Purple Martin systems include a string or multiple strings of gourds and one or many multi unit houses. The houses should be mounted on a pole in the middle of an area of open space and more than 10 yards from any frequently travelled areas or buildings and far away from any tall trees that can harbor predators. Most Purple Martin hosts mount their houses and systems on poles and lines that are about 10-20 feet off the ground. Since stabilizer wires and ropes can present flight hazards and easy access for predators, they should be avoided. Bottom line - they fly fast and they are busy so you need open space and flying insects to successfully host Purple Martins.