These bred from birds that escaped or were freed from captivity. Many zoos observe interesting behaviors of Emperor tamarins held in captivity. Measurements are usually taken from specimens reared in captivity. Belugas were among the first whale species to be kept in captivity. Overall, only 14,000 of the Australian prisoners taken by the Japanese survived captivity. White lions were selected for breeding in captivity. Ball pythons are one of the most common reptiles bred in captivity. Belugas were the first whales to be kept in captivity. White lions are selected for breeding in captivity. There have been attempts to keep baleen whales in captivity. There were three attempts to keep minke whales in captivity in Japan. There were three attempts to keep grey whales in captivity. Natural breeding of horseshoe crabs in captivity has proven to be difficult. They are also popular to hobbyists who want to breed marine species in captivity. It is a 400 ha estate for lions born in captivity.