Red-Crowned Crane
They are also called the Manchurian crane or Japanese crane and 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. Adult red-crowned cranes are named for a patch of red bare skin on the crown, which becomes brighter during mating season. Overall, they are snow white in color with black on the wing secondaries, which can appear almost like a black tail when the birds are standing, but the real tail feathers are actually white. Males are black on the cheeks, throat, and neck, while females are pearly gray in these spots. The bill is olive green to greenish horn, the legs are slate to grayish black, and the iris is dark brown.
Habitat
In the spring and summer, the migratory populations of the red-crowned crane breed in Siberia (eastern Russia), northeastern China and occasionally in northeastern Mongolia. The breeding range centers in Lake Khanka, on the border of China and Russia. Normally, the crane lays two eggs, with only one surviving. Later, in the fall, they migrate in flocks to the Korean Peninsula and east-central China to spend the winter. Vagrants have also been recorded in Taiwan. In addition to the migratory populations, a resident population is found in eastern Hokkaidō in Japan. This species nests in wetlands and rivers. In the wintering range, their habitat is comprised mainly by paddy fields, grassy tidal flats, and mudflats. In the flats, the birds feed on aquatic invertebrates and, in cold, snowy conditions, the birds switch to mainly living on rice gleanings from the paddy fields..
Diet
They have a highly omnivorous diet. They eat rice, parsley, carrots, redbuds, 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, shrimp, small mammals like rodents and small birds like ducklings. They prefer a carnivorous diet, although rice is now essential to survival for wintering birds in Japan and grass seeds are another important food source. While all cranes are omnivorous the two most common crane species today (the sandhill and common cranes) are among 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 a high content of crude protein and low content of crude fiber. They typically forage by keeping their heads close to the ground, jabbing their beaks into mud when they encounter something edible. When capturing fish or other slippery prey, they strike rapidly by extending their necks outward, a feeding style similar to that of the heron. Although animal prey can be swallowed whole, red-crowned cranes more often tear up prey by grasping with their beaks and shaking it vigorously, eating pieces as they fall apart. Most foraging occurs in wet grasslands, cultivated fields, shallow rivers, or on the shores of lakes.
Breeding
Breeding maturity is thought to be reached at 3–4 years of age. 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. 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. 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 50cm 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 150g 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 75 years of age in captivity. It is one of the longest-living species of bird.
Population
The global population is estimated to number 3,050 individuals (range 2,800-3,300). Given the opportunities for missing individuals or double counting, three-year averages (for winters 2012-13, 2013-14 and 2014-15 have been calculated: China 580; Korea 1,000, and Hokkaido 1,470. The number of mature individuals is roughly 1,830 The population in Japan has increased but that on the continent is declining due to a number of factors, most importantly the degradation of breeding and wintering sites. Apparent recent increases are likely to reflect increased concentrations at fewer sites, and the global population is thought to have declined by at least 20% over the past 37 years or three generations.
Threats
The main threat is the loss and degradation of wetlands in its breeding and wintering grounds, but also aquaculture and industrial and economic development. Due to habitat loss, the winter range in China is now only 8% of what it was in the 1980s. This loss of habitat is leading to the over-concentration of cranes at a few sites. In China, wetlands are becoming drier as a result of surrounding development. In Russia and China, spring fires destroy suitable nesting grounds, and the proliferation of dams lowers water levels, allowing predators access to nests and destroying suitable breeding sites. Human disturbance has been so high as to prevent individuals from nesting in some areas and has been found to influence vigilant behaviour. Rainfall patterns in the breeding grounds appear to follow a 30-year cycle, and the current dry period has meant birds, people and livestock have had to depend on ever smaller areas of wetland, also resulting in increased pressure to divert water from rivers and lakes. Wetland restoration at Zhalong Nature Reserve (China) was recorded as causing inappropriately-timed floods leading to nest failure. Important sites on the Song-nen plain, Shuangtai Hekou and Yellow River delta are on or near major oilfields and pollution is a potential threat. There is high adult mortality in some continental wintering areas which is apparently due to poisoning; the species has been found to carry high levels of heavy metal contamination, and the incidence of poisoning has been increasing in recent years. Future construction of dams on the Amur river and its tributaries is a threat. Poaching has also been suggested as a threat and some cranes and their eggs are taken for the captive trade. In the Demilitarised Zone of North/South Korea, the shift to autumn ploughing is reducing access to waste grain, and there is great uncertainty regarding the long-term fate of the crane habitat, whatever the political future delivers. Also the DMZ in Korea is under pressure for development due to the recent relaxation of tensions between South and North Korea; restrictions on human activities in the adjacent Civilian Control Zone are being eased so that smaller areas are free from agriculture structures and human activity incompatible with cranes. In Japan, the concentration of birds at feeding stations means there is a risk of disease, especially given the low genetic diversity of the population, which passed through a bottleneck in the 1950s.
Conservation
Conservation Actions Underway
CITES Appendix I and II. CMS Appendix I and II. Part of the European Endangered [Species] Programme of the European Association of Zoos and Aquaria. It is legally protected in all range states. Key protected areas include Khingansky, Muraviovka and Lake Khanka (Russia), Zhalong, Xianghai, Hui River, Shuangtai Hekou, Yellow River delta and Yancheng (China), Kumya and Mundok (North Korea), Kushiro, Akkeshi-Bekanbeushi and Kiritappu (Japan). All cranes surveyed in the Sanjiang Plain region were recorded within one of seven National Nature Reserves, which collectively cover 6994 km2. Surveys of the wintering population in China have been carried out since 2006. The International Red-crowned Crane Workshop was held in Japan in November 2008, where it was concluded that international cooperation was necessary to stop development from threatening crane habitat across the species's range. Artificial feeding has been set up at some sites.
Conservation Actions Proposed
Identify breeding times during which particularly stringent protection rules should be implemented, as has been done at Liaoning Shuangtai Estuary. Improve general monitoring procedure, with complete censuses, satellite tracking and aerial counts. Determine Area of Occupancy to a more accurate level. Initiate a study of heavy metal contamination on the mainland. Expand the area/number of wintering sites in Japan. Establish a transboundary protected area at Tumen estuary, between Russia/China/North Korea. Secure the conservation status of the Cholwon and Han estuary in the Demilitarised Zone. Strengthen management of protected areas on the Sanjiang plain (China), reducing human disturbance. Halt tidal-flat reclamation along the Yancheng coast (China), and control the highly invasive cordgrass Spartina alterniflora. Improve management of wetland restoration at Zhalong, to prevent floods from causing breeding failure. Prevent poisoning from pesticides and poaching. Control fires in the breeding grounds. Establish interest groups and a communications organisation for crane conservation in China and extend captive breeding programmes for future reintroduction and population supplementation.