The Purple Martin is the largest swallow found in North America. The adult has a slightly forked tail which aids it in flight, giving it speed and agility. When approaching its housing, the purple martin will dive from the sky at excellent speed with its wings tucked.
It takes two years for this species to reach its full adult breeding plumage and only then is it possible to, effectively, identify them. Adult males are entirely black with a glossy steel blue sheen even though adult females are dark on leading with some steel blue sheen and lighter under parts.
The eastern species of the purple martins nest exclusively, in man-created bird houses. It is the only species of bird totally dependent on humans for nest web sites. It is important to note that purple martin houses that are unmonitored usually grow to be breeding houses for starlings and sparrows—species that are a main reason for the declining of the martin population in North America. These species typically kill martins for their nest cavity. Since of the devastating impact that these intruders have on the martins, a lot of landlords trap these species to insure the survival of the martin colonies.