The lower Colorado Desert has one of the most arid climates in California, but includes several widely-spaced patches of microphyll woodland, much of which is associated with washes that flow east into the Colorado River. The larger ones include Chemehuevi Wash (San Bernardino Co., opposite Lake Havasu City, AZ), Vidal Wash (San Bernardino/Riverside Co., southwest of Parker, AZ) and Milpitas Wash (Imperial Co., west of Cibola NWR). Another major occurrence of this habitat lies along the northeastern base of the Algodones Dunes about 30 miles west of the river, halfway between the river and the south end of the Salton Sea. Dominant trees include Ironwood (Olneya tesota), Paloverde and Honey Mesquite. Essentially the entire IBA falls under the jurisdiction of the BLM.

Ornithological Summary

Because this area is located along the flight path of migrant songbirds moving up into California from Mexico (toward the Transverse Ranges and into the Sierra Nevada), any patch of green vegetation can attract large numbers of birds in April. In the Algodones Dunes woodland, any rain from the previous winter runs off the Chocolate Mtns. to the east and collects in sumps that can remain boggy for months (occasionally with small ponds forming), which make the habitat even more attractive to migrants. Long-eared Owls breed locally, and can form large winter roosts here. The scrubby woodland here also represents westernmost outposts for several primarily Mexican species more common in Arizona, such as Elf Owl (recently discovered in the Indian Pass Wilderness southeast of the Chocolate Mtns.), Gila Woodpecker (west to the Algodones Dunes), and Northern Cardinal (Vidal Wash). Vidal Wash also reaches the southern portion of the range of Bendire's Thrasher (England and Laudenslayer 1989).

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Conservation Issues

While portions of these sites are secure due to their remoteness, those closest to roads are heavily used by OHV enthusiasts. The unique woodland at the Algodones Dunes has been the site of recent controversy between the BLM and OHV riders, thousands of which descend upon the "town" of Glamis during winter weekends. Various lawsuits over the management of these riders have forced the closure of several areas, further angering riders and inviting retaliation. Mining is also an issue locally. Resort/marina development associated with the Colorado River has removed large tracts of mesquite woodland within this IBA (e.g. "Big River", part of Vidal Wash), which has led to regional extirpations of scarce taxa such as Elf Owl.

Ownership

Essentially the entire IBA falls under the jurisdiction of the BLM.

Habitat

The lower Colorado Desert has one of the most arid climates in California, but includes several widely-spaced patches of microphyll woodland, much of which is associated with washes that flow east into the Colorado River. Another major occurrence of this habitat lies along the northeastern base of the Algodones Dunes. Dominant trees include Ironwood (Olneya tesota), Paloverde and Honey Mesquite (which should be categorized as "Desert Wash").

Habitat Type: "Shrubland/ Shrubland/ Desert Riparian" refers to "Desert Wash" with Ironwood, Paloverde, and Honey Mesquite.

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