Bears, drones or humans may have caused mass walrus suicide

Polar bears, drones and a documentary film crew may have been responsible for a mass suicide of walruses.

Walruses atop a Siberian cliff in the Our Planet film.

Polar bears, drones and a documentary film crew may have been responsible for a mass suicide of walruses that a David ­Atten­borough documentary has blamed on climate change.

Controversy has dogged the WWF-sponsored program since it was launched on Netflix this month with footage of walruses plunging to their deaths over a sea cliff in Siberia.

In the Our Planet documentary, Sir David said the walruses had been driven to the cliffs because of melting sea ice. “Walruses’ eyesight out of the water is poor, but they can sense the others down below; as they get hungry, they need to return to the sea,” he said.

“In their desperation to do so, hundreds fall from heights they should never have scaled.”

Doubts about the sequence were raised after it was revealed to be a historical event that had been well publicised in which polar bears had stalked and eaten the walruses.

Canadian zoologist Susan Crockford said records of walrus “haul-outs” on to land went back more than a century.

“The idea that walruses are being driven on shore by sea ice decline is entirely incorrect,” she said.

The US Fish and Wildlife Service said while walruses used sea ice for a variety of activities, including breeding, birthing, resting and avoiding predators, they had shown an ability to adapt to sea ice loss and did not require a higher conservation status.

Attention now centres on whether the film crew had blocked the walruses’ exit path after they had been spooked by drones used in filming.

“Walruses often flee haul-outs en masse in response to the sight, sound and especially odours from humans and machines,’’ a spokesman for US fisheries said.

Documentary-maker Sophie Lanfear defended the film crew’s actions.

“When approaching the walruses, we made sure we were downwind of them and that we could not be seen,’’ she said.

“We only stood up when it was safe to do so and when we weren’t at risk of scaring any walruses.’’

The filmmakers used a walrus behaviour expert supplied by WWF.

“Fundamentally, the reason walruses used this haul-out location is because of a lack of sea ice in the region, meaning they are coming ashore more frequently than they did in the past,” Ms Lanfear told British media.