Great Blue Herons Kill Wetland Forest Trees

A great Blue Heron rookery kills all wetland forest trees and was very likely the reason Carcajou Club lost the trees and land. Cormorant rookeries also kill wetland forest trees as they did over at Blackhawk Mud Lake in the middle 90's.



From the DNR

Floodplain forest Koshkonong Creek Woods

Locally large stand of lowland hardwood forest bordering much meandering Koshkonong Creek as it enters the lake. "Seemingly Un-disturbed and rich in wildlife," according to Jim Zimmerman (1980).

A Great Blue Heron rookery occurred near the lakeshore.

Water quality in the creek is poor due to pollutants from Sun Prairie and Cambridge. Diverse habitat in area includes: shrub-swamp, marsh, hardwood swamp, and scrubby disturbed forest.

There have been so many birds on this 15-acre island for so long that they were having a serious effect on it. At the peak of their population there were as many as 4,000 adults and young inhabiting the island.

With a diet rich in fish and other aquatic food and so many birds nesting in so small an area, the accumulated guano, or droppings, was over-fertilizing the ground beneath.

This resulted in changes to the soil chemistry which affected the trees that these birds nest in.

Essentially, they were destroying the very habitat on which they depended.

In addition to guano accumulation, tree diseases, such as Dutch elm disease and oak wilt, have destroyed many large trees. It is likely that the birds were stressing the health of the trees making them more susceptible to diseases.