Purple Martin Nest Box
Being a Purple Martin manager may require a bit more effort and skill than with other species, especially for the beginner. It is recommended that you research Purple Martins thoroughly before you embark on this enjoyable, but sometimes, challenging project. An additional excellent resource for the new Purple Martin manager is the Purple Martin Conservation Association (PMCA) website.
* Housing for Purple Martins should be built to last and easy to maintain
* Wood should have a natural, unpainted interior
* The exterior of the house and the pole benefit from exterior treatments to reduce the effects of weather
* Paint the exterior with white or other bright colors that reflect sunlight and prevent hot interior temperatures
* Compartments 7" wide and up to 12" deep that offer greater protection from predators and the elements, and will keep nestlings more comfortable. Adult martins are 8" long, so compartments must be large enough to accommodate 4-6 nearly-grown nestlings and both parents.
* Crescent shaped entrance holes help prevent problems with starlings and should measure 3" wide and 13/16" tall. These entrances should be positioned no higher than 1/2" above the porch or floor, or can be mounted flush with floor.
*Housing should have door plugs to prevent occupation by other birds during the non-breeding season.
* Be sure your Purple Martin house can be easily lowered and raised. Some wooden houses are very attractive but also very heavy and can be difficult to manipulate. The best types have pulley systems that raise and lower the house vertically while the pole remains fixed. Winch and pulley systems should be oiled regularly and rope and cables should be checked routinely for signs of wear. Frayed rope or cable should be replaced.
Martin houses should be placed in an open location, at least 40 ft. from trees or buildings.
Martins prefer to have clear access to houses from all sides, and like to have perching sites like utility wires nearby, but not attached to the nest box.
The height of the housing can be anywhere from 12-20 ft. Keep tall bushes, shrubs, and vines away from the pole.
If your yard has too many trees near the box, relocate it to a more open area, mount it higher, or remove trees to create a more open site.
If you live near a body of water, boat docks make ideal locations for mounting a martin house or gourd rack. Set the pole in concrete, with 18-25" below the ground, to provide a strong base for a new box system.
A cone-shaped predator guard placed on the pole will protect the birds from snakes, raccoons and other mammals. The top of the pole guard should be placed at least 4' above the ground.
Even with deep compartments, PMCA recommends that you equip your house with an external owl guard. If commercial guards are not available, you can fasten hardware cloth (2" x 4" mesh) to the outside of the house, creating a protective cage that can be removed for nest checks and monitoring
We recommend ensuring that the house is open and cleaned out before the first martins return in early March in Tennessee. Until you have an established Purple Martin population, controlling nest-site competitors may require repeatedly lowering the housing to remove nests of competitors like House Sparrows and European Starlings.
When monitoring the nesting box(es), check for evidence of predation on the ground under the housing (dropped owl feathers, plucked martin feathers, chewed-off martin wings, etc.).
We recommend NOT checking on the status of eggs and nestlings during the nesting season as different pairs of birds are often in different stages of the nesting cycle. Some birds may have eggs while others have young nearly ready to fledge. Disturbance at the wrong time could have negative results for many nests.
Some weather conditions may contribute to a large increase in the population of external parasites normally found in martin nests, including fleas, nest mites, and blowfly larvae. The safest way to reduce the number of nest parasites is to conduct a "nest replacement." Never use pesticides in nests or boxes.
Your Martin house can be cleaned out after the birds leave in September. We recommend blocking the holes with plugs to prevent House Sparrows and other birds from roosting in or nesting before martins return.