Bald Eagles Face a New Silent Threat

The bald eagle in the United States is, without a doubt, a banner species for the power of conservation initiatives to stop the unnecessary destruction of the environment. The species—which had an estimated population as high as 500,000 individuals in the mid 18th century—was diminished to only 412 nesting pairs in the 1950s. Thanks to several efforts—most notably the banning of DDT, which caused deadly thinning of egg shells—the bald eagle was revived and, in 1995, officially removed from the endangered species list.

Now, bald eagles are facing a new threat—and researchers are racing to identify the source.

The culprit is a neurological disease known as avian vacuolar myelinopathy (AVM) that causes brain lesions and impaired motor skills that ultimately result in death. First observed in Arkansas in 1994, instances of the condition have steadily increased and spread across the country.

Now, Susan Wilde—a professor at the University of Georgia Warnell School of Forestry and Natural Resources—believes she has found the cause of AVM. Her research suggests that AVM has its source in a neurotoxin produced by cyanobacteria—better known as "blue-green algae."

This algae, which coats the leaves of aquatic plants, has become more common and, as a result, is becoming concentrated in bald eagle prey species.

Identifying the potential cause of the problem has allowed researchers to begin mapping problematic areas. The next step, is working with watershed managers to prevent—or at least limit—bald eagle exposure to this deadly new ingredient in their food.

Bald Eagles Face a New Silent Threat
The iconic bald eagle was brought back from the brink of extinction thanks in large part to legislation banning DDT. Now, the birds face a new silent threat that could reverse this progress.

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