More bald eagles are soaring over the Twin Cities as they continue their comeback along the Mississippi River.

An aerial count over the weekend found 38 active nests, two more than last year, in the 72-mile stretch from Dayton to Hastings that makes up the Mississippi National River Recreation Area. The 2013 and 2012 numbers are also quite a bit higher than any of the previous counts, which have been done since 2006, a year before the bald eagle came off the federal endangered species list.

“Twenty years ago we never would have imagined they would come anywhere this number,” said Mark Martell, bird conservation director for Audubon Minnesota. “The fact that they keep increasing is startling, to say the least. It’s a good indicator they are doing well and that the river itself is improving.”

Thirty-two of the nests are in tall trees from Pig’s Eye Lake in St. Paul south to Hastings. Two were sighted near Fort Snelling and the other four are north of the Interstate Hwy. 694 bridge over the Mississippi, between Brooklyn Center and Fridley.

“I would say from Pig’s Eye Lake on down is just incredibly busy. The nests are almost on top of each other,” said Bill Route, eagle count manager for the National Park Service. He counted the nests from a small plane for three hours on Saturday. Route said 34 nests had an eagle sitting on them and four more had signs of activity.

Martell, who has helped with Audubon Minnesota’s January eagle count for about 20 years, said the first eagles returned to the Pig’s Eye area below downtown St. Paul in the mid-1980s.

The last eagle count statewide was an estimated 1,312 pairs in 2005, said Erica Hoaglund, a nongame wildlife specialist for the Department of Natural Resources. Bald eagles made a gradual comeback nationally after DDT, a farm pesticide that decimated them, was banned in 1972. The bird that is a national symbol was on the federal endangered species list from 1967 until 2007.

Closer quarters

Although eagle nests are often a mile apart in northern Minnesota, many are only about half a mile apart, and in some cases a quarter mile, between Pig’s Eye and Hastings. Route said one Pig’s Eye-area nest sits on an island rookery of great blue herons, where eagles occasionally swipe a heron chick.

“It’s a very productive area for eagles,” Martell said. “One nest at Pig’s Eye is getting four eaglets a year and there’s four or five nests in that area. I think the river is such a good habitat for them and such a good food source, there’s no reason to fight over stuff if everybody has enough.”

Eagles usually lay eggs in March. Eaglets hatch 35 days later and fledge in July. On average, each eagle pair in the river corridor produces two eaglets a year. But counters have seen many nests with three eaglets between St. Paul and Hastings. Route plans to fly over the nests in May to count eaglets.

The Twin Cities corridor 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.

Eagles also are a common sight for folks traveling or living around the Anoka-Champlin Mississippi River Bridge.

“I see eagles all time” on the Mississippi and its tributary Rum River in Anoka, said Martha Weaver, Anoka County’s spokeswoman. She even spotted the big birds in downtown Anoka this winter near the Main Street Bridge, where they divebombed ducks on the Rum.

“The ducks on the ice are a perfect target,” she said. “The eagles send the ducks into a panic.”