Iowa is in the middle of its annual bald eagle population survey and although the numbers are still coming in, all indications point to 2022 being a really good year for eagles wintering in Iowa.
Bald eagles are migratory, but only travel as far as necessary to find food. Eagles wintering in Iowa likely came from Minnesota, Wisconsin and Michigan, that have large resident populations, and join resident Iowa eagles looking for river sections with open water to dine on fish and waterfowl.
For years, the Mississippi River along eastern and southeastern Iowa was home to the highest number of eagles – both resident and wintering – but in recent years, the Iowa River and the Des Moines River have hosted more eagles.
“This year, we’ve had routes on the Iowa River in east central Iowa report more than 700 eagles, including 400 in a one-mile stretch,” said Stephanie Shepherd, wildlife biologist with the Iowa Department of Natural Resources Wildlife Diversity Program. “The lower stretch of the Des Moines River had a lot as well with more than 1,500 eagles reported from three routes. It looks like it’s going to be a pretty good count this year and we still have the traditional hot spots from the Mississippi River yet to come in.”
The survey began nationally in the 1980s when states were recruited to join the study. Participants would identify stretches along rivers as places where eagles would gather in the winter making them more easily counted. The survey routes are driven during the first two weeks of January. These initial routes have been part of Iowa’s surveys since the state joined the count in 1991.
The population census had been managed by the U.S. Geological Survey, but is now housed with the U.S. Army Corps of Engineers. As many as 44 states have participated in the survey providing an important long-term dataset when the U.S. Fish and Wildlife Service considered removing the bald eagle in 2007 from the endangered species list.
That long-term dataset was more than just raw eagle totals; it includes both juvenile and adult eagles and the percentage of juveniles, which is an important metric in determining if the population is steady and not decreasing. The dropping juvenile numbers was one of the alarms that brought attention to the plight of bald eagles during its population crash.
“The survey has mirrored what we understand is going on in the population, like the rapid increase in the 1990s and the leveling off in the 2010s,” she said.
The bald eagle population trend extends beyond Iowa’s border to include other Midwestern states, as well. “We may be reaching population capacity, which is pretty cool,” Shepherd said.
Iowa’s resident eagles rarely leave the state. The state population is measured by nesting success and since the late 1990s, the number of nests in Iowa has increased four to five times, now numbering more than 500 across the state.
The best eagle viewing is along Iowa’s rivers where there is open water and roosting trees nearby. Eagles use these areas for food and one of the most popular areas for eagle viewing has been in Keokuk.
Bald Eagle Days originated in Keokuk who is hosting its 38th annual bald eagle days Jan. 15-16, and while the attendance numbers may not be as high as it was during the peak years in 2013-2014, eagle viewing over the Mississippi River still attracts a crowd.