Arizona Center for Nature Conservation/Phoenix Zoo The Arthur L. and Elaine V. Johnson Conservation Center at the Phoenix Zoo has announced the birth of a bumper crop of 21 black-footed ferrets. The Arthur L. and Elaine V. Johnson Conservation Center at the Phoenix Zoo has announced the birth of a bumper crop of 21 black-footed ferrets. The animals are one of North America's most endangered species. The four litters join the more than 500 kits born during the Zoo's 30 years of black-footed ferret breeding, and more births may be on the way. The newborns will stay with their mothers inside special boxes designed to mimic ferret dens.