Why are muskrat sets required to be 2 inches below the water or in a covered set in the spring?

Additional placement restrictions for muskrats and other water sets in the spring are required to deter incidental take of nontarget water birds, such as ducks, coots and herons. Spring is a time of increased water bird activity in North Dakota due to migration and breeding behaviors, therefore we want to ensure that trapping activities do not negatively impact these birds.