Purple martins are swallow-like birds that nest in cavities. Unlike most other bird species, purple martins have become almost completely dependent on human-supplied nest boxes. Providing housing for these birds allows people to enjoy their aerial acrobatics and insect-catching abilities near their homes. When setting up a new purple martin colony, it is important to put nest boxes up at the right time of year to attract these migratory birds. The optimal timing depends on your location.
What are purple martins?
Purple martins are the largest species of swallow in North America. They have dark blue-purple plumage, forked tails, and long, pointed wings. Martins are agile flyers known for their aerial maneuvers catching insects in flight. They eat a variety of flying insects like dragonflies, flies, moths, bees, wasps, and ballooning spiders. A group of martins flying together is called a “scout” and their flight patterns when searching for insects are a spectacular sight.
Martins are colonial, cavity-nesting birds that originally nested in tree cavities made by woodpeckers. But as human settlement expanded, they adapted to using artificial nest structures provided by Native Americans and early European colonists. This allowed their range to expand eastward. Now, they rely almost entirely on man-made nest boxes in most of their range.
Purple martin migration
Purple martins spend their winters in South America east of the Andes Mountains. They migrate north to breed in summer, with most martins wintering in Brazil.
Spring migration starts in January and February. Martins start arriving back in the southernmost parts of their North American breeding range like Florida and Texas by late January. They continue moving northward in February and March. Most martins have reached their breeding grounds by April or May.
Fall migration back to South America starts in August. By late October, most purple martins have left their summer range in North America. A few stragglers may linger into November in the southernmost states.
When to put up a new purple martin house
If you live in an area with purple martins, providing nest boxes can attract a colony to your yard. However, it is important to time it properly for the best chance of occupancy.
In the South
In the southernmost states like Florida, Texas, Arizona, and southern California, martins start scouting for nest sites in January and February. Here, you will have the best luck getting your new martin house occupied if you put it up in late fall through early winter. Having the house up and ready for when the first prospecting martins arrive gives it the greatest chance of being used.
Aim to have new martin houses up by December or January at the latest in the southernmost states. You may even see martins checking it out or roosting in it on warm nights during winter. The key is having it ready before breeding pairs form and make commitments to nest elsewhere.
In the Mid-South
In mid-south states like Louisiana, Mississippi, Alabama, Georgia, South Carolina, North Carolina, Arkansas, Oklahoma, and southern portions of surrounding states, most purple martins arrive in February and March.
Here, it is best to put brand new martin houses up in January or February to catch the early arrivals. You may start seeing martins checking it out within a couple weeks of putting it up if you time it right. February is ideal for maximizing occupancy rates of new martin houses in these mid-south areas.
Midwest and Northeastern States
Farther north in the Midwest and northeastern states, most purple martins do not arrive until April or even May.
In these cooler areas, it is recommended to wait until March or April to erect a new martin house. This avoids exposing the interior cavities to months of cold winter weather. Extended freezing temperatures and precipitation can make a new house less appealing to arriving martins if put up too early.
If you live in the Midwest or northeast U.S., March and April are the key months to put up new martin houses. Just be sure they are ready for the massive waves of scouts that come through in April and May.
Western States
In western states like Colorado, Utah, Nevada, Oregon, Washington, Idaho, Montana, Wyoming, and western portions of surrounding states, timing also depends on latitude and elevation.
At lower elevations and southern latitudes, follow similar timing recommendations as the Midwest and put new martin houses up in March or April. At higher elevations and northern areas of the western states, wait until April and May to erect them. Placement in sheltered sites which warm early may allow for slightly earlier martin house installation.
Tips for attracting purple martins to a new house
Here are some tips to maximize your success at enticing martins to take up residence in a new martin house:
- Paint the interior compartments white to mimic natural cavities.
- Ensure drainage holes in each compartment to prevent waterlogging.
- Install porches to shield entries from rain.
- Place multiple compartments (6-12) together in a house.
- Locate the house in an open area near open flying space.
- Position the house on a pole 15-20 feet high.
- Avoid obstructions, wires, trees within 40 feet.
- Install martin house east of your viewing area so the sunrise illuminates it.
- Clean out old nests and sanitize the house before each season.
- Be patient – it may take a year or two for martins to find and accept a new house.
Making the house visible, obstruction-free, and mimicking natural cavities will all help attract scouting martins to use your new birdhouse.
When to take martin houses down for winter
Purple martins completely vacate their breeding range in North America by late October. Some martin landlords take their houses down in fall before the birds’ southern migration. However, many choose to leave houses up over winter. This makes them ready for scouts returning in very early spring.
If taking martin houses down in fall, do so once all martins have left your area, typically by late October. Then conduct maintenance like removing old nests, cleaning, and sanitizing. The houses can then be reinstalled according to the spring timing above.
Leaving houses up is less work and ensures your site is available at the earliest opportunity for returning martins. Just be sure the fall maintenance is done after the martins fledge their young and depart.
Alternatively, some landlords remove compartments/gourds in fall but leave the racks, poles, and porches up over winter. This also reduces maintenance and signals to martins the site is active. The compartments can then be added back in spring according to schedule.
Conclusion
In summary, purple martin housing should go up according to the following general timeline by region:
- December-January: Southernmost States
- January-February: Mid-South States
- March-April: Midwest and Northeast
- March-May: Western States
Aim to have new houses up and ready about a month before martins arrive in your area for best results. Proper placement and maintenance will also help attract martins. Then be patient, as it can take a year or two for martins to find and occupy a new site. Follow this seasonal schedule for the highest success rates enticing martins to nest in your new birdhouse.
Frequently Asked Questions
What time of year do purple martins migrate?
Purple martins migrate north to their breeding grounds in North America between January and May. Fall migration back to South America occurs between August and October.
How early can I put up a purple martin house?
In southern states, put houses up starting in late fall to early winter. In mid-south states, begin in January/February. Farther north, wait until March-May to install new martin houses.
Do I take my martin house down in winter?
Leaving houses up over winter is recommended so sites are ready for early arriving martins. But if taking down, do so once martins have migrated south, by late October.
Where should I mount my purple martin house?
Install martin houses on 15-20 foot poles in open areas with no obstructions within 40 feet. Face houses east for morning sun.
How do I attract purple martins to a new birdhouse?
Paint interior white, provide drainage, porches, multiple compartments together (6-12), mount properly on a tall pole, and keep the area obstruction free to attract martins.
Key Takeaways
- Southern states: Put up new martin houses in December-January
- Mid-South states: Put up new martin houses in January-February
- Midwest & Northeast states: Put up new martin houses in March-April
- Western states: Put up new martin houses in March-May
- Make sure new houses are up at least 1 month before martins arrive in your area
- Proper placement, maintenance, and patience help attract martins
