Eagles return to Dells, just like tourists
By Trevor Kupfer, Dells Events
About 30 area residents gathered at the Stewards' meeting Wednesday to hear Jeb Barzen review his research on eagles in the Sauk Prairie area and link it to the population in Wisconsin Dells and even community development.
Since an increasing number of eagles are populating the Dells river corridor, the group invited Barzen to talk about the territorial birds.
"We're here because eagles are cool. Right?" asked Barzen, of the International Crane Foundation and Ferry Bluff Eagle Council. "If this talk was about habitat and ecosystems, how many of you would be here?"
Barzen began with a brief overview of eagle biology, including the immature period, adult plumage and gender. Females, he said, can be up to 30 percent larger than males and have a thick, short bill. Throughout the discussion Barzen included eagle pictures, and challenged audience members to identify the sex.
He then segued into the state's eagle population, which plummeted to an all-time low in the 1970s because of DDTs.
"What DDT did was build up in the fat, and birds come to their breeding areas and metabolize that fat during the egg-laying period as a source of energy," he said. "When they had DDT contamination, they put it in their body all at once. So when they produced eggs, they were very thin-shelled and would break. So the population kept going down."
In 1975, when the DNR surveyed the number of eagle nests in the state, they counted a mere 111 occupied nest areas. The number rose gradually over the years, and hasn't plateaued yet, and the DNR counted 1,065 just two years ago.
"It's a wildlife success story. The eagles have recovered dramatically," he said. "How many of you have seen an eagle nest no more than 20 miles from here?" More than half the audience raised their hands.
Barzen then reviewed eagle habitats and the areas they tend to visit most, which lean heavily toward those with hills or bluffs, agricultural land, undeveloped shorelines and, most of all, rivers.
"The question is, why are eagles here? The obvious answer is open water caused by the dam. But wait a minute, how many dams are there on the hardest-working river in the U.S.? Twenty-something. But there aren't that many concentrations of eagles in winter along the Wisconsin River. So it can't be just that," he said.
"Another answer is the bluffs, where they like to sleep at night. But, once again, there's lots of places with dams and bluffs but not eagles," he added.
"Undeveloped shorelines are important, because they're interested in saving energy. In winter, if you had a choice to fly with your wings extended, or sit in a tree folded up watching food float by, what will you choose? And we also think that agricultural areas are important," he said, adding they like to eat various elements in the soil.
Another key aspect to attracting eagles is road kill, Barzen said, and one of the biggest killers of eagles in the state is cars.
While the state's eagle population has risen dramatically, Barzen said the population in the Sauk Prairie area — from Spring Green to Devil's Lake — doesn't reflect it. "There's something going on, but what? It's not a simple question."
Ferry Bluff Eagle Council has done extensive research to try to answer that question, including reviewing the populations in each winter season. What they found is the eagle numbers vary from week-to-week. In early December they counted 314, but found a mere 50 by February.
Barzen hypothesized that weather may be a factor.
"Yeah, just like the tourists," Steward Dave Simerson said with a laugh. "Do you have research on that correlation?"
Their findings took them further, as they placed transmitters on the birds hoping to find out where the eagles go from day-to-day in the winter. They did this over the period of three years using 17 eagles they captured in Sauk Prairie.
When they compiled the data, clusters appeared on the map, but not where they anticipated. The eagles went as far as Iowa and Illinois, while others flew to the Chippewa Valley and Prairie du Chien. Some of the eagles appeared in Wisconsin Dells, with the most near Fisherman's Luck.
The data suggests that eagles rarely deviate from major rivers, such as the Wisconsin, Chippewa and Mississippi. But Barzen noted other research from a group in western Wisconsin saw its eagles going north to Canada instead of west to the Wisconsin River. Though only a hypothesis, Barzen said a reason for this behavior may be their territorial instincts.
Barzen then related the group's success with balancing environmental issues with development, as townships have included eagles in town plans and zoning considerations.
He relayed an anecdote of a recent development they worked with, imparting some hope to the environmentalist group that may hope to do the same.
"This parcel came up for sale across critical eagle areas. We talked to the developer that purchased it, and he wanted to build a lot of houses. But there was a critical line coming through the parcel, Columbia County and Dane County. So he could put up a gazilion houses in Columbia County, but Dane was exclusively agriculture. So we came in and said houses aren't a problem, but it matters where they are and how many. So we figured out a way to allow him to make a profit and maintain the habitat. We arranged it with the counties to change the zoning, and have him agree to only 10 houses scattered evenly."