Varanasi, Nov. 13 -- With winter around the corner, migratory Siberian birds have once again returned to their seasonal abode in Kashi, turning the waves of the Ganga into a lively four-month sanctuary.

Arriving in India between October and November, these winged guests stay through the winter before making their journey back home with their young in March, just as the chill begins to fade in the area.

Their migration is a matter of survival. In Siberia, Russia's coldest and snowiest region, temperatures plunge to minus 40 degrees Celsius during October and November, freezing lakes solid and cutting off food supplies, driving the birds south to India's warmer waters.

To get here, they undertake a gruelling 5,000 to 8,000-kilometre jour...