Nanmangalam Reserve Forest, the scrub-covered hills along the Velachery to Tambaram road, is a protected forest, and you need permission from the District Forest Officer to walk inside it, as Citizen Matters has reported. That rule surprises many residents who drive past it every day, but it is the reason this 320-hectare patch still holds breeding Indian eagle owls in the middle of a growing suburb.
A botanical survey published in 2012 measured the forest at 321 hectares and recorded 449 species of flowering plants, six of them endemic, according to the paper in the journal Check List. Its authors called it an isolated fragment of the original vegetation surviving inside metropolitan Chennai. Here is what lives there, what threatens it and how to see it properly.
The owls and other birds
The forest’s best-known residents are Indian eagle owls, also called great horned owls, large brown owls with ear tufts and orange eyes. They roost in a ravine that was once a quarry, according to Citizen Matters. The species is protected, and a March 2025 Citizen Matters report described the forest as its exclusive breeding site in the area, while noting that pollution of the nearby lake may be cutting into the insects the owls feed on.
Studies cited in those reports put the bird list at 100 to 125 species, along with about 40 butterfly species and close to 20 kinds of dragonflies and damselflies. A writer for Outlook Traveller who walked the woodland with a guide recorded a coucal, black-shouldered kite, shikra, ashy prinia, spotted dove, common iora, Indian robins, bulbuls and drongos in a single morning, before finding the owl perched high in a tree.
The lake on the forest’s edge adds water birds. The 2025 report recorded painted snipe, Temminck’s stint, common snipe and western marsh harrier, and a Korean flycatcher, which it described as a first record for Tamil Nadu.
A forest that was once a quarry
Limestone quarrying began here in the early 1960s and scarred much of the land. The Forest Department took over in 1974, and mining has been banned since, according to Citizen Matters. The old pits now fill with rain each monsoon and serve as water holes. Replanting has added Terminalia, Bauhinia and Syzygium alongside older plantings of eucalyptus and acacia.
The damage has not stopped entirely. As far back as 1998, The Hindu reported sand extraction, clearing and vehicle washing on the forest’s fringe. The 2025 report lists encroachment, sewage from apartment complexes without treatment plants, meat-shop waste and garbage dumped in Nanmangalam lake, about 44 private water tankers drawing water around it, and spreading water hyacinth. Residents’ groups have asked for desilting, a halt to sewage inflows and CCTV to stop dumping.
Access rules and how to visit
- Apply for permission first. Entry needs written permission from the District Forest Officer. Contact the Tamil Nadu Forest Department, whose 24×7 helpline is 1800 425 4409, and ask which division office handles Nanmangalam requests.
- Go with a group. Outlook Traveller lists the Madras Naturalists’ Society among groups that run guided bird walks in Chennai; a guide who knows the owl roosts saves hours.
- Time it right. Bird walkers in Chennai generally go between 5 am and 8 am from September to March, the period Outlook Traveller recommends for the city.
- Keep your distance from the owls. Do not use flash, call playback or approach roosts and nests, especially in the breeding season.
- Carry out what you carry in. There are no facilities inside.
The edges of the lake and the main road are public and offer some birding without entering the reserve, but the forest interior is off limits without permission. Treat the rule as protection, not red tape: owls that are disturbed at the roost often abandon it, and a forest this small has few spare ravines.
The quarry pits matter beyond the owls. In 2017 the city’s water board looked at them as a possible water source, though the plan did not go ahead, Citizen Matters reported.
How it fits into the state’s bird counts
The Forest Department now runs a statewide synchronised bird estimate each year. In the March 2025 terrestrial phase, the Chennai forest division surveyed 21 spots and logged 114 species and 3,813 birds, according to the department’s report. The report recommended night surveys for owls and nightjars on the census days, the kind of effort that matters for a forest whose most famous bird hunts after dark.
Quick answers
Can I walk into Nanmangalam Reserve Forest?
Not without permission. It is a reserve forest, and entry requires approval from the District Forest Officer.
Which owl lives at Nanmangalam?
The Indian eagle owl, also called the great horned owl, which roosts in the old quarry ravines.
How big is the forest?
About 320 hectares; a 2012 botanical survey measured it at 321 hectares.
Where exactly is it?
Along the Velachery to Tambaram main road, about seven kilometres beyond Velachery.
Information checked against official sources on 18 October 2026. Fees, dates and rules can change; confirm on the linked official pages before acting.
Sources
- Angiosperms of Nanmangalam Reserve Forest, an urban forest in Metropolitan Chennai (Check List, 2012)
- Inside Nanmangalam Reserve Forest, Chennai’s lesser-known natural gem (Citizen Matters)
- Chennai’s last lung space: Nanmangalam Lake faces an ecological emergency (Citizen Matters)
- Birding in Chennai (Outlook Traveller)
- Misuse, neglect threaten Nanmangalam forest area (The Hindu, via India Environment Portal)
- Tamil Nadu Synchronised Bird Estimate 2025: Terrestrial Birds (TN Forest Department)
