Critter Corner No. 1 – The Muskrat

MuskratBy George Sly When most people think of Goose Pond Fish and Wildlife Area, they automatically picture birds. It is true; the restoration of the Goose Pond wetlands has resulted in the creation of some of the finest bird habitats in the eastern United States. The opportunity to see the evening influx of thousands of Sandhill Cranes during their Spring migration is an experience both exhilarating and never to be forgotten. What lover of all things wild would not be thrilled by the chance to monitor Bald Eagles rearing their young or watch as they snatch a shad from the surface of a vast marsh? And then there are the rarities. Who would have foreseen this part of Indiana being graced by such rare visitors as the Roseate Spoonbill, Neotropic Cormorant, Wood Stork, Hudsonian Godwit, American Avocet, or Hooded Crane? Yes, Goose Pond FWA certainly deserves its growing reputation as an American birding hotspot. But, lest we forget, the Goose Pond represents a very large (8000 acres) ecosystem with a variety of habitats and an equally diverse assemblage of animals other than birds. Granted, many of these mammals, reptiles, amphibians, fishes, and invertebrates don’t make themselves as visible as the area’s avifauna. Nevertheless, among these other animal groups there are adaptations, behaviors, and lifestyles sufficient to entertain all of us who have an interest in natural history. With this notion in mind, we hope to periodically offer a glimpse into the lives of some of the Goose Pond’s non-avian fauna. Let’s begin with one of the most archetypical mammals of the wetlands. On more than one occasion, visitors to Goose Pond FWA have asked, “What in the world are all of those dark-colored mounds protruding from the water?” These masses of rounded vegetation really become apparent in late Fall after much of the emergent vegetation has been culled by the first frosts of the year. Scattered far and wide over the shallow waters, their numbers are quite remarkable. The mammals who have engineered these structures are muskrats and these are their lodges. It is thought that the name Muskrat has its origins in a Native American appellation for the animal, musquash. Musquash appears in many Native American mythological narratives ( Coincidentally, the name Muskrat is also a title of practical significance. They use musky secretions from their preputial glands to scent their urine. This is then used, as other with mammals, to mark territorial boundaries and home ranges. Muskrats belong to that large assemblage of mammal species collectively categorized as rodents. Technically speaking, we may think of them as very large mice because they are placed into the same subfamily as voles. Muskrats are the largest of the so-called arvicoline rodents in America. Indiana muskrats average a little over a pound in weight and about twenty-four inches in total length. Half of this length consists of the tail which is laterally compressed as an adaptation for sculling their way through the water. The hind feet are partially webbed and used for paddling. Muskrat pelage has a dense under-fur. Air trapped in this fur provides the Muskrat both water-proofing and buoyancy. Muskrats, like beavers, can close their lips behind their large central incisors. This is an adaptation which prevents water from entering the mouth while they are feeding. The aforementioned lodges are constructed from aquatic vegetation. Cattail is a favorite construction material but muskrats will also use plants such as rushes, sedges, and smartweed to build lodges. Inside the lodge there is a chamber which lies above the water line. An underwater entrance leads to this elevated platform and also provides a passageway for escape should danger threaten. Young muskrats are born in these lodge chambers. In Indiana, muskrats have two or three litters per year averaging six young per litter. The life span of muskrats, like many wild mammals, is not long. Only 10-15% of individuals reach an age of one year (Mumford and Whitaker. 1982). Incidentally, muskrats may also burrow into banks and construct dens in lieu of the aquatic lodges. Muskrats are primarily vegetarians. As one would surmise, their foods are comprised mostly of various aquatic plants. Foods mentioned in Mumford and Whitaker’s Mammals of Indiana include cattails, bulrush, water lilies, pondweeds, smartweeds, sedges, and grasses. Some animal foods may be consumed including dead fish, crayfish, frogs, and mussels. Of course, muskrats have their enemies too. The Mink, a common wetland member of the weasel family, may stalk muskrats along the shore or attack by digging through the side of a lodge. Raccoons, coyotes, domestic dogs, and foxes also kill muskrats. Birds of prey such as the Bald Eagle, Osprey and the larger owls are known to do so as well. Muskrats have been the quarry of fur trappers for many decades. Hunting and trapping are an integral part of the Goose Pond FWA management plan and so muskrats are taken there too. Locally, the average price for a Muskrat pelt is currently around eight dollars. The GPFWA staff reported that nearly three dozen trappers pursued muskrats there last year and took 1600 “rats”. This represents a value of over twelve thousand dollars in pelts, yet another example of how Goose Pond FWA impacts the local economy. For those interested in more details of Muskrat natural history the following are quite useful. Mammals of Indiana: A Field Guide. John O. Whitaker, Jr. Mammals of Indiana. Russell E. Mumford and John O. Whitaker, Jr.