By Laci Jones
A national symbol and an endangered species success symbol, the bald eagle, makes its return to the Oklahoma Great Plains each winter.
Ryan VanZant, director of education at the George Miksch Sutton Avian Research Center in Bartlesville, Okla., said bald eagles are divided into two subspecies, the northern and southern bald eagle.
“Southern bald eagles are smaller by a fair amount,” VanZant explained. “When they become mature, they take up residence in the southern United States.”
The northern bald eagle mainly lives in Alaska and Canada and migrates to the southern United States, he added.
“Bald eagles are primarily fish eagles,” said Megan Judkins, assistant manager at the Iowa Tribe of Oklahoma Grey Snow Eagle House in Perkins, Okla. “When those large bodies of water start freezing over, the eagles start moving down south.”
A theory behind the migration is the northern bald eagle would follow the bison migrations and feed off of winterkill, VanZant explained.
“Nowadays, there’s obviously no bison migration,” VanZant said, “but, especially here in Oklahoma, we built these large reservoirs which don’t freeze through the winter.”
Bald eagles spend a lot of time in these reservoirs because both waterfowl and fish are available in these ice-free locations, VanZant said.
Unfortunately, bald eagle numbers declined due to a pesticide used to help combat mosquitoes called DDT, Judkins said. The bald eagle landed on the endangered species list in 1967.
“If DDT was in a female’s body, then it interfered with how calcium is deposited into the egg,” Judkins said. “It would cause the egg shells to be thin. When the bird went to incubate the eggs, the weight of the adult bird’s body would actually crush the eggs.”
Pick up the January issue of OKFR to read more.