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The bird on the cover of Mastering Perl/Tk is an emu (Dromaius novaehollandiae). This large, flightless bird is found throughout the Australian bush steppes. The emu is one of the largest birds in existence, second only to its cousin, the ostrich. Adult emus stand about 5 feet high and weigh up to 120 pounds. The grayish-brown emu’s small wings contain only six or seven feathers. They are hidden by the long, hairlike rump plumage. Emus have extremely long legs, which they use as defensive and offensive weapons when fighting. A human limb can be broken by a kick from an emu. Their powerful legs make emus strong swimmers and fast runners; they can reach speeds of up to 50 kilometers per hour.
Male emus, which are slightly smaller than females, tend to the incubation of eggs and the raising of the young. An emu nest contains as much as fifteen to twenty-five deep green eggs, laid by several hens. Incubation of the eggs takes from twenty-five to sixty days. The large discrepancy in incubation time occurs because the male needs to leave the nest periodically to find food and drink. The length of time he is away affects the time for incubation. Newly hatched emus weigh about 15 ounces. They are fully grown at two to three years.
The relationship ...