Purple martins are a type of swallow that migrates to North America each spring to breed. They are the largest member of the swallow family in North America and rely on humans to provide housing for them in the form of birdhouses or gourds. Purple martins prefer very specific types of birdhouses in order to successfully raise their young.
Size Requirements
One of the most important factors in attracting purple martins is providing a birdhouse with the proper interior dimensions. Purple martins prefer a spacious cavity that is at least 6 inches high, 6-7 inches wide, and 12-15 inches deep. This allows the adult martins plenty of room to enter the house, move around, and feed their nestlings. It also gives the young room to exercise their wings before fledging.
The entrance hole is also an important consideration. It should be 2 1/8 to 2 1/4 inches in diameter – large enough for adults to pass through but small enough to exclude potential predators like starlings. A perch or porch extending 3-6 inches below the entrance hole gives the birds a place to land and rest.
Compartment Size
In addition to the overall size, purple martins prefer multiple compartments or rooms inside the birdhouse. This allows colony nesting, where several pairs nest close together. Compartments should measure at least 6 inches high, 12 inches deep, and 7 inches wide. Partitions between compartments should be 1-2 inches thick.
Having between 6-12 compartments in a house provides good options for scouting martins to choose from. The compartments can be arranged in rows or columns. Make sure to include a few compartments with porches rather than entrance holes to allow subadult martins a place to perch and roost overnight.
Material
Purple martins will nest in birdhouses made from many materials, but they seem to prefer wood over plastic or metal. Cedar and pine work well as they naturally resist rot and insect infestations. Make sure any treated wood is non-toxic and any paints or stains on the house are non-lead-based.
The interior of compartments should not be painted or stained, as some fumes may be harmful to the birds. Exterior paint or stain will simply make the house more durable and weather-resistant.
Height
Mounting the purple martin house at the proper height is critical. Their houses should be placed 15-20 feet above the ground, higher than surrounding trees, wires, or other structures. This allows the martins to easily access the house and provides some protection from predators.
Purple martins like an open, unobstructed flying space around their housing. Make sure to mount the birdhouse in an area clear of branches, bushes, fences or power lines. The house can be placed on a pole, the side of a building, or a martin house stand.
Placement
Purple martins prefer open areas for foraging, so place the birdhouse at least 30-120 feet away from trees or bushes. Being near open water is also ideal, as martins frequently hawk for insects over water. Position the entrance holes facing east or southeast to avoid hot afternoon sun.
Make sure to place the birdhouse where you can easily monitor it and access it for maintenance. Purple martins will readily nest in elevated birdhouses in backyards, fields, or even in urban areas.
Protection from Predators
Purple martins face threats from predators like raccoons, snakes, hawks, and owls. There are a few things you can do to make the birdhouse safer:
- Add a pole guard to prevent climbing predators
- Use a predator guard below the entrance holes
- Keep vegetation cleared several feet around the pole
- Use stainless steel screws to discourage squirrels
- Plug cracks and crevices in the house
Weather Protection
Purple martins benefit from some design features that protect the compartments from excessive heat, cold, wind, or rain:
- Ventilation holes under the roofline improve air circulation
- Light colored exteriors reflect heat from the sun
- Extending the roof beyond the entrance holes prevents rain from entering
- Placing the compartments together provides shared warmth
- Sealing cracks helps retain warmth and exclude drafts
Maintenance
It is important to perform regular maintenance on a purple martin house:
- Inspect often for any holes, damage, or leaks
- Clean out old nests after the breeding season
- Replace or repair any loose/damaged parts
- Apply fresh protective coatings as needed
- Occasionally scrape out compartments to remove parasites, debris, etc
With proper maintenance, a durable purple martin house can last for many years and provide safe nesting sites for generations of martins.
Gourds
In some parts of their range, purple martins have taken to nesting in artificial gourds rather than wooden houses. Gourds offer excellent natural insulation and many pairs can nest together on a gourd rack.
The best gourds for purple martins are tear-drop or elongated shapes about 12 inches long x 7 inches wide. Make sure to clean out old gourds before the next breeding season. Plug the drainage holes and add a circular entrance hole to mimic natural cavities.
Decoys and Audio
It can be challenging to initially attract purple martins to a new birdhouse. Using decoys and audio recordings of martin dawn song can entice them to investigate and explore new housing.
Place 2-3 realistic plastic martin decoys on the birdhouse. Move them around occasionally to make them appear alive. Play dawn song recordings near the birdhouse for an hour at sunrise during spring migration.
Conclusion
Providing the ideal purple martin birdhouse will attract a thriving colony to your yard. Look for a spacious multi-compartment house, mounted high on an open pole or stand. Make sure the interior dimensions meet martin requirements and predator guards are in place.
A properly constructed and placed birdhouse that is cleaned and maintained annually will be eagerly adopted by scouting purple martins returning each spring. Enjoy watching the aerial antics of these skillful mosquito-eating birds as they swoop and dive around their new home.
