Four of the six species of harriers found in India, including the Montagu’s harrier pictured here, are declining. Credit: Albin Jacob

A study based on 30 million field observations has identified that 178 wild bird species in India -- including teals, sarus cranes and greater flamingos -- need immediate attention.

The State of India’s Birds 2023 report finds that while Asian koel and Indian peafowl populations have increased significantly, most bird species are in decline, imperiled by habitat loss or degradation and climate change.

The study analyzed 942 bird species observed by 30,000 birdwatchers and submitted to the online platform eBird. 348 of these species had enough data over 25 years, and 60% of them showed long-term decline, while 40% of 359 species assessed since 2015 were currently declining.

Raptors such as vultures, migratory shorebirds, and ducks have declined the most. The report recommends urgently reassessing the IUCN status of 14 species, including the Indian roller, listed as a species of ‘least concern.’

The database was analyzed for trends and distribution by experts at 13 government institutions, conservation NGOs, and independent professionals.

217 species were stable or improving in numbers in the last 8 years, including ashy prinia, rock pigeon, Asian koel, and the country's national bird-Indian peafowl. Other familiar species, including baya weaver and pied bushchat, were relatively stable.

Declining trends across habitats

The report shows that grassland birds dipped by more than 50%. Western marsh harrier, a grassland bird in Nannaj, Maharashtra, has consistently reduced, with zero sightings in a specific study area in 2021.

Long-distance migrants have declined by over 50%, followed by short-distance migrants. Shorebirds that breed in the Arctic and migrate to coastal habitats of India have been declining by nearly 80% as a group.

Threats to birds in India

• Monoculture plantations of coffee, tea, cardamom, rubber, and teak, modify or clear natural habitats like forests and grasslands. Oil palm cultivation in biodiversity hotspots such as the Andaman & Nicobar Islands and the north-eastern Himalayas threaten numerous endemic bird species.

• Aceclofenac, ketoprofen, and nimesulide are three emerging non-steroidal anti-inflammatory drugs with toxic effects similar to diclofenac. These drugs threaten to undo the benefits of the ban on diclofenac imposed to save dwindling populations of iconic vultures.

• Heavy metal pollution from mining metallic ores, refineries for metals, and thermal power plants is also known to affect birds adversely.

• Deforestation clears natural habitats, whereas rapid urbanization creates noise and light pollution. Urban noise compels birds to abandon their habitats. Light pollution can confuse and disorient birds during their migration.

• The expansion of wind energy and related transmission lines also threatens large-bodied birds such as vultures, storks, eagles, bustards, and cranes.

Birds endemic to the Western Ghats have fallen in numbers rapidly over the past few decades. In the Western Ghats grasslands, exotic and invasive trees like wattle threaten the future of birds like the Nilgiri pipit. Bustards that live in open habitats have also dwindled. The three bustard species found in India face imminent extinction, according to the report.

Raptors are declining globally, as well as in India. Pallas’s fish eagle, one of the few raptors that breed in India during winter, shows evidence of rapid decline. Malabar grey hornbill seen in the Western Ghats has reduced by 56% between 2004 and 2018.

Among woodpeckers living mostly in the Himalayas and north-eastern India, the white-bellied and yellow-crowned woodpeckers are in poor health. Riverine ground-nesting birds show a 50–80% decline over the long term and some continue to decline.

Ashwin Viswanathan, at Mysuru-based Nature Conservation Foundation, which analysed the data, said species-specific decline data will help prioritize habitats for conservation.