Friday, August 31, 2007

Eagles Soar!

June 28 the majestic bald eagle spread its wings and flew off the endangered species list. The eagle population in the lower 48 states went from a paltry 417 pairs in 1963, to over 10,000 pairs today. How do we know there are that many? Well, a dedicated band of volunteers keep track of them all over the United States. In parts of Washington County, OR, Dennis Manzer of Beaverton has been watching and counting the birds since 2000.
On a hot day in May, Manzer has his scope set up, pointed toward a bald eagle nest in a fir tree near Hagg Lake in western Washington County. The female is in full view, shielding 3 chicks from the hot sun. An hour goes by. Occasionally Manzer takes the binoculars around his neck and focuses them on other birds. A female Western tanager, her yellow feathers particularly beautiful in the sun, perches on a nearby tree. A red-bellied sapsucker makes two appearances. They’re pleasant diversions, but always Manzer returns his attention to the eagle nest. As early evening comes and the temperature cools, the female takes off, exposing triplet eagle chicks to view. They are 5 weeks old now, about the size of very fat crows, and a rich brown in color. One stands, revealing large yellow talons. About 10 minutes later, the female returns with a fish and lands in the nest. The male follows immediately, landing in the nest too. Manzer lets out a whoop as the male flies to a nearby tree, watching his brood as the female shreds the fish and feeds the chicks. “How many times have you seen five bald eagles in a nest at one time?” he asks.
About 8 miles away as the eagle flies is another nest in Jackson Bottom. That nest also has triplet chicks, and the adults are busy. It takes about 35 days for each egg to hatch. By 11 weeks, they’ll be nearly adult size, and taking flight. Finding food to sustain that kind of growth is a challenge for the adult eagles who usually have one or two chicks. Add a third and the work load increases significantly. The adults will continue to feed the youngsters for several more weeks. Then they’re on their own.
It’s several weeks later, June 22, and Manzer is observing the Jackson Bottom nest. On June 19, at just nine weeks of age, one of the chicks was found on the deck of a nearby house. It appeared unhurt, and after 5 hours disappeared. Manzer theorized if the bird was on the ground, the parents would perch in close proximity, and bring prey to the chick. It did appear that occurred several times. He’s been to the area frequently, but after a month, there are still just two chicks in evidence. One fledged July 11, the other July 12. Manzer still holds out some hope that one day he’ll see three juvenile bald eagles in flight. So far, though, it’s not looking good. Possible predators include bobcat, coyote, fox, mink and or a large raccoon. Still, the day is not without its pleasures.
At 8 a.m., Manzer has spotted the two adults and both chicks. Keep in mind these “chicks” are the same size now as their parents. They’re dark brown all over, lacking the white tail and head feathers they’ll sport in 4 or 5 years. The adults are in trees equal distant—about 1,000 feet from the nest. One juvenile is in the nest, the other in a dead tee, a snag about 500 feet away from the nest. Suddenly the female dives toward the water and then heads to the nest. She’s got a small prey item in her talons and the young eagle in the nest is calling to her. Not to be left out, the other fledgling flies to the nest to share in the bounty.
The female disappears, flying out of sight, while the male continues to watch from his sentinel tree. The adventuresome chick flies to a snag, and lands on the top of it, next to and about 12 feet above some open water at Jackson Bottom. Suddenly the juvenile flies into the water, just a few feet from shore. Whether it was going after a fish or a bird is anyone’s guess. Once in the water, the young eagle is motionless for a few seconds. Then it paddles and walks a few inches to shore, shaking its wings. After about 5 minutes, it flies to a large branch in the water, about 5 feet from the surface. It’s all part of the eagle’s task of learning to fend for itself eventually, says Manzer. He adds the bird is doing an admirable job. He’s been watching this particular bird since the egg was laid back in early March. He’s watched nests in several spots around the county. While it’s great to have triplets, not every pair is so lucky.
A nest just outside of Banks was abandoned while the adults were incubating the eggs. Again, it’s speculation but Manzer thinks there’s a good chance the nest failed because of people stopping to look at the nest along Highway 6. “I liken that kind of gawking to a strong-arm home invasion,” he says. “I always watch from a distance. Not only is it better for the eagles, it’s also better for me. I can see more. Just think about it. If you stand next to tall building downtown and look up, you don’t see the top floors. If you cross the street, you can see more. The further away you get, the more you can see,” he adds. When it comes to eagles, each pair is different, he says, and it’s not always clear how much disturbance the eagles will tolerate. And that brings him to the topic of the bald eagle’s removal from the endangered species list.
Bald and golden eagles, along with other migrating birds, were first protected in 1918 by the Migratory Bird Treaty Act. Despite that act, eagles were hunted and killed. Congress responded in 1940 by passing the Bald and Golden Eagle Protection Act. By 1963, however, bald eagles were in even greater decline, down to 417 pairs in the lower 48 states. An insecticide, DDT, had thinned egg shells, leading to failed reproduction. DDT was banned, but drastic action was needed. The Endangered Species Act was adopted in 1973 and the bald eagle added to it. Among other things, people were prohibited from viewing an eagle’s nest no closer than ¼ mile with a visual screen, and ½ mile without a visual screen. Now it’s 100 and 200 meters. Under the Endangered Species Act, nest trees were protected up to five years after being used. Other trees used by the eagles have never been protected. Manzer points out 4 trees in use at the moment by 4 eagles, including the nest tree. Those usage trees, he says, deserve the same protection as the nest tree. As noted earlier, the eagle listing was successful, with over 10,000 pairs of bald eagles reported last year. “It’s far short of the ½ million thought to exist 300 years ago,” says Manzer, “but we’ll never see those kind of numbers again because we’ve paved and roofed and fragmented so much of their habitat. We need a clear definition of what habitat means,” he says. “I’m afraid the current administration’s attitude is that endangered species aren’t going to encroach on economics.” Indeed, the current administration has added far fewer species to the protected list than were added under the previous two administrations, and in most cases under court order.
Manzer and his counterparts across the country will continue monitoring and counting eagles. If the numbers start to drop again, the bird can be put on the endangered list again, as long as the Endangered Species Act continues to exist.
Eagle facts
Adult females weigh about 13 pounds, and adult males weigh about 10 pounds.
Eagles form a life-long pair bond and use the same nest for years. One nest in Florida has been in use for 25 years.
A month after leaving the nest, the adults take the young as far as British Columbia and Alaska, teaching them to hunt. When the chicks are 6 months old, the adults return to the nest site, leaving the chicks who will stay until freeze up.
The chicks will wander for 4 or 5 years, finally settling on a nest site often within a hundred miles of where they were hatched.
Oregon has about 470 nesting pairs.

1 comment:

Melissa said...

Your passion for birding as well as other things has always been inspiring to me. You are an amazing role model for living life to the fullest!