<p>In general, chimney swifts are a dark grayish to brownish-gray, sooty color. Males and females look alike. The tail has stiff bristle-like or spiny feather tips (Palmer and Fowler, 1975; Whittemore, 1981). There may be as many as seven tail spines (Chantler and Driessens, 2000). They have been described as resembling a "flying cigar" (Palmer and Fowler, 1975). Chimney swifts have large eyes. They weigh 21.33 g on average. Wing length averages 130.4 mm and tail length averages 39.1 mm (Chantler and Driessens, 2000).<span> (Chantler and Driessens, 2000; Palmer and Fowler, 1975; Whittemore, 1981)</span></p>  <p><strong>Other Physical Features: </strong>Endothermic; Bilateral symmetry</p><p><strong>Sexual Dimorphism: </strong>Sexes alike</p>