Dogs, cats, fish, rodents, lagomorphs, ferrets, birds, certain reptiles and amphibians, and a wide variety of arthropods such as tarantulas and hermit crabs are the most common pets in North America. Horses, elephants, oxen, and donkeys are usually made to work, so they are not usually called pets. Some dogs also do work for people, and it was once common for some birds (like falcons and carrier pigeons) to work for humans.