The case of the vanishing Siberian cranes

Badly planned strategies, along with other reasons, have resulted in a failure to conserve the habitats of wild animals. An example: fewer numbers of a rare migratory bird are now visiting the Keoladeo National Park.

 
By Nitya Jacob
Published: Saturday 04 July 2015

-- ILL-CONCEIVED human intervention can all but destroy a wild animal's habitat and this has been amply illustrated at the Keoladeo National Park (KNP) in Bharatpur, Rajasthan. Successive years of worsening food and water scarcity are blamed for the lessening number of rare Siberian white cranes visiting the park.

This year, only five cranes arrived at KNP -- and they were one month late. Last year, the number was seven, compared to about 100 in the early 1970s. Though KNP field director A S Brar expresses hope that a flock sighted recently over Pakistan will arrive soon, the fact is the number of cranes arriving is precariously low.

Experts say the Siberian crane's survival is endangered by various factors, the most plausible being a shortage of food. This is a direct fallout of the denial of grazing rights to villagers beginning November 1982, because the number of cranes visiting the park has stayed low since.

Lack of food
Siberian cranes feed primarily on the tubers of sedges Vetivera, a kind of grass. But, says Brar, "The ban encouraged the proliferation of a grassy weed that obstructed the growth of plants providing food for the cranes." A 10-year study by the Bombay Natural History Society showed that from 1983 to 1986, the quantity of the weed increased five-fold. But in the past two years, because villagers have been allowed to harvest from April to July, the weed growth has been checked considerably.

Other reasons suggested for the Siberian crane's decline include one by wildlife researcher Vivek Menon of the World Wide Fund for Nature, who says Bharatpur water is contaminated with pesticides and chemicals and this accumulates in the crane's body fat. When the cranes return to Siberia, the fat reserves are used up and the chemicals released, which kills the birds.

Menon says even if food and water availability improves, "an increase in numbers (of cranes visiting Bharatpur) will take place only gradually." The Siberian crane's migratory route also appears to work against its survival. It flies 6,000 km from its marshy breeding grounds in Central Asia to Bharatpur, stopping off at Lake Ab-i-Istada in Afghanistan, where they run the risk of being shot by hunters.

A clue to the whereabouts of the missing birds is offered by Prakash Cole, who has studied cranes extensively. "I feel they have shifted to another place," he says. "These birds have been sighted outside Bharatpur in a lake near Gwalior. They have probably found better nesting places."

His theory was checked last year by a US-Russian-Indian team. Its members tracked a radio-collared chick the Afghan border but lost it there. The project will be attempted anew soon, but this time with two hand-reared radio-collared chicks, Cole disclosed.

KNP attracts some 300 species of birds annually from all over the world. The rarer species include garganey teals, pochards, purple herons, barheaded geese and black-capped kingfishers. Hence, says Brar, "The probable extinction of a species will not seriously damage the park's reputation. Serious bird watchers and naturalists are unlikely to be deterred from visiting the park."

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