Eagle nests soar in Wisconsin, Crawford County

By Ted Pennekamp

Wisconsin’s and Crawford County’s bald eagle population continues to soar as revealed in the 2018 Wisconsin Bald Eagle Nest Survey.

The survey showed a record number of nests statewide, and Crawford County’s total increased from 62 in 2017 to 101 in 2018, said Laura Jaskiewicz, the Department of Natural Resources research scientist who coordinates the statewide aerial survey effort.

“2018 was another great year for the bald eagles’ remarkable comeback in Wisconsin,” said Jaskiewicz. “The number of nests is still increasing throughout the state and we now have them documented in 71 of 72 counties.”

The 2018 surveys found a total of 1,695 bald eagle nests occupied by breeding adults, an increase of 105 nests from 2017. That’s a 6.6 percent increase and more than 16 times as many nests found in the first detailed surveys in 1974, when bald eagles were listed as state and federally endangered species and only 108 nests were documented. Walworth County confirmed its first documented nest in at least a half century.

As in past years, Vilas County with 172 nests, and Oneida County with 154 nests, had the highest totals. Bald eagles prefer to nest in tall trees along water, and these two counties have some of the highest concentrations of freshwater lakes in the world. Tall trees along water obviously work well for some counties along the Mississippi River as well. While Crawford County’s total zoomed up to 101 (third highest in the state), Grant County went from 70 in 2017 to 81 in 2018 (fourth highest), said Jaskiewicz. Crawford and Grant counties also have the advantage of bordering part of the Lower Wisconsin River. In addition, Crawford borders the Kickapoo River.

“In part, the large spike in numbers for Crawford County eagle nests from 2017 to 2018 has a lot to do with many new nests being discovered in the Mississippi River Valley,” said Richard Staffen, zoologist and conservation biologist with the DNR.

Staffen oversaw the survey in Area 6 which includes Crawford, Grant, Richland, Sauk, Columbia, Dane, Iowa, Lafayette and Green counties.

“They are incredibly packed into that floodplain forest along the river. In places, there are pairs nesting well within a half mile of each other,” Staffen said. “We typically do not see that. That said, for many years, the U.S. Fish and Wildlife Service did the surveys on the Mississippi River and there was some lull in the data. The past three years, we (the DNR) have been doing these surveys and there has been a boost in numbers, perhaps due to more intensive searching, but the number of birds are definitely increasing. They are also filling in more and more on the Lower Wisconsin River and the Kickapoo.”

The high number of eagle nests in Crawford and Grant counties are very much due to the excellent habitat afforded by the extensive floodplain forests associated with the large river systems (foraging opportunities) in those counties, said Staffen. 

“The other counties with high numbers are all related to high densities of water bodies (usually lakes in the northern part of the state), but in Southwest Wisconsin, it is these magnificent rivers,” Staffen said. “The relatively flat nature of these large forests conceal the nests from other pairs really well, allowing pairs to nest in higher numbers. The eagle pairs don’t like to nest within viewing distance of each other, so these floodplain forest offer good cover, large trees to place nests, and a very abundant food source.”

Staffen said that for many years, it was thought the numbers of nesting eagle pairs would level off, similar to what had been seen for Osprey, as the suitable nesting habitat was saturated. However, this still hasn’t taken place, so perhaps there is still good habitat to be utilized. 

“At some point, these large river systems will become saturated, but as we branch out and search other smaller rivers and streams, we continue to find more nesting eagles,” said Staffen. “I don’t think we have exhausted all of the smaller systems and there are likely still more pairs to discover. We continue to hear of new nests/pairs, and discover others by flying stretches of rivers/streams not surveyed previously. So, I think the trend likely will continue to go up for the near future.”

“It doesn’t seem like we’ve hit any ceiling yet,” Laura Jaskiewicz said. “Eagles are still finding places to nest, some continuing in the same nests for many years and some new ones popping up here and there.”

While the aerial nest surveys were conducted in March and April by DNR conservation biologists and DNR pilots, the nest documented in Walworth County was reported by a private citizen. Sharon Fandel, a DNR district ecologist with the Natural Heritage Conservation program, went to the site and confirmed the nest.

Confirming the Walworth County nest means that Milwaukee County remains the lone county in the state without a known active eagle nest. 

People who have seen new, small nests can report them by searching the DNR website, dnr.wi.gov, for bald eagle watching and click on the link on the right hand navigation column for “Report a plant or nongame animal.”

The record number of nests documented this year results from protections under the state and federal endangered species laws, declining levels of DDT in the environment, and DNR and partner efforts to help monitor and aid recovery. Bald eagles flew off the state endangered species list in 1997 and the federal list in 2007; eagles and their nests are still federally protected under the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act.

The 2018 Wisconsin Bald Eagle Survey also contains results from the 2018 winter eagle survey conducted by DNR staff and many volunteers, and the report details a new effort in Dane County using volunteers to help monitor nests from the ground to see if the eagle nests produced young and if they fledged. The Madison Audubon Society is leading that pilot program.

All of the eagle survey information allows the DNR and the U.S. Fish and Wildlife Service to monitor eagle populations and enables the DNR to provide up-to-date information to land owners, companies and communities that have an active nest on their property, so they can avoid disturbing the nests and eagles during breeding season.

The bald eagles’ comeback in Wisconsin is celebrated in the new Endangered Resources bald eagle license plate. The plate raises money for the DNR’s work to protect and restore native and endangered wildlife, plants and state natural areas. The plate costs an extra $25 annually on top of regular registration.

There are several events scheduled throughout the state in the coming weeks aimed at getting people out to see eagles. With colder weather forecast, rivers that don’t ice over near locks and dams, like on the Mississippi, Wisconsin, Fox and other large rivers, become very good places to see large concentrations of wintering eagles.

Eagle Watching Events

Southwest Wisconsin offers numerous opportunities to view eagles and learn more about these majestic birds. Events coming up include Bald Eagle Appreciation Days, Feb. 22-23, in Prairie du Chien, and Eagle Watching Day in Ferryville on March 2.