 Federal authorities in the United States use trapping as the primary means to control predators that prey on endangered species such as the San Joaquin kit fox ("Vulpes macrotis mutica"), California least tern ("Sterna antillarum browni") and desert tortoise ("Gopherus agassizii").Animals may also be trapped for public display, for natural history displays, or for such purposes as obtaining elements used in the practice of traditional medicine.Trapping may also be done for hobby and conservation purposes.