Thunderbird reports in Wisconsin
1 case, best-documented first. Page 1 of 1.
We map claims, not creatures. A case is what some source says someone saw or heard, with the link to that source. It is not proof that anything was there, and a retelling counts once, not as a second sighting.

Thunderbird · Town of Hartford, Wisconsin · 2010s
Witnesses report seeing a massive bird with a curved beak and 15-16 foot wingspan near Pike Lake that they identify as a Thunderbird.