This occurs in many parrot species, cockatiels, macaws and budgerigars. Among the occupants are zebra finches, budgerigars, cockatiels, canaries, and golden pheasants. Visitors can feed and interact with over 600 grass parakeets, cockatiels, and eastern rosellas. The zoo now houses a "Wild Bird Walkabout" featuring over 400 parakeets and cockatiels. It is a free-flight aviary featuring rosellas, macaws, cockatiels and budgerigars. Cockatiels, rose-breasted cockatoos, and greys also produce smaller amounts of feather dust. Cockatoos and cockatiels possess crests which may be raised or lowered at will. The aviary is home to&colon; galahs, lorikeets, cockatiels, kookaburras, and shelducks, among others. Parrot species (including cockatiels) are biologically vegetarian species. As a caged bird, cockatiels are second in popularity only to the budgerigar. Amazons and cockatiels prefer horizontal bars, as they like to climb. Albino animals have the Blue genetic mutation, but cockatiels do not have the Blue gene. Prior to Cook's voyage, cockatiels had been imported only in small numbers as exotic cage-birds. Wild cockatiels are grey with visible differences between males and females. Cockatiels do not actually have green pigment in their plumage, thus yellow-suffusion specimens don't either.