A barnacle gosling plummeting more than 120m (400ft) to follow its parents has been recorded by BBC filmmakers.
The chick’s death-defying tumble is a rite of passage among the birds that nest high up the cliffs in eastern Greenland.
In order to reach the grassy feeding grounds below, the geese call to encourage their chicks to take an alarming leap down sheer rocks.
Filmmakers recorded the spectacle for BBC One series Life Story.
Leap of faith
In their first few days of life, tiny barnacle goslings are faced with one of the most extreme survival challenges in the natural world.
Barnacle geese nest hundreds of feet up to avoid predators such as Arctic foxes. The geese eat only grass and as parents don't feed their young, the only way for the goslings to survive is to make the daredevil descent.
Without robust wings necessary to fly down the cliff, the newly hatched goslings’ best chance is a lucky parachute-style drop. How the chicks land is the ultimate decider of life or death.
If the chicks bounce on their fluffy bellies on the way down, they are more likely to survive the impacts. They must be reunited with their parents on the scree slope below – then evade hungry predators.
Getting the shot
Producer Tom Hugh-Jones described the experience of filming in the extreme Greenland location as a “classic, old-school filming trip”.
“It was about as remote as I’ve ever been… It was just a couple of tents and a generator in the middle of nowhere,” he said.
To understand the birds’ behaviour he scaled the vertiginous cliffs at the edges of the Orsted Dal valley, alongside cameramen Mateo Willis and Mark Payne-Gill.
Tom explained how the male bird’s 'twitchy' behaviour was the tip-off for the cameramen to prepare to hit record. This was followed by the mother bird leaving the nest and calling her distinctive 'kaw' for the chicks’ attention.
The young are imprinted, meaning they will follow their mother anywhere, but they still exhibited some reluctance to jump off the cliff.
“It would range from about half an hour from that moment to half a day, depending how nervous they were,” Tom said.
He was the nest spotter, relaying information to the cameramen positioned on and below the cliffs so they could co-ordinate to film the short but shocking action.
The team successfully captured the breath-taking falls of two nests of goslings and the pitiful peeping calls they made as they tried to stay in contact with their parents.
Tom said he felt very paternal towards the chicks: “Having watched the geese brooding their eggs through the arctic summer and making all that effort, then their chicks hatching… I felt like an expectant father!”
Successful survival strategy
As seasoned natural history filmmakers, the team are used to recording the behaviour of predators and prey but described witnessing one group of chicks snatched by an arctic fox as “bleak”.
“You’re sort of impressed by how they manage to get down there, I guess you could call it the courage of these chicks. [But] to then just be obliterated by these foxes… It was surprisingly sad for three hardened men!” said Tom.
Fortunately, the other chicks filmed were luckier and the team had the satisfaction of following them all the way to their feeding grounds.
Discussing the vulnerable chicks’ seeming unsuitability to their predicament, Tom explained that the birds have a lot to contend with.
“Barnacle geese have to do all sorts of different things through their lives to survive through the Arctic summer, then the British winter, they have to fly but they have to float on water. So they can’t be too specialised just at that one moment.”
The behaviour may look extremely risky but enough chicks survive that Greenland’s population has actually grown since they were last filmed in the 1980s.
Many of the barnacle geese that nest in Greenland migrate to Scotland and Ireland for the winter.
The International Census of Greenland Barnacle Geese, run by a partnership of conservation bodies including the Wildfowl and Wetlands Trust, monitors wintering birds in Scotland and Ireland. Their figures currently estimate the population of the birds at over 80,000.
Watch the goslings' astonishing tumble in episode one of Life Story at 21:00, Thursday 23rd October, BBC One.