Petting zoos feature a variety of domestic animals. Common animals include sheep, guinea pigs, goats, rabbits, ponies, alpacas, llamas, pigs and miniature donkeys, and a few exotic animals such as kangaroos. Petting zoos are popular with small children, who will often feed the animals. In order to ensure the animals' health, the food is supplied by the zoo, either from vending machines or a kiosk. Food often fed to animals includes grass and crackers, and also in selected feeding areas hay is a common food.