This IBA encompasses the Moapa Valley and the upper reaches of the Muddy River. Upon descending into the valley, the visitor is immediately struck by the lushness of the area, as the original Mormon settlers surely were. Another anomaly that is immediately apparent is the presence of a tall grove of Washingtonia palms surrounding the site of the now-defunct Warm Springs Resort. Extensive research in the area has revealed that most of the bird activity is concentrated on the Warm Springs Ranch (owned by The Nature Conservancy). The Muddy River flows through this ranch and supports a lush-if-narrow band of riparian vegetation. Irrigation canals for the ranch transport water around the valley floor and support even narrower strings of cottonwoods, willows, and tamarisk. Interspersed among these stringers of trees are fallowing pastures (the area is no longer grazed) and stands of screwbean mesquite.

Ornithological Summary

Moapa Valley supports significant breeding populations of the Endangered Southwestern Willow Flycatcher. Breeding populations of other significant species include Western Yellow-billed Cuckoo and Phainopepla. The site has been documented as a significant migration stopover for passerines, and numerous species of raptor winter in the valley.

Conservation Issues

off-road vehicle use. Site could be impacted by water pumping for power generation, Las Vegas expansion. 70% private holdings--could be developed if conservation buyers not identified.


Abandoned grazing and agriculture fields in various successional stages.

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