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Birds of the Indian Subcontinent
This article is based on the publication by Dr Ranjit Manakadan and Asif N. Khan of the Bombay Natural History Society, which was published in the BNHS-ENVIS newsletter BUCEROS (Vol. 24 Issue 2&3) in March 2020. The article is a brief summary of the biogeographic zones of the Indian subcontinent with its avifauna in mind.

The Indian Subcontinent
The Indian Subcontinent rests largely on the Indian Plate and encompasses India, Pakistan, Nepal, Bhutan, Bangladesh and Sri Lanka, along with Andaman and Nicobar Islands in the Bay of Bengal, and the Maldives and Lakshadweep archipelagos in the Arabian Sea. Birds of South Asia: the Ripley Guide also includes Afghanistan (usually clumped with Central Asia) and the Chagos Peninsula (the group of islands in the Indian Ocean south of the Maldives). In recent times, the Indian Subcontinent is often referred to as South Asia.

The Indian Subcontinent is separated from Central Asia by the Himalayas. The mountain barriers to the northwest and northeast are the Hindu Kush (in Afghanistan and Pakistan) and Arakan (bordering northeast India and Myanmar) respectively. The seas/oceans that fringe its southern expanse are the Arabian Sea to the west, the Bay of Bengal to the east, and the Indian Ocean to the south.

Profile of the Avifauna of the Indian Subcontinent
The Indian region has one of the most diverse avifauna on earth, brought about by the diversity of climatic and physical features of the landmass, which have given rise to an assortment of habitat types ranging from desert to montane forests. About 1,300-odd species of birds are reported from the Subcontinent, these constituting c. 13% of the world’s birds. About 193 (taxonomy- dependent) endemic/near-endemic species occur in the Subcontinent. With bird studies, birdwatching and bird photography picking up momentum especially in recent years, new species are getting discovered and described to science, the most spectacular being the Bugun Liocichla in 2006 from the Eaglenest Sanctuary in Arunachal Pradesh.

Even as these discoveries are coming to light, the Indian Subcontinent is losing its species. For instance, the Himalayan Quail and Pink-headed Duck are now presumed to be extinct.

The Siberian Crane, which was a regular winter visitor to the Keoladeo National Park in Rajasthan, has not been recorded in India since the winter of 2001– 2002. Two species that were considered extinct, Jerdon’s Courser and Forest Owlet were rediscovered, but the status of the former is uncertain again.

The IUCN (International Union for Conservation of Nature) has placed 17 species that occur in the Subcontinent as Critically Endangered (some of which are probably extinct): Himalayan Quail, Baer’s Pochard, Pink-headed Duck, Siberian Crane, Great Indian Bustard, Bengal Florican, White-bellied Heron, Christmas Island Frigatebird, Sociable Lapwing, Spoon-billed Sandpiper, Jerdon’s Courser, Red-headed Vulture, White-rumped Vulture (or Oriental White-backed Vulture), Indian Vulture (or Long-billed Vulture), Slender-billed Vulture and Yellow-breasted Bunting and Bugun Liocichla. Other than these, there are species categorized as Endangered (26 species), Vulnerable (77 species), and Near Threatened (92 species), bringing the total number of threatened birds to 212 species.

Based on the residency status and migration/ movement pattern, the birds of the Indian Subcontinent may be grouped as follows:

Residents
The avifauna of the Indian region comprises typical birds of the Indo-Malayan region (e.g., leafbirds, fairy-bluebirds, barbets and junglefowl), and characteristic groups of the Indian Subcontinent (e.g., pheasants, pittas, Old World babblers and flowerpeckers). There is also a good chunk of Palearctic birds in the Himalayas (e.g., Eurasian Jackdaw,, snowcocks, snowfinches, nuthatches, treecreepers, and accentors). And, Afrotropical groups of North Africa and West Asia (e.g., coursers, bustards, honeyguides and hypocolius), along with families that are common to both the Afrotropical and Indo-Malayan region (e.g., bulbuls, sunbirds and weavers). As for native waterbirds comprising about 12% of the Subcontinent’s avifauna (and 50% of the region’s waterbirds), they are discussed towards the end of the article under waterbirds of the Indian subcontinent. For further insights into the biogeographic aspects of the resident birds of the Indian Subcontinent.

Some of the world’s most cosmopolitan species (e.g., Peregrine Falcon, Osprey, Common Barn-Owl, Gull-billed Tern, Cattle Egret, Great White Egret, House Sparrow and Rock Dove/Rock Pigeon) have resident populations in the Indian Subcontinent. Populations of some of the resident species get augmented in winter by an influx of migrant populations of their kin from the Palearctic region, e.g., Great White Egret, Grey Heron, Glossy Ibis, Eurasian Spoonbill, Common Kestrel, Peregrine Falcon Falco peregrinus, Eurasian Coot Fulica atra, Kentish Plover, Little Ringed Plover, Common Gull-billed Tern,, Common Tern, Common Hoopoe and House Sparrow.

