<p>Swifts are in the order <span class="taxon">Apodiformes</span>, suborder <span class="taxon">Apodi</span> and family <span class="taxon">Apodidae</span>. There are two subfamilies of swifts: 13 species of <span class="taxon">Cypseloidinae</span> (primitive American swifts) and 79 species of <span class="taxon">Apodinae</span> (swiftlets, spinetails and typical swifts). The subfamily <span class="taxon">Apodinae</span> is divided in to three tribes: 28 species of <span class="taxon">Collocaliini</span> (swiftlets), 24 species of <span class="taxon">Chaeturini</span> (spinetails) and 27 species of <span class="taxon">Apodini</span> (typical swifts). The tribe <span class="taxon">Chaeturini</span> is sometimes listed as its own subfamily <span class="taxon">Chaeturinae</span>. There are 19 genera of swifts and a total of 92 species.</p>  <p>Swifts are very aerial species and spend much of their lives on the wing. Their sickle-shaped wings are well adapted for high-speed flight. As their name <span class="taxon">Apodidae</span> (meaning “without feet”) suggests, they have tiny feet and are not able to perch. However, modified tail feathers help swifts land on and move around on vertical surfaces. Their plumage is dull black or brown; some species have white or gray patches, and a few have brighter chestnut-reddish throats. Males and females look similar and both play equal roles in nesting and rearing young.</p>  <p>Many swifts nest in caves, on cliffs or in hollows of dead trees. They often use saliva as glue to hold their nests together and to attach them to the substrate. The nests of edible-nest swiftlets (<span class="taxon"><em>Aerodramus fuciphagus</em></span>) are a delicacy in some parts of the world and are used to make bird nest soup.<span> (Chantler and Driessens, 2000; Chantler, 1999)</span></p>