BENGALURU: Increasing and unregulated use of chemicals like insecticides and pesticides – especially neonicotinoids – and change in agricultural patterns have drastically affected grassland bird species across India.
This is compromising soil nutrient cycle, pollination, seed dispersal and eco-system engineering in which the threatened bird species play a key role. This is bound to have an adverse impact on public health ultimately, says a study by Bengaluru-based National Centre for Biological Sciences (NCBS).
The NCBS researchers point out that avian species are not just aesthetically important, but are valuable tools in the large food-chain and agricultural pattern. They feed on insects, bees and other pests. They noted that while many western countries have banned the use of pesticides and fertilizers, unregulated usage continues in India, affecting local and migratory bird species.
Similar is the case with the continued use of banned drugs like the Diclofenac and non-steroidal anti-inflammatory drugs (NSAIDs) - painkillers given to cattle and consumed by humans. This has forced a drastic decline in populations of all six Indian vulture species.
Neonicotinoids are a class of insecticides chemically similar to nicotine, and are being rampantly used in agriculture and veterinary medicine. They are absorbed by plants and transported throughout their tissues, including pollen and nectar.
Birds like tawny eagle, Indian bustard at risk from toxic farmlands
Neonicotinoids have raised concerns due to their potential harm to beneficial insects like bees and other pollinators, and bird species dependent on them.
The NCBS study points to rampant and unregulated use of neonicotinoids, depriving grassland and raptor bird species like the Tawny Eagle, Greater Spotted Eagle, Saras Crane, Great Indian Bustard, Indian Roller, Bengal Florican and Common Pochard, of their prey. This has forced a decline in populations of these bird species.
The report noted the drastic decline in wetland and aquatic bird species including the Northern Pintail Duck, Tufted Duck, Greater Flamingo, Sarus Crane, Eurasian Spoonbill, Black-capped Kingfisher, Greater Flamingo, Baillon’s Crake, Sarus Crane, Spot-billed Pelican, Eurasian Spoonbill, Lesser Adjutant, Painted Stork and Pied Kingfisher. The study, based on data from 2000 to 2023, stated that this was because of pollution in water bodies, silt accumulation, contamination, agricultural pollution, unscientific desilting and poor lake rejuvenation methods where there is no spillway and increased use of concrete.
Vivek Ramachandran, co-author of the study, says population loss in birds with specialised diets – like those feeding on vertebrates, carrion or invertebrates – has averaged over 25%. In contrast, species dependent on fruits or nectar have remained stable or even increased.
He said birds play a very important role in the health of people and in the ecosystem, and indicate the health of the community.
The NCBS study, “State of India’s Birds: 2023: A framework to leverage semi-structured citizen science for bird conservation”, was published in Ecosphere, an ESA Open Access Journal, on July 17, 2025, and released to the public on Tuesday.
Researchers assessed the status of 942 bird species using data contributed by scores of bird watchers on eBird. It highlighted that 204 bird species suffered long-term decline and 142 species were facing a current decline. Also, 178 bird species have been classified as ‘high conservation priority’, 323 species are listed as ‘moderate priority’ and 441 are listed as ‘low priority’.