the Dumbarton Bridge in Fremont, take the Thornton Ave./Paseo Padre Parkway exit, and go south 0.5 mile to Marshlands Road, the refuge entrance. Turn right and go 0.5 mile to a stop sign, then left into the parking area. The trailhead is at the west side of parking area, just below the large flagpole.

      This easy loop, with habitat ranging from upland to salt marsh, is a perfect introduction to the amazing variety of plants and animals, especially birds, found in the refuge. Fall, winter, and spring, when bird populations are highest, are the best times to visit; avoid afternoons, when wind and glaring sunlight may make viewing difficult. Binoculars and/or a spotting scope, along with bird and plant guides, are recommended. Consider also taking one of the guided walks, offered by refuge personnel and volunteers, which concentrate on either birds or plants. (Coyote Hills Regional Park is just north of the refuge, across Highway 84; it would be easy to explore both areas on the same day.)

      As you walk up the stairs from the west side of the parking area toward the visitor center, you pass a native plant garden containing coyote brush, black sage, toyon, and bush monkeyflower. When you reach a T-junction with a paved path, turn left and continue uphill to the visitor-center entrance, passing eucalyptus, coast live oak, and coast silk tassel on the way. After exploring the visitor center, with its many exhibits, books, and other publications, walk back outside to an observation area overlooking San Francisco Bay.

      Looking southwest, the section of the refuge in front of you extends roughly to the middle of the Bay, and includes salt ponds enclosed by levees, as well as Newark Slough, a river of tidewater flowing through the salt marsh just below the visitor center. Salt ponds, remnants of an extensive salt industry that flourished here in the mid-1800s, still exist on the Bay today. Water moves from pond to pond via channels, the salinity concentrates through evaporation, and the highly saline water is eventually processed into salt.

      This is our nation’s largest urban wildlife refuge, with more than 20,000 acres of open space set aside to protect wildlife. Three hundred species of birds and other wildlife, including a number of threatened and endangered species, live here year-round or pass through on migration. The refuge extends from Newark to Alviso and contains a variety of habitat, including open water, salt ponds, mudflats, salt marshes, and upland areas. The refuge was renamed to honor Don Edwards, a congressman from San Jose, now retired, who was instrumental in creating and then expanding the refuge through Congressional acts.

      Tidelands Trail, bridge over Newark Slough.

      Walking uphill from the visitor center, you follow the self-guiding Tidelands Trail, a loop that will take you through an upland area, beside a salt marsh, across Newark Slough, and along the shore of a salt pond. Gaining elevation on a gentle grade, you can see east to a large salt marsh bordering Marshlands Road, a good area to search for shorebirds on a rising or falling tide. As you climb to a high point, you pass some of the plants growing on the refuge, including toyon, California sagebrush, curly dock, pearly everlasting, and California buckwheat.

      A few hundred yards from the visitor center you reach a fork. Going left takes you uphill to an observation deck perched on a bluff overlooking Newark Slough; staying right bypasses the bluff. Bear left, and when you reach the observation deck via steps on your right, take a moment to enjoy a 360-degree view that encompasses much of San Francisco Bay, one of the world’s great wildlife areas. Approximately 250 species of birds can be found here, including more than one million shorebirds and waterfowl that use the Bay as a wintering area. Descending from the observation deck on a gentle grade that soon steepens, you pass some picnic tables and then the bypass trail, merging from the right.

      As you descend, the route bends left and heads toward the marsh. Shorebirds, terns, ducks, and grebes are the main avian attractions of this refuge, but there are other birds to watch for, including raptors, hummingbirds, and songbirds. A dried fennel