Biodiversity at Risk: 72% Decline in Bird Species at Assam’s Bordoibam-Bilmukh Sanctuary Over 27 Years
Why in News:
Assam’s Bordoibam-Bilmukh Bird Sanctuary has reported a 72% reduction in its bird species count over the past 27 years.
About Bordoibam-Bilmukh Bird Sanctuary
Location and Size:
- Situated on the boundary between Dhemaji and Lakhimpur districts in Assam.
- Spans an area of about 11.25 sq. km at an altitude of 90–95 meters above sea level.
History:
- Designated as a wildlife sanctuary in 1996 by the Assam government.
- Previously part of the River Subansiri, a Brahmaputra tributary, which is now 7 km away from the wetland.
Climate and Vegetation:
- Experiences a moist tropical climate with an average annual rainfall of 2,000 mm.
- Dominated by flooded valley grasslands and wetland vegetation.
Avian Biodiversity:
- Supports diverse migratory waterfowl during winter.
- Habitat for globally threatened species like the Spot-billed Pelican (Pelecanus philippensis) and the Lesser Adjutant (Leptoptilos javanicus).
Overview of the Crisis
Over the last 27 years, the sanctuary has seen a 72% decline in its bird species count due to anthropogenic activities such as fishing, poaching, egg collection, and land-use changes.
Decline in Avian Diversity
Species Count:
- 1997: Recorded 167 bird species.
- 2022–2024: Studies found only 47 species, reflecting a decline of 71.85%.
Temporal Trends:
- 2011 survey: Documented 133 species (86 resident, 23 migratory, 24 local migrants).
- 2017–2018 survey: Recorded 120 bird species, along with 133 macrophytes, 68 fish species, and seven aquatic fern species.
- Since 2018, there has been a notable decline in species diversity.
Migratory Species:
Recent sightings include winter migrants such as the Brown Shrike, Citrine Wagtail, and White Wagtail, along with the summer migrant Lesser Kestrel.
Where is the Bordoibam-Bilmukh Bird Sanctuary located?
The sanctuary is situated at the boundary of Dhemaji and Lakhimpur districts in Assam, covering an area of approximately 11.25 sq. km.
When was the Bordoibam-Bilmukh area declared a wildlife sanctuary?
It was designated as a wildlife sanctuary by the Assam government in 1996.
What kind of climate and vegetation does the sanctuary have?
The sanctuary experiences a moist tropical climate with an average annual rainfall of about 2,000 mm. It is characterized by flooded valley grasslands and wetland vegetation.
Why is the Bordoibam-Bilmukh Bird Sanctuary significant for avian species?
The sanctuary serves as a vital habitat for migratory waterfowl during the winter and is home to globally threatened bird species such as the Spot-billed Pelican and Lesser Adjutant.
What alarming trend has been observed in the sanctuary’s bird population?
Over the past 27 years, the sanctuary has experienced a 72% decline in its bird species count, with the numbers dropping from 167 species in 1997 to just 47 species in recent surveys conducted between 2022 and 2024.
What are the major reasons for the decline in bird species?
The decline is attributed to anthropogenic pressures, including fishing, poaching, egg collection, and changes in land use.
What migratory birds have recently been recorded in the sanctuary?
Recent records include the Brown Shrike, Citrine Wagtail, White Wagtail (winter migratory species), and Lesser Kestrel (summer migratory species).
What actions can be taken to protect the sanctuary’s biodiversity?
Conservation efforts such as stricter enforcement against poaching and habitat destruction, wetland restoration, and community engagement in biodiversity preservation are essential to safeguard the sanctuary’s avian population.
What was the historical connection of the sanctuary to the River Subansiri?
The sanctuary was originally part of the River Subansiri, a tributary of the Brahmaputra. However, the river now flows approximately 7 km away from the wetland.
Why is this sanctuary important in the broader context of biodiversity conservation?
The Bordoibam-Bilmukh Bird Sanctuary serves as a critical refuge for threatened species and migratory birds, making it an essential site for preserving regional and global biodiversity.
Responses