Animal Planet: Lake Mendota Edition

Gulls and common mergansers enjoy Lake Mendota in January - Credit: Adam Hinterthuer

An interesting scene has been playing out in Lake Mendota lately. Right outside the doors to Hasler Lab, common loons and common mergansers are busy fishing all day long. In January, this is undoubtedly easier than in the summer. Low productivity in the lake means crystal clear waters and the cold temperatures mean sluggish fish. It would be easy pickings, if it weren’t for one other variable – the gulls.
Herring and ring-billed gulls are what’s known in the animal world as “opportunists.” While the loons and mergansers are busy working for their meal, the gulls wait patiently for one of the diving ducks to surface with a fish in its beak – they then make a charge, scare the successful fisher away and gobble up any dropped fish.
A merganser had just surfaced with a fish in its beak when this gull chased it away, then returned to eat the dropped fish. Credit: Adam Hinterthuer

The scene is one we at the CFL usually enjoy during the fall migration, so it’s definitely interesting to see it all unfold in the middle of January. By this weekend, though, temperatures should finally drop enough to give Lake Mendota its winter cover of ice. Then the fish will be safe from the mergansers and the mergansers safe from the gulls.
Until then, we’ll enjoy a view associated with an entirely different season.
January 10th and Lake Mendota is more reminiscnet of Spring. Credit: Adam Hinterthuer