As late as 1800, tens of thousands of bald eagles soared over the United States, but their population later dwindled because of habitat loss, environmental contaminants, and illegal shooting. By the 1960s, only 400 adults remained. With public support and legal protection, the bald eagle was removed from the endangered species list in August 2007, though it is still protected by the Migratory Bird Treaty Act and the Bald and Golden Eagle Protection Act and can now be seen in substantial numbers throughout its range. On the refuge, nest building and courtship begin in late November or December, and the eagle nest, or eyrie, is usually built of sticks in the crook of a large live pine tree near water, measuring three to six feet wide and two to three feet deep. Bald eagles mate for life and return to the same nest year after year. Eggs are generally laid in late January or early February and incubated for 35 days; one to three chicks hatch between mid-March and April and leave the nest by late July. The largest raptors in Maryland, bald eagles stand nearly three feet tall, have a wingspan of over 6 feet, and weigh between 8 and 15 pounds. Adults have white heads and tails, dark brown bodies, and yellow bills and talons, while immature eagles are the same size but do not acquire white head and tail feathers until four or five years of age. Primarily fish eaters, they also prey on waterfowl, muskrats, and turtles, and they scavenge dead fish and other animals.