Purple Martin House Types, Compartments and Pole Systems Compared

Purple martin house types at a glance

Three types of purple martin house cover nearly every setup in the East, and each one needs a pole that lowers, whether that is a purple martin house pulley system, a telescoping pole or a winch. Multi-compartment houses hold one pair per room. Gourds hold one pair each. A gourd rack stacks or strings several gourds on a single support. The Purple Martin Conservation Association (PMCA) states that a single pair nests in each individual compartment of a house, and that martins also nest in human-made and natural gourds. NestWatch, from the Cornell Lab, adds a regional note: multi-compartment boxes are more common in the east, and hollowed gourds strung close together more common in the west.

The Pacific Northwest is its own case. The PMCA says martins there use gourds and single boxes, not multiple-room houses, and it suggests groups of three or four on a pole. In the Southwest, according to the PMCA’s landlord hints, martins nest only in old woodpecker cavities, so a purchased house there is a long shot.

Anyone choosing between the types should look past the label. The PMCA’s hints warn that many published plans and some manufactured houses are made to improper dimensions, so a housing that fails to attract martins deserves a measuring tape before it deserves blame. Compared by type, none of the three is a mistake as long as the dimensions are right. The overview in the purple martin house guide covers siting and the entrance figures; this page stays with the structure of the housing itself.

Compartments: how much room a martin pair gets

The PMCA gives 6 by 6 inches as the smallest acceptable compartment floor and 7 by 12 inches as the size that offers better protection against predators and weather, provided starlings are controlled. Compartment height can run from 4 1/2 to 6 or 7 inches, and the entrance should sit about 1 inch above the floor. Those are the figures from the PMCA’s landlord hints, and the housing page repeats the minimum and recommended sizes.

Depth matters because of owls and hawks. The Missouri Department of Conservation notes that conventional 6 by 6 inch compartments offer little to no protection, since an owl can easily reach to the back. A deeper room, sometimes with the opening set slightly off center, keeps nestlings out of sight and reach, and old houses can be reworked: leave the interior wall in place and put an offset hole through it to make an internal baffle.

Room count is the other number. The PMCA recommends a minimum of four cavities and describes six to twelve as a great start for a colony. Its T-14 house, a design the Missouri Department of Conservation calls a traditional Amish plan, has 14 extra-large compartments with access doors and slide-out nest trays, and it winches up and down. Every cavity, whatever the count, should open for easy access while martins are nesting.

Purple martin gourds: sizes, entrances and upkeep

Purple martin gourds follow their own size rules, and purple martin gourds of any material need the same lowering pole as a house. The PMCA wants no less than 8 inches in diameter and calls 10 to 12 inches ideal. The Missouri Department of Conservation points to plastic gourds around 10 inches wide with a crescent-shaped starling-resistant entrance, and notes that gourds of at least 9 inches let martins nest back from the entrance, out of easy owl range.

Plastic and natural gourds trade ease for texture. The department says plastic gourds are easy to care for and last a long time, and that a side access lid makes nest checks and end-of-season cleaning simple; some come with a rain canopy over the door. Natural gourds have rough interior walls that let the female spin a nest without slipping, and a darker interior that may feel more secure to the birds. They take more work: scour the rough exterior to a smooth finish with water and a nylon pad, soak the gourd in an antifungal solution so it does not rot, add a coat of white paint to prevent overheating, then cut a crescent entrance. For birds that have trouble getting through the doorway, the department describes a cling rod, a slightly concave wooden dowel of about 3/8 inch glued flush just below the entrance.

Gourds live on racks, and a gourd rack is only as good as the pole under it. The department describes a simple weighted pulley rack as an economical way to begin, and says the PMCA has blueprints for a winch-operated rack that suspends up to 16 gourds. That brings the discussion to the pole, which is where a purple martin house succeeds or fails after the rooms are right.

The purple martin house pole and the systems that lower it

Housing that cannot come down is the wrong housing. The PMCA says martin housing needs to lower, sometimes daily, to remove competitor nests and to monitor nests, and it names three mechanisms: telescoping, rope and pulley, or winch. The Missouri Department of Conservation gives the same list and adds that a tilt-down housing system on a hinged pole is not recommended, because it cannot be used once martins begin nesting.

Weight decides between them. According to the department, wooden houses are heavy enough that they are best mounted with a winch. Smaller wooden houses with six or eight compartments, at 25 pounds or less, may sit on a telescoping pole. A purple martin house pulley system suits gourd racks and lighter loads, which is why the weighted pulley rack above counts as a pulley system in its simplest form, with the rope tied off where the lowered housing can be held steady. The same source calls a telescoping pole, pulley or winch system the common solutions, so none of the three is a compromise in itself.

Two small details matter more than the mechanism. First, orientation marks: the department tells landlords to mark the house so compartments return to the same compass directions after every nest check, and to fit a locking mechanism so the house cannot spin in the wind. If houses do not always face the same direction, it says, martins become disoriented and abandon their nests. Second, depth: the PMCA specifies a pole set 18 to 25 inches below ground, and a recommended height of 12 to 18 feet. NestWatch gives 10 to 15 feet and says to mount the house on a pole that can be lowered for cleaning and maintenance.

A purple martin house pole also carries the predator guard, which belongs on every active pole. In practice the purple martin house pole is the one part of the housing that decides whether a landlord can check nests at all. The pole guard page covers those.

Materials and finish

Color is not a style choice here. The PMCA’s hints say houses and gourds should be white or a light pastel, with trim in any color, because white housing reflects the sun’s heat and keeps nestlings cooler. The Missouri Department of Conservation says the exterior of a wooden house should be painted white and the interior of the compartments left unpainted, with 3/4-inch stock best for insulation against heat and cold. Cypress or cedar last longest, pine or redwood also work, and exterior plywood will not last as long as solid stock.

Changing housing without losing the colony

Martins return to the housing they know. The PMCA says they may abandon the site if the housing is gone or drastically altered. Its advice for replacing a single active house is to put the new housing near the one being removed and give the birds a whole season to adjust, and not to take the old one down until some martins have bred in the new one. Landlords with several active houses can replace one between seasons without risk of losing the colony.

Housing also needs a winter plan. Store it indoors or close it up so paper wasps, squirrels and other birds cannot claim it before the martins are back. Anyone also fitting out boxes for other species can find those sizes in the birdhouse guide, and the seasonal food question is on the feeding page.