Conservation Corner: February 8, 1999

Eagle Killer Appears Again
by James L. Cummins

Mississippi's mild climate, numerous lakes and rivers and abundant forests make the Magnolia State an excellent wintering place for bald eagles.

The Bald Eagle (Haliaeetus lecocephalus), which means white-headed sea eagle, was designated by the U. S. Congress as our national symbol on June 20, 1782. Since that time eagles have been slowly declining. The brunt of the decline hit around the 1950's when water pollution, shooting, loss of habitat and human intrusion were threatening populations of the eagle in the lower 48 states to the point that the bird was placed on the federal endangered species list in 1973.

On a related issue, for the second year in a row, a neurological disease affecting American coots has been confirmed in the Southeast United States. The disease has been confirmed in two sites in North Carolina and Georgia.

Scientists from the Southeastern Disease Study Group in Athens, Georgia, and the U.S. Geological Survey's National Wildlife Health Center in Madison, Wisconsin, have identified this disease as the same one that killed many coots and at least 58 bald eagles at numerous sites in southwest Arkansas from 1994 until the present.

To date, no bald eagles have been diagnosed with this disease in North Carolina or Georgia or even Mississippi. Scientists are conducting an investigation in the three states where the disease has occurred to determine if more bald eagles are dying. They are also investigating reports of sick or dead coots at other sites.

According to officials at the National Wildlife Health Center, "Birds that are affected have very erratic flight patterns or are unable to fly, swim tipped to the side or with one or both legs extended and may be trying to swim on their backs. The birds stagger and have difficulty walking when on land. They usually appear alert and may be unable to escape when approached."

"The disease is diagnosed by microscopic observation of spaces in the white matter of very fresh brain tissue from affected birds. Through electron microscopy, it has been determined that the spaces are caused by separation of the myelin layers that surround the nerves," stated the health officials.

Myelin is the protective outer covering of nerves. It is similar to the outer covering of electrical wire. Disruption of this covering changes the transmission of messages through the central nervous system.

Since 1994, scientists have conducted extensive laboratory and field studies of the disease. They have not succeeded in identifying the cause of the disease, but believe it is either a natural or artificial toxin. However, tests for toxins known to cause similar diseases in other species have been negative. Tests for infectious diseases have also been negative.

James L. Cummins is Executive Director of the Mississippi Fish and Wildlife Foundation in Stoneville, Mississippi. Known as "Wildlife Mississippi," the Foundation is a non-profit, conservation organization founded to conserve, restore and enhance fish, wildlife and plant resources throughout Mississippi.