
The sarus crane (Antigone antigone) is a large nonmigratory crane found in parts of the Indian subcontinent, Southeast Asia, and northern Australia. The tallest of the flying birds, standing at a height of up to 1.8 m (5 ft 11 in), they are a conspicuous species of open wetlands in South Asia, seasonally flooded Dipterocarpus forests in Southeast Asia, and Eucalyptus-dominated woodlands and grasslands in Australia.
The sarus crane is easily distinguished from other cranes in the region by its overall grey colour and the contrasting red head and upper neck. They forage on marshes and shallow wetlands for roots, tubers, insects, crustaceans, and small vertebrate prey. Like other cranes, they form long-lasting pair bonds and maintain territories within which they perform territorial and courtship displays that include loud trumpeting, leaps, and dance-like movements. In India, they are considered symbols of marital fidelity, believed to mate for life and pine the loss of their mates, even to the point of starving to death.

The main breeding season is during the wet season, when the pair builds an enormous nest "island," a circular platform of reeds and grasses nearly two meters in diameter and high enough to stay above the shallow water surrounding it. Increased agricultural intensity is often thought to have led to declines in sarus crane numbers, but they also benefit from wetland crops and the construction of canals and reservoirs. The stronghold of the species is in India, where it is traditionally revered and lives in agricultural lands in close proximity to humans. Elsewhere, the species has been extirpated in many parts of its former range.

In flight, the black primaries contrast with the otherwise grey wings (Bharatpur, India)The adult sarus crane is very large, with grey wings and body, a bare red head, collar and nape, a greyish crown, and a long, greenish-grey, pointed bill. In flight, the long neck is held straight, unlike that of a heron (which folds it back), and the black wing tips can be seen; the crane's long, pink legs trail behind them. This bird has a grey ear covert patch, orange-red irises, and a greenish-grey bill. Juveniles have a yellowish base to the bill and the brown-grey head is fully feathered.
The bare red skin of the adult's head and neck is brighter during the breeding season. This skin is rough and covered by feather follicles, and a narrow area around and behind the head is covered by black, bristly feathers. The sexes do not differ in plumage, although males are on average larger than females; males of the Indian population can attain a maximum height around 180 cm (5.9 ft), making them the world's tallest extant flying bird. The weight of nominate race individuals is 6.8–7.8 kg (15–17 lb), while five adults of A. a. sharpii averaged 8.4 kg (19 lb). Across the distribution range, their weight can vary from 5 to 12 kg (11 to 26 lb), height typically from 115 to 167 cm (45 to 66 in), and wingspan from 220 to 250 cm (87 to 98 in).

While individuals from northern populations are among the heaviest cranes, alongside the red-crowned and wattled cranes, and the largest in their range, birds from Australia tend to be smaller. In Australia, the sarus can easily be mistaken for the more widespread brolga. The brolga has the red colouring confined to the head and not extending onto the neck. Body mass in Australian sarus cranes was found to average 6.68 kg (14.7 lb) in males and 5.25 kg (11.6 lb) in females, with a range for both sexes of 5.0 to 6.9 kg (11.0 to 15.2 lb). Thus, Australian sarus cranes average about 25% lighter than the northern counterparts and are marginally lighter on average than brolgas.
The species has historically been widely distributed on the lowlands of India along the Gangetic plains, extending south to the Godavari River, west to coastal Gujarat, the Tharparkar District of Pakistan, and east to West Bengal and Assam. The species no longer breeds in Punjab, though it winters regularly in the state. Sarus cranes are rare in West Bengal and Assam, and are no longer found in the state of Bihar. In Nepal, its distribution is restricted to the western and central lowland plains, with most of the population occurring in Rupandehi, Kapilvastu, and Nawalparasi districts.

Two distinct populations of sarus cranes occur in Southeast Asia: the northern population in China and Myanmar, and the southern population in Cambodia and Vietnam. The sarus used to extend to Thailand and further east into the Philippines, but may now be extinct in both these countries. In 2011, 24 captive-bred cranes raised from five founders were reintroduced into Thailand. A reasonably sized population of over 150 breeding pairs of sarus cranes has been discovered in the Ayeyarwadi delta, Myanmar, with additional cranes confirmed in the states of Kachin, Shan, and Rakhine. In Australia they are found only in the north-east, and are partly migratory in some areas. The global range has shrunk and the largest occupied area, and the largest known population, is in India. Increasing paddy fields accompanied by an increase in the network of irrigation canals during and prior to the Green Revolution may have facilitated increases in the distribution and numbers of sarus cranes due to an increase in reliable moisture levels in various locations in India. Although now found mainly at low elevations on the plains, some historical records exist from highland marshes further north in Harkit Sar and Kahag in Kashmir. The sarus crane breeds in some high elevation regions such as near the Pong Dam in Himachal Pradesh, where populations may be growing in response to increasing rice cultivation along the reservoir. In rice-dominated districts of Uttar Pradesh, sarus crane abundance (estimated as occupancy) was highest in the western districts, intermediate in the central districts, and minimal in the eastern districts. Sarus crane abundance was positively associated with percentage of wetlands on the landscape, and negatively with the percentage of area under rice cultivation.