Despite the species' large numbers, local extinctions and extirpations have taken place in part of its range, and an ongoing reintroduction project is underway in the United Kingdom.

[3] The first formal description of the common crane was by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under the binomial name Ardea grus.

Males are slightly heavier and larger than females, with weight showing the largest sexual size dimorphism, followed by wing, central toe, and head length in adults and juveniles.

The forehead and lores are blackish with a bare red crown and a white streak extending from behind the eyes to the upper back.

This combination of colouration ultimately distinguishes it from similar species in Asia, like the hooded (G. monacha) and black-necked cranes (G. nigricollis).

Every two years, before migration, the adult common crane undergoes a complete moult, remaining flightless for six weeks, until the new feathers grow.

It is a rare breeder in southern and western Europe, with larger numbers breeding in the central and eastern parts of the continent.

It has reappeared in several western European countries where it had been extirpated as a breeding bird decades or even centuries ago, including the United Kingdom and, since 2021, the Republic of Ireland.

In Asia, the breeding range of the common crane extends as far south as northern China, Turkey and the Caucasus region.

[1][10] The species is a migrant and common cranes that breed in Europe predominantly winter in Portugal, Spain and northern Africa.

[13] Important staging areas occur anywhere from Sweden, the Netherlands and Germany to China (with a large one around the Caspian Sea) and many thousand cranes can be seen in one day in the Autumn.

[14] Common cranes that breed in far eastern Europe, including European Russia, winter in the river valleys of Sudan, Ethiopia, Tunisia and Eritrea with smaller numbers in Turkey, northern Israel, Iraq and parts of Iran.

The third major wintering region, primarily used by those breeding in central Russia, is in the northern half of the Indian subcontinent, including Pakistan.

In northern climes, it breeds in treeless moors, on bogs, or on dwarf heather habitats, usually where small lakes or pools are also found.

Primarily, the largest number of common cranes are found breeding in wooded swamps, bogs and wetlands and seem to require quiet, peaceful environs with minimal human interference.

Later, after the migration period, the birds winter regularly in open country, often on cultivated lands and sometimes also in savanna-like areas, for example on the Iberian Peninsula.

It largely eats plant matter, including roots, rhizomes, tubers, stems, leaves, fruits and seeds.

They also commonly eat, when available, pond-weeds, heath berries, peas, potatoes, olives, acorns, cedar nuts and pods of peanuts.

Their animal foods are insects, especially dragonflies, and also snails, earthworms, crabs, spiders, millipedes, woodlice, amphibians, rodents, and small birds.

Aggressive displays may include ruffled wing feathers, throwing vegetation in the air and pointing the bare red patch on their heads at each other.

If humans approach the nest both parents may engage in a distraction display but known ground predators (including domestic dogs (Canis lupus familiaris)) are physically attacked almost immediately.

However, the flocks of the species are not stable social units but rather groups that ensure greater safety in numbers and collectively draw each other's attention to ideal foraging and roosting sites.

[26] Possibly due to a longer molt, younger and non-breeding cranes are usually the earliest fall migrants and may band together at that time of year.

During these migratory flights, common cranes have been known to fly at altitudes of up to 33,000 ft (10,000 m), one of the highest of any species of bird, second only to the Ruppell's Griffin Vulture.

[35] The carrion crow (Corvus corone) is locally a successful predator of common cranes' eggs, trickily using distraction displays to steal them.

[10][15][48] In the United Kingdom, the common crane became extirpated in the 17th century, but a small and increasing population now breeds again in the Norfolk Broads[49] and a reintroduction began in 2010 in the Somerset levels.

[9] The main threat to the species and the primary reason for its decline comes from habitat loss and degradation, as a result of dam construction, urbanisation, agricultural expansion,[51] and drainage of wetlands.

Although it has adapted to human settlement in many areas, nest disturbance, continuing changes in land use, and collision with utility lines are still potential problems.