They come in ones and twos, then by the dozen. A cloud of swallows circles in a holding pattern above the Bagmati Bridge, before sweeping down one by one through the door for a landing. Then begins the noisy squabble for their
favourite perches on the rafters. The chirping is shrill, as 600 birds get ready to call it a day. Slowly, the cheep-cheep subsides into a sleepy rustle of feathers.

By this time, Dhana Shrestha has covered most of the wares in her pasal with a large plastic sheet to protect them from swallow droppings. She moves around the pasal under a small umbrella as she attends to her clients- most are from the neighbourhood and they have got accustomed to a ceiling alive with birds. One little bird doesn't make much poop, but multiply that by 600 and you have a guano factory.

No one's quite sure why the swallows have adopted Dhana's pasal as their base camp. But for Dhana's family, it is an auspicious sign and a good luck omen. It started with one pair nearly 35 years ago and the numbers just grew and grew. After you cross Bagmati Bridge while going from Kathmandu to Patan, there is a small shop with a yellow sign on the right. The shop itself smells like the inside of a cave with the pungent odour of birdie do-do. "These are free birds, and when they come in every evening, it is like your children coming home," says Dhana. "They are free birds, and we are honoured that they have chosen our house." Dhana's mother who passed away last year believed that they were the luckiest people in town when the swallows decided to move in. She persuaded her family to let them stay even though the poop situation got worse and worse as the swallow population swelled. No one in the family touches the birds. "If you touch them they die," says Dhana. "Sometimes they sit on our shoulders, but we never touch them." Over the years of growing up with the birds, Dhana, herself in her mid- 30s, has become rather attached to them, and also it seems, they to her.

With so many, they may look like an anonymous flock, but Dhana suspects there are one or two that are particularly close to her. "Once they are comfortable in the ceiling, some of them look down at me quizzically, as if wanting to communicate," she says. By the first light of dawn, the swallows swoop out once more for a day on the wing above the Kathmandu skyline. You see them in the glint of the morning sun, soaring past temples or skimming the surface of the Bagmati to take an in-flight sip of water.

And that is what worries Dhana, if the people of Kathmandu are so badly affected by the dirty water, polluted air and the garbage, what is happening to the health of her swallows? So far though it seems, not much. However, Kathmandu's loss of green cover and pollution has affected other migratory birds that used to make Kathmandu their stopover. And resident scavengers like crows have driven all other birds away.

But with the Kupondole swallows, it is the other way around. They have stopped migrating south in winter and have now decided to stay in Kathmandu all year round. The biggest calamity for the birds was during the uprising in 1990.
Because there were curfews that lasted days, Dhana's mother had to keep the shop doors closed and the swallows could not go out to feed. Many died. The swallow house also draws curious Kathmandu residents, school children on field trips and even birdwatching tourists from Britain, Japan and Taiwan. Some of them, like the Wild Bird Society of Taipei, leave their banners, with the date of visit: February 1994.

Next time you are crossing the Bagmati Bridge, do take the time off to go and say hi to Dhana Shrestha and her amazing swallows.