Sir David Attenborough was kept away from fledging chicks during filming for his new series in Pembrokeshire, after an infectious diseases expert warned a case of avian flu could be fatal for the 96-year-old.

Executive producer Alastair Fothergill made the decision after being told that while it was “extremely hard” for humans to catch the disease the consequences for Sir David could be serious.

Fothergill has worked with Sir David for more than 30 years on various flagship BBC series including The Blue Planet in 2001 and Planet Earth in 2006.

Their latest project, Wild Isles, highlights the British Isles and the challenges they face across five episodes.

One segment called for Sir David to be present while Manx shearwater chicks on Skomer Island off the Pembrokeshire coast of Wales left their underground burrows for the first time and took flight on a 6,000-mile migratory journey.

He said: “The shearwaters are not great at taking off, so what the warden on the island said is, ‘If you sit David close to the burrows, they will almost certainly climb up his arm onto his head and take off from his head,’ and we thought, ‘Wow, that could be TV gold.’ That was the plan.”

However, two weeks before filming was due to start, reports emerged of avian flu on the neighbouring island of Grassholm, and could be present on Skomer.

Fothergill said: “I have an old friend who’s an expert on infectious diseases and I rang him up for his opinion.

“He said, ‘Well, bird flu is actually extremely hard to catch, but if he gets it he will die.’”

Fothergill decided to keep Sir David away from the chicks and instead used two infrared cameras to capture the moment – one facing Sir David and the other a boulder a few feet away from where they hoped the chicks would take flight.

The plan was successful, with Fothergill describing the final footage as like one of Sir David’s “classic” moments.

Avian flu is infecting wild bird populations across the globe and could potentially infect endangered species.

Episode One: Our Precious Isles will air on BBC One and iPlayer on March 12 at 7pm.