Whenever I see migrating birds I recall an aerodynamics lesson. Wind draft as taught by my college physics instructor. Ducks and Geese oftentimes migrate in a V formation. The lead duck works the hardest creating wind draft for the next duck. Likewise the next duck creates draft for the next in formation. Each succusive duck creates draft pulling forward. Farthest back in the formation works slightly less than the rest.
Look closely to the example photo and you may observe the V formation is longer on one side than the other. The physics instructor was the first to point out that often times V formations are longer so he asked the class to theorize why. Silence filled the room --- more ducks on that side.
South central Wisconsin. Best described as west of Hwy 41, bisected by Hwy 28. Google mapsaccurately shows its location. Park along side Hwy 28 provides great views of birds. There is a parking area for hiking and access on the south side of Hwy 28.
How to find the parking area:
A good size parking lot is at the end of a long drive. South side of Hwy 28 there is a sign pointing to the parking area access road. Or you can park along side Hwy 28, be careful its a busy road. Note there is no admittance to the marsh by foot on Hwy 28. Sign posted as protected area.
I do not recall a restroom at the parking area. No sign prohibiting dogs so I took that to mean pets welcome on a leash.