On a clear, cool fall morning, a bald eagle swoops in from its perch on a cliff overlooking Trinity Lake in Northern California.
With grace and speed, the eagle flies low over the water and snatches a bass any fisherman would be happy to catch. Chased by three crows, the eagle settles atop a tree, high on the cliff overlooking the water below.
The American bald eagle is an amazing comeback story; 40 years ago, the species was nearly extinct. Today, bald eagles have experienced a turnaround.
Each winter near the California-Oregon border, the largest gathering of bald eagles in the continental United States takes place. The Klamath Basin comes alive when hundreds of thousands of migrating waterfowl and hundreds of bald eagles settle in the area to hunt and feed. The eagles are a sight: Full-grown adults can weigh 14 pounds, with wingspans reaching 8 feet.
In 1963, only 417 nesting eagle pairs were counted in the United States, according to the U.S. Fish and Wildlife Service. By comparison, as many as 100,000 nesting eagles thrived in 1782, when the species was adopted as a national symbol.
Hunting and loss of habitat were blamed for initial population declines, and the federal government reacted by creating the Bald Eagle Protection Act of 1940. The possession, selling and killing of the species were prohibited, yet the population continued to dwindle into the 1960s. The use of the pesticide DDT was a major factor. Chemical runoff contaminated the fish eaten by the eagles. The eagles' eggshells were weakened to the point that the shells broke during incubation, or the young failed to hatch.
The Environmental Protection Agency banned DDT in 1972, yet in 1978 the Fish and Wildlife Service listed the bald eagle as endangered in 43 states and threatened in five.
That was the beginning of an American success story.
The Fish and Wildlife Service created partnerships with organizations such as the San Francisco Zoo and the Institute for Wildlife Studies.
A plan was launched to reintroduce the species to areas of the state where the bird had disappeared. Over 22 years, 103 eagle chicks were hatched and released through a captive breeding program.
Now, 200 pairs of nesting bald eagles reside in California, with about 9,789 pairs in the Lower 48 states. In 2007, the raptors were removed from the threatened and endangered species lists, though bald eagles in Arizona's Sonoran desert -- considered a distinct population -- are listed as threatened.
Fish and Wildlife officials list two main factors in the recovery of the bald eagle: the DDT ban and the protection of roosting, feeding and nesting sites under the Endangered Species Act. Wildlife officials will monitor the eagles' numbers for up to 20 years to see if at any point the bird needs to be put back on the list.
At Klamath Basin, the eagles start arriving in November and stay in large numbers until March, but the population peaks in January and February, when from 300 to 1,000 gather, said Dave Menke of the Fish and Wildlife Service. The eagles come from California, the West and as far as the Northwest Territories of Canada.
The number of tourists to the refuges and the Klamath Basin swells during the Presidents Day weekend and the annual Winter Wings Festival, sponsored in February each year by the Klamath Basin Audubon Society.
For the past 24 years, Fran McDermott has been leading trips to the Klamath Basin to watch the eagles.
"They're a charismatic species," said McDermott, of San Leandro, Calif. "They have a long and storied history in this country, from being named the national symbol, to the DDT era, (when) they were almost wiped out, to a very successful recovery. The bald eagle attracts people."
During Presidents Day weekend last month, dozens of cars lined the dirt road leading to the Bear Valley National Wildlife Refuge in Oregon. Bird-watchers poured out of a school bus. More than 50 people stood in the early morning darkness bundled up from the cold, binoculars in hand. They came to watch the bald eagles leave their nighttime roosting homes among old-growth ponderosa pines and Douglas firs.
As the sun crept over the horizon, making eagles' silhouettes visible in the sky. Bird-watchers shouted the location of more than 100 eagles leaving the Bear Valley refuge. They soared over the snow-capped hills and down to the flooded farm fields and refuge marshes in the basin.
Fields used for growing hay and cattle grazing in the summer months are flooded in winter, attracting large groups of geese and other migrating birds. Bald eagles settle into the fields to feed. Across the road from the Lower Klamath refuge, more than 30 bald eagles sit in a newly flooded field with thousands of waterfowl.
Their prey is not geese or ducks, but mice and other rodents. A dark-colored juvenile eagle grabs a mouse and sits on a dry plot of ground to pull apart its catch. A raven runs up and pulls on the eagle's tail feathers, trying to distract it long enough to steal a bite to eat.
Menke, of the Fish and Wildlife Service, said bald eagles are opportunistic feeders by nature, and rodents in flooded fields have been prevalent this year. When there is a waterfowl die off, eagles will dine on dead geese or ducks.
Just over the Oregon border, McDermott's group of 18 bird-watchers lines the side of Township Road, looking at a field full of bald eagles.
"Pretty cool," said Phil Henry, of Orinda, Calif. "You can see six or eight together of different ages."
That's what McDermott enjoys about leading the groups.
"They were saying they could stay here all day and just watch the field for hours and hours," McDermott said. "The people were just listening to the geese, watching the bald eagles. It's just magical."
• Diet: Fish is a staple but bald eagles will feed on waterfowl, turtles, rabbits, snakes, mice and carrion.
• Life span: Up to 30 years.
• Size: Bald eagles stand at least 3 feet tall, with wingspans between 6 and 8 feet. Females can weigh up to 14 pounds; males weigh seven to 10 pounds.
• Flight: They can fly to an altitude of 10,000 feet, reach speeds up to 35 mph, and lift up to 4 pounds.
• Habitat: Alaska and Canada south to Florida and Southern California. Concentrations of eagles occur in Florida, the Chesapeake Bay, the Mississippi River Valley, and the Pacific Northwest.
• Status: Removed from the federal endangered and threatened wildlife list in 2007, but still listed as threatened in the Sonoran desert of Arizona and in recovery for the Lower 48 states.
• Other: Bald eagles mate for life. They were named the national bird in 1782.
Sources: National Geographic, U.S. Fish and Game, baldeagleinfo.com
Explore further: Can monogamy undermine intelligence?