Delhi Bird Atlas released on June 5: Among global capitals, Delhi ranks second in bird diversity

The Delhi Bird Atlas, released on June 5, which claims to have mapped the distribution and abundance of bird species across the city for the first time, has placed the Capital “second only to Nairobi among the world’s national capitals in bird diversity”.

The atlas cites the rare mix of the city’s geography, including the northern edge of the Aravallis, proximity to the western Himalayas, the Yamuna and Sahibi floodplains, and its location near the Central Asian Flyway (CAF) — a key bird migration route stretching from the Arctic down to the Indian Ocean — as the primary reason behind the bird diversity.

The atlas was developed by the Delhi Forest Department, Bird Count India, World Wide Fund for Nature (WWF)-India and other partner organisations, with the participation of birdwatchers, students, researchers, forest staff and citizen volunteers.

According to the atlas, “The Delhi Bird List now stands at 471 species”, excluding another 22 species that have not been re-recorded since 1975.

The atlas covers 11 per cent of Delhi’s area in its sampling design. The survey started in January 2025, takes place twice a year, in winter and summer, and will run for at least two years. Winter surveys document resident species and winter migrants, while summer surveys record breeding activity, resident birds, summer migrants and early-returning migrants.

In the first year, 221 species were recorded across the city, including 200 in winter and 152 in summer. Of these, 126 were resident species, 81 were winter migrants and 14 were summer migrants. Nearly half the recorded bird assemblage comprised invertebrate feeders, that is, 108 species or 48.87 per cent. Plant and seed feeders accounted for 37 species, omnivores for 34, vertebrate and carrion feeders for 33, and fruit and nectar feeders for nine.

The atlas also records 18 endemic bird species, that is, species found exclusively in one specific geographic region. It also lists several vulnerable bird species, including the Endangered Egyptian Vulture and Black-bellied Tern, the Vulnerable River Tern and Common Pochard, and Near Threatened species such as the Black-tailed Godwit, Ferruginous Duck, Painted Stork, Black-headed Ibis and Oriental Darter.

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Unlike other bird lists, the atlas used a grid-based method. Delhi was divided into grids of 6.6 km by 6.6 km, further subdivided into smaller quadrants and subcells. A total of 145 subcells were randomly selected for sampling to reduce bias and ensure representation across habitats. Each subcell required four 15-minute checklists, with birds recorded on foot and uploaded to eBird. The atlas says this “systematic approach” of collecting “equal-effort lists from randomly placed grids across the city” helps reduce sampling bias and ensures that results reflect the “true distribution and abundance of species”.

Experts associated with the atlas attribute Delhi’s bird diversity to the city’s position at an ecological intersection: the Ridge brings the Aravalli landscape into the Capital, while the Yamuna floodplains and associated wetlands provide refuge for waterbirds and migrants. The city’s proximity to the western Himalayas, meanwhile, facilitates seasonal movement. The atlas notes that Delhi “lies almost at the heart of the Central Asian Flyway”, making it “a seasonal haven for species arriving from as far as Central Asia and the Arctic”.

The exercise, according to the atlas, provides “a robust scientific baseline” against which future atlases, to be conducted five years from now and beyond, can measure ecological change. Repeated surveys will help track shifts in bird populations, habitat preferences and environmental stress over time, officials said.

Meanwhile, the atlas also describes Delhi as “a meeting point of history, geography, and biodiversity”, noting that such diversity persists despite the pressures of one of the world’s most populous urban regions. It also underlines the importance of protecting “the green and blue spaces that sustain it”, pointing repeatedly to forests, wetlands, riverine systems, grasslands, urban greens and floodplains as habitats that continue to support birdlife. The Yamuna floodplains, in particular, are identified as a key ecosystem for conservation and habitat restoration.

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The Delhi Bird Atlas was prepared by Dr Lynette Gomes, nodal officer, Delhi Forest Department; Pankaj Gupta, state coordinator, Bird Count India; and Arnav Gupta.

However, efforts to document and record Delhi’s birdlife isn’t a new phenomenon. The atlas itself includes an extract from renowned birdwatcher Sudhir Vyas’s study of avian inhabitants in Delhi-NCR, noting that the first checklist of birds in the Capital was prepared by S Basil-Edwards in 1924–25, when New Delhi was being built. That early effort listed around 202 species. By 1950, the Delhi Bird-Watching Society, an NGO, had brought out a checklist of 356 species, and later work continued to document Delhi’s bird species.