Purple Martin housing is an investment. How do you choose? Careful selection of equipment can increase your chances of becoming a successful Purple Martin landlord.
For years, a 6″x6″ compartment has been considered standard and was found in almost all commercial houses. Purple Martins can and do nest in these compartments and six humans have lived in a one-room efficiency apartment. Neither is very comfortable. Larger compartments 6 1/2″ to 7″ wide and 9″ to 12″ deep are better but they have some drawbacks in that they attract Starlings. Many landlords are currently modifying commercial houses to combine two small compartments into one large one. When using larger compartments more attention must be given to the size and shape of the entrance hole. Most new commercial houses offer large units.
Typically, entrance holes have been round and anywhere from 1 3/4″ to 2 1/2″ in diameter with 2 1/8″ seeming to be preferred. The bottom of the hole has been placed 1/2″ to 1 1/2″ above the floor of the compartment. Since Starlings are attracted to the larger compartments, many landlords are now using holes adapted to keep Starlings out. Several crescent shapes measuring 1 3/16” high by 2 ½” to 3” wide are now available. Some Martins can’t get in these holes and some Starlings can, but most Martins can get in and most Starlings are excluded. The “Snyder Excluder” a specially shaped entrance hole has been successful at keeping Starlings out of Purple Martin compartments.
Houses can be made of wood, metal (preferably aluminum), or plastic, while gourds are generally either natural or plastic. Different people prefer different materials but all will suffice if used properly. Aluminum is most frequently used for Martin houses and it is very satisfactory when painted white. Brushed or milled aluminum doesn’t seem to be quite as attractive to Martins. Plastic houses have recently become available and are promising if the house is properly designed and well constructed. Wood houses, usually cypress, cedar or redwood, are heavy and require regular maintenance (painting & caulking, etc.). All woods used in the manufacture of Martin houses should be untreated. Natural gourds will last for years if soaked in copper sulfate and painted yearly and kept out of the elements during the off- season. Plastic is becoming more popular as a gourd medium since it is easily cleaned and maintained and is relatively inexpensive.
White is highly recommended for all Purple Martin houses and gourds since it reflects heat better than other colors. Dark colors absorb heat. Some manufacturers believe that green, red or metallic (aluminum) roofs help attract Purple Martins. It’s generally recommended that pastel colors be used for trim or accent if desired. Natural gourds are most often painted white.