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The animal on the cover of JavaScript with Promises is a white-crested helmetshrike (Prionops plumatus). These birds are widespread and common throughout southern Africa, inhabiting tropical and subtropical woodlands, savanna, and shrubland. The name comes from ornamental frills of white feathers that sprout from the forehead.

Helmetshrikes are medium-sized birds, ranging from 19 to 25 centimeters and weighing between 25 to 37 grams. Their plumage is black, white, and gray, with a distinctive white stripe on the wings. Other distinctive features include a hooked beak and bright yellow eyes. They primarily feed on caterpillars, moths, crickets, and grasshoppers, in addition to small lizards and fruit.

Helmetshrikes are extremely sociable birds, rarely seen unaccompanied. They are also cooperative breeders, forming small groups that assist a single dominant mating pair in nesting duties. The breeding pair selects the nesting site, but all members help build the nest, incubate the eggs, and feed and protect the nestlings. Nests are made of bark and held together with cobwebs, which serves for camouflage. The helmetshrike’s head feathers are advantageous in this regard, enabling it to pick up spiderwebs for nest construction.

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 loose plates (original source unknown). 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.