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State Plans Arizona
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Sonoran Desert
(Area - 11,362,300 ha)
Description - The Sonoran Desert receives a low and unevenly distributed
amount of precipitation over extensive plains and isolated mountains surrounding the
northern end of the Gulf of California. In the United States it is centered in southwest
Arizona and southeast California and extends south through most of Baja California Norte
and Sur and the western half of the state of Sonora. Vegetation is sparse and differs from
other American deserts by a greater dominance of trees, including arborescent cacti such
as the saguaro. Creosote is a common and widely distributed shrub.
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Conservation recommendations and needs - Grazing, water use, fire, and increasing human populations are among the notable conservation issues in the Sonoran Desert.
Riparian forests and woodlands are the most severely threatened habitat type in this physiographic area. Dams, water diversions, clearing for agriculture or development, and grazing are among the pressures on riparian strips, and birds dependent on these systems have declined significantly as a result. Conservation objectives focus on Common Black-Hawk, Yellow-billed Cuckoo, Willow Flycatcher, and Lucy’s Warbler. The varying needs of these four species, in combination, capture the ecological processes that should support the entire riparian avifauna. Existing quality habitat must be maintained for each of these birds and significant additional areas restored to ensure health of populations. This riparian habitat also supports many wintering temperate migrants and is key habitat for in-transit migrants moving through the Sonoran Desert.
The vast majority of priority birds in this system breed in Sonoran Desertscrub habitat. In some cases, particularly in Arizona, large areas of this habitat have been developed for human occupation, driving out many of the more sensitive birds. With the spread of invasive non-native grasses that can serve as better fuel than bare ground, the incidence of fire in this habitat has increased. Native plants are not fire-adapted, and fire-induced changes in the plant community may be harming some bird populations. Grazing, particularly by feral burros, may also be altering vegetative structure and thus the bird community. Maintaining large saguaros and other key components of native vegetation over large areas is an important recommendation.
Sonoran Desert Grasslands are fire-adapted features of some of the larger plains and river valleys of this area that have been seriously reduced largely due to grazing. Birds negatively affected by this change include the Rufous-winged Sparrow and the Masked subspecies of Northern Bobwhite. Maintenance of core remnant grasslands and restoration of additional areas through improved grazing regimes is a high conservation priority.
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