Rock dove

Name and taxonomy

Johann Friedrich Gmelin described the species in 1789 and named it Columba livia. Columba is the Latin word for a pigeon or a dove. The root behind it is a Greek word for a diver, after the bird's plunging flight. The second name comes from a Latin word for a bluish grey colour.

Rock dove is the standard English name set by the International Ornithological Congress. Most people simply say pigeon, and rock pigeon and common pigeon are also in use. A specimen from Fair Isle in Scotland now serves to define the species. Nine subspecies are recognised across the natural range. A young pigeon is called a squab. Two other birds also carry the English name rock pigeon, which confuses matters.

Evolution and relatives

Fossils suggest the species began in southern Asia. Bones from Israel show the bird lived there at least 300,000 years ago. Its history with people is so long that the first natural range cannot be traced. The nearest relative in the genus is the hill pigeon. The snow, speckled and white-collared pigeons come next.

Breeding under human care produced about 1,000 domestic breeds. Those breeds vary in size, shape and colour far beyond anything in the wild. Charles Darwin used that range of forms to argue his case for selection. A study of feather pigment found the reason for the extra colour. Mutations changed how much black and reddish pigment each feather holds. Darker birds may store more trace metal in the feathers, which helps in dirty air.

Appearance

An adult is 30 to 35 centimetres long and weighs 238 to 380 grams. The wings span 62 to 68 centimetres. The head, neck and chest are dark bluish grey. Green, purple and red light plays over the neck feathers as the bird turns. Two black bars cross the pale grey wing, and the lower back is white.

A black band closes the tail, and the outer tail feathers are edged in white. The iris is red-brown, the bill grey-black, and the feet red to pink. A female looks almost the same, with less shine on the neck and breast. The white underwing shows well when a bird circles overhead. The bird glides often, holding its wings in a sharp V. Feral birds may be red, brown, chequered, plain or pied. Subspecies differ in size and in how dark the mantle and the back are. One North African form is almost black on the head, rump and underparts.

Habitat and range

The natural range covers western and southern Europe, North Africa and South Asia. European ships carried the bird to the rest of the world from 1603 onward. With the feral flocks counted, the range covers about 10 million square kilometres. Wild birds nest in crevices on sea cliffs, in canyons and in caves. They will hold ground in the Sahara where there is rock, water and some plant food.

The species avoids thick vegetation and needs open ground to feed on. Tall buildings, bridges and farm sheds copy the ledges of a cliff. Town birds do best where there are high walls, green space and spare food. Outer suburbs with dense streets and few tall buildings suit them least. One flock in Tunisia lives inside a deep well. Records for the species come from 241 countries and territories on GBIF. Farm country suits the bird better than woodland does.

Diet and feeding

The rock dove eats mainly plant food, above all seeds, grain and fruit. It swallows any seed that fits down the gullet. Worms and insect larvae go down now and then as extra protein. One study of semi-rural birds in Kansas found a diet of 92 per cent corn. Town birds add bread, cake, peanuts, popcorn and currants.

Flocks feed on open ground in the early morning and again in mid-afternoon. Some birds act as producers and find the food. Others act as scroungers and eat what the producers have found. A flock usually holds more scroungers than producers. A pigeon drinks by dipping the bill and sucking, without tipping its head back. A female needs more protein and calcium in the weeks before she lays. A long flight range lets a desert flock reach water far from the roost. Kidneys, not a salt gland, keep the water balance of the body in order.

Behaviour and social life

Rock doves live in flocks of 50 to 500 birds, depending on the food supply. Pairs keep together within the flock through the breeding season. A startled bird takes off with a loud clap of the wings. That clap tells the rest of the flock to go, and a faster beat means a worse threat. Birds walk and run with the head rocking forward and back.

Other sounds without the voice include hissing, bill snapping and foot stamping. A bird starts stamping with the same foot each time, much as a person favours a hand. Squabs snap the bill when something comes at the nest. Both parents peck an intruder on the head. The birds take cover at night and in the hottest part of the day. They flock to roost, to sun themselves and to feed, and no play has been seen.

