The high level of biological activity associated with the often complex structure of their vegetation allows wetlands to retain or recycle nutrients and to perform other water-purifying functions. Some wetlands provide important aesthetic, educational, or recreational values for trapping, hunting, fishing, nature observation, and scientific study. Wetlands provide habitat for an impressive diversity of plants and animals, including many which are considered rare or endangered. About 122 species of shore and wading birds, waterfowl, and some song birds perform most of their activities in, on, or around wetlands. Some game birds, such as turkey, depend on wetlands especially in the winter.
Mammals associated with wetlands include muskrat, otter, and beaver.
Only as a result of an increased understanding of the functions of wetlands and a recognition of their values for flood protection, water quality maintenance, fish and wildlife habitat, aesthetic, recreational, and other uses, have wetlands been afforded special protection nationally and in Pennsylvania, at least on paper, for the past two decades. Indeed, almost all AMD-treatment systems currently being funded by BAMR utilize constructed wetlands in some phase or aspect of the treatment process. Longwall mining today is a major threat to natural wetlands.