Carrier pigeons

The homing pigeon is a variety of domestic pigeon (Columba livia domestica) derived from the rock pigeon, selectively bred for its ability to find its way home over extremely long distances. The wild rock pigeon has an innate homing ability, meaning that it will generally return to its nest, (it is believed) using magnetoreception. This made it relatively easy to breed from the birds that repeatedly found their way home over long distances. Flights as long as 1,800 km (1,100 miles) have been recorded by birds in competitive pigeon racing. Their average flying speed over moderate 640 km (400 miles) distances is around 80 km/h (50 miles per hour) but speeds of up to 140 km/h (90 miles per hour) have been observed in top racers for short distances.

Because of this skill, homing pigeons were used to carry messages as messenger pigeons. They are usually referred to as "pigeon post" or "war pigeon" during wars.

Homing pigeons are often incorrectly categorized as carrier pigeons, a breed of fancy pigeons selectively-bred for its distinctively rounded hard wattle.

Male and female pigeons (cocks and hens, respectively) can be differentiated by physical characteristics of the head, beak, height, and breast, though visual identification of sex by physical characteristics alone can be inaccurate. Males usually stand taller, and have larger beaks, crops, wattles, and eye ceres (fleshy growth around the eyes), as well as round heads and thicker napes. Females, on the other hand, tend to be shorter with smaller beaks, wattles, and ceres, as well as flatter heads and fuller breasts.

Male and female pigeons show different behaviours. The "coo" of males is louder and more insistent, especially when courting. Display behaviour also differs between the sexes. Most notably, a male often turns 360 degrees with an inflated crop and a loud "coo", to show interest in a female or to defend or discourage another pigeon from entering its territory (usually a nesting box), while females almost never turn full circle, but rather do a 270-degree back-and-forth rotational motion.

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Wikipedia