The animal on the cover of Test-Driven Infrastructure with Chef, Second Edition is an edible-nest swiftlet (Aerodramus fuciphagus). This small bird, of the swift family, is found in southeast Asia.
The bird itself is 11–12 cm long and weighs around 15–18 grams. The top plumage is a blackish-brown with paler underparts; its bill and feet are black. It has a slightly forked tail and long, narrow wings. When in caves—usually for breeding—these birds are known to use loud, rattling calls for echolocation.
This swiftlet’s diet consists of flying insects that get caught in its wings. It feeds in large flocks, often with other species of swift and swallow. The swiftlet’s nest, shaped like brackets, is made from solidified saliva and is among the most expensive animal products consumed by humans, going for an average of $2,500 per kg in Asia. It is used primarily as an ingredient in bird’s nest soup, where the nest is soaked and steamed in water. The nests are said to be an aphrodisiac with medicinal qualities. Because of extensive commercial harvesting, the IUCN has labeled several populations—in the Andaman and Nicobar Islands—as critically threatened. To combat the effects of harvesting, the use of artificial bird houses is growing.
The cover image is from Cassells Natural History. The cover font is URW Typewriter and Guardian Sans. The text font is Adobe Minion Pro; the heading font is Adobe Myriad Condensed; and the code font is Dalton Maag’s Ubuntu Mono.