The winter migratory birds appear to be adapting to the climate change in a big way and this year despite Delhi witnessing a harsh summer, a large number of them have stayed back at the Okhla Bird Sanctuary here.

According to ecologist and environmentalist T. K. Roy, who as the coordinator of the Asia Waterbird Census, monitors and tracks the presence and movement of these birds, climate has been playing a very important role in the migration pattern of the birds. “They are a sensitive indicator of environment. A large number of water birds migrate long distances globally during winter. In the winter of 2013 (January to February), as many as 42 species of water birds migrated to the Okhla Bird Sanctuary and in March most of the migrants left. By late April almost all the winter migrants left the sanctuary and northern India as the mercury started rising fast.”

However, what has surprised the ecologist is that despite the searing heat in Delhi and nearby areas, some of the long distance winter migratory water birds have stayed back in the sanctuary. “Despite the temperature going as high as 47 degrees Celsius, to avoid the energy sapping long journey or migration back home as far as Europe, Central Asia, Tibet or coastal regions of South Asia, some of the water birds have decided to stay put. May be this is so because they find the Okhla sanctuary a suitable breeding habitat,” said Mr. Roy, while adding that normally these birds breed in the cooler climes of North Asia, Central Asia, Tibet or Ladakh.

Among the migratory birds that have made Delhi their home this summer are the bar-headed geese and brahmini duck, which normally breed in Central Asia, Tibet or Ladakh; common coot and river lapwing (a red-listed threatened species) that breed in North Asia; the black-tailed godwit (another threatened species) that breeds in North Asia and East Asia; and greater flamingo that breeds in coastal regions of South Asia (India, Bangladesh, Pakistan and Sri Lanka).

Apart from this there are other species of summer migratory birds that have come to the Okhla Bird Sanctuary during the breeding period. These include the streaked weaver bird which is a summer migrant from South and South-East Asia. Referred to as teliya baya in Hindi, it nests in a small colony on typha plant just above the water surface. Then there is another threatened species, the black-bellied tern, which is a resident of South Asia and is popularly know as tihari or Ganga cheel, which is enthusing the bird watches at the sanctuary this year.

However, environmentalists have expressed concern over permission being given to domesticated animals to intrude into the sanctuary. “A large number of cattle are allowed to graze in the core area or the islands and they pose a threat to the nesting of the breeding species,” warned Mr. Roy.