Birding on Mount Diablo
An Introduction to Birding on Mount Diablo
By Kevin Hintsa, December 1999
Mount Diablo (here defined as Mount Diablo State Park and Diablo Foothills Regional Park) is located in Central Contra Costa County and provides birders with a large public area in which to explore birds of several habitats (including chaparral, oak woodlands, grassland, and rock outcrops). Over two hundred bird species have been sighted on the mountain, and it is well known to birders for its superb examples of chaparral birds, spring migrants, numerous raptors, and such locally elusive species as Prairie Falcon, Hermit Warbler, Hammond's Flycatcher, Calliope Hummingbird, Sage Sparrow, and Black-chinned Sparrow. Mount Diablo is also known for its spectacular views, odd rock formations, fascinating geology, over seven hundred plant species (including several endemics), about seventy butterfly species, and interesting wildlife (including Bobcats and Coyotes).
Preparing for your visit
Before venturing on the mountain, a few words of caution. Dress for erratic weather: the park is well known for its bitter cold in winter. Fog is prevalent in winter and often persists into June. Windy weather can occur anytime and extreme heat is present in summer. Keep in mind that the summit is over 3800 feet in elevation and often has totally different weather than halfway up the mountain. Much of the area is wilderness (often with steep trails), so bring sunscreen, water, and food.
The roads are narrow, often rough in spots and winding. Shoulders are often uneven and the pullouts on the lower half of the mountain should be avoided in rainy weather. Watch out for bad drivers and bicyclists. Avoid all days where there is snow on the top and try to avoid early spring weekends (unless you like crowds). Avoid climbing on rock formations. Watch for loose rocks, ticks (especially around chaparral), yellow jackets and rattlesnakes. Poison Oak is one of the most common and widespread plants in the park, so avoid going off trails. Consult a map of the mountain and read up on park rules (and leave your pets at home).
In general, the majority of good birding is in the canyons and the lower half of the mountain. Probably the three finest areas of birding are Pine Canyon, Mitchell Canyon, and the Rock City area. The best examples of chaparral birds can be found in the area from just below Toyon Picnic area to Pioneer Horse Camp and also around Muir Picnic Area. The canyon areas such as Dan Cook Canyon and Curry Canyon can provide some shade in the heat of summer but avoid these two sites in winter. The area from Curry Point to Knobcone Point has the driest trail in rainy weather (and one of the hottest temperatures in summer). All of the canyons can be terribly muddy during the rainy season. Mitchell and White Canyon can be very exciting in April and May and is perhaps one of the least demanding of the trails. Donner Canyon can be equally exciting during this same time, but it is very rugged as are most of the areas around the peaks (such as Eagle and North Peaks). The Summit area is generally very poor birding, although I have seen some good birds here (mostly during spring migration) like Black-chinned Sparrow, Hermit Warbler (sometimes common), Calliope Hummingbird, Lawrence's Goldfinch (probably regular here in late spring) and once a Cassin's Finch. Blue Oak and Oak Knoll picnic areas can be superb in May, especially for warbler flocks. If on a short driving tour of the mountain in spring, start at South Gate Road and check the areas of Rock City, Curry Point area, Junction Campground area, Wildcat Group Camp, and Blue Oak-Oak Knoll picnic areas and, if time permits, a few pullouts along North Gate Road (especially for Lark Sparrow, Rufous-Crowned Sparrow, Rock Wren, and Golden Eagle).
The most sought after bird in the park by visiting birders is probably the Black-chinned Sparrow. It is best found by looking for singing males in the morning from mid-May to mid-June, probably peaking soon after Memorial Day weekend. Its preferred habitat is burned-over areas of chaparral (or stunted chaparral with large gaps) that are dominated by chamise that is more than two years, but less than twenty years old. In some years the species is fairly common and in other years it is nearly absent. In recent years, the best sites have been along Fossil Ridge (hike out of Uplands Picnic Area through the gap in the grassland), South Gate Road at about two-tenths of a mile below South Gate kiosk (also park at Uplands Picnic Area and hike back down the road as there is no parking below Rock City), the area around Pioneer Horse Camp to Blue Oak Picnic Area, and Muir Picnic Area. I've also had birds (mostly far from the trail) at Wall Ridge (excellent habitat at present), Mitchell Canyon, the south side of the Fire Interpretive Trail, Prospector's Gap Road, Juniper Campground, and at various burn sites along lower South Gate Road.
