There is a misconception among many people of purple martin temperament. Tapes of purple martin song are sold to attract martins to newly established birdhouses. The purple martin factory has been recently been sold to a Chicago businessman. Historically, a purple martin colony has nested in the open field. The purple martin migrates to the Amazon basin in winter. Nest boxes are usually wooden, although the purple martin will nest in metal. Just as the purple martin, this species may compete with other passerines for nesting cavities. Thus, unmonitored purple martin houses are often overtaken by more aggressive, non-native species. Allen's hummingbird, purple martin, acorn woodpecker, Steller's jay, Townsend's western big-eared bat, and pallid bat. The purple martin ("Progne subis") is the largest swallow in North America.