Many wildlife species benefit from these open field habitats. Waterfowl, bobolinks, and many other songbirds, pollinators and small mammals use open fields to nest and rear young. Birds of prey such as kestrel, northern harriers and rough-legged hawks glide over these same grasslands in search of prey such as mice, voles and other small mammals. In addition to 5000 acres of natural marsh, the refuge includes 1200 acres of managed wetlands formed by three impoundments. Water levels in these areas are manipulated to encourage the growth of waterfowl food and cover plants such as wild rice and buttonbush, while also exposing hummocks of soil and vegetation that support nesting by mallards, American black ducks and other wetland birds. Fauna Historically, the largest great blue heron rookery in Vermont is located on the refuge's Shad Island. This rookery fluctuates from about 250 to almost 600 nests each year. This rookery has been reduced in recent years, likely due to an increasing bald eagle population. More than 20,000 ducks converge on the refuge each fall and find habitat for feeding and resting. In the spring, a small percentage of those use the refuge habitats for nesting. All of Vermont's endangered black terns nest on the refuge. A significant percentage of Vermont's nesting ospreys are found on the refuge. Spiny softshell turtles, a state threatened species, use the refuge to feed and bask from April through September. Mammals that inhabit this refuge include raccoon, black bear, coyote, skunk, beaver, red fox, river otter, bobcat, porcupine, muskrat, and mink. References External links Refuge website See also Missisquoi River Missisquoi Bay Lake Champlain Highgate, Vermont National Wildlife Refuges in Vermont Protected areas of Franklin County, Vermont Swanton, Vermont Champlain Valley National Heritage Area Wetlands of Vermont Landforms of Franklin County, Vermont Ramsar sites in the United States