New Delhi: Wetlands International's largest annual waterbird census across Asia and Australasia, "Asian Waterbird Census" (AWC) 2023 was carried out recently at Okhla Bird Sanctuary in active participation of the volunteers from Wetlands International South Asia, Aditi College, Delhi, Delhi Technological University in presence and coordination of TK Roy Ecologist and AWC Delhi State Coordinator, Wetlands International South Asia.
Okhla Bird Sanctuary, located on River Yamuna in NCR of Delhi falls in Central Asian Flyway, usually attracts good number and species diversity of long distant winter migratory water birds but being most degraded, polluted and disturbed wetland habitat by various factors fluctuate and decline the number and species diversity every year.
Although global climate change impact is the prime issue delays winter, migration, slow migration, lesser number of migration of the long distant winter migratory water birds from far Central Asia, North Asia including Russia and Siberian part almost everywhere in Indian sub-continent as being recorded since past several years. Apart from climate change impact several other factors for declining number of water birds and species diversity at any particular wetland. Okhla Bird Sanctuary is the most degraded, polluted and disturbed habitat in all respect decreasing overall water birds number and species diversity including migratory birds every year.
The wetland habitat several times in a year remains completely dried and latest during the recent migration season in October-November, 2022 about a month impacts on breeding of the resident birds, lesser arrival of winter migratory water birds and till December, 2022 was least number of migratory water birds results overall decreased population.
During AWC 2023 recorded further decreased species diversity: 47 (2022) to 36 (2023) and total number: 9,143 to 6,083 (2023) dominates the total number by common winter migratory species Northern Shoveler and then Eurasian Coot in comparison to previous years. Out of 36 species (18 resident species including local .migratory species and 18 long distant winter migratory species) includes 2 species (2023) from 4 species (2022) of IUCN Red-listed threatened birds in comparison to previous years. Several resident species and regular migratory species not at all found during the census. Now, as usual it will partially increase number of some migratory birds for some days to get flocked together as soon as climate starts warming in February onward on their way back to native countries.
Comparison of last four years AWC record:
Among the regular winter migratory water birds recorded in larger number this time but comparatively lesser than previous years are Northern Shoveler, Eurasian Coot, Common Teal, Gadwal and least number of other migratory birds as Graylag Geese, Bar-headed Geese, Northern Pintail, Black-headed Gull, Common Pochard, Tufted Duck, Eurasian Wigeon, Garganey, Pallas's Gull, etc in comparison to previous years:
IUCN Red-listed Threatened Species recorded on this wetland:-