• Help for an endangered species
• Fall gatherings
• Eagles and fish
• Bald eagle anatomy
• Please! Give them room to live.
• Viewing tips

Help for an endangered species

Bald eagles joined the list of endangered species in 1967 (southern race) and 1978 (northern race) after their numbers plummeted nationwide. Researchers traced the main cause of the decline to the pesticide DDT, which concentrates as it moves up the food chain from insects to fish to eagles. High levels of DDT in eagles caused thinning of egg shells and poor nesting success. After the banning of DDT use in the United States in 1972, bald eagles started to recover and to move back into historical nesting areas. In Montana, the number of active bald eagle nests has increased steadily over the past decade, from 25 in 1979 to more than 150 in 1993.

The journey toward recovery, however, is a long one and can be hindered by shooting, electrocution from power lines, poisoning and especially loss of habitat. The Montana Bald Eagle Working Group—a consortium of natural resource agencies and organizations—actively works to ensure the long-term conservation of bald eagles and their habitat. The group has published management guidelines and works with private landowners to help them protect eagle habitat.

Fall gatherings

Montana's rivers and lakes now support more than 150 pairs of nesting bald eagles in the summer and up to 700 eagles in the winter. Starting in October, numbers swell as eagles from Canada fly south for the winter. Some remain in Montana, while others move on to other western states. Eagles can be seen in migration corridors. Most fly along major rivers.

Black specks clear the rocky ridge high above a river, circling and descending until viewers can see outstretched wings and flashes of white heads and tails. It's November. Bald eagles are flying south from Canada through Montana. Their sharp eyes scan land and open water from food. It takes energy to fly long distances and to stay warm in chilling weather.

When bold eagles find food in abundance, spawning kokanee for instance, they linger to feast. Migrating eagles sport others feeding and stop to investigate. Such eagle congregations can grow to 500 birds or more, depending on how much food there is to go around. Eagles will return each year, in ever increasing numbers. However, if fish are not present, the birds will move on south, feeding on fish, waterfowl or carrion.

To see our national symbol swooping and souring above Montana's rivers in great numbers is to witness a powerful drama.

Eagles and fish

Migrating eagles need clean water to drink, sheltered places to rest and food free of toxins to eat. Fish are the staple of bald eagles throughout most of North America. In Montana, fall migrating eagles detect fish below the turbines of Libby Dam on the Kootenai River and spawning salmon on the Missouri and other waters. An eagle may eat as many as six salmon per day.

Kokanee, a landlocked salmon related the Pacific Coast sockeye, have been introduced in many places in Montana. Each fall, adult salmon swim upstream, spawn (deposit eggs) and then die, their task completed. The dead kokanee are especially important to young eagles just learning to fish.

Kokanee populations seem to boom and bust. Eagle gatherings follow the same pattern. The kokanee run on McDonald Creek in Glacier National Park attracted eagles by the hundreds and viewers by the thousands until the salmon run declined severely in the mid-19880s. The future of any kokanee run is hard to predict. Bald eagles, however, will thrive with or without certain kokanee runs if their essential needs are met.

Bald eagle anatomy

• Head—The white head identifies adult birds of at least four years in age.
• Eyes—An eagle may see three times better than a human and can spot a small animal a mile away.
• Beak—The long, hooked beak is adapted to tearing food. Its color changes with age from black to brown to bright yellow.
• Wings—Powerful wings propel an eagle in level flight up to 35 mph. The same wings act as brakes to pull the heavy bird safely from a swift dive. Wingspan ranges from 6.5 to 8 feet.
• Body—An adult weighs from 7 to 13 pounds and is the largest bird of prey in Montana. Females are up to 30% larger than males.
• Talons and Toes—Sharp, black talons grasp and kill prey. Tiny spikes on the bottom of yellow toes hold prey in place. An eagle may fly several miles gripping a fish.
• Tail—Twelve tail feathers act as a rudder in flight. When spread wide, the tail increases lift. As an eagle matures from juvenile to adult, the while color gradually increases and length of feathers decreases.

Please! Give them room to live.

The best way to appreciate a gathering of eagles is from a distance and from one place. Remember that when an eagle flies off to avoid people, that bird may be using energy needed to make it through the winter. However, when onlookers remain in one predictable place, eagles can adjust their feeding patterns. Those birds sensitive to the presence of people will fish undisturbed up or downriver. Tolerant eagles will move in as close as 50 yards to viewers.

Viewing tips

• Come early in the day to see eagles at peak of fishing and feeding. Listen to high pitched chittering calls. See immature attempt to steal catches from other eagles, sometimes locking talons in midair. At dusk, eagles depart for a communal roost site protected from weather and disturbance.
• Bring binoculars and a spotting scope. Scan trees from silhouettes of perching birds. Some trees will hold as many as 30 birds. Watch an eagle preen itself by nibbling on a special oil gland above its tail, then smoothing the oil over its feathers. Oil keeps water from soaking through feathers.
• Photographing eagles is best with a long lens (at leas 200 mm) and tripod. Camera flashes may disturb birds.
• Bring bird and mammal field guides. You will probably see more than eagles from a designated viewing spot. Search for tracks of deer, raccoon, porcupine, mink, or coyote. Study the soils, grasses and rocks underfoot. Tracks, feathers and bones tell stories of river life. Be sure to leave them for others to enjoy. Watch for ducks, geese, ravens, crows, magpies and other birds.
• Warm clothing is essential. Eagle watching involves standing still. Montana temperatures in late fall and early winter may drop below freezing.

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Acknowledgements

Produced by the Montana Bald Eagle Working Group
in cooperation with Montana Fish Wildlife & Parks, Montana State Parks and Wildlife Interpretive Association, and the U.S. Army Corps of Engineers
Paper brochure design by Great Divide Graphics, Helena, MT.
October, 1993