IOWA COUNTY (WKOW) -- Every other week, from December through February, volunteers head out to nine different eagle roosts along the Wisconsin River.
It's part of the Ferry Bluff Eagle Council's 30-year effort to keep track of the birds and add to its database.
"The first count was done in 1989," said Lone Rock roost coordinator Jennie Lanzendorf.
She's been counting eagles for five years and coordinating the roost for about three.
"Starting around October, November, I start sending out emails and Facebook posts looking for people to help me out," she said. "Whoever responds I try and get them out and utilize them."
Two weeks ago, Lanzendorf said the volunteers counted more than 70 eagles at the Lone Rock roost.
Statewide, there were a record number of nests counted by the Department of Natural Resources in 2018.
Eagles stick to the roosts more down river when the weather's warmer and the river hasn't ice over. It's easier for them to hunt in open water.
The recent warm temperatures may influence their roosting habits, but Lanzendorf said that's hard to predict.
The counts can help track those trends. The data that the council collects is also key in tracking the spread of disease among the birds, as well as a way to help governments or private landowners coordinate the best times to start construction projects so as not to disturb the eagles.
"They've amassed a huge database," said Lanzendorf. "They examine trends and distribution and population levels."
During the winter, popular state nature areas like Ferry Bluff are closed to the public in order to protect vulnerable eagle roosts from being disturbed.
If eagles are distressed, they'll leave. Lanzendorf said the opportunity to count them and gather the scientific data could be lost.
"It's really tempting when it's beautiful like this to take that hike, and they don't realize what a stress they're putting on the eagles," said Lanzendorf.
She said the Alliant Energy Dam is a popular place to view eagles, but asks that people stay in their cars because again, getting too close to the eagles can disturb and distress them.
For Lanzendorf, coordinating and participating in these counts is a way for her to do something she loves and make a practical contribution at the same time.
"I love interacting with my community and contributing to citizen science," she said. "And I love birds."