Studies indicate that martins produce about the same number of young in each type, so this is not a major reason to select one over the other. There are, however, advantages and disadvantages to both types. Normally, only 50-65 percent of any martin house, particularly those with porches connecting adjoining compartments, is occupied, because male martins will defend more than one closely spaced cavity. Martin houses with porch dividers, which limit a territorial male to one compartment, will increase occupancy by as much as another 40-50 percent of the remaining compartments. However, full occupancy of a martin house is seldom achieved.
Durability is another factor to be considered when selecting housing.
Properly maintained wooden houses will last for many years, and houses made of aluminum will last even longer. Gourds left untended will normally last three to five years, perhaps longer in dry climates. If you want to use plastic gourds, be sure to select those that are made from white, non-translucent plastic. In martin housing, especially gourds, heat buildup will occur if sunlight is absorbed. No matter what the design, white is the only acceptable color for martin housing.