Though they were in a sanctuary in India, the birds flew into high-tension wires when spooked.
The flamingos were spooked by a vehicle and as the flock took off, 139 flamingos were caught by nearby high-tension wires.
The wildlife sancturary has seen more flamingos than usual this year, around 500,000 migrating from Sibera.
Nearly 140 greater flamingos were killed in a wildlife sanctuary in western India when they were startled and flew into a string of high-tension power lines, a forest official said Friday.
Tens of thousands of flamingos turn the flat, warm marshes of the Khadir region of Gujarat state into a sea of pink every year when they fly in from Siberia to breed.
This year, their numbers were unusually high, with around 500,000 birds making the migratory flight from Siberia, district chief conservator of forests D.K. Sharma told AFP.
Sharma said the mass electrocution took place some 12 days ago, when a large flock of flamingos was startled at night by the noise of a vehicle.
"The entire flock took off. Many of them flew straight into the electric wires and 139 were killed instantly," he said.
S.K. Nanda, a senior official in the Gujarat Forests and Environment Department, said a feasibility study had been ordered into the possibility of insulating the cables or having them moved underground.