According to a WII study, high-voltage transmission lines with multiple overhead wires are the largest threat for GIB.
New Delhi: Research on Bustards across the world and studies carried out by the Wildlife Institute of India (WII) has identified power-lines, particularly overhead transmission lines, as the biggest threat for the survival of Great Indian Bustards, a critically endangered bird species.
The Supreme Court last month asked the Rajasthan government to mull options for laying underground cables to protect its official state bird. The GIB is protected under Schedule I of the Wild Life (Protection) Act of 1972. Last year, the environment ministry had submitted a report, prepared by WII, on the issue to NGT.
“Two of the five GIBs tagged by WII have died because of collision with power-lines and at least four more birds have been detected during a year-long survey in Thar (Jaisalmer), where the single viable population of GIB survives at present,” said Sutirtha Dutta, Scientist at WII in a conversation with ETEnergyworld.
According to the WII report, GIB is a long-lived species with a very slow reproductive rate – it lays one egg every 1-2 years, and the success rate of these eggs under the ideal situation is around 60-70 percent. However, the current nesting habitats have a high density of predators such as fox and dogs, which has reduced the nest success rate to 40-50 percent. Because of a slow reproductive rate and specific habitat requirements, the species is inherently vulnerable and cannot sustain.
Dutta said such a high mortality rate is unsustainable and will push the species to extinction within a few decades if this critical threat is not mitigated urgently.
“The problem arises because of the low frontal vision and heavy flight of bustards, because of which they cannot see power-lines from far and fail to maneuver over them in the nick of time, thereby suffering fatal injuries and death. However, this threat can be mitigated by burying power-lines in habitats used by GIB,” he said.
During the hearing in the apex court, Manish Singhvi, senior counsel appearing for the Rajasthan government, stated that he would take appropriate instructions from the state and would apprise the court about the manner in which these lines can be laid underground.
“Despite directions from the Ministry of Environment, Forest and Climate Change and Ministry of New and Renewable Energy to mitigate critical power-lines, actions on the ground are largely pending as yet. Given these contexts, the attention of the Supreme Court on this matter is an important and much-required step for conserving the Critically Endangered GIB,” Dutta said.
The supreme court order came on a petition filed by M K Ranjitsinh, a retired IAS officer. He had contended in his plea that over the last 50 years the population of the GIB has recorded a decline of over 82 percent, falling from an estimated 1,260 in 1969 to a little over 100 by 2018.
According to the plea, it is the same story for another bird Lesser Florican, whose population has also seen a decline of 80 percent over the past few decades. The number of species has been reduced from 3,530 individuals recorded in 1999 to less than 700 individuals in 2018.
The WII report states that for such long-lived and slow reproducing species, adult mortality is the most decisive parameter for population persistence. Adult mortality is still very high due to collisions with power-lines that criss-cross their flypaths.
According to WII power-lines, particularly high-voltage (33-440 KV) transmission lines with vertical alignment, are the biggest threat to GIB. The habitats of this bird have a high density of transmission lines because of the impetus on renewable energy production in Rajasthan and Gujarat.
Since the natural death rate of large bustards is about 4-8 percent, the current additive mortality rate due to transmission lines is significantly higher and can result in the species’ extinction.
GIB habitats, comprising short grasslands and scrublands, which were traditionally the support system for rearing livestock, have been marginalized as ‘unproductive wastelands’ and are not being managed sensibly, according to the report. Also, development activities like mining, setting up of industries, wind turbines, and associated infrastructure growth have caused habitat degradation and disturbance to birds.
News Source: ETEnergyWorld