FARGO, N.D. (AP) -- Minnesota's growing bald eagle population is running out of room.
The bald eagle, once almost extinct, has made a remarkable comeback.
So much so in Minnesota that the highly territorial birds are fighting over turf and nesting closer to urban areas, scientists say.
''The optimal habitat is probably becoming saturated,'' said Jim Grier, a zoology professor at North Dakota State University.
''What we're finding is that they're actually spilling over and starting to nest in areas that we wouldn't consider typical eagle habitat,'' said Grier, a world-renowned expect on eagles.
The bald eagle's placement on the Endangered Species List and the 1972 ban of the pesticide DDT saved the species and triggered its population rebound, Grier said.
And what a rebound.
''We've basically manipulated a population drastically on a continental scale,'' Grier said.
In the Lower 48, the number of breeding pairs has grown from about 400 in 1963 to about 6,000 today, he said.
In Minnesota, the number of breeding pairs has grown from less than 100 in the mid-1970s to about 680, said Joan Galli, a non-game wildlife specialist with the Minnesota Department of Natural Resources.
''You could see the distribution changing across the state over time, spreading out from this core that was sustained on the Chippewa National Forest,'' she said. ''They have expanded their range and are repopulating the state along the main river corridors.
''About 10 years ago they started to reappear on the Minnesota River in places they hadn't been in 100 years,'' Galli said.
Minnesota's bald eagle population ranks fourth behind Florida, Wisconsin and Alaska.
The raptors, with wingspans up to eight feet, build huge nests in the tops of trees near major rivers, lakes and marshes to support their main diet of fish. Their nests can reach 20 feet across and weigh up to 4,000 pounds, according to information provided by the U.S. Fish and Wildlife Service.
North Dakota's eagle population has rebounded as well, but the state's habitat can't support the number of birds found along the thousands of Minnesota lakes, said Roger Collins, a biologist with the U.S. Fish and Wildlife Service in Bismarck.
North Dakota is home to at least nine pairs of bald eagles, Collins said.
''Overall the bald eagle has made a remarkable comeback in the state of North Dakota,'' Collins said.
''Our first nest in modern times was documented in 1988 on the Missouri river near Stanton,'' he said. ''Before that there were no sightings of eagles since the 1940s.''
Most of the state's bald eagles nest along the Missouri River. Wildlife officials have also found an occupied nest near Devils Lake, Collins said.
''We could find them nesting up in the Turtle Mountain area, the Devils Lake area and the Red River Valley,'' he said. ''All of these areas potentially could support bald eagle nest populations.''
Although no eagle nests have been found in the Red River Valley, sighting of the once-imperiled species is again common in the region, especially during the spring and fall migrations, Grier said.
''This time of the year and in the fall there are literally hundreds of bald eagles moving through this area -- the Red River Valley -- going up into Canada,'' Grier said.
''As you get over into Minnesota you'll see more and more,'' he said. ''And from the Tamarac National Wildlife Refuge going east there's bald eagle nests all over.''
But Minnesota's steady increase in the eagle population is tapering off, Grier said.
The raptors are taking it upon themselves to control their numbers, he said.
''Eagles aren't communal,'' he said. ''They maintain territories -- they space themselves out.''
''So now one of the biggest survival problems for eagles is eagles because they fight a lot as the population goes up,'' Grier said.
''It's already happening within their main habitat,'' he said. ''They're killing each other and reducing their reproduction.''
Two female eagles fought to the death Tuesday near the southeastern Minnesota town of Benson.
Conservation officers found them hanging upside down in a tree with their talons locked together.
One of the birds was dead and the other had to be put to sleep at the University of Minnesota's Raptor Center in St. Paul.
''There's just less and less habitat for them and their numbers are increasing,'' said Lori Arent, rehabilitation coordinator at the Raptor Center.
''Over the last couple of years we've treated more (eagles) because of territorial disputes,'' Arent said.
(Distributed by The Associated Press)
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