San Diego Natural History Museum--Your Nature Connection[San Diego County Bird Atlas Project]
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Exploring the Santa Rosa Mountains

Salton Sea from the Santa Rosa Mountains, photo by Lori Hargrove, 2000

The Santa Rosa Mountains rise like a knife blade from the floor of the Anza-Borrego Desert over a mile into the sky. Designated wilderness, the portion of the range in San Diego County is accessible only by a round-trip hike of at least 12 miles or by helicopter. Intrepid hikers occasionally make the trip but exploration of the mountains' biology is just beginning. The Santa Rosa Mountains are so remote from any road that one simply cannot hope to hike in, have time enough for any meaningful study, and carry enough water to make it out alive. Yet they are of great interest biologically, in their undisturbed isolation and supporting the largest stands of pinyon pines in San Diego County.

Park biologist Paul Jorgensen is making coverage of the Santa Rosa Mountains a priority for the San Diego Natural History Museum's San Diego County Bird Atlas project. To this end, he has hired a helicopter to carry birders and botanists into the mountains, in tandem with other of the park's projects requiring transportation by air. Paul and botanist Larry Hendrickson visited the Santa Rosa Mountains in early June 1999 but their trip was plagued by bad weather—the mountains' rugged topography, combining cool mountain and hot desert air, itself often induces fierce winds.

Nolina parryi, photo by Lori Hargrove, 2000

From 19 to 21 January 2000 park ranger Robert Thériault, birder Lori Hargrove, and Natural History Museum ornithologist Philip Unitt visited the Santa Rosa Mountains, each in a different area. The habitat is like nothing else in the county, the north-facing slopes dominated by the pinyon trees, few of which exceed a height of 15 feet. The juniper trees are low and shrubby, suppressed by the ferocious wind that so often sweeps the ridge. Scrub oaks were numerous and seemed to attract birds more than the pinyons (which seemed already to have been stripped of their nuts). Many Mojave Yuccas and patches of Desert Agave implied a habitat good for Scott's Orioles in the breeding season. Most spectacular was the yucca look-alike Nolina parryi, some of them enormous with trunks two feet in a diameter. Cacti were abundant: the Beavertail, the yellow-spined prickly pear Opuntia chlorotica, and a silver-spined cholla. Balancing these desert plants were chaparral shrubs: mountain mahogany, manzanita, and, strangely, the Yellow Bush Penstemon, Keckiella antirrhinoides, more expected in coastal sage scrub than in the Santa Rosa Mountains. In more open areas the Blackbrush, Coleogyne ramosissima, proliferated, evoking the high, cold desert of the Great Basin. An undetermined species of Heuchera was growing from under rocks on the steepest north-facing slopes, suggesting that further biological surprises await discovery.

Birds of any kind were remarkably scarce, perhaps owing in part to the dryness of the past two winters. Yet these were an interesting mix of coastal species, like the Scrub Jay, Bewick's Wren, Spotted Towhee, and Bushtit, with desert birds like the Black-throated Sparrow and Ladder-backed Woodpecker. Several Rufous-crowned Sparrows along the east base of the mountains extended the known range of that species 15 miles to the east. Surprising were several Sage Sparrows of the pale desert subspecies Amphispiza belli nevadensis—expected on alkaline flats on the desert floor but not in pinyon woodland on high ridges. Also unexpected were Scott's Orioles. Though the habitat is good for breeding of this striking black and yellow bird, it wasn't expected in winter. The nectar of agave and yucca flowers is the staple of its diet, and these plants bloom only in summer. There were no Pinyon Jays, so we can now put to rest the fantasy that a population of this bird is resident anywhere in San Diego County—despite its being resident just a short distance to the north in Riverside County and to the south in the Sierra Juárez of Baja California.

As remote as the Santa Rosa Mountains are by today's standards, Indians once visited the area regularly to harvest the pinyon nuts. Pottery fragments, a sleeping ring, and petroglyphs remain as a silent reminder of the people whose toughness and determination now leave us in awe. Discovery of a previously unrecorded rock art site was an unexpected by-product of this expedition focused on birds!

For more on identification and distribution of the Orioles, see Focus on the Scott's, Bullock's, and Hooded Orioles.

View east from the Santa Rosa mountains over the Salton Sea, over a mile below.
Nolina parryi, perhaps the most striking plant of the Santa Rosa mountains
Pinyon woodland on the crest of the Santa Rosa Mountains (next page).
Photographs by Lori Hargrove, 2000.