State of India’s birds evaluated status of 867 species, using data from birdwatchers
The population of raptors — a group of preying birds — is declining, according to the State of India’s Birds 2020. The report was released at the 13th Conference of Parties (CoP) of the United Nation Environment Program’s (UNEP) Convention on the Conservation of Migratory Species of Wild Animals’ (CMS).
The report included scavengers such as vultures in the category.
Raptors, typically vertebrates, are high on the food chain — like mammalian carnivores such as tigers. They are also often sensitive to environmental changes.
The population of those raptors whose habitats are specialised can decline if such habitats are degraded or lost. Some species may respond to toxin bioaccumulation.
According to the report:
Generalist species (which occupy a range of habitats, including human habitats), and woodland species appear to have suffered the least declines in the long term. However, all woodland species, and white-eyed Buzzard and Common Kestrel among generalists, continue to decline, but possibly at a lower rate than earlier. In contrast, open country specialists show a particularly strong decline both in the long term and currently, although Black-winged Kite and Western Marsh Harrier show trends that are roughly stable in the long term. Finally, as is known from other evidence, scavengers (mostly vultures) have been in severe decline over the past 25+ years.
Water birds have also been on the decline, according to the report. These species are sensitive to changes in water, vegetation and the substrate quality of their habitats.
The group has faced a long-term decline. But “migratory shorebirds and gulls and terns appear to have declined the most, although waterfowl (ducks & geese) and other resident water birds (like swamphens, coots and storks) also show clearly discernible declines,” the report added.
It couldn’t pinpoint “whether these declines are due to changing conditions at breeding, staging or wintering sites (or all three).”
Among habitat specialists, forest species have suffered the most, followed by grassland / scrubland species and wetland species. The report, however, attributed the decline to reasons other than habitat change, saying the species have great habitat flexibility.
Rajah Jayapal, senior principal scientist at Salim Ali Centre for Ornithology and Natural History, said such declining numbers have had a link with urbanisation. “For example, the population of common birds such as the house sparrow has declined in urban areas. However, in rural areas, their population is stable,” Jayapal, a contributor to the report, said.
The report looked into the status of 867 bird species, using data uploaded by birdwatchers to the online ‘eBird’ platform. The assessment was based on three indices, two of which measured any change in abundance and the third the distribution.
Of the 261 species for which long-term trends (for about a quarter of a century) could be determined, the population of 52 per cent have declined since 2000. The declines were strong among 22 per cent. Only 5 per cent showed an increasing trend.
Current annual trends were estimated for 146 species and nearly 80 per cent of their populations were declining, with almost 50 per cent declining strongly. A little over 6 per cent were stable and 14 per cent increasing.
The range size of all but six species was estimated: While 46 per cent had moderate range sizes, a third large or very large, and 21 per cent restricted or very restricted sizes.
The population of 126 species were either stable or increasing, according to the report. These include the popular House Sparrow, as well as the Indian Peafowl, Asian Koel, Rose-ringed Parakeet and Common Tailorbird.
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