Communication and senses

The call is a soft wavering coo with a slight break in it. There is a separate nest call, an alarm grunt and a set of begging notes. A displaying male puffs his throat, fans his tail, struts and bows. The display is part courtship and part threat. Wings clap in flight during a chase and after mating.

Homing birds find their way with a map and compass system. They use the sun for direction and a magnetic sense through a nerve in the face. Smell, landmarks such as roads, deep sound and slight shifts in gravity all help. Racing birds have covered 1,800 kilometres in a single flight. Over a middle distance a racing bird keeps up roughly 97 kilometres per hour. Messenger birds were already flying in Egypt about 3,000 years ago.

Reproduction and life cycle

The species can breed in any month, because crop milk frees it from an insect season. The peak falls in spring and summer, when food is easiest to find. A pair may lay as many as six times in one year. A male puffs his crop, walks at the female and coos in short repeated notes. He bows, turns in half circles, and then feeds her from his crop.

Pairs form at any time of year and usually last for life. The bond is not absolute, and males in particular mate outside the pair. The nest is a thin platform of straw and sticks on a sheltered ledge. The female lays two white eggs. Both birds sit, and the eggs hatch after 17 to 19 days.

A squab hatches with pale yellow down and a flesh-coloured bill. Both parents make crop milk and feed it to the chick for the first days. Seeds are then added, and the young bird leaves the nest at about 30 days. Birds can breed at about 140 days old. A wild bird lives 3 to 5 years, while one captive bird reached 35. Predators and people are the main causes of death in the wild. The eggshell carries fine pores that let water pass and keep the embryo from drying.

Predators and threats

Flight is the only real defence the rock dove has. Peregrine falcons hunt it hard and are very good at catching it. Kestrels, golden eagles, great horned owls and screech owls also take pigeons. Raccoons and opossums raid nests in North American towns.

Body feathers sit loosely in the skin and pull out at a touch. A hunter often ends up with a mouth of feathers while the bird escapes. Tail feathers drop in the same way under a fright. People are the other main cause of death, through shooting and control work. Droppings can carry histoplasmosis, which is one reason towns act against flocks. Hunters shoot pigeons for food in many countries within the natural range.

Population and conservation

The IUCN lists the rock dove as Least Concern. Europe alone holds an estimated 17 to 28 million wild and feral birds. The world total may reach 120 million. Watchers have logged 453,113 records of the species on iNaturalist.

The pure wild form is in a weaker position than that headline suggests. Feral birds breed with wild ones and blur the original type. In Britain the truest stock hangs on in northern and western Scotland. The Outer Hebrides hold the strongest population of that kind. No conservation body treats the species as a whole as being at risk. City feeding keeps feral numbers high whatever the weather does.

Relationship with humans

People may have kept rock doves for as long as 5,000 years. The birds probably gave meat, eggs, manure and company from the start. Messenger birds were flying in Egypt about 1350 years before the common era. Fanciers later built up hundreds of breeds for show and for racing. Homing birds became a working postal service in peace and in war.

Armies used pigeons because they were fast and hard to stop. About 95 per cent of the messages sent by pigeon arrived. American forces trained 54,000 birds during the Second World War. Cher Ami carried 12 messages at Verdun and flew on after being shot. That last flight is credited with saving 194 trapped soldiers. In all, 32 pigeons have received the Dickin Medal for bravery.

Feral flocks are less welcome, and many cities treat them as a nuisance. Droppings damage stone and metal, and large roosts foul buildings. Farmers lose grain where flocks are large. Other people feed the birds in parks, which keeps the numbers high.

In culture and myth

In Mesopotamian religion the dove belonged to Inanna and to Ishtar. In Greek religion it was the bird of Aphrodite. In the Hebrew flood story a dove returns with an olive branch. In Christian art a dove stands for the Holy Spirit.

The white dove of peace grew out of that long religious history. In modern politics a person who wants peace is called a dove. In British and American memory the war pigeon is a small national hero. Cher Ami now stands mounted in a museum in Washington. In science the bird is remembered for the part it played in Darwin's argument.