Story Purple Martin Bird House Plans
You can always add a second story to these plans or as many as you think you need depending on how big the purple martin population is in your area. Photo of plans courtesy of Ohio Department of Natural Resources.
Note About How House Sparrows and Starlings Have Affected Purple Martin Populations
House sparrows and European starlings are purple martins greatest threat. In fact, some biologists had estimated that today's purple martin population is only 1/10 of what it was during the mid-1800s before these species were introduced. Purple martin house plans have been now designed in a way to maximize nesting discouragement of house sparrows and starlings.
How to Build a Purple Martin Bird House
Here is a video that gives some general information about Purple Martins as well as the types of houses they are attracted to nest in:
The Purple Martin Conservation Association
This is a great starter page for information about attracting and managing purple martins. Includes info on location, timing, competition, housing dimensions, competitors & predators.