A group of local students and an experienced birder try to locate a bird by closely listening to its song during a school excursion through the vast Mangar Bani forest on an April tour organized by birders and environmental activist Chetan Agarwal. (Enrico Fabian/ For The Washington Post)

The schoolchildren enter the forest at dawn on a bird-watching field trip. They step softly on crisp fallen leaves and speak in hushed whispers.

A metallic tuk-tuk-tuk sound fills the air. The bird watcher points at the entangled branches above. The pre-teens gasp as they spot a tiny green-bodied, yellow-necked bird with a red face.

“Coppersmith barbet,” whispers Sourajit Ghosal, the bird-watcher looking through his binoculars.

A vast, centuries-old unspoiled grove sits secretly sandwiched between India’s polluted capital, New Delhi, and its affluent suburb Gurgaon. And because of a hard-fought and long-running legal battle, it looks as though it might be preserved in its pristine splendor.

The Mangar Bani forest, with its thick cover of trees — laburnum, frankincense, flame of the forest — and its dozens of chirping birds, wild leopards and rare species of insects and flowers, survived untouched for centuries because the local villagers believed it was a sin to cut its trees.

A small part of the vast Mangar Bani forest in Mangar, Haryana. (Enrico Fabian/ For The Washington Post)

But in recent years, Gurgaon — called “a suburb on steroids” — has experienced frenzied urban sprawl. An explosion of luxury condos, office buildings, tollways, malls and nightclubs threatens to swallow hundreds of acres of Mangar Bani.

Real estate companies and residents argued in India’s National Green Tribunal, known as the green court: Is Mangar Bani a forest, farmland or just a bunch of arid rocks? The designation was crucial to its future.

Now, after almost six years of intense battle in courts, government departments and on the streets, citizens have managed to save the 677-acre Mangar Bani sacred grove from builders, even though developers own dozens of acres of forestland. The state government has declared it a no-construction zone.

The Mangar Bani forest sits sandwiched between India's capital, New Delhi, and its affluent suburb Gurgaon. With the area undergoing frenzied urban growth, the forest was in danger of being paved over. (Rama Lakshmi/Enrico Fabian for The Washington Post)

But the defenders of the forest aren’t relaxing. Some developers have attempted to carry out illegal logging there. The state forest department has deployed guards around the clock.

“It is like a mini war situation out there,” Mrigendra Dhari Sinha, conservator of forests in the area, said. “For many people, steel and glass buildings are the only expression of development. But we need water and forest, too.”

A small sculpture of the Hindu god Hanuman, often closely associated to nature, is seen placed at a banyan tree. (Enrico Fabian/For The Washington Post)

A Eurasian Collared-Dove, one of the many species of birds which can be found inside the vast Mangar Bani forest. (Enrico Fabian/For The Washington Post)

An experienced birder tries to locate a bird during a school excursion through the vast Mangar Bani forest. (Enrico Fabian/For The Washington Post)

Two local students look for a bird during a school excursion through the vast Mangar Bani forest. (Enrico Fabian/For The Washington Post)

The fight reflects India’s struggle to save its green cover amid a wave of urban growth and depleting groundwater. In some places of Gurgaon, groundwater levels have dropped to 300 feet below the surface, from about 50 feet just two decades ago, officials said, because the recent population and construction booms have sucked its underground reservoirs dry with overuse. Forests such as Mangar Bani act as critical aquifers to recharge groundwater for the capital and its suburbs.

The battle for Mangar Bani began in the 1980s, when real estate companies and affluent investors lined up to buy pieces of land from the villagers.

“By the time people woke up and realized what was happening, much of the forest was already sold to real estate companies,” said villager Sunil Harsana, 28. “Villagers blocked the takeover when they realized that the buyers actually wanted to cut trees and construct.”

In 2012, the development master plan for the region did not even acknowledge the existence of Mangar Bani forest. Real estate companies sent as many as 90 applications to the government urging it to designate the forest as farmland. Environmentalists pushed the authorities to call it a forest in the records.

A lawyer representing a firm called Kenwood Mercantile, which official records show owns about 200 acres of Mangar Bani forest, said his client was a victim of faulty land records.

“My client bought the land from villagers. A few years later, villagers started saying, ‘Sorry, there is a forest here,’ ” said Pinaki Mishra, the lawyer. “The records did not call it a forest back then. The problem is that our government land records are not updated or digitized.”

The sun rises behind a vast construction site of apartment and office buildings in Gurgaon, Haryana. (Enrico Fabian/For The Washington Post)

Builders filed photographs of dry Mangar Bani taken in the summer season at the green court. Activists countered by presenting photographs of the forest in its full glory after the monsoon. A tree survey of Mangar Bani that the court ordered reported 30 species of trees and a total of more than 100,000 large trees.

Then, last year, Manohar Lal Khattar, the chief minister of Haryana, took a four-hour helicopter ride to survey the forest. He was convinced.

This year, his government prohibited construction in the forest and the 1,200-acre buffer around it. Now, businesses such as Kenwood cannot build on the land.

Khattar said he was “determined to protect the Mangar Bani sacred grove and the rest of Aravalli hills in Haryana.”

“The groundwater security of the entire national capital region depends upon protecting and conserving water conservation zones in this region,” Khattar said via text message, referring to the rapidly falling water table in New Delhi and Gurgaon.

“We have a responsibility towards future generations, and real estate companies would be kept out of this ecologically fragile area.”

For village elders, it is the triumph of their age-old faith once again.

“We believe if you break even a twig in this forest for your personal need, misfortune strikes you. That fear has kept the forest alive for nearly 1,000 years,” said Fateh Singh, 90.

“We believe if you break even a twig in this forest for your personal need, misfortune strikes you,” says Fateh Singh, 90. “That fear has kept the forest alive for nearly 1,000 years.” (Enrico Fabian/For The Washington Post)

In the past two years, environmental analyst Chetan Agarwal has conducted dozens of school field trips, bird-watching tours, research studies by college students and residents’ walks in the forest.

He wants to train a new generation of forest defenders. “They have to understand,” Agarwal said, “that this forest can easily disappear if they are not alert.”

On a recent day, residents, tree lovers, students, bird watchers and conservationists marched to celebrate the victory.

Asked Nandini Gulati, a health coach: “Can we afford to lose the last of our city’s lungs?”