The animal on the cover of HTML5 Cookbook is a common kestrel (Falco tinnunculus), a member of the falcon family. A more archaic name for this bird is “windhover,” based on its unique hunting style. By facing into the wind and spreading its wings to catch and slow the air, the kestrel can hover in one place and scan for prey on the ground below.

The common kestrel is the most widespread bird of prey in Europe, and it can also be found in Asia and Africa. It prefers open habitats like fields, shrubland, and marshes, but it is very adaptable as long as there are places to perch and prey. Kestrels almost exclusively eat small mammals like shrews, mice, and most commonly, voles. Depending on the season and energy expended, each bird needs to eat the equivalent of 4–8 voles each day.

The plumage of the common kestrel is chestnut brown with black spots, with a lighter underside and black wings. The tails differ by sex; females have black bars, and the males have gray feathers with a black tip. Male kestrels also have gray heads. These birds measure 13–15 inches long, with a wingspan of 26–32 inches (making them somewhat smaller than other birds of prey). Kestrels can see in the ultraviolet spectrum, which helps them locate prey—voles mark their trails with urine, which reflects ultraviolet light. This leads the hunting bird to either the vole itself or its nest.

The cover image is from Cassell’s Natural History. The cover font is Adobe ITC Garamond. The text font is Linotype Birka; ...

Get HTML5 Cookbook now with the O’Reilly learning platform.

O’Reilly members experience live online training, plus books, videos, and digital content from nearly 200 publishers.