Medium-sized swift, dark overall with a white throat patch. Like Common Swift, nests in buildings and cliff faces, often in coastal regions, and forages over a wide range of habitats. Very similar to Common Swift but with slightly paler plumage overall (plumage tones of both species greatly influenced by lighting), subtly blunter wings, and less deeply forked tail. Shrill screaming call is subtly different from that of Common Swift as well: slightly deeper, and sometimes incorporating a slight “hiccup” at the end. Many dark swifts are not safely identified in the field.