Sarus Crane

Appearance

The adult Sarus Crane is very large with grey wings and body; a bare red head and part of the upper neck; a greyish crown; and a long greenish-grey pointed bill. In flight, the long neck is held straight, unlike that of an 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, an orange-red iris 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 papillae, 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; male Sarus of the Indian population can attain a maximum height of about 180 cm making them the world's tallest extant flying bird.

The weight of nominate race individuals is 6.8–7.8 kg, while five adult "sharpii" averaged 8.4 kg. Across the distribution range, the weight can vary from 5 to 12 kg, height typically from 115 to 167 cm and the wingspan from 220 to 250 cm. Birds from Australia tend to be smaller than birds from the north.

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 into the neck.

Naming

The common name of "sarus" is from the Hindi name for the species. The Hindi word is derived from the Sanskrit word "sarasa" for the "lake bird",. While Indians held the species in veneration, British soldiers in colonial India hunted the bird, calling it the "serious" or even "cyrus". The specific name of "antigone"—after the daughter of Oedipus, who hanged herself—may relate to the bare skin of the head and neck.

Distribution

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 the Punjab, though it occurs sporadically on the Indian side in winter. Sarus Cranes are rare and occur in very low numbers in West Bengal and Assam, and are no longer found in the state of Bihar. In Nepal, its distribution is restricted to the western lowland plains, with most of the population occurring in Rupandehi, Kapilvastu, and Nawalparasi districts.

Status

There were about an estimated 15–20,000 mature Sarus Cranes left in the wild in 2009. The Indian population is less than 10,000, but of the three subspecies, is the healthiest in terms of numbers. They are considered sacred and the birds are traditionally left unharmed, and in many areas they are unafraid of humans. They used to be found on occasion in Pakistan, but have not been seen there since the late 1980s. The population in India has however declined. Estimates of the global population suggest that the population in 2000 was at best about 10% and at the worst just 2.5% of the numbers that existed in 1850.

Behavior

Unlike many other cranes that make long migrations, the Sarus Crane is largely non-migratory; it may however make short-distance movements in response to rain or dry weather conditions. The only migratory population is in South-east Asia. Breeding pairs maintain territories that are defended from other cranes using a large repertoire of calls and displays. Non-breeding birds occur as flocks of various sizes that vary from 1–430 birds.

In semi-arid areas, breeding pairs and successfully fledged juveniles depart from territories in the dry season and join non-breeding flocks. In areas with perennial water supply, like in the western plains of Uttar Pradesh, breeding pairs maintain perennial territories. The largest known flocks are from the 29 km2 Keoladeo National Park – as many as 430 birds, and from wetlands in Etawah and Mainpuri districts in Uttar Pradesh, ranging from 245–412 birds.

Flocks of over 100 birds are also regularly reported from Gujarat and Australia. During the breeding season, breeding pairs displace non-breeding birds from some wetland sites, and local populations can appear to decline. Sarus Crane populations in Keoladeo National Park have been noted to reduce from over 400 birds in summer to just 20 birds during the Monsoon.

They roost in shallow water, where they may be safe from some ground predators. Adult birds do not moult their feathers annually and replace them only once every two or three years.

Habitat

Sarus Cranes preferentially use wetlands or uncultivated patches amid flooded rice paddies for nesting in India. Breeding pairs are territorial and prefer to forage in natural wetlands, though wet crops like rice and wheat are also frequented.

Reproduction

Sarus Cranes have loud trumpeting calls. These calls are, as in other cranes, produced by the elongated trachea that form coils within the sternal region. Pairs may indulge in spectacular displays of calling in unison and posturing. These include "dancing" movements that are performed both during and outside the breeding season and involve a short series of jumping and bowing movements made as one of the pair circles around the other.

Dancing may also be a displacement activity when the nest or young are threatened. The cranes breed mainly during the Monsoons in India in diameter and nearly a metre high. Pairs shows high fidelity to the nest site, often refurbishing and reusing nests for as many as five breeding seasons. The clutch is one or two eggs which are incubated by both sexes for about 31 days. Eggs are chalky white and weigh about 240 grams. When disturbed from the nest, parents may sometimes attempt to conceal the eggs by attempting to cover them with material from the edge of the nest.

The eggshells are removed by the parents after the chicks hatch either by carrying away the fragments or by swallowing them. The chicks are fed by the parents for the first few days, but are able to feed independently after that and follow their parents for food. When alarmed, the parent cranes use a low "korr-rr" call that signals chicks to freeze and lie still. Young birds stay with their parents for more than three months. In captivity, birds breed only after their fifth year. The Sarus is widely believed to pair for life, however cases of "divorce" and mate replacement have been recorded.

Food

Sarus Cranes forage in shallow water depth of water or in fields, frequently probing in mud with their long bills. They are omnivorous, eating insects, aquatic plants, fish, frogs, crustaceans and seeds. Occasionally tackling larger vertebrate prey such as water snakes, Sarus Cranes may in rare cases feed on the eggs of birds and turtles. Plant matter eaten includes tubers, corms of aquatic plants, grass shoots as well as seeds and grains from cultivated crops such as groundnuts and cereal crops such as rice.

Predators

Eggs are often destroyed at the nest by Jungle and House Crows.

In Australia, predators of young birds include the dingo and fox while Brahminy Kites have been known to take eggs. Removal of eggs by farmers or children, or by migrant labourers for food are prominent causes of egg mortality. Between 31 and 42% of nests with eggs can fail to hatch eggs for this reason.

Chicks are also prone to predation but more than 30% die of unknown reasons. Breeding success has been estimated at about 20%. In areas where farmers are tolerant, nests in flooded rice fields and those in wetlands have similar rates of survival. Pairs that nest later in the season have a lower chance of raising chicks successfully, but this improves when territories have more wetlands.

Little is known about the diseases and parasites of the Sarus Crane, and their effects on wild bird populations. A study conducted at the Rome zoo noted that these birds were resistant to anthrax. Endoparasites that have been described include a trematode, "Opisthorhis dendriticus" from the liver of a captive crane at the London zoo and a Cyclocoelid from an Australian bird. Like most birds, they have bird lice and the species recorded include "Heleonomus laveryi" and "Esthiopterum indicum".

Cultural

The species is venerated in India and legend has it that the poet Valmiki cursed a hunter for killing a Sarus Crane and was then inspired to write the epic Ramayana.

The species was a close contender to the Indian Peafowl as the national bird of India. Among the Gondi people, the tribes classified as "five-god worshippers" consider the Sarus Crane as sacred. The meat of the Sarus was considered taboo in ancient Hindu scriptures.

It is widely believed that the Sarus pairs for life and that death of one partner leads to the other pining to death. They are a symbol of marital virtue and in parts of Gujarat, it is a custom to take a newly wed couple to see a pair of Sarus Cranes. Being ubiquitous in the flood plains of the Ganges, observations on their biology had been made by the Mughal emperor, Jahangir around AD 1607. He noted, for instance, that the species always laid two eggs with an interval of 48 hours between them and that the incubation period was 34 days.

Although venerated and protected by Indians, these birds were hunted during the colonial period. It was noted that killing a bird would lead to its surviving partner trumpeting for many days and it was traditionally believed that the other would starve to death. Even sport hunting guides discouraged shooting these birds. According to 19th century British zoologist Thomas C. Jerdon, young birds were good to eat, while older ones were "worthless for the table". Eggs of the Sarus Crane are however used in folk remedies in some parts of India.