Bengaluru’s proposed Hebbal short tunnel alignment passes through an ecologically rich landscape where researchers have recorded 92 tree species and 199 bird species, including a vulnerable eagle, according to a rapid environmental impact assessment by Azim Premji University researchers.
The assessment, conducted on October 21 across 12 stretches, surveyed 1,128 trees along the 2.2-km alignment proposed for removal or transplantation. Researchers Harini Nagendra, Seema Mundoli, Prachi Gupta and Vivek G recorded 36 trees with girths ranging from 200 cm to 800 cm. The inventory includes an 800-cm-girth banyan and a Mysore fig with a girth of 600 cm.
The survey also identified 63 Madras thorn trees, 31 jamun trees and 13 jackfruit trees. Other recorded species included 67 Pongamia, 57 gulmohar, 45 yellow copperpods and 30 rain trees, along with guava, tamarind, coconut, Singapore cherry and gooseberry. Together, the trees have sequestered an estimated 77 metric tonnes of carbon, the assessment found.
The findings extend beyond the tree count. Data from eBird and iNaturalist showed that 199 bird species had been recorded in the area over the past decade. They included the greater spotted eagle, classified as vulnerable, and the spot-billed pelican, classified as near threatened on the International Union for Conservation of Nature Red List. Around 50 waterbird species were recorded around Hebbal Lake.
The assessment identified 165 trees marked for removal within the Hebbal Lake premises along Ballari Road and another 159 trees within the University of Agricultural Sciences staff quarters. The survey covered the areas affected by the tunnel alignment and examined the ecological value of the trees and habitats recorded along the route.
The university researchers’ inventory is larger than some earlier counts. Citizen-led surveys had identified 72 tree species along the affected stretch, while eBird records showed 183 bird species around Hebbal Lake and 95 on the Veterinary College campus. The separate datasets indicate the area supports a wider range of urban biodiversity than a tree-removal count alone would show.
The proposed project therefore involves both transport infrastructure and changes to a connected urban ecological setting. The reported tree markings span lake premises, a major road corridor and institutional land, while the bird records include lake-associated waterbirds and species of conservation significance.
The rapid assessment provides the latest reported inventory of trees and birds along the 2.2-km alignment. The project’s next steps, including decisions on removal, transplantation and implementation of the tunnel plan, will determine how the marked trees and the surrounding habitats are treated.
