High-tension transmission cables should be laid underground in areas having high concentration of birds that are vulnerable to collision, says a study conducted by Bombay Natural History Society (BNHS). It recommends for setting a ‘biodiversity offset’ which can help to avert such avian loss.
The study points to the incident in 2011 in which 76 Greater and lesser Flamingos and Greater Flamingos were killed in the Gulf of Kutch when they came in contact with high-tension wires. It suggests that in places where it is not possible to lay underground cables, the concerned authorities should mark overhead cables using ‘defectors’.
The BNHS study further suggests that construction should not be undertaken during the nesting or breeding season in areas having a high density of birds. In the case of migratory birds, it is important to keep in mind their migration season. The risk is likely to be greater to foraging and roosting sites of birds or to migratory flyways or local flight paths, mentions the study.
large birds with poor maneuverability are generally at greater risk of collision with such structures while species that habitually fly at dawn, dusk or at night are perhaps least at risk as they are likely to detect and avoid such risky set ups.
Collision risk may also vary for a particular species, depending on age, behaviour, and stage of annual cycle. The study reveals that in some cases, the number of bat carcasses retrieved, considerably outnumber those of birds.
The study recommends that in places where development projects are inevitable, the forest department should consider setting up ‘biodiversity offset’.
It is a system used by the planning authorities and the project proponents to prevent loss in biodiversity and, in some circumstances, create biodiversity gain through the planning process.