The male purple martin has feathers that are a dark purple and almost look black. They have a forked tail and a small beak.
The female has an upper body that is a darkened gray color with streaks of purple. The underbelly is white and there is a band of gray across the breast and throat.
The typical purple martin is eight inches in length and has a pair of long wings that are pointed. It has a wingspan of up to 16 inches.
The purple martin can be distinguished from similar swallow species because it is the only swallow that has a dark belly.
The head of the purple martin is large for the size of its body and the bird has a thick chest. It always eats while on the fly, catching insects, and also drinks by skimming over the water and scooping some up.