As I drove down the highway past a pond shortly after ice-up a few weeks ago, I noticed a few small piles of what looked like mud and vegetation on the ice. I suspect that some of you may have noticed something similar. What is that all about?
They were mud and vegetation! In short, they were muskrat push-ups. These push-ups are often constructed by muskrats shortly after ice-up on area ponds and marshes. The muskrats chew through the thin sheet of ice, creating a hole large enough for them to crawl up onto the ice. They then bring up plant material and mud onto the ice, and form it into a small hut or lodge, just large enough for one muskrat to use as a feeding platform or resting spot that is well insulated and safe from predators.
Most everyone is familiar with muskrat lodges, those structures made of vegetation such as cattails, rushes, grasses, and mud that dot many marshes and ponds across the state. Odds are a family unit of muskrats will occupy the lodge during the winter months. The number of occupants will vary, of course, but a crude method to estimate the muskrat population of a pond or marsh is to count the lodges and multiply by five. So, five muskrats, more or less, will occupy a lodge.
Muskrats are active throughout the winter. And unlike beavers that cache food, muskrats have to forage for their food. They feed mainly on the roots, stems, and leaves of aquatic plants such as cattails and bulrushes. So during the winter they may have to swim a considerable distance to acquire their food before returning to their lodge to consume it. That is where push-ups come in. I have read that push-ups are often constructed at intervals in a line leading from the lodge to a favorite feeding spot. This enables the muskrat to come up for a breather occasionally, “breather” being another common name for the structure. They can also rest and have lunch in it. And of course, it enables the muskrats to forage further from the lodge. The muskrats will maintain these push-ups throughout the winter, but as the snow cover increases, they may not be as conspicuous to the casual observer.
So be on the lookout for these muskrat push-ups as you travel about.