Here are some key points to remember:
- Use a spacious, multi-compartment house with 6-12 rooms
- Entrance holes should be 2 1/8 – 2 1/4 inches diameter
- Mount the house 15-20 feet high in an open area
- Place 30-120 feet from trees, with open flying space
- Protect from predators and weather
- Use decoys and audio recordings to attract martins
Comparison of Recommended Purple Martin House Dimensions
| Feature | Recommended Size |
|---|---|
| Cavity depth | 12-15 inches |
| Cavity height | At least 6 inches |
| Cavity width | 6-7 inches |
| Entrance hole diameter | 2 1/8 – 2 1/4 inches |
| Number of compartments | 6-12 |
| Compartment floor dimensions | At least 6 x 7 inches |
| Porch length | 3-6 inches |
| Mounting height | 15-20 feet |
| Distance from trees/buildings | 30-120 feet |
Types of Purple Martin Houses
There are several common types of manufactured purple martin houses available:
Traditional wood houses
- Multi-level stacked squares or rows of compartments
- Made of pine, cedar, or cypress wood
- 6-12 compartments per house
- Painted or natural stained wood
- Range from basic to decorative/ornamental
Aluminum houses
- Lightweight and durable
- Resists weathering and rot
- Reflective to keep compartments cooler
- May have interchangeable porcelain entrance holes
- Typically 6-18 compartments
Plastic houses
- Inexpensive but weather resistant
- Molded compartments of polyresin or PVC
- Vented attic space for air circulation
- May include wire guards or reflectors
- Compartments often detach for easy cleaning
Gourd racks
- Natural gourd colonies mounted on pole stands
- 12-36 decorative gourds per stand
- Excellent insulation keeps compartments warm/cool
- Gourds must be replaced every 2-3 years as they deteriorate
Condos
- “High rise” houses with stacked tiers or columns
- Allow large martin colonies of up to 60-100 pairs
- Aluminum or wood construction
- Winches make servicing easy
- Can be costly at $500-$2,000 or more
There are also many creative hand-made purple martin house designs using recycled items like buckets, crates, and pipes.
Sample Plans for Building a Purple Martin House
Here are some sample instructions for building your own purple martin house:
Single Square House
Materials:
- 1 x 10 cedar board (cut into one 24″ x 24″ piece, two 24″ x 20″ pieces, and two 24″ x 12″ pieces)
- 1 x 6 cedar board (cut into one 23 1/2″ x 23 1/2″ piece)
- Outdoor wood glue
- 2″ deck screws
- Saw or drill for 2 1/8″ diameter entrance hole
- Exterior paint/stain
Assembly:
- Glue and screw 24″ x 24″ piece to the bottom of the 23 1/2″ x 23 1/2″ piece to form three sides of the box.
- Glue and screw the 24″ x 20″ pieces to the ends to complete the four sides.
- Glue and screw the 24″ x 12″ pieces across the interior to form a partition.
- Cut entrance hole in the center of the front, 2 1/8″ diameter.
- Paint/stain exterior and mount on pole.
Six Compartment House
Materials:
- 1 x 8 cedar board (cut into two 24″ x 24″ pieces, four 24″ x 16″ pieces)
- 1 x 6 cedar board (cut into one 23 1/2″ x 23 1/2″ piece, two 23 1/2″ x 11″ pieces)
- Glue, screws, entrance hole saw, paint
Assembly:
- Glue and screw 24″ x 24″ pieces together at 90 degree angle for bottom and back.
- Glue and screw side pieces to form box.
- Glue and screw partition pieces across interior to create six compartments.
- Cut entrance hole in each compartment.
- Paint exterior and mount on pole.
Add porch roofs, vent holes, predator guards, etc. to both plans as desired. Use weatherproof wood and exterior grade paint or stain.
Tips for Attracting Purple Martins
Here are some helpful tips to attract purple martins to nest in your birdhouse:
- Provide housing where no martins currently nest – they are social and scout for colonies
- Select an open site at least 30 feet from trees/buildings
- Mount the house on a stable pole 15-20 feet high before martins arrive
- Initially add 2-3 plastic martin decoys to attract scouts
- Play dawn song recordings daily in the morning during spring
- Keep compartments clean, dry, and pest free
- Use guards to protect from predators and weather
- Leave nests in place after young fledge until fall migration
- Repair and refresh the house each season for longevity
With a properly constructed purple martin house in a prime location, plus patience, you can eventually host a thriving martin colony!
Frequently Asked Questions
How big should a purple martin house be?
Purple martins prefer fairly spacious houses. The interior cavity dimensions should be about 6-7 inches wide x 6 inches high x 12-15 inches deep per compartment. The house itself should have 6-12 compartments total. Large “martin condos” can house 60-100 pairs.
What height should a purple martin house be?
Mount purple martin houses on an extendable pole or fixed pole 15-20 feet above the ground. This allows easy flight access for the martins and helps protect them from many predators.
Do purple martins reuse the same nest?
Purple martins do not reuse nests between seasons. Old nests should be cleaned out of compartments every fall after the martins have migrated. Martins will rebuild fresh nests with mud and grass each spring.
When should I put up a purple martin house?
Put up purple martin houses 4-6 weeks before martins arrive in your area in spring. In most northern locations, late February to early March is ideal. Make sure entrances are sealed until nesting season.
How often do you clean out purple martin houses?
Purple martin houses should be cleaned out annually. After the martins migrate in late summer/fall, remove all old nests, feathers, droppings, dead nestlings, etc. before sealing up the house for winter.
Do all purple martin houses have to be white?
White is a common color for purple martin houses, but other light colors like tan, gray or blue are also fine. The light colors reflect heat from the sun. Avoid darker stains and paints which may cause the interior compartments to overheat.
How can I keep predators out of my purple martin house?
Predator guards around the pole, entrance holes and under porches can deter climbing predators. Eliminate nearby perches or hiding spots. Plug any small holes in the house. Use stainless steel screws and keep the pole slick and clean.
