15. Deer — Can you believe the common White-Tailed Deer was an endangered species in the U.S.? By 1930, commercial exploitation, unregulated hunting and deforestation had reduced the population to less than 300,000. After outcries from hunters and other conservationists, laws were passed to make commercial exploitation of deer illegal. These protections, along with conservation programs and regulated hunting, have brought the White-Tail back in a big way: recent estimates of populations in the U.S are over 30 million! They are also widespread with subspecies even found as far south as Brazil!