The number of avian species in a major wetland in north-eastern Assam has declined by almost 72% in 27 years, according to a study.
- The study focused on the Bordoibam-Bilmukh Bird Sanctuary (BBBS), located along the Dhemaji and Lakhimpur districts of Assam.
Wetland of Assam
- Assam, known for its rich biodiversity, boasts a vast network of wetlands, primarily comprising oxbow lakes and seasonal floodplain lakes called “beels.”
- These wetlands play a crucial role in flood mitigation, water regulation, and supporting diverse flora and fauna.
- Deepor Beel, designated as a Ramsar site, is the only Ramsar Site of Assam.
- The state is home to several bird sanctuaries, providing safe havens for a wide array of avian species.
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Key Highlights of the Study on Avian Diversity at BBBS
- Sharp Decline in Avian Species: In 1997, the bird sanctuary recorded 167 avian species. The most recent study (2022-2024) found only 47 species, indicating a 71.85% decline over 27 years.
- Of the 47 bird species observed:
- 3 species are winter migratory: Brown shrike, Citrine wagtail and White wagtail.
- 1 summer migratory species: Lesser kestrel
- The remaining 43 species are resident birds.
- Causes of Decline :
- Anthropogenic Activities such as Overfishing, Excessive harvesting of aquatic plants and Poaching of wild birds and bird egg collection.
- Disturbances such as use of high-decibel machines for farming near the sanctuary and conversion of the sanctuary into pastureland.
- Poached Bird Species: Lesser whistling duck, Fulvous whistling duck, White-breasted waterhen, Indian pond heron, Eastern spotted dove and Yellow-footed green pigeon.
- Environmental Impacts: Wetland degradation may lead to lowering of the water table, disruption of the food chain,decline in migratory bird populations and slowing of the nutrient cycle.
- These changes pose threats to the ecosystem, environment, and human livelihoods.
- Call for Conservation: The study stresses the need for intense conservation efforts to restore and protect BBBS’s biodiversity.
- Biodiversity in Assam: Assam is home to about 950 bird species, including 17 endemic species.
- The State has 55 Important Bird and Biodiversity Areas that serve as critical habitats for various avian species.
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About Bordoibam-Bilmukh Bird Sanctuary (BBBS)
- BBBS is a small wetland located on the boundary of Dhemaji and Lakhimpur districts, Assam.
- Origin: Formed as a result of the 1950 earthquake.
- Declared a wildlife sanctuary by the Government of Assam in 1996.
- Hydrology: Initially part of the Subansiri River, a tributary of the Brahmaputra.
- The Subansiri River now flows 7 km away from the lake.
- Climate: The sanctuary experiences a moist tropical climate and receives approximately 2,000 mm of rainfall annually.
- Vegetation: Features flooded valley grasslands and wetlands.
- Fauna
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- Hosts large numbers of migratory waterfowl during winter.
- Home to globally threatened species such as:
- Spot-billed Pelican (Pelecanus philippensis): Near Threatened
- Lesser Adjutant (Leptoptilos javanicus): Endangered
- Swamp Francolin (Francolinus gularis): Vulnerable
21 Dec 2024
