McCosker Loop Trail

Dogs No Dogs

Features Birding · Views · Wildflowers · Wildlife

Parking is free. The bathroom is located up the trail from the parking lot near the junction with the Pacific Pea Trail. Be cautious of poison oak. It is very common in this park. Know how to identify it and never touch it. Some sections of this trail can be a bit overgrown, especially the lower portion between the Arroyo Willow Trail and the Gudde Ridge Trail. Pants and boots are a good idea, and you may want to use gaiters too.

This is one of the most rewarding runs in the Eastport region of Sibley Volcanic Regional Preserve. The trail can be done in either direction, but in my opinion it is best done clockwise, which gives the best views at the top. To reach the trail, park at the main parking lot off of Pinehurst Road and take the Ninebark Trail. In 100 feet, continue straight onto the Gudde Ridge Trail. Follow this trail uphill for about 0.25 mi. On the right is the trail terminus. Continue straight (northeast) uphill. After about another 0.25 mi, and a steep climb, reach a small saddle. The Gudde Trail continues left (northwest). Straight is a gate with a no trespassing sign (behind it is EBMUD land). Right (southwest) is the start of the McCoscker Loop Trail.

The trail climbs up the hill to south, the slowly descends, allowing for great views over Orinda, Moraga, and Canyon. Flowers in the springtime are abundant on these open grassy slopes. Keep an eye open for blooming bush lupine and California Poppies.

The trail descends gradually for about 0.5 miles, followed by a short climb. Afterwards, the trail drops into shaded oak forest as it curves towards Leatherwood Creek. At 1.4 mi from the start of the trail, reach a junction with the Arroyo Willow Trail (left, west). You can choose to take the Arroyo Willow Trail down to the Ninebark Trail, which makes a convenient shortcut down to the parking lot. The McCosker Loop Trail continues right (north), where it continues to curve northward around the hillside, ultimately reaching the junction with the Gudde Ridge Trail that you passed earlier. Left (southwest) returns to the parking lot.

Typical flora and fauna of the oak chaparral. Trees include oak, madrone, California Bay, toyon, and buckeyes. Near the creek is the Arroyo Willow. Coyote brush, blackberries, and seasonal flowers like lupine and California Poppies are common. Watch out for poison oak! Birds are the most typical fauna, especially juncos, chickadees, finches, towhees, and nuthatches. Occasionally acorn woodpeckers can be seen, as well as hawks, jays, crows, etc. Other fauna include deer, coyotes, ground squirrels, etc.