In the mid-to-late 1900s, bald eagle numbers declined because of trapping, hunting, and DDT poisoning. In 1978 the bald eagle was listed for protection under the Federal Endangered Species Act, and with increased conservation efforts and the banning of DDT use, its numbers began to increase dramatically. In 1995 bald eagles were down-listed from endangered to threatened, and in 2007 they were removed from the Federal Endangered Species list altogether. By 2020, listed as least concern by the IUCN, bald eagles remained protected by the Migratory Bird Treaty Act and the Bald and Golden Eagle Act. Despite their impressive recovery, they were still vulnerable to lead poisoning from ammunition, car and building collisions, habitat destruction from the ever-growing human population, and environmental pollution, including oil exposure that killed an estimated 247 eagles during the 1989 Exxon Valdez oil spill and required over six years for the local eagle population to return to pre-spill numbers.