By: Robert Zimmer
As waterfowl season arrives, the Butte des Morts Conservation Club and Wisconsin Department of Natural Resources aim to create new wetland habitat to attract nesting ducks and other water birds.
Over the past several years, the arrival of American white pelicans to the area has created an unexpected problem. The Winnebago basin has become so attractive to the birds as a breeding area that some of their nesting areas are over-crowded and no longer desirable habitat for breeding waterfowl.
To restore a portion of wetland habitat to attract nesting waterfowl, the BDMCC, working with the DNR, is focusing on a series of five nesting islands located, with the Terrell's Island Wetland Restoration Area, along the south shore of Lake Butte des Morts.
The islands, within a protective limestone breakwall, are sheltered from wave action and erosion on the big lake.
Originally built to attract nesting diving ducks, such as redheads, and other waterfowl, recent years have seen them taken over by breeding pelicans. The population of white pelicans, as well as double-crested cormorants, has exploded in our area since the early 1990s. Conditions at the islands have become so severe that the club, along with the DNR, had to rethink ways to make them more attractive to nesting ducks and less attractive to the pelicans and cormorants.
To do this naturally, a restoration project began in September to return the islands to their original intended state.
DNR Winnebago System Biologist Arthur Techlow III said: "We are creating emergent plant beds that, if they become dense enough, may attract other water-nesting birds, such as Forster's terns, grebes and diving ducks, such as redheads. The main goal is to create additional wetland habitat while reducing the available nest area for cormorants and pelicans. The sheer numbers of these birds has caused a significant decline in local water quality and the fishery."
At last count, more than 1,200 pelican nests and 920 cormorant nests were located on the small series of islands.
According to Techlow, the islands offer the perfect nesting conditions for these birds — isolation from predators and human disturbance, as well as good foraging opportunities. The pelican population has become so high and the concentration of birds so dense that concerns such as avian botulism and other disease is sufficient cause to disperse the birds.
Pelicans dispersed from the nesting islands have other suitable habitat in the area for breeding.
"They have also been nesting on the breakwall itself and nearby privately owned islands," Techlow said.
Other nesting areas for pelicans around the area include colonies at Horicon, Green Bay and Lake Winnebago.
To deter some of the pelicans and cormorants from nesting here, the DNR will plant four species of emergent vegetation. Hardstem bulrush, river bulrush, three-square bulrush and bur-reed will be planted along the perimeter of each nesting island to create a barrier as they grow.
Diving ducks and grebes will be right at home in this shoreline barrier, while the pelicans, which prefer an open shoreline where they can waddle ashore quickly, will be deterred. Trees from the island, which were never intended but colonized there all on their own, will be removed to deter tree-nesting cormorants.
The restoration project, lower pelican numbers on the nest islands, and ongoing maintenance will result in higher numbers of nesting waterfowl in the area, as well as grebes and terns.
A population of redheads is especially desirable. The redhead is a stocky diving duck with reddish-maroon head and grayish back. Most redhead nesting areas exist west of the Mississippi River, but the bird has established several nest sites in Wisconsin wetlands, including Horicon.
By: Robert Zimmer