Are you looking to attract and house Purple Martins?
The first thing you need to know is whether you live within the breeding range of Progne subis subis - the Purple Martin that is attracted to man built housing. In the United States, this is typically the eastern ½ of the country.
When should you be ready?
The map also indicates when you can expect mature adult martins to return to established breeding sites. Sub-adult martins, those in their first breeding years, tend to follow the mature adults 3-6 weeks later.
Getting Ready for your Colony to Return:
If you have an established colony, you should be ready for the mature adults (within the red time lines shown on the map). However, if you are establishing a new colony - wait for the arrival of the sub-adults and don’t open your housing for another 3-6 weeks. Waiting will help prevent problems with sparrows, starlings and other birds.
If birds other than Purple Martins try to nest in your house, lower the house and remove the nest – temporarily plugging the entry holes if necessary to keep them from returning.