Purple Martins are colony nesters. Their houses support large groups of birds. Purple martins depend on people for their housing. The Bird House offers purple martin houses both in wood and aluminum, as well as the 15 to 20-foot poles needed to mount them. Buy a house with a winch system to easily raise and lower the house for monitoring. Purple martins are also known for nesting in gourds, which we have in stock. If the purple martin was raised in a house, it is more likely to nest in a house. If they were raised in a gourd, they are more likely to nest in a gourd.