The Odd Reason Flamingos Are Flocking to Mumbai

There are now roughly 121,000 flamingos that flock to Mumbai each season, and if that seems like a lot, it is. The Bombay Natural History Society did a headcount of the leggy pink birds earlier this year, tallying the number of lesser flamingos and greater flamingos that had moved into India's largest city.

Flamingos began migrating to Mumbai in the early 1990s, arriving in late fall, and staying until the end of May, when the monsoons begin, according to The Wall Street Journal. Reports say there were anywhere from 20,000 to 40,000 flamingos each season in those days.

But now, nearly four decades later, those numbers have tripled.

"It is very encouraging to see large number of flamingos arriving around Mumbai. This underlines the importance of the critical habitats in and around the Mumbai region. It also highlights the necessity of such long-term comprehensive studies to understand migratory birds and chart future conservation plans," said Rahul Khot, the project's principal investigator and BNHS assistant director, in a release announcing the survey results.

Choosing the perfect spot

Most of the birds settle in Thane Creek, which may hold some clues for the flamingos' skyrocketing population increase. As The Guardian points out, Thane Creek "has become a dumping ground for untreated domestic sewage and industrial effluents from the city" and one of the most popular places for flamingos to congregate is near the Bhandup water treatment plant. The sewage in the creek triggers the growth of high levels of blue-green algae, which means dinner for the flamingos.

Sunjoy Monga, a naturalist and author of the book "Birds of Mumbai," tells The Guardian that the creek may have reached "what one might call perfect levels of pollution."

"Over the years the industrial discharge dispelled by the industries of the Sewri Bay may have warmed the water," Monga says. "The nitrate and phosphate levels in the creek water are just right for the prolific growth of the algae."

The trade-off from this pollution, Monga says, is this "double-edged sword" where good comes with the bad.

"Here, wilderness merges with human impact and some species are able to thrive in it."

But this somewhat-perfect balance may soon come to an end. With ongoing expansion and construction in the area, continued dumping of sewage and waste is predicted to eventually dry out the creek, which means the birds will leave.

In announcing the population numbers, Khot says the goal is to be proactive. "It is an excellent news. But it also means that we have to be more responsible and sensitive while planning development in the region. We also need to focus and work to clean the highly polluted eastern sea front so that we provide toxicity free habitat for flamingos and other migratory birds."