Red-crowned crane: survival is at risk



by LORENZO CIOTTI

Red-crowned crane: survival is at risk

The red-crowned crane is one of the most endangered species of the Gruidae family. The number of specimens of this species native to East Asia probably reached an all-time low in the years immediately following the Second World War.

Since then, however, the population has increased again in some areas. Over the past sixty years, however, large parts of this species' habitat have been converted to farmland. In the late 20th century, between 1,700 and 2,000 cranes lived in the wild.

Therefore, the IUCN classifies this species as endangered. East Asian populations winter in coastal areas, while those that breed on the Japanese island of Hokkaidō are largely sedentary. The main threats to this species are human activities leading to habitat loss.

The draining of marshes, the grazing of livestock, the harvesting of hay, the use of chemicals that contaminate the soil and water, going to deteriorate the food chain at the base, have led to the disappearance of nesting grounds largely of the area.

The disturbance caused to nesting pairs also had very negative consequences: if particularly stressed, the parents leave the nesting ground and the chicks left alone are therefore exposed to the risk of predation by crows.

In some areas, protection programs for the red-crowned crane clash with the needs of the local population. On Lake Chanka, whose shores are located in both China and Siberia, the riversides are some of the most economically valuable agricultural land.

Indeed, the Siberian side was the only point in the entire USSR where rice was grown, as well as other cereals, soybeans and tomatoes. On the Chinese side, too, the soil is just as fertile. In the Zhalong Nature Reserve, the black-crowned crane, which prefers a patchwork of islands and open waters, could benefit from the fact that the population living in the adjacent area can legally harvest only half of the reeds present here.

For these people, however, cane harvesting represents between 70 and 80% of their income. The inhabitants are therefore forced to collect more reeds than is compatible with the protection of the birds. Red-crowned cranes are found in a large number of zoos and reserves.

Indeed, the captive population is so numerous that there is no global genealogical register, but only a regional one, especially within the genealogical registers relating to a single continent. In Japan, captive flightless males have been found to attract free-ranging females to enclosures and raise offspring with them, which join flocks of wild cranes as soon as they are able to fly.

In the Zhalong Nature Reserve, some red-crowned cranes have been hand-raised and released into the swamps. During the winter months the specimens in question were caught again to avoid losses. Over the next few years, these birds mated with each other or with wild red-crowned cranes and raised their offspring near where they grew up.

Also these chicks were kept in captivity during the first winter months together with their parents. These semi-wild cranes are more tolerant of humans than their wild counterparts; this goal is precisely what conservationists have set out to achieve with these measures.