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In Kathmandu, when the falcon’s away, pigeons come out to play. And poop

  • Once treated as pets, Kathmandu’s pigeons have now become a menace.
  • With their population growing unchecked, the birds invade homes, soil buildings, and frequently carry parasites.
  • Ornithologists attribute the pigeon population boom to the decline in urban birds of prey, such as peregrine falcons that once kept pigeon numbers under control.
  • The long-term solution to the problem, they say, is to identify and fix the factors that have pushed the raptors out of the city.

KATHMANDU —They can be seen nesting in tight spaces between buildings, on window panes and rooftops across Kathmandu.

Common pigeons (Columba livia) were once a beloved site in this city, flocking to religious and tourist sites where people would buy special grains to feed them. Now, though, residents say the birds have turned into a menace.

“They poop everywhere, especially in the terrace of my house,” says Rojina Maharjan, a resident of downtown Kathmandu. Until five years ago, she kept around half a dozen pigeons as pets by building a home for them. But she decided to let them go as they dirtied her terrace. “To add to that, they enter the house from the window of the bathroom during the dry season looking for water,” Maharjan tells Mongabay. “My experience says that their numbers have gone up in the past few years.”

Her experience is backed by the numbers. According to the Kathmandu Urban Bird Survey 2022, the pigeons, also known as rock doves, were among the top five species recorded in the city.

“I also think that the number of pigeons has gone up substantially in the city,” says ornithologist Hem Sagar Baral. “I also have firsthand experience of this. I made some wooden birdhouses at home for barn owls to use. But the pigeons have occupied them.”

Baral says he believes the pigeon overpopulation indicates a disruption to the local avian food chain. Birds of prey that once hunted pigeons have become rare in the city in recent years.

Pigeons at Patan Durbar Square in Lallitpur, one of the three cities in the Kathmandu Valley, Image by Abhaya Raj Joshi for Mongabay

“In the past, we used to see peregrine falcons [Falco peregrinus], considered the fastest animal in the world, in Kathmandu’s skies. But they have now stopped laying eggs here,” Baral says. The falcon was the primary predator of the pigeons and would keep their population in check.

“The best way to naturally manage the population of these pigeons would be to reintroduce the falcons in Kathmandu,” Baral adds. “However, we don’t clearly know what drove them out in the first place.”

Ornithologists cite several possible factors for the decline in the bird of prey population in Kathmandu. For example, the construction of high-tension power lines ringing the Kathmandu Valley may have made it difficult for the critically endangered white-rumped vultures (Gyps bengalensis) that once frequented the city to soar in and out. Other likely factors include the city’s urban sprawl and loss of habitat.

Baral says that for peregrine falcons to be reintroduced, the reasons for its disappeared need to be assessed first: “We then need to address the issues identified to make suitable habitats for them so that they can control the population of the pigeons.”

He adds that while residents of Nepal’s southern plains hunt pigeons for food, that’s not the case in the capital. Instead, Kathmandu residents often encourage the birds by feeding them, especially in the temples.

But there’s now a growing recognition that the birds can cause problems if left unchecked.

The pigeons roaming the Kathmandu Valley have been found to be infected with various parasites. A 2017 study found heavy gastrointestinal parasite infection in pigeons at two temples in the valley. Ninety percent of the 120 fecal samples collected for the study had either protozoa or parasitic worms. The study authors recommended that action be taken to control the infection and keep the pigeons healthy.

“We don’t know if the parasites make it to humans interacting with the birds, but it’s better to exercise caution,” Baral says.

City’s residents have started calling in pest control services to install mesh wires and nets around their houses to keep the birds out.

“We receive up to a dozen inquiries a week to install mesh wires to fend off pigeons,” says Biddha Nanda Jha, who runs the Orange Ball pest control company.

A study published earlier this year assessed the impact of pigeon poop on monuments of cultural importance in the Kathmandu Valley. The researchers found that the droppings cause significant corrosion on structures made from pure copper.

Banner Image: A man feeds pigeons at the Bouddhanath Stupa in Kathmandu. Image by Abhaya Raj Joshi for Mongabay.

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Citations:

Gurung, A., & Subedi, J. R. (2018). Prevalence of gastrointestinal parasites of pigeons (Columba sp. Linnaeus, 1758) in three temples of Pokhara valley, Nepal. Journal of Natural History Museum, 30, 287-293. doi:10.3126/jnhm.v30i0.27604

Shrestha, S., Khanal, L., Pandey, N., & Kyes, R. C. (2022). Conservation of heritage sites in Kathmandu, Nepal: Assessing the corrosion threat from pigeon excreta on metal monuments. Conservation, 2(2), 233-243. doi:10.3390/conservation2020015