All might not be well in our wetlands, as indicated by -disturbing migratory trends of birds. "The disappearance of Siberian cranes is not the only cause for concern," says Ravi Aggarwal, member of the Delhi-based NGO, Srishti, which carried out the north India census for the Asian Wetland Bureau. "Only one Blacknecked crane, an endangered species, was spotted in Gujarat this year and most others like demoiselles, common cranes and Dalmatian pelicans were found only in clusters in a few areas, instead of being evenly distributed over the wetlands of the sub-continent."

Large migratory birds are extremely sensitive indicators of the health of wetlands. They skip these annual breeding grounds for several reasons: too little water, too many weeds, too little food or excessive human interference. "The migratory pattern of the birds visiting Delhi and Calcutta seems to indicate too much human interference," points out Iqbal Malik, honorary director of Srishti.

The lake at Alipore Zoo in Calcutta did not receive its usual share of winter visitors this season, as the birds preferred the more peaceful Santragachi lake nearby. In the Sultanpur lake near Delhi, a bund built for bird watchers reduced the water level drastically, resulting in most of the fish-eating species like the osprey leaving early.