PRBO Conservation Science
Quarterly Journal of PRBO Conservation Science, Number 137, Summer 2004: 2004 Notes from the Field


Sonoran Desert Saga

Chris McCreedy

Lasting Legacy
Sonoran Desert Saga
Central Valley Wetland Life
Bering Sea Bonanza
Urban Least Terns
Eastern Sierra Education
Bird Bio
Measuring Ocean-Climate Change
Focus on Fall Migration
Estate Gift to PRBO

Chris McCreedy charts a course through desert habitat. Photo by Chris Rintoul.

I am in the middle of the Colorado Desert-a section of the Sonoran Desert, the hottest, driest section, bisected by the Colorado River. Today I am surveying several kilometers of Milpitas Wash, one of a number of ephemeral watercourses that "flow" from the mountains of southeastern California to the Colorado. I am looking for Gila Woodpeckers and scouting out areas for nest-searching plots in 2005. Gila Woodpeckers are endangered in California; they have only been found to nest in riparian forest on the Colorado River and at Brawley near the Salton Sea. They are apparently sensitive to both habitat fragmentation and off-highway vehicle (OHV) use. On Milpitas, we have found four nests and aim to see if there are more. Yet their territories are nearly a kilometer across. . . maybe I should have packed a second liter of water.
Gila Woodpecker. © Peter LaTourrette (

Though I am in the middle of the desert, I am surrounded by old-growth trees. Most stand over seven meters high and are over a meter across at their base. Milpitas Wash supports the largest Sonoran Desert woodland in the United States. Most of the trees are legumes: mesquites, acacias, palo verdes, and ironwoods; there are also desert-willows. Most of the trees are in flower, and insects are everywhere. The air is heavily perfumed.

I am also surrounded by birds: though miles from the closest surface water, spring migrants are everywhere. Bullock's and Hooded Orioles are gorging on the fragrant desert-willow flowers. One mesquite in full flower has attracted enough bees to be heard at 100 paces. In it are Lucy's, MacGillivray's, Nashville, Wilson's, Yellow, and Audubon's Warblers all feeding on and amongst the bees. Spring grasses are supporting unbelievable numbers of Green-tailed Towhees, White-crowned Sparrows, and Brewer's sparrows. The Brewer's Sparrows will often sing in unison, making me feel like I am in some sort of UFO demolition derby. The concept of a bird, and what it means to be a migrant, is brought home by the sight of Northern California riparian species such as Wilson's Warblers foraging in creosote, or Black-headed Grosbeaks singing early-spring song from saguaro cacti.

California's desert washes remain virtually uninvestigated for birds. Population trends are largely unknown for several California desert breeders, such as Bendire's Thrashers, Crissal Thrashers, Black-tailed Gnatcatchers, and Lucy's Warblers. The extent to which western neotropical migrants rely on these habitats remains a mystery.

Throughout the deserts, washes make for scenic and useful OHV thoroughfares. The Bureau of Land Management, with the assistance of the California Parks and Recreation Green Sticker Program, has partnered with PRBO to inventory and monitor OHV impacts on birds across the Mojave and Sonoran Deserts of California.

Each wash holds new secrets, and simultaneously monitoring several (from Needles, California, to the Mexican border) will enable us to investigate ephemeral populations across a region notorious for its spotty rain.

I cannot wait to get to the next wash. I just need to find a little shade first.

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