A cloaca is a single posterior opening for a birds digestive, urinary, and reproductive tracts. It is used to expel feces and lay eggs. The cloaca is found on the rear of the body under the base of the tail, covered by feathers on the extreme lower abdomen. The cloaca is also frequently called the vent. Birds reproduce using their cloaca, which occurs during a cloacal kiss in most birds. During this process, birds that mate using this method touch their cloacae together, which is sufficient time for sperm to be transferred from the male to the female. For some birds, such as ostriches, cassowaries, kiwi, geese, and some species of swans and ducks, the males do not use the cloaca for reproduction, but have a phallus. The cloaca is where birds excrete feces, urinate, and reproduce.