Conserving the Nature of America
Fish and Wildlife Service Determines Sonoran Desert Area Bald Eagle Is Not a Listable Entity Under the ESA

February 24, 2010


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After evaluating current scientific information, the U.S. Fish and Wildlife Service has determined that the bald eagle in the Sonoran Desert area does not meet the criteria of a distinct population segment, and is therefore not a listable entity under the Endangered Species Act. Bald eagles in the Sonoran Desert area will continue to be protected under the Bald and Golden Eagle Protection Act and other federal and state statutes, as do all other bald eagles in the U.S.

“We recognize that bald eagles in the Sonoran Desert area have great importance to people of our region, especially Native Americans,” said Benjamin Tuggle, the Service’s Southwest Regional Director. “We will continue to work with Tribes, the states and other conservation organizations in this region to conserve the bald eagle in the Sonoran Desert Area and will continue to protect it under the Bald and Golden Eagle Protection Act.”

In 2004, the Service was petitioned to classify the southwestern desert nesting population of the bald eagle as a distinct population segment (DPS) so it could be eligible for continued protection under the ESA should the bald eagle be removed from the federal list of threatened and endangered species nationwide. In July of 2007, bald eagles in the lower 48 states, including the Sonoran Desert area, were determined to be recovered and were removed from the list.

Following a U.S. District Court order on March 6, 2008, the Service published a rule restoring protection for the Sonoran Desert area bald eagle as threatened under the ESA, pending a court-ordered completion of a full evaluation and finding as to whether the population constitutes a DPS.

For a population to be recognized as a DPS, the Service must complete a two-step process. The first step is to determine if a vertebrate population is discrete. If the population is discrete, then we proceed to the second step, which is to determine whether the population is significant. If the population is determined to be both discrete and significant, then it is recognized as a DPS, a listable entity under the Endangered Species Act.

The Service’s current evaluation of the best available information on the bald eagle in the Sonoran Desert area found that the population is discrete – it is markedly separate from other populations of the species due to a lack of immigration to and emigration from surrounding bald eagle populations. In addition, the areas immediately surrounding the Sonoran Desert Area lack the appropriate bald eagle habitat parameters of water, fish, and nesting areas and contain no known breeding bald eagles.

However, although eagles persist in an arid region, Sonoran Desert area bald eagles do not appear to express any adaptations that are not found in bald eagles elsewhere, and were not found to have any biologically distinguishing factors important to the species as a whole. Therefore the population does not meet the significance criteria of the agency’s DPS policy.

The Service conducted numerous meetings with Native American tribes, entered into consultation with affected tribes, and evaluated extensive tribal records pertaining to eagles to ascertain the traditional ecological knowledge provided by area Native Americans. Traditional ecological knowledge was included in the Service’s DPS finding.

The assessment of bald eagles in the Sonoran Desert area included all bald eagle territories within Arizona, the Copper Basin breeding area in California near the Colorado River, and the territories of interior Sonora, Mexico, that occur within the Sonoran Desert vegetation community or adjacent, transitional communities.

In the Sonoran Desert, bald eagles breed and forage in close proximity to a variety of aquatic habitats, including reservoirs, regulated river systems, and free-flowing rivers and creeks. Nests are placed mostly on cliff edges, rock pinnacles, and in cottonwood trees. Recent survey and monitoring efforts have generated new information on bald eagle distribution in Arizona. The number of known breeding areas, which numbered only three in Arizona in 1971, has increased to 59 in 2009. The number of bald eagle pairs occupying these sites increased from 3 in 1971 to 48 in 2009.

“The bald eagle has made a remarkable recovery across the nation. Even in the Sonoran Desert, where the population is constrained by the harsh conditions, bald eagle numbers and active nests have continued to climb,” said Tuggle. “While the bald eagle in the Sonoran Desert area does not meet the criteria for a DPS based on the agency’s policy, it will retain significant federal and state protection and benefit from ongoing conservation efforts.”

Tuggle noted that cooperative conservation efforts led by the Arizona Game and Fish Department, including the Arizona Nest Watch Program, will continue to promote bald eagle conservation in Arizona.

For more information on this decision and bald eagles in the Southwest, please visit


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