Pine Canyon is located on the southwestern side of Mount Diablo. It has numerous access points, each having its own merit. My two favorite access points are Macedo Ranch parking lot (at the very north end of Green Valley Road out of Danville, self-registration parking here for two dollars) and the Castle Rock Road parking area for Diablo Foothills Regional Park and the private Castle Rock Park (free public parking just outside the kiosk for Castle Rock Park out of Walnut Creek. The public trail goes around the edge of Castle Rock Park, access through Castle Rock Park is uncertain but usually permitted if you don't linger here). It is also possible to access this area from Burma Road (at North Gate Road 3 miles up from the kiosk, this is rather short but steep and has virtually no shade) or from the Barbeque Terrace-Wildcat Group Camp area of South Gate Road (a longer hike and furthest from the best birding sections).
No matter what direction you access Pine Canyon from, the best birding is the Pine Pond area and much of the lower half of the canyon. This canyon can have miserable footing from December through at least March in rainy weather (note numerous stream crossings, plus much of the soil here is clay). At present Pine Creek flows down the main fire road near Pine Pond during the winter, creating a real mess (plus the overflow from Pine Pond bisects the trail). Also a word of warning, rattlesnakes are regular in this canyon, especially by Pine Pond. The canyon can be crowded on weekends. Regular birds in the general area include Golden Eagle, Canyon Wren (difficult to actually see), Rock Wren (especially by Sulphur Spring area, the rocky area above Macedo Ranch called "China Wall", and a rocky area in the upper part of the canyon), Brown Creeper, Lawrence's Goldfinch (I've found the nest twice here), Red-shouldered Hawk, Cooper's Hawk, Willow Flycatcher (mainly mid-August through September at Pine Pond), Rufous-crowned Sparrow, Lark Sparrow, Varied Thrush, White-throated Swift (mainly morning and evening), White-tailed Kite (mainly near Barbeque Terrace), Cassin's Vireo, Chipping Sparrow, Lazuli Bunting, Hairy Woodpecker, Hammond's Flycatcher (mainly in April and early May), Bullock's Oriole, Black-headed Grosbeak, Ash-throated Flycatcher, Western Kingbird, etc.
Pine Pond and the adjacent forest is often a magnet to birds. In about 11 years we've seen nearly 150 species within a half-mile of the pond. Pine Pond has been slowly filling in over the years and seems to have fewer rarities every year, but here is often the only chance of finding waterbirds in the park. Some of the birds I've seen by Pine Pond include Wild Turkey, Spotted Sandpiper, Black-crowned Night-Heron, Green Heron, Virginia Rail, Sora, Pied-billed Grebe, Buffiehead, Ring-necked Duck, Wood Duck, Cinnamon Teal, Green-winged Teal, American Wigeon, White-throated Sparrow, Barn owl, Lincoln's Sparrow, Yellow-breasted Chat, MacGillivray's Warbler, Sage Sparrow (out of their normal habitat here - probably post-breeding birds), Lewis's Woodpecker, etc. Many of these birds are quite rare here.
Mitchell and White Canyon
Mitchell and White Canyon are mainly accessed from Mitchell Canyon Road in Clayton. This canyon is by far the easiest canyon to bird by foot. The trail can be muddy in winter and is heavily used on weekends (watch out for speeding bicyclists, ticks, and rattlesnakes). Mitchell Canyon generally lacks the water birds of Pine Canyon (though there is a small pond between Mitchell and Donner Canyon) but has more chaparral birds. In late April to mid-May, these canyons can sometimes have a massive warbler fallout (including MacGillivray's and Hermit). Hammond's Flycatcher seems to be a regular (often common) migrant here in spring. White Canyon (and sometimes middle to upper Mitchell Canyon) is by far the best site in the park for Calliope Hummingbird, mainly from late April to mid-May. Black-chinned Sparrow is sometimes seen here, and Sage Sparrow is regular here. Phainopepla has been seen at Deer Flat and elsewhere in the canyon (also check just outside of the park along Mitchell Canyon Road in winter and spring). Lawrence's Goldfinch is regular here in spring in some years.
For further information on chaparral birds, check out Chaparral Birds. Also, much of the park (except Pine Canyon) is covered in Jean Richmond's book Birding Northern California published by Mount Diablo Audubon Society. A bird checklist is available for Mount Diablo from Mount Diablo Interpretive Association or the State Park.