Seventy years ago today, an expedition on a Castle Harbour island made science history with a discovery that brought the Cahow back from presumed extinction.

David Wingate, who would spend much of the rest of his life bringing the Cahow back from the brink, was there that day, aged 15 and thankful it was the weekend so he did not have to be in school.

He was the youngest in a group of naturalists who were searching for the elusive seabird which had been presumed extinct for centuries.

Bermuda had swarmed with endemic Cahows before the arrival of man in the 1500s.

Invasive pigs landed in Bermuda to feed stranded seamen, followed by the arrival of the Sea Venture in 1609 that began continuous British settlement, all but wiped out what is now Bermuda’s national bird.

Dr Wingate, keen on nature and ornithology from childhood, was already convinced the Cahows had survived.

He said this week: “The species had been rediscovered from time to time, but people didn’t know what it was, or they only had a specimen.

“The significance of 1951 was we knew where they were nesting. There was something we could do about it – protect the birds.”

The young Wingate salvaged bones from caves in the Walsingham area of Hamilton Parish, identified as Cahows by the Bermuda Aquarium, Museum & Zoo.

He recalled: “It indicated just how abundant they had once been.

“One sunny day I came out of the cave with a bunch of Cahow bones in my hands, wondering what this thing had looked like. I looked out at Castle Harbour and the islands across the water.

“Somehow coming back to fresh air and the real world captured my imagination. I looked out and thought, ’Are they still out there? I bet they are’.

“After that experience, it became my goal to rediscover them”

Dr Wingate stood out as a Saltus schoolboy. Birdwatching had taken off with the advent of better binoculars and the landmark Peterson’s Guides to birds.

But it and he were often misunderstood, especially given his lack of interest in sports.

He said: “My parents didn’t understand it, but they gave me encouragement.

“When visiting naturalists came to Bermuda, my parents told me to show them around Spittal Pond, the place that really triggered my interest. Every time I went back, there was something different, some new and exciting bird.”

The 1951 expeditions for the Cahow were organised by Louis Mowbray, curator at the Bermuda Aquarium, with Robert Cushman Murphy and his wife, Grace EB Murphy, of the American Museum of Natural History.

Cahows are seabirds, and their onshore range had shrunk to rocky islets on Castle Harbour where it was difficult to come ashore.

“Nobody went out there in those days,” Dr Wingate said.

He and some friends had built a kayak a couple of years earlier, certain the little islands would be the Cahows’ last refuge, but were unable to land on them.

Dr Wingate said finding clues on the islands early in the year, such as dropping or tracks, would have led easily to the Cahow.

“The only seabird in Bermuda nesting in holes and cliffs was the Longtail. They didn’t come back till March, and nest in April and May. The evidence would have been straightforward.

“My opportunity came with the Murphy visit. I was there when they hauled the Cahow out of the nest, and Mowbray declared it a Cahow.”

Because Cahows are so accustomed to the open sea, they have “no fear, no understanding of man as a predator – they are totally blasé about being handled”.

The discovery of the dwindling population came in the nick of time, and Dr Wingate dedicated himself to reviving their numbers.

He said: “By the time we found them, they were so marginal, so desperately close to extinction.”

He later cut his studies short, coming home after four years at Cornell University with a Bachelor of Science degree to dive into Cahow research and preservation.

Dr Wingate later led the cahow conservation programme, with grants from the New York Zoological Society and the Bermuda Government, and served as the government conservation officer from 1966 to 2000.

He led the conversion of Nonsuch Island to a “living museum” complete with a colony of the birds and 100 per cent endemic vegetation.

A secret to the Cahow’s survival was its longevity: some may live to be 50 years old, producing just enough chicks to keep a population going.

Dr Wingate said it was the nights he ended up trapped on the islands by storms that he realised “Cahows are birds of the wind”.

A calm night is the wrong time to search for the Cahow.

He said: “They come ashore at night on dangerous offshore islands where nobody in their right mind would be. That says a lot about me.”

Dr Wingate, who learned to imitate the Cahows’ calls, invented a technique for landing safely on the islands that has been taken up by Jeremy Madeiros, who now leads the conservation project.

Mr Madeiros has pioneered techniques that include helping to feed up Cahow chicks just before they venture out to sea, fattening the young birds and boosting their survival rate.

Dr Wingate said: “The cacophony of them at night is quite an experience.

“Nonsuch Island on a windy night is just like pre-colonial Bermuda.”