The tundra swan (Cygnus columbianus) is the most common and widespread swan in North America. After near extinction in the late 1800s, protection from passage of the Migratory Bird Treaty Act of 1918 helped their population grow to over 133,000 by the early 1970s. Their numbers have continued to increase slowly and their current Eastern population is roughly 80,000. Tundra swans breed from Northern Alaska, south along the Alaska Peninsula, and east near the Arctic Coast. They winter in two regions: populations in Alaska and Yukon Territory chiefly winter in the Central Valley of California and along Pacific coastal regions, while others migrate southward to the interior Great Lakes region or to coastal marshes from Maryland to North Carolina. Tundra swans mate for life, produce 2 to 8 young cygnets each summer at their Arctic breeding grounds, and can fly up to 100 mph in a V-formation with a tail wind. Males weigh about 20 pounds, have a bill-to-tail length of 4 to 4-1/2 feet, and have a wingspan up to 7 feet. Tundra swans eat submerged aquatic vegetation (SAV). Their nest is an elaborate platform, 12 to 18 inches high, composed of aquatic grasses and mosses. The greatest threats to tundra swans living in the Chesapeake Bay are loss of habitat and competition for food from the 3,000 mute swans that live in the Bay area all year and eat 8 to 10 pounds of Bay grasses each day. Approximately 5,000 tundra swans spend several weeks each year at Eastern Neck from late October to December after migrating over 4,000 miles to take shelter in the Bay area. Only a few hundred stay all winter, weather and food permitting. A major shift in the 1970s resulted in the majority wintering in North Carolina's intercoastal waters. On December 3, 2003, a tundra swan cygnet was released at Eastern Neck NWR after being rescued from an oil impoundment at Prudhoe Bay in Alaska in September. She was rehabilitated at the International Bird Research and Rescue Center, but by the time she was ready for release, her family group had already left on fall migration to the Atlantic Coast. The young swan was then transported to Tri-State Bird Rescue in Delaware to wait for the arrival of migratory flocks at Eastern Neck. Named TR after the founder of the Refuge System, she was fitted with a satellite transmitter collar to relay data on the survival and movements of a rehabilitated hatching-year swan that did not physically migrate. Tracking of TR ended in 2004.