ENHS Nature Trails Jan 99 Article 3

"A Season of Eagles! Five Reasons for Joy..."
by Louise Shimmel
of The Cascade Raptor Center on Fox Hollow Road
(Condensed here with Louise's permission)

Three bald eagles and two goldens underwent successful diagnosis and rehabilitation at the Eugene facility this year. (In the first ten years of operation the Center had only received nine eagles in total.)

EAGLE 1: A US Forest Service biologist brought in a golden eagle found in the driveway of a residence in McKenzie Bridge. Besides being thin (7 _ pounds) and very anemic, she exhibited a flaccid paralysis of the feet. Handlers could open her balled feet but she could not. This type of leg paralysis is typical of poisoning from either an organophosphate/carbamate pesticide or lead.. Intravenous treatment began immediately for starvation and anemia and for the prevention of aspergillosis, a fungal disease common in eagles, especially those debilitated or stressed in captivity. After test results confirmed lead poisoning, the golden began a chelation treatment ($75 a teaspoon) that eventually decreased her neurological impairments. She could move a toe after three days. 10 _ weeks later, she reached 12 pounds and moved to a new home at the Chintimini Wildlife Rehabilitation Center in Corvallis for flight conditioning. This eagle, the most expensive the raptor center has rehabilitated, soared to freedom after five and a half weeks of flight training--a total of four months in care.

"How does a bird get lead poisoning?" It is likely that the eagle ate a game bird or small mammal killed or injured by lead shot, or she ate a duck or other waterfowl who had ingested spent shot while picking up grit. After the eagle consumed this prey, the lead sat in the acidic environment of its stomach long enough to leach lead and cause a toxicosis. (It is now illegal to shoot waterfowl with lead shot but not illegal to shoot other birds and/or small animals with lead shot.)

EAGLE 2: This bald eagle was found literally "spread eagled" in a grass seed farm in Lebanon by a sheep rancher who loves seeing these raptors fly overhead. Crossing the muddy field to reach the stricken eagle, Louise sank to mid-calf with every other step and lost her boots once in an attempt to extricate herself. The mud made it clear, however, that the bird's incapacitated condition was sudden; the tail and wing tips were not dirty or frayed. The eagle had an extremely rigid paralysis of the legs, but otherwise, "she was in good flesh, 10 1/2 pounds, strong and alert." Her pupils occasionally were constricting and dilating spastically. Diagnosis ruled out spinal or head trauma, and the Center initiated treatment for both organophosphate and lead poisoning. Later lab results determined a deeply depressed level of the enzyme cholinesterase, affected by organophosphates and carbamates. Normal levels are 2000 IU/L; hers were 62. After five days of treatment, she could bend her legs and sit on her hocks; by the ninth day she was standing. After 2 1/2 weeks the Center transported her to Corvallis for conditioning, and this very fortunate bald eagle soared to freedom two weeks later.

"How does a top-of-the-line predator get poisoned by an insecticide? Although most current pesticides do not remain long in the environment as lethal toxins, they do "bio-accumulate." EX: A bird eats a number of insects, each with a small amount of pesticide--the poison usually gets stored in the fat cells of the bird; a predator eats a number of these birds who have eaten a number of these insects who have ingested the pesticide. At any level there could eventually be enough accumulation for death. Worse yet, some ranchers or farmers illegally lace carcasses with organophosphate toxins with the specific goal of poisoning the scavengers. The dose ingested in these cases is usually so overwhelming it inevitably leads to death. If the predator bird is flushed from the carcass soon enough however, the result may be the scenario described for Eagle 2.

Find the very interesting sagas of Eagles #3, #4, and #5 and the complete stories of Eagles #1 and #2 in "The Wildlife Lifeline," The Cascades Raptor Center Newsletter. Phone: 541-485-1320 e-mail: raptors@efn.org Web page: http://www.efn.org/~raptors.

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