Hebbal Short tunnel project threatens green corridor supporting 199 bird species: Study

According to the Greater Bengaluru Authority’s public notice, 1,128 trees along the proposed Hebbal Short Tunnel alignment have been marked for removal.

A decade-long record shows that 199 bird species have been documented in the vicinity of the proposed Hebbal Short Tunnel alignment, according to a rapid environmental impact assessment conducted by ecologists and researchers.

The report primarily stresses on the vulnerable greater spotted eagle and the near-threatened spot-billed pelican reported in the region.

The report was prepared by Harini Nagendra, Seema Mundoli, Prachi Gupta, and Vivek G. of Azim Premji University, Bengaluru. The researchers used secondary data from eBird and iNaturalist to document bird sightings between 2016 and 2026.

The report notes that nearly 50 species of waterbirds have been recorded around Hebbal Lake. These include kingfishers, plovers, herons, storks, teals, cormorants, and moorhens. The area is also home to the Indian peafowl, the national bird, and the Indian roller, Karnataka’s state bird.

The report has come amid concerns over the environmental impact of the proposed 2.28-km underground twin-tube tunnel road. The alignment passes through the green spaces in the northern part of the city, including the space inside the Karnataka Veterinary Animal and Fisheries Sciences University (KVAFSU).

According to the Greater Bengaluru Authority’s public notice, 1,128 trees along the proposed corridor have been marked for removal, either through felling or transplantation. The researchers’ field assessment, conducted on October 21, found that these trees belong to 92 species, which is also the number as per the GBA document accessed by The Hindu.

The report highlights several environmental consequences of the proposed tree removal, including the loss of habitats and ecological corridors for birds and other wildlife, reduced carbon sequestration, increased dust and air pollution, and higher local temperatures.

The report stresses that the project, cutting through many ecosystems, raises concerns over potential loss of ecological functions that those ecosystems support.

The trees along the stretch have collectively sequestered around 77 metric tonnes of carbon. Among them are 30 rain trees with spreading canopies that help mitigate the urban heat island effect and 17 fig trees belonging to seven species, which are considered keystone species in ecosystems. Paper mulberry, with 173 trees, is the most abundant species along the stretch and has a high dust-accumulation capacity.

The researchers warn that removing trees could fragment habitats and restrict the movement of birds between feeding, nesting, and resting locations. Nearly 50 species of waterbirds recorded around Hebbal Lake depend on the lake and surrounding greenery for food and habitat.

“Trees act as corridors for wildlife such as birds, insects, etc. to move from one location to another, such as between lakes and other green spaces. Removing them can result in fragmented habitats and restrict movement for nesting or feeding,” the report notes.

The assessment notes that further loss of mature trees could intensify Bengaluru’s existing challenges of rising temperatures, air pollution, and declining biodiversity. It is also likely to place additional pressure on the city’s remaining green spaces.

It also cautions that even transplantation may not preserve the trees’ ecological benefits. The process would require severe pruning, reducing their size, while their survival rates remain uncertain.

The BDA, however, maintains that it is ensuring maximum tree retention and minimising environmental impact. “We are committed to exploring methods to retain as many trees as possible,” a source said.