A bird enclosure is a structure used to house birds, and there are four common types: an AVIARY (6 letters), a COOP (4 letters), a CAGE (4 letters), and a COTE (4 letters). An AVIARY is a large enclosure, often outdoors, that allows birds to fly freely. A COOP is a smaller structure, usually made of wood, that is used to house chickens or other poultry. A CAGE is a metal or wire enclosure that is used to contain birds, often as pets. Finally, a COTE is a small, enclosed structure, usually made of wood, that is used to house pigeons or doves.