Guwahati: Once a flourishing refuge for numerous bird species, Assam’s Bordoibam-Bilmukh Bird Sanctuary now faces an alarming biodiversity crisis, with avian diversity plummeting by over 70%. Once home to 167 recorded bird species, recent surveys reveal a staggering decline, with only 47 species now remaining.
Researchers have documented this drastic decline, underscoring the serious impacts of human activities on local bird populations. Their findings are detailed in the study, A drastic decline in avian diversity in and around the Bordoibam-Bilmukh Bird Sanctuary, Lakhimpur, Assam, published in the Journal of Threatened Taxa.
Bordoibam-Bilmukh, located on the boundary of Assam’s Dhemaji and Lakhimpur districts, is one of the important bird areas and ecotourism hotspots of the northeastern region.
This wetland, spanning 11.25 sq km, was formed by the river Subansiri following a major earthquake in 1950. Recognizing its ecological value, the Assam government designated it as a Bird Sanctuary in 1996 due to its rich biodiversity.
A survey conducted in 1997 recorded 167 bird species, but this number had dropped to 133 by 2017-18. Researchers surveyed the area between October 2022 and March 2024, cataloging bird species across seasons using visual counting techniques and binocular observations. They found that only a few migratory birds remained, along with species such as the Lesser and Greater Adjutants, both listed as “Near Threatened” on the IUCN Red List.
Primary Causes of Decline
Researchers attribute the sharp decline in bird diversity to several human-induced factors. Local residents frequently fish in the sanctuary’s wetland, endangering birds with fishing nets and noise from agricultural machinery. “Out of the 154 days of fieldwork, on around 101 days, local residents were observed fishing in the wetland area, which serves as a primary foraging and breeding ground for many resident and migratory bird species. During fishing, they spread nets just below the water’s surface and wait for 7–8 hours. Tragically, the birds’ feet often get trapped in the nets, leading to suffering or death,” the study noted.
Additionally, poaching remains a concern, with birds targeted for meat and eggs. Local children also engage in hunting as a sport, while expanding agriculture has led to habitat degradation, impacting the sanctuary’s ability to support its avian population. The use of tractors and other machinery in rice cultivation on lands adjacent to the wetland’s shore is further threatening species diversity.
Call for Action
“If no action is taken immediately, more damage will occur in the coming years, and the sanctuary’s significance as a bird habitat may be lost forever,” the study warns. Researchers have recommended urgent habitat restoration efforts and the development of management initiatives to protect avian diversity in the Bordoibam-Bilmukh Bird Sanctuary.
The report emphasizes that preserving the sanctuary’s habitat is essential for safeguarding Assam’s bird species and maintaining its ecological significance in the region.
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