More than ever, Twin Cities residents are looking up to see the majestic flight of a bald eagle.

The great bird is continuing its robust comeback along the Mississippi River. A spring helicopter count found 36 active nests in the 72-mile stretch from Elk River to Hastings that makes up the Mississippi National River Recreation Area -- several more than last year.

"The eagle population is increasing and highly productive" in the area, said Bill Route, an eagle project manager for the National Park Service. Aerial counting isn't precise, but the 36 nests counted in late March are up from 28 last year and 30 in 2010, he said.

The aerial surveys, begun in 2006, when 11 active nests were sighted, have documented the dramatic comeback in the metro area of the majestic bird, which was on the federal endangered species list from 1967 to 2007.

On average, each eagle pair in the area produces two eaglets a year. But counters have seen many nests with three eaglets between St. Paul and Hastings, Route said. That means the river is clean enough to produce plenty of fish and fowl for the big birds.

The Twin Cities area has the highest reproduction rate of three areas surveyed by the Park Service. The other two areas are along the St. Croix River and in the Apostle Islands on Lake Superior.

Siah St. Clair often sees eagles flying over Springbrook Nature Center on Fridley's northern border. He is director of the park, which lies about half a mile east of the Mississippi River. Dozens of people have called him this past winter about eagles adding on to two tree-crotch nests, he said. One is on a nearby Mississippi island; the other near busy Hwy. 10 in Coon Rapids. The latter is on the edge of a sprawling wetland in plain view of Hwy. 10 between Main Street and Hanson Boulevard. It's about 2 miles from the Mississippi.

"We had at least 30 people stop or call about the Highway 10 nest," St. Clair said. "It is so easy to see the birds there. It's special." He said the eagle activity was aided by a warm winter that left the river open for them to fish, instead of flying south in search of open water.

Showing up in back yards

John Moriarty counted nests from a helicopter on March 28, as he has since 2006. Moriarty, a Ramsey County Parks natural resources manager, found almost all the existing nests full and spotted four new ones.

Eagles, which mate for life and usually return to the same nest each spring, are persistent, he said. One pair had a nest on Pike Island upstream of the Mendota Bridge. But the nest tree blew down, so the eagles relocated last year across the Mississippi near the marina by Crosby Farm Regional Park in St. Paul. That nest fell down, too, and last month Moriarty spotted a new nest a quarter-mile downstream just below the Interstate 35E bridge.

Another pair built a new nest in Fridley near their old one, which had been borrowed by some geese. The new nest is on an island just upstream of the Interstate 694 bridge, Moriarty said. Four of the 36 nests spotted this year are north of I-694. Four more are between Fort Snelling and the Mounds Park neighborhood in St. Paul. The other 28 are between Pig's Eye Lake Park in St. Paul and Hastings.

"Overall, they seem to be doing very well," said Mark Martell, bird conservation director for the Minnesota Audubon Society, of the eagles. "This [aerial] count is along the river only. A lot of pairs nest away from the river.

"They are showing up all over the place; some are in people's back yards," including a Minneapolis home near the Lake Street Bridge, he said.

Martell recalls when the first eagles returned to the Twin Cities in the mid-1980s to nest in the Pig's Eye area below downtown St. Paul. Since the federal Clean Water Act was passed in 1972, the Mississippi has been cleaned up, providing more prey for eagles.

By early June, the Park Service again will fly a plane over the Mississippi corridor to count the number of eaglets in each nest, Route said. Every other year, the service sends climbers up to occupied nests to take samples of eaglets' blood and feathers, which are tested for toxins found in the fish they eat. Those test results offer an indication of the health of the eagles, fish and river.

Back and spectacular

The pesticide DDT, banned in 1972, had leached from farm fields into waterways and into fish that eagles ate, according to the U.S. Fish and Wildlife Service. The toxin contributed to the sharp decline of the eagle population, which fell to a low of 417 nesting pairs in the lower 48 states in 1963.

The last eagle estimate by the state Department of Natural Resources said Minnesota had 1,312 pairs in 2005, including 78 active nests in the Twin Cities metro area. "It wasn't that long ago we didn't have many eagles around here," said St. Clair, the nature center director.

The bird's growing numbers probably contributed to St. Clair's witnessing a rare aerial display a few springs ago from his Brooklyn Park home, about a block from the Mississippi: a pair's acrobatic courting ritual.

"They fly up high in circles and lock talons. They tumble down, let go and take off," he said. "It's one of those rare instances in nature when you get to see things not many see."

Jim Adams • 952-746-3283