520 ILCS 5/2.32

It shall be unlawful for any person at any time to molest, destroy or attempt to destroy any feed bed, nest, den, house or other cavity of any of the wild mammals protected by this Act except as provided in Section 2.37. For the purpose of this Act, a feed bed is defined as a mound, pile or mat of branches, cattails or other vegetation gathered and piled by muskrats or beaver.