Population of over 200 bird species dwindled sharply in 25 yrs: Bengaluru scientists

New Delhi: India’s bird species are on a decline, according to Bengaluru scientists, who analysed extensive bird watching data to find out that the population of over 200 species have dwindled sharply compared to the situation 25 years ago.

They have reported that 204 species suffered long-term declines when compared to their numbers in the pre-2000 period, while 142 species show current annual decline. As many as 178 species have been classified as high conservation priority whereas 323 species have moderate priority in conservation.

The population of raptors, migratory shorebirds and ducks have declined the most while India peafowl and Asian Koel continue to thrive.

Some of the species that recorded the biggest long term decline are Black-capped Kingfisher, Dunlin, Eurasian Griffon, Eurasian Curlew, Pied Avocet, Curlew Sandpiper, Terek Sandpiper, Grey Plover, Tufted Duck and Pallid Harrier.

Birds with specialised diets, such as those feeding on vertebrate prey, carrion, or invertebrates, have declined the most, averaging over 25 per cent long-term population loss.

In contrast, species dependent on fruits or nectar have remained stable or even increased.

Birds that need grasslands, scrub-lands, and wetlands have experienced the steepest fall. Winter migrants to India have dropped more sharply than resident species, raising further alarm.

Among all winter migrants to India, Black-capped Kingfisher has declined the most in the long term (86 per cent). A large proportion of the species that have declined the most are migratory shorebirds.

The only non-wetland migratory species that feature in the top 10 declining birds are Eurasian Griffon and Pallid Harrier with declines of 79% and 73% in the long term, whereas Forest Wagtail is among the top ten with high current annual decline.

Others in the list of high current annual decline are Sandwich Tern, Eurasian Oystercatcher, Baillon's Crake, Dalmatian Pelican, Northern Shoveler, Northern Pintail, Spotted Redshank and Ruddy Turnstone.

Researchers from Nature Conservation Foundation and National Centre for Biological Sciences team up with scientists from other institutes and independent scholars to analyse data collected by 30,000 bird watchers.

Since birdwatching is a day-time affair, the study was restricted to 942 diurnal species, leaving out the nocturnal ones.

“Such data will help understand the reasons behind the rapid disappearance of some of the birds,” NCF scientist Ashwin Vishwanathan, who led the study, told DH.

The scientists developed a method to analyse the data collected by bird enthusiasts - contained in the State of India’s Birds 2023 report - since such data do not fall into the format of a scientific study.

“This framework allowed for the assessment of a larger number of avian species than previously possible and is intended to serve as a blueprint for regions with limited resources for traditional surveys,” said NCBS researcher Vivek Ramachandran, an author of the study.

"Populations of migratory ducks are in rapid decline in India, providing insights into source populations that breed east of Europe. Rates of decline appear very similar to those in Europe. Our results suggest that ducks and wetlands require focused conservation attention across Eurasia,” the scientists said in the study published in the journal Ecosphere.