Native Americans were hanging empty gourds as Purple Martin bird houses long before Europeans arrived in North America. No one really knows when this practice started, but it is thought that the Native Americans started doing it to aid with pest control.

Native Americans determined that martins would protect their Purple Martin bird houses from predators like crows and hawks which in turn protected the nearby food crops. They found another advantage to having Purple Martins close by was that they consumed large amounts of flying insects. The Native Americans learned that if they hung more gourds there were fewer flying insects.

Purple Martins have adapted to nesting in artificial Purple Martin bird houses to the point that, today Purple Martins in the eastern parts of North America depend solely on Purple Martin houses for breeding.

Since Purple Martins are completely dependent on nesting sights furnished by humans, it is crucial that the housing utilized for nesting meet a couple of minimum requirements.

Minimum Requirements for Purple Martin Bird Houses:

Martin houses should have easy accessibility for checking nests and performing general maintenance. A pole system that raises and lowers is the most convenient and safest.

Nesting compartments should be at least 6" wide x 5 ½" high and 9" deep. A larger size will work, but any thing smaller is insufficient. Having a nesting compartment at least 9” deep will keep the family of martins out of the reach of flying predators like hawks.

Martin bird houses should be white (including gourds). Research has shown that light colored houses stay 10 to 15 degrees cooler than dark colored ones. Houses that over heat may cause fledglings to jump out the nest to escape the heat before they are ready to fly.

Nesting compartments should have hinged or removable panels for easily accessibility. As the landlord you will be cleaning out old nests, performing nest checks, controlling insect pests, removing unwanted pest birds and performing general maintenance.

Appropriate ventilation is a necessity. Several ½" diameter holes close to the top of the nesting compartments will provide proper airflow. This design feature is particularly important in the southern breeding locations. Lowering the temperature will greatly increase the young birds' chances of survival.

Starling Resistant Entrance Holes (SREH's) will give the Purple Martin family an even better chance of survival. Many martin houses feature SREH's, but if your martin house does not, adapters are available. Several styles of SREH's are available but the height should be exactly 1 3/16" high. This measurement is crucial because any larger and starlings will be able to get in and any smaller the Purple Martins won't be able to get in.

New studies have proven that porches inside and outside the nesting compartment help the Purple Martins negotiate these smaller openings while making it harder for starlings to get inside. Porches should be at least 3" x 3". They should be situated no more than 1/8" below the bottom of the crescent shaped opening.

Purple Martins have several predators, but the starlings have done the most harm to their population. Starlings were introduced into North America in the 1800's. The trouble with starlings is that they take over the nesting sites of Purple Martins. They are so aggressive that they will actually kill nesting Purple Martins to take over the nest. Since martins raise just one brood per year, this can do a lot of damage to population levels. You will have to remove any starling nests found in your martin bird houses. House sparrows are another non-native species that cause problems for nesting Purple Martins. Their nests also have to be removed when found in martin bird houses.

If you are interested in supporting a Purple Martin colony you need to find the best location for your Purple Martin bird houses. You should put them as far away from tall trees as you can. Here is a good rule to follow; your martin bird house should be as far away from any tree as that tree is tall. For example, if a tree is 50 feet tall then the house should be located at least 50 feet from that tree. Flying predators like hawks and owls hide in tall trees. Martins are sensitive to this risk and will not nest in houses where they do not feel safe. The more open the area is around the martin bird house, the better chance you have at attracting a colony of Purple Martins.

Putting Purple Martin bird houses around your yard takes some effort, but it is very worthwhile. These gorgeous birds are entertaining to watch and good for our environment, but they do need our assistance for survival.