A juvenile male osprey (top) with his mate have returned to nest beneath the South Capitol Bridge on the Anacostia in Washington. (Linda Davidson/The Washington Post)

About three weeks ago, an osprey named Rodney left his wintering grounds among the sand dunes of western Venezuela and started his spring migration to Washington’s Frederick Douglass Memorial Bridge on the Anacostia River.

On March 27, he struck out across the Caribbean near the Colombian town of Riohacha, crossed hundreds of miles of open water, and hit the coast of Cuba two days later, after about 40 hours in the air.

Ospreys — elegant brown and white fishing birds — can fly for long periods in a state of semi-sleep, experts said.

Rodney lingered in Cuba, then crossed the Florida Straits and cruised up the East Coast.

He arrived in the District last week, completing a 2,900-mile journey and a year-long community project to track two of the area’s majestic raptors from their urban haunts to their exotic wintering grounds and back.

Tracking the District's ospreys

No befuddled snowy owl, Rodney zeroed in on the area where he probably was born, experts said, and is now feasting on the Anacostia’s choice spring herring run.

Rodney and an osprey named Ron were captured on the river last spring and fitted with small transmitters that enabled scientists to follow their travels via satellite when they migrated south last fall and returned this spring.

The project was headed by the Earth Conservation Corps, an urban ecology organization founded by residents of southeast Washington and dedicated to the preservation of the city’s environment.

The corps has been crucial to the return of the Anacostia to health, by advocating for its wildlife and cleaning debris and refuse from the river. There are now about 40 osprey living on the river, the corps estimates.

And by arranging for the osprey tracking, the corps has provided an important batch of information about the details of their migration, and the remote locales where they spend the winter.

The organization has a base on the river, not far from a local osprey colony, and is supported by, among others, D.C. Police Chief Cathy L. Lanier.

“They’re amazing birds,” said Lanier, who was on hand last year when the birds were fitted with the transmitters. She said she climbed to where the nests were on the bridge abutments and helped remove the osprey.

“Raptors are big birds,” she said. “I don’t think most people realize just how big they are . . . [but] they’re amazingly light considering their size.”

Both birds, which have yellow eyes and special talons to grab slippery fish, flew to South America.

Ron, who wintered between two tributaries of the Amazon River in northwestern Brazil, returned April 10.

Rodney got back less than 48 hours later.

Bob Nixon, a local falconer who helped start the corps, said that 20 years ago there were no ospreys on the Anacostia. It was so polluted there were few fish to be had.

And before that, the pesticide DDT got into the fish that were in the area. When raptors ate those fish, it resulted in weakening the birds’ eggshells, he said.

“Ospreys got wiped out,” he said.

After the pesticide was banned in the 1970s and the river was cleaned up, ospreys were spotted again by the mid-1990s.

“We were the ones that were actually here when they came back,” said Rodney Stotts, a falconer, a founding member of the corps, and the man for whom one of the birds is named.

“Slowly we started seeing more species of fish come back and more birds coming back,” he said.

Now, along with numerous ospreys along the Anacostia, there are several nests on the Frederick Douglass Bridge abutments.

The tracking project

Nixon said the project began when the corps heard about the work of Rob Bierregaard, a Philadelphia-based raptor expert who has been tracking the migration of ospreys for over a decade.

Nixon contacted Bierregaard, a research associate at the Academy of Natural Sciences at Drexel University, and asked whether he wanted to track some Anacostia birds. Bierregaard liked the corps’s mission and traveled to Washington to capture Rodney and Ron.

The corps said it raised $20,000 to fund the project. An osprey cam is expected to be operational soon.

The capture was done with a special sombrero-shaped wire mesh that was woven with fishing line to ensnare the birds’ talons. The mesh was placed over a nest that had eggs, and when the osprey returned, their feet became caught.

The birds were freed from the mesh and taken to the corps’s headquarters, where one-ounce, solar-powered transmitters were attached to their backs. They were then released.

The transmitter has a GPS unit in it, Bierregaard said.

“Once an hour for 12 hours a day the device records where the bird is, how high it is, what direction its flying and how fast it’s flying,” he said. “It stores up that information . . . and every three days it dumps that information down to us by satellite.”

The birds usually fly about 25 to 30 mph, at an altitude of several thousand feet.

Bierregaard said the birds head south because inland fishing waters can freeze during the northern winter, and coastal fish tend to head away from the surface and osprey can’t catch them.

Aside from that, much about the birds’ migration is a mystery, he said. Ron journeyed about 3,500 miles, and Rodney about 2,900 miles, one way.

“When they’re migrating, they like to use thermals,” Bierregaard said. “They fly in hot air that’s rising. They can fly for hours almost without flapping their wings. . . . They circle up several thousand feet or more, and then when they . . . start losing lift, then they’ll drop off and glide down and look for another thermal.”

As for sleep, ospreys apparently can rest half their brain en route. “They shut one eye and sleep half their brain,” Bierregaard said. “They can multitask. They can sleep and migrate at the same time.”

“The annual cycle typically is five months in the winter, one month migrating north, five months in the nest area and one month migrating south,” he said.

“We’re not getting a Nobel Prize for what we’re figuring out here,” he said. “But every little bit that we can learn about the natural world around us helps us understand it better. It’s easy to keep our fingers on the pulse of the environment by just watching what the ospreys are doing.”

In blustery weather Monday morning, Nixon and John Mein, a police department civilian community outreach specialist, boarded a small boat to check the osprey nests at the bridge.

“Take a step back,” Nixon said as the boat circled the bridge abutments.

Overhead, ospreys seemed to be everywhere — their high-pitched chirps mingling with the wind, distant police sirens and the traffic rattling over the bridge.

“This is a huge conservation success story,” Nixon said. “We almost lost these birds.”