Our Southern Birds relates that Martins "live by preference in colonies, hence a real martin-box should be a double tenement affair or a small hotel, having several compartments and entrances. It should be mounted on a bare pole in an open space, never in a tree; and should not be put up until the time of the Martin's arrival from South America in early April,--unless you wish the trouble of dispossessing whole families of English Sparrows to make room for the latecomer" (138-9). Martins prefer open land to forest, hence the admonition against placing the box in a tree.