Winter Migrants
About 23% of the 1,300-odd species reported in the Indian Subcontinent are winter migrants. These originate largely from the Palearctic region beyond the Himalayas, breeding mainly in northern Asia (Russia, Mongolia, and China) and the countries of Central Asia (Kazakhstan, Turkmenistan, Uzbekistan, Kyrgyzstan, and Tajikistan). A few species come from as far as extreme Western Europe. More well-known and common among the winter migrants are the raptors, storks, ducks and geese, waders (shorebirds), cranes and the passerines comprising swallows, flycatchers, warblers, thrushes, chats, wheatears, redstarts, pipits, wagtails, buntings and finches.

Some of the migratory waterbird species have populations/races that breed (mostly in small numbers) in the Trans-Himalayas in summer, e.g., Bar-headedGoose, Ruddy Shelduck, Mallard, Lesser Sandplover, Common Sandpiper, Common Redshank and Brown-headed Gull. As in the case of most other migrants, these also migrate southward after breeding, to spend the winter in the warmer climes of the Subcontinent. Besides, there are some other species among waterbirds and landbirds that have populations/races breeding in different areas of the mainland, as discussed under Residents.

Not all winter migrants spend the entire winter in the Subcontinent. Instead, they only make stopovers to rest and feed while passing through the region enroute to their wintering grounds in Africa or the Middle East: Amur Falcon, Common Cuckoo Ortolan Bunting, Common Whitethroat, Rufous-tailed Scrub-Robin, Rufous-tailed Rock-Thrush and and Red-backed Shrike. Vagrants (e.g., swans and divers) have been recorded wintering in the Subcontinent on rare occasions. They mostly arrive following extreme weather conditions in the northern climes.

Summer (Breeding) Migrants
Similar to the migration pattern of the extralimital migrants to the Subcontinent is the movement of birds to the Himalayas and the Northeast hills in summer to breed. Post-breeding, these species winter in northern India or migrate further south into the Peninsula. These summer (breeding) migrants behave like true migrants from the Palaearctic, and this is like a compacted case of the North-to-South migration brought about by the presence of the Himalayas and the adjoining hills, which due to their elevation, mimic the conditions of the breeding grounds in the northern climes.

Altitudinal Migrants
A much shorter migration is undertaken by resident Himalayan birds. These species move down to the lower reaches and foothills of the range with the advent of winter (to escape the cold conditions) and return with the onset of spring. Examples are Grandala, Ibisbill, Wallcreeper and treecreepers. Other than arboreal species, the cursorial pheasants and their allies undertake such migrations, travelling largely on foot. Attitudinal migration by resident birds also takes place in the Western Ghats, for example, in the Square-tailed Bulbul, with birds moving to the foothills during the cold weather.

Local (Seasonal) Migrants
Many resident species of the Indian Subcontinent undertake regular, seasonal internal movements, while some undertake irregular, nomadic movements. Little precise information is available on the movements of local migrants. Well-known among the local (seasonal) migrants are the Indian Pitta, Indian Paradise-Flycatcher, Indian Golden Oriole, and Blue-tailed Bee-eater.

Among the resident bustards, the Lesser Florican is a species that is presumed to undertake seasonal, long-distance movements. Its stronghold is in northwestern and central India (mainly in Gujarat and western Madhya Pradesh) where it breeds during the monsoon, and it has been recorded widely across India outside the season. BNHS studies have documented that it breeds regularly in the protected grassland enclosures of Rollapadu Wildlife Sanctuary (Kurnool district, Andhra Pradesh). It is conjectured that the birds migrate and breed in winter in the southern parts of the Peninsula if the monsoon has been poor in their northern strongholds.

Among the waterbirds occurring in the Indian Subcontinent that undertake significant seasonal/ nomadic movements are the flamingos. Both the Greater Flamingo and Lesser Flamingo largely breed in the Kutch region of Gujarat, and from winter up to the onset of the southwest monsoon, flamingos are recorded from many sites in the mainland, especially in peninsular India. However, the origin/origins of these wintering birds are still uncertain. Till date, the movement pattern of these birds into southern India (and elsewhere) is unknown with no recoveries either from the nearly two hundred young individuals ringed in the 1940s from the Great Rann of Kutch, or from birds ringed over the decades from BNHS field stations in southern India. Likewise, there is uncertainty on the origins of the Lesser Flamingo wintering in the Subcontinent. Since the mid-1990s, up to 100,000 Lesser Flamingos have been recorded in the Mahul-Sewri Creek of Mumbai. This when compared with the low numbers and scarce nesting records reported in Kutch in the past, and also the significant numbers reported in winter in Kutch (as in the wetlands around Mumbai) in recent years, suggests migration/movements of birds between Africa (the stronghold of the species) and India.