With the onset of winter, the banks of the Rapti and Narayani rivers, which flow through the borders of Chitwan National Park, resonate with new sounds. Flocks of numerous migratory birds are found in the river area in search of food.

The sound of these birds flying in search of food and shelter and gathering in one place after finding it makes the riverbank ripple. These birds are colorful, clean and graceful. The body is white but not pure, almost gray.

Yellow beak, bright white head with a black stripe from one eye to the other and another black stripe parallel to it.

There are about 50 to 60 species of migratory winter birds. But this is the identity of the Bar-headed Goose.

The front part of whose neck is light black and white stripes are drawn on the right and left. The light black color is also mixed in the wings. This bird lives in flocks. It crosses the northern mountains and reaches Narayani.

Nawalparasi conservationist DB Chaudhary has been monitoring migratory birds in this way for 30 years. According to him, when winter sets in, snow freezes in the highlands of Siberia, Mongolia, and China, covering all their food. Where do the birds live and what do they eat when they are covered in snow?

That is why they set out on a journey to warmer places south. Among the many migratory birds, the bar-headed goose is called the Khoya Hans in Nepali.

A large flock of Khoya Hans lives on the banks of the Narayani River at Pithauli Ghat in Nawalparasi (east of Bardaghat Susta). DB Chaudhary's team found 567 Khoya Hans at Pithauli Ghat four or five years ago.

Less than two to three hundred Khoya Hans never come there. This time too, the familiar sound of the Khoya duck has started echoing on the banks of the Pithauli. DB Chaudhary's team had gone to that area on Thursday.

This time, up to 660 Khoya ducks were found in a circle in Pithauli. 250 Chakhewa were mixed with them. Chakhewa also migrate here.

The flock of Khoya ducks that have crossed the mountains swim in the Pithauli Narayani River and eat the nectar. DB is surprised that the Pithauli area is a good habitat for Khoya ducks. But the ruins of the Narayani River are moving away.

Not only farms, but houses have been added to the farmland. Even as the agricultural area is shrinking, the amount of chemical fertilizers and pesticides used has increased. Conservationists fear that the birds will be in danger due to pollution.