Walruses seen falling to their deaths as they scaled high cliffs to escape climate change could have died because they were being chased by polar bears, a zoologist has claimed.

Footage from Sir David Attenborough's Netflix documentary Our Planet showed walruses plunging off 250ft high cliffs in northeast Russia.

The animals were said to be making the dangerous climb to higher ground to escape receding sea ice due to warming seas.

Hundreds of walruses became confused by a combination of shrinking ice cover and their own poor eyesight, causing them to scale cliffs and often plummet to their deaths when they attempt to return to sea, the show stated.

In the disturbing clip, walruses could be seen perched precariously on the edge of the rocky cliffs, unaware of just how high up they were.

It's not the first time a David Attenborough-narrated programme has been faced accusations of faking dramatic wildlife footage.

In 2011 Frozen Planet admitted after the show aired that filmmakers used footage of cubs taken at a zoo using fake snow in the Netherlands and spliced it with polar bear clips from the wild.

As zoologist said the walruses were plummeting to their deaths after being chased by polar bears in northeast Russia

Polar bears were said to have chased the walruses off the cliff, but this claim was disputed by the filmmakers who stood by the footage

Sir David Attenborough at the Our Planet global premiere at the Natural History Museum on April last Thursday

Then the BBC's Blue Planet 2 series in 2017 saw creators defend the use of studio shots taken in laboratories as it featured images of coral bleaching that could only be filmed with lights and specialised cameras.

The Blue Planet team also recreated a rock pool on board a ship to film up-close zebra mantis shrimp and the long teeth of the fangtooth fish.

In the recent Our Planet episode of the Frozen Worlds series, Attenborough says that all the walruses know is that they need to join the others and find food.

But a leading zoologist has accused filmmakers of using 'tragedy porn' and 'emotional manipulation' to gain viewers.

Susan Crockford, of the University of Victoria in British Columbia, Canada, claims the animals were more likely to have been driven over the cliffs after being chased by polar bears.

She cited a famous incident in 2017 near where the Netflix series was filmed, where 20 polar bears chased walruses over to top of cliffs at Kozhevnikova Cape, Ryrkaypiy, in eastern Russia, according to the Siberian Times.

Describing the footage as 'contrived nonsense', Dr Crockford told the Telegraph: 'This powerful story is fiction and emotional manipulation at its worst.

'The walruses shown in this Netflix film were almost certainly driven over the cliff by polar bears during a well-publicised incident in 2017, not because they were confused by a combination of shrinking ice cover and their own poor eyesight.

Walruses were seen in the Netflix documentary Our Planet falling 250ft. The show claimed this was due to receding ice

The walruses could be seen falling from the high cliffs in the shocking footage. What caused the animals to fall has been disputed by a zoologist

A shocking segment of Netflix's Our Planet showed the gruesome fate of walruses as they tumbled down the high cliffs

'Even if the footage shown by Attenborough was not the 2017 incident in Ryrkaypiy, we know that walruses reach the top of cliffs in some locations and might fall if startled by polar bears, people or aircraft overhead, not because they are confused by shrinking sea ice cover.

'The bears were then able to feed off the many carcasses after the survivors took to the water.'

Sophie Lanfear, director of the Frozen Worlds series that features the Our Planet episode, defended the footage, saying two crew members watched the animals fall and claimed they were not being chased by polar bears.

She said: 'We filmed Pacific walrus falling from high cliffs. They were not being driven off the cliffs by the polar bears and we know this because we had two team members watching the cliffs from afar who could see the polar bears and were in radio communications with us to warn us about any bears approaching the crew closer to the walrus and the cliffs.

'Once the walrus had rested at the top for a few days they wanted to return to sea when all the others below started to leave.

'We would watch them for hours teetering back and forth on the edge before finally, falling off.

'Fundamentally, the reason walrus 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.

Susan Crockford, of the University of Victoria in British Columbia, claims the wakruses were more likely to have been driven over the cliffs after being chased by polar bears

Frozen Planet with David Attenborough next to a polar bear in 2011. Filmmakers admitted after the show aired that some scenes were shot in a Dutch zoo and included fake snow

Shots of a polar bear den, showing a mother tending to her cubs was actually shot in a zoo in the Netherlands and not the wild

'Especially mothers with their pups. And at this particular site, once the beach below the cliffs was full, they spread out and up the cliffs and were unable to find their way safely down, with tragic consequences.'

During the scene in Our Planet, Sir David said: 'A walrus' eyesight out of water is poor.

'But they can sense the others down below. As they get hungry, they need to return to the sea.

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

Previous David Attenborough-narrated shows accused of faking wildlife footage Preparing for the new arrivals: The fake nest being built in a Dutch zoo, ahead of the birth of the polar bear cubs Dramatic footage of a polar bear tending to her newborn cubs in the 2011 BBC show Frozen Planet was actually filmed in a Dutch zoo using fake snow. The tiny bears were shown mewling at their mother and nuzzling her for milk. Eight million viewers were led to believe the scene had been captured by BBC cameramen inside an underground cave in the brutal sub-zero temperatures of the Arctic wilderness. But the footage which was interspersed with real shots of the Arctic, was in fact filmed in a den made of plaster and wood in a wildlife enclosure. At the time Sir David defended the methods used by Frozen Planet, saying: 'If you had tried to put a camera in the wild in a polar bear den, she would either have killed the cub or the cameraman.' The six years later, Blue Planet II also had to defend its use of studio footage filmed in laboratories. Unlike in Frozen Planet, the Blue Planet team would not tell viewers which scenes were filmed in a studio. The BBC's Natural History Unit was also criticised for filming footage in zoos rather than in the natural world. Advertisement

Walruses are among the top Arctic species feeling the effects of climate change as they rely heavily on sea ice to rest between hunts.

As the ice shrinks, more and more are coming onto shore, according to the WWF.

In addition to unfamiliar and dangerous terrain, 'on land, they're highly susceptible to disturbance from humans, aircraft or predators such as polar bears, which can spook them and cause crushing stampedes,' according to the WWF.

In the disturbing footage walruses could be seen perched precariously on the edge of the rocky cliffs, unaware of just how high up they are. They then fell below, amid bodies and other living walruses

The pair of two-day-old polar bear cubs shown on the Frozen Planet documentary in 2011. At this age they weighed less than a kilo, but were filmed in a zoo

Members of the BBC Frozen Planet team with Sir David Attenborough and a polar bear during the 2011 series

These massive marine mammals also give birth on sea ice, and turn to the ice edges to mate.

Sea ice also provides crucial shelter from storms and predators, according to an NOAA report.

While the loss of sea ice may not drive them to extinction, scientists say it will have devastating impacts on their population.

'It is certain that land-based sites alone will not support the same number of walruses that the mixed seasonal use of sea ice and land has permitted in the past,' scientists wrote in a 2015 study.

'Additionally, documented declines in the northern Bering Sea among dominant clam populations that are critical prey for walruses, associated with reductions in sea ice declines, provide cause for concern; such ecosystem changes are clearly important for walruses and other animals.'