State of India’s Birds 2023

The 2023 State of India’s Birds Report was released in August 2023. The report is a periodic assessment of the distribution range, trends in abundance, and conservation status for most of the bird species that regularly occur in India. With their ubiquity and ecological importance, birds are excellent indicators of the state of our natural world and are potent cultural symbols of nature. As a comprehensive, national-level assessment, the report points the way towards conservation needs of India’s birds.

The report was produced as a partnership between the 13 organisations including the Bombay Natural History Society, WWF, Wildlife Institute of India, and Wetlands International.  

The report assesses the status of 942 bird species largely using data uploaded by birdwatchers to the online platform eBird. The assessments are based on three indices. Two are indices of change in abundance: Long-term Trend (i.e., change over c. 30 years) and Current Annual Trend (i.e., annual change over the past eight years); the third is a measure of Distribution Range Size within India.

Key points of the report:
•    30,000+ birdwatchers contributed 30 million observations analysed for trends and distribution.
•    942 Indian birds assessed for conservation priority.

o    178 classified as High Conservation Priority.
o    217 species stable or increasing in the last eight years.
o    14 species, including Indian Roller, recommended for IUCN Red List reassessment.
o    Asian Koel has increased in the past three decades.
o    Indian Peafowl continues to thrive.
o    Raptors, migratory shorebirds, and ducks have declined the most.
o    Birds that live in key habitats like open ecosystems, rivers, and coasts have declined.

•    Policy and action must align to highlight species of high conservation priority, address problems of neglected habitats, and promote research and monitoring.

Of the total of 942 species, 523 had sufficient data for estimating Long-term Trends. Among the 523, Long-term Trends could be determined for 338 species (the remaining 185 had trends categorised as inconclusive trends). Of these 338 species, 204 have declined in the long term, 98 show a trend that is indistinguishable from stable, and 36 have increased.

Using these three indices together with the IUCN global Red List of Threatened Species 2022 (hereinafter ‘IUCN Red List’), species were classified into categories of Conservation Priority for India: 178 as High Priority, 323 as Moderate Priority and 441 as Low Priority. Species of High Priority include those whose abundance indices have declined considerably in the long term and continue to decline today. Species were also categorised as High Priority species for India, if their current range is Very Restricted, or if their abundance trend could not be assessed but they are classified as Globally Threatened in the IUCN Red List. 

Threats to birds
The report also listed the following threats to the birds of India:

Monocultures: Monoculture plantations (or monocultures) include commercial plantations of coffee, tea, arecanut, cardamom, rubber, teak, or other species, which are created by large-scale clearance or modification of natural habitats like forests and grasslands. Commercial monocultures are known to harbour fewer bird species than natural forests within the same biome.

Environmental Pollutants: Heavy metals, pesticides and even veterinary drugs are on top of the list of known environmental pollutants endangering birds. The evidence implicating environmental pollutants in the massive decline of vultures is clear. However, the long-term consequences of other toxic chemicals for birds are still unclear in the absence of rigorous research that combines systematic sampling of pollutants in the environment together with toxicological studies on birds.

Forest Degradation: Forest degradation is a well-known driver of biodiversity loss. As a result, specialist bird species, including forest specialists, have suffered long-term declines. One evident impact is a reduction in species richness and overall abundance in degraded forest in comparison with protected forest. Further, species composition also changes, mainly due to the decline of forest specialists, large-bodied frugivores, and understorey insectivores.

Urbanisation: Urbanisation has become a key driver of global land-use change in the past 50 years. As roads and built-up areas increase, the resulting loss and fragmentation of natural habitat for birds exposes them to novel stressors such as elevated pollution levels, increased temperature, and increased density of free-ranging domestic predators like cats and dogs. Food subsidies in urban areas can result in the increase of behaviourally dominant species such as House Crows and feral Rock Pigeons, thereby crowding out other species. The most urbanized areas have the least number of species, the least number of rare species, and the fewest insectivorous species.

Energy Infrastructure (Wind energy and power lines): A wide range of bird species are known to be killed by collisions with wind turbines. The species most at risk appear to be large-bodied birds, such as storks, bustards, cranes, vultures, eagles, but other smaller species suffer collisions too.

Avian Disease: Anthropogenic drivers such as land-use change, intensive livestock production, wildlife trade, and climate change are now known to have indirect effects on the emergence and cross-species transmission of pathogens. Globally, birds are hosts for an astonishing diversity of parasites such as Plasmodium, avian influenza virus and West Nile virus. The impact of disease on avian population declines in India is poorly understood due to a lack of long-term studies. India is considered a hotspot for endemic vector-borne diseases. Avian influenza outbreaks in 2020–2021 swept through many Indian States, causing mass mortality of wild birds.

Illegal Hunting and Trade: Illegal hunting is the hunting or capture of wild species without legal sanction. Live birds are trapped for the pet trade, or hunted for their derivatives such as meat, eggs, feathers, claws, beak, and casque. Further, superstitious beliefs can lead to the illegal hunting of species like owls or Indian Roller. Fashion or hobbies can lead to a demand for feathers for hats, for fly-fishing, and other body parts for amulets or curios. To tease out the synergistic effects of land-use change (habitat loss/alteration) and illegal hunting on a bird species may be difficult and extremely challenging, and hence hard to generalise. Within India, it is this combined effect that is likely to be the most critical, as exemplified by the decline of Manipur Bush Quail and Green Munia.

Climate Change: Shifting baselines caused by climate change make it challenging to diagnose threats to birds. Researchers commonly compare disturbed and undisturbed habitats to infer degree of suitability for birds. However, climate-driven changes in avifauna make modern bird communities in undisturbed habitats different from historic ones. Without long-term data, the unknown extent of climate change impact on comparison benchmarks makes it difficult to assess land-use change effects on birds.

One way in which climate change affects bird survival and reproduction is through the disruption of species interactions by phenological mismatches and range shifts. Mismatches in seasonal timing (of migration, breeding, emergence) between birds and their prey can reduce survival and reproduction and also lead to fatal competition with other species. In parallel, range shifts lead to the loss of overlap between species in space, and thereby loss of their interactions. Additionally, new and dangerous interactions might emerge.

Climate change can also push mountain species directly towards extinction. Terrestrial bird species diversity is concentrated in tropical mountains, with each species adapted to a specific temperature range tied to altitude. The Himalaya and Western Ghats are particularly rich in bird diversity, with the latter being a hub for bird endemism. However, climate change poses a threat to high-elevation bird species as favourable conditions shrink at mountain summits, potentially causing local extinctions.