Colophon

The animal on the cover of Network Security Through Data Analysis is a European merlin (Falco columbarius). There is some debate as to whether the North American and the European/Asian varieties of merlin are actually different species. Carl Linnaeus was the first to classify the bird in 1758 using a specimen from America, then in 1771 the ornithologist Marmaduke Tunstall assigned a separate taxon to the Eurasian merlin, calling it Falco aesalon in his book Ornithologica Britannica.

Recently, it has been found that there are significant genetic variations between North American and European types of merlin, supporting the idea that they should be officially classified as distinct species. It is believed that the separation between the two kinds happened more than a million years ago, and since then the birds have existed completely independently of each other.

The merlin is more heavily built than most other small falcons and can weigh almost a pound, depending on the time of year. Females are generally larger than males, which is common among raptors. This allows the male and female to hunt different types of prey animals and means that less territory is required to support a mating pair. Merlins normally inhabit open country, such as scrubland, forests, parks, grasslands, and moorland. They prefer areas with low and medium-height vegetation because it allows them to hunt easily and find abandoned nests that they take on as their own. During the winter, European merlins are known to roost communally with hen harriers, another bird of prey.

Breeding occurs in May and June, and pairs are monogamous for the season. The merlins will often use the empty nests of crows or magpies, but it is also common (especially in the UK) to find merlins nesting in crevices in cliffs or buildings. Females lay three to six eggs, which hatch after an incubation period of 28 to 32 days. The chicks will be dependent on their parents for up to four weeks before starting out on their own.

In medieval times, chicks were taken from the nest and hand-reared to be used for hunting. The Book of St. Albans, a handbook of gentleman’s pursuits, included merlins in the “Hawking” section, calling the species, “the falcon for a lady.” Today, they are still trained by falconers for hunting smaller birds, but this practice is declining because of conservation efforts. The most serious threat to merlins is habitat destruction, especially in their breeding areas. However, since the birds are highly adaptable and have been successful at living in settled areas, their population remains stable around the world.

Many of the animals on O’Reilly covers are endangered; all of them are important to the world. To learn more about how you can help, go to animals.oreilly.com.

The cover image is from Wood’s Animate Creation. The cover fonts are 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.