In August of 2007 the bald eagle was removed from the federal list of Threatened and Endangered Species in Montana and most of the rest of the continental United States. Montana currently supports over 500 active bald eagle territories in the state, which far surpasses both the recovery goal of 99 breeding pairs cited in the 1986 Bald Eagle Recovery Plan and the estimated carrying capacity of 352 territories identified by the Montana Bald Eagle Working Group in 1994. In 1978 there were 12 known breeding pairs of bald eagles in the state.
Bald eagle numbers, estimated at a quarter of a million in the lower 48 states before 1800, declined steadily throughout the late 1800s and early 1900s. Raptors at this time were regarded as vermin and shot on sight. The Bald Eagle Protection Act of 1940 increased public awareness and made indiscriminate shooting, poisoning, collecting, and trading of bald eagles illegal, stemming the decline for a time. Yet, the advent of DDT and related pesticides during World War II and their widespread post-war use soon caused eagle reproduction to plummet. In 1963, a National Audubon Society Survey reported only 417 active nests in the lower 48 states.
After years of research, scientists determined that DDE, a breakdown product of DDT, accumulates in the fatty tissues of female birds, including eagles and peregrine falcons, and impairs the calcium release necessary for eggshell formation. This induces thin eggs and reproductive failure during incubation. These findings eventually led to the banning of DDT and related chemicals in the U.S. in 1972. Recovery efforts focused on removing DDT from the environment and protecting eagles and their habitats.
Currently, Bald Eagles continue to receive protection from the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act. These federal regulations protect eagles from direct persecution and human disturbance that could cause nest abandonment or reproductive failure.
The Bald Eagle is clearly a conservation success story. However, increases in human population growth and development may still threaten bald eagle nesting, foraging and roosting habitat. The Montana Bald Eagle Working Group, formed in 1982 and composed of representatives from federal and state agencies, tribes, universities, conservation groups, and private industry, continues to monitor nesting and wintering bald eagles across the state and cooperates with the federal post-delisting monitoring strategy that calls for monitoring every 5 years between 2009 and 2029. The Montana Bald Eagle Work Group also has prepared several documents to guide the management and conservation of bald eagles and their habitats in Montana.