Long ago, as a continental glacier retreated northward, it left a jumble of ice blocks at its edge. If it stood still for a while, great quantities of rock and soil built up at the southern end, forming a "moraine." When huge chunks of ice were buried by the debris, "kettle holes" were created as the ice finally melted. Swan Pond is one of several shallow (2 to 3 feet deep) water-filled kettles in this hilly moraine area.
Kettle holes have no stream to supply them with water, so Swan Pond's water level fluctuates greatly through the year. In March and April, when the pond swells with rains and melting snow, flocks of snow-white whistling swans stop on their trek from the Atlantic seaboard to Yukon breeding grounds.
The pond gradually shrinks in summer. Newly exposed mud flats immediately sprout a thick growth of smartweed and other shore plants, which supply seeds for next spring's migrating waterfowl. Shore birds flock to the pond in summer. A common inhabitant is the long-legged, robin-sized killdeer, named for its call.
As the water rises in fall, muskrats harvest the plants and create open water again for waterfowl. By the time the pond freezes, they have piled the plants into domed huts. Muskrats survive the winter by eating their houses from the inside out!
Swan Pond is on private property — an excellent example of the compatibility of farming with preservation of wildlife habitat.