Red-Crowned Crane

The **red-crowned crane** (*Grus japonensis*), also called the **Manchurian crane** or **Japanese crane** (traditional Chinese: 丹頂鶴; simplified Chinese: 丹顶鹤; pinyin: *dāndǐng hè*; Japanese: 丹頂鶴 or タンチョウヅル; rōmaji: *tanchōzuru*; Korean: 두루미; romaja: *durumi*; the Chinese character '丹' means 'red', '頂/顶' means 'crown' and '鶴/鹤' means 'crane') , is a large East Asian crane among the rarest cranes in the world. In some parts of its range, it is known as a symbol of luck, longevity, and fidelity.

## Description

The Japanese crane (Grus japonensis), also known as the red-crowned crane, is sacred and seen as a symbol of fidelity, good luck, love and long life in the Orient. It is also the second rarest crane species in the world. These tall, graceful birds are mainly white in colour with black lower wings. In male Japanese cranes, the cheeks, throat and neck are also black, whilst in females they are a pearly-grey. Adults have a bare patch of skin on the crown of the head, which is bright red in color. The bill is an olive-green color and the legs are black. Juvenile Japanese cranes are similar in appearance, although they lack the red crown and have black-tipped outer flight feathers.

## Biology

Japanese cranes forage using a 'walk and peck' technique. They have a broad diet that varies depending on the site, including insects, aquatic invertebrates, amphibians, rodents, fish, reeds, grasses, and other plants.

Adults usually pair for life and these bonds are reinforced in a mesmerising synchronised courtship dance. Japanese cranes arrive in the coastal marshes in the spring to breed, and nests are made in areas of dead reeds between 30 and 200 centimetres tall. A clutch will normally contain two eggs, which hatch after a 29 to 34 day incubation period. The chicks then leave the nest after only a couple of days to follow their parents on foraging trips; only one chick is likely to be reared successfully by each pair.

### **Diet**

Red-crowned cranes have a highly omnivorous diet, though the dietary preferences have not been fully studied. They eat rice, parsley, water plants, carrots, reed buds, acorns, buckwheat and a variety of water plants. The animal matter in their diet consists of fish, including carp and goldfish, amphibians, especially salamanders, snails, crabs, dragonflies, small reptiles, and other birds, especially waterfowl. They seem to prefer animal food matter throughout the year, although rice is now essential to survival for wintering birds in Japan and grass seeds are an important food source. While all cranes are ominivorous, per Johnsgard, the two most common crane species today (the sandhill and common cranes) are amongst the most herbivorous species while the two rarest species (the red-crowned and whooping cranes) are perhaps the most carnivorous species. When feeding on plants, red-crowned cranes exhibit a preference for plants with high content of crude protein and low content of crude fiber.

They typically forage by keeping their heads close to the ground, jabbing their bills into mud when something edible is encountered. When capturing fish or other slippery prey, they may quickly jab in a similar fashion to a heron. Although animal prey can be swallowed whole, usually red-crowned cranes more often tear up prey by grasping with their bills and shaking it vigorously, eating pieces as they fall apart. Most foraging occurs in wet grasslands, cultivated fields, and shallow rivers, or on lakeshores.

### **Migration**

The population of red-crowned cranes in Japan is essentially nonmigratory, with the race in Hokkaido moving only 150 km (93 mi) to its wintering grounds. Only the mainland population experiences a long-distance migration. They leave their wintering grounds in spring by February and are established on territories by April. In fall, they leave their breeding territories in October and November, with the migration fully over by mid-December.

### **Sociality**

Flock sizes are affected by the small numbers of the red-crowned crane, and given their largely carnivorous diet, some feeding dispersal is needed in natural conditions. Wintering cranes have been observed foraging, variously, in family groups, pairs, and singly, although all roosting is in larger groups (up to 80 individuals) with unrelated cranes. By the early spring, pairs begin to spend more time together, with nonbreeding birds and juveniles dispersing separately. Even while not nesting, red-crowned cranes tend to be aggressive towards conspecifics and maintain a minimum distance of 2 to 3 m (6.6 to 9.8 ft) to keep out of pecking range of other cranes while roosting nocturnally during winter. In circumstances where a crane violates these boundaries, it may be violently attacked.

### **Breeding**

Breeding maturity is thought to be reached at 3–4 years of age. All mating and egg-laying is largely restricted to April and early May. A red-crowned crane pair duets in various situations, helping to establish formation and maintenance of the pair bond, as well as territorial advertisement and agonistic signaling. The pair moves rhythmically until they are standing close, throwing their heads back and letting out a fluting call in unison, often triggering other pairs to start duetting, as well. As it is occurs year around, the social implications of dancing are complex in meaning. However, dancing behavior is generally thought to show excitement in the species. To strengthen the bond, red-crowned cranes engage in dual honking rituals before performing a dance.

Pairs are territorial during the breeding season. Nesting territories range from 1 to 7 km2 (0.39 to 2.70 sq mi) and are often the same year after year. Most nesting territories are characterized by flat terrain, access to wetland habitat, and tall grasses. Nest sites are selected by females, but built by both sexes and are frequently in a small clearing made by the cranes, either on wet ground or shallow water over waters no more than 20 to 50 cm (7.9 to 19.7 in) deep. Sometimes, nests are built on the frozen surface of water, as frigid temperatures may persist well into nesting season. Nest building takes about a week. A majority of nests contains two eggs, though one to three have been recorded. Both sexes incubate the eggs for at least 30 days. They also both feed the young when they hatch. Staying in the nest for the first few weeks, the young start to follow their parents as they forage in marshes by around 3 months of age. New hatchlings weigh about 150 g (5.3 oz) and are covered in yellow natal down for two weeks. By early fall, about 95 days after hatching, the young are fledged and are assured fliers by migration time. Although they can fly well, crane young remain together with their parents for around 9 months. Young cranes maintain a higher-pitched voiced that may serve to distinguish them from outwardly similar mature birds, this stage lasting until the leave parental care. The average adult lifespan is around 30 to 40 years, with some specimens living to 70 years of age in captivity. It is one of the longest-living species of bird.

## Range and Habitat

There are currently two main populations of Japanese crane; one is resident to the Island of Hokkaido in northern Japan and does not migrate. The second population breeds in north-eastern China, Russia and Mongolia and migrates to eastern China, and North and South Korea where it spends the winter. Recent estimates of the total population of these birds stand at around 2,200 individuals. Japanese cranes are highly aquatic birds. They feed in much deeper water than other crane species; feeding on pasture lands in summer and moving to coastal saltmarsh, rice paddies, cultivated fields, rivers and freshwater marshes in winter.

## Threats and Conservation

These beautiful birds were almost hunted to extinction in Japan at the beginning of the 20th century for their stunning plumage. Habitat losses due to agriculture and development have been further causes of the decline in the Japanese crane. Wetlands are fragile ecosystems and both the wintering and breeding grounds are under increasing risk of degradation and loss due to conversion to agriculture and industrial development.

A number of international agreements have been made to protect crane species and their habitats, and it is illegal to hunt Japanese cranes in all countries in which they occur. Protected areas have been established to safeguard the species; furthermore, conservation and educational programmes have been developed with the involvement of local communities, and a number of reintroduction attempts have been made. Research into the ecology, habitat needs and breeding biology of this graceful crane has been carried out since 1970.