(CNN) Ornithologist Stephen Kress remembers the first time he encountered puffins, more than 50 years ago on an island near the US/Canada border.
"I was totally amazed from the moment I first saw them," he says. It was the beginning of a lifelong passion for the little seabirds known for their red tipped beaks and expressive faces.
"My mission in life has been to learn more about the ocean birds ... and do what I can to help them survive into the future," says Kress.
Two years after his first encounter, while teaching at a nature camp in Maine, Kress learned that the state's Atlantic puffin colonies were all but destroyed by hunters in the late 1800s. The puffins were exploited for their eggs, meat and feathers, which were used to decorate hats.
Kress decided to learn more about these "special birds." Puffins can dive to depths of over 100 feet in the sea and fly through the air at 50 miles an hour, while on land they are adept at scampering over boulders and digging holes. "They can live in all worlds," he says.
Kress's fascination grew into Project Puffin, a decades-long effort to bring the puffin back to Maine. Kress ran the project while working for the National Audubon Society, a major bird conservation nonprofit in the United States. Thanks to his pioneering methods, Project Puffin says there are now around 1,300 pairs of puffins nesting on islands in the Gulf of Maine. What's more, the techniques Kress developed to save puffins are now used by seabird conservationists around the world.
Project Puffin's origins lie on an uninhabited seven-acre island, six miles off the coast of Maine, called Eastern Egg Rock. The tiny island, accessible only by rowboat, is ideal puffin habitat -- free from predators and edged with granite boulders under which the puffins nest. It was home to a puffin colony before hunters arrived in the 19th century.
Kress had a theory that if the Project Puffin team could transplant puffin chicks -- also known as pufflings -- to Eastern Egg Rock and hand rear them, the birds would create a mental map of the island's location. He hoped they would return there to nest, after going out to sea.
Getting the puffin chicks to the island was no easy task. Starting in 1973, the team collected chicks from Great Island, off the coast of Newfoundland, Canada, which had a healthy puffin population. The pufflings were transported by boat, motor vehicle, a small charter plane, another vehicle, another boat and then a rowboat to get ashore on Eastern Egg Rock.
The team hand-reared puffins in artificial burrows, feeding them vitamin-enriched fish twice a day.
"They would come out when they were six weeks old and they would work their way to the edge of the island and swim off," says Kress.
For four years, none of the birds returned to the island to breed. The project's supporters began to question whether they would ever succeed -- but Kress was determined.
That's when "I began trying to think like a puffin," he says.
Puffins nest in colonies because they like being with others of their kind and large groups provide protection from predators, Kress says.
He speculated that the young puffins did remember the island but were "too timid" to come ashore.
Kress's new idea was to place wooden decoys of puffins around the island, to help the birds feel safe.
It worked. In 1977, a few days after the decoys were installed, the first puffin returned to the island. Four years later they started breeding and now there are nearly 200 breeding pairs nested on Eastern Egg Rock. After this first success, Kress and the National Audubon Society used the same techniques to restore a colony on the larger Seal Island, now home to around 500 puffin pairs.
Kress's experiment with decoys on Eastern Egg Rock became the basis for a new method of bird conservation called social attraction, in which scientists use decoys, audio recordings, mirrors, scent, artificial burrows and fake eggs to simulate the presence of other members of the species.
"Those techniques sort of give birds a little encouragement just to start the nucleus of a new colony," says Kress.
According to Project Puffin, at least 42 seabird species in 14 countries have benefited from the colony restoration techniques developed by Kress and his team.
In 2013, Kress and fellow conservationist Don Lyons advised researchers in China on how to use social attraction to help save the critically-endangered Chinese crested tern, a bird so rare it was presumed extinct. Decoys and sound recordings were used to lure the birds to safe nesting islands, where they are now breeding successfully.
In the Pacific, conservationists are using Kress's methods to help the short-tailed albatross. This endangered seabird's main breeding ground lies on the slope of an active volcano on an island in Japan. Japanese ornithologists have used decoys to encourage the birds to nest in an area that is less exposed to eruptions. Researchers are also trying to establish new short-tailed albatross colonies on other Pacific islands, by translocating and hand-rearing chicks like Kress did in the 1970s.
"Steve Kress is among the most influential seabird conservationists in the world," says Lyons, who is now the director of Conservation Science at the National Audubon Society's Seabird Institute, the formal name for Project Puffin. "It's really hard to overstate his contribution."
Kress retired from Project Puffin in 2019, but he still pursues his passion for seabirds and recently co-authored "The Puffin Plan," a young adult book about Project Puffin.
There is a giant threat hanging over Kress's life work -- climate change.
According to Lyons, the Gulf of Maine is warming "at an incredibly high rate." Maine's Puffin colonies are thriving, but they are very sensitive to temperature changes which is cause for concern.
"As the water warms, the fish become less available for the puffins," Kress explains. "They move to deeper, colder water or they move further from the islands and the puffins can't bring home enough food."
Last year, Project Puffin began putting miniature GPS tags on the seabirds and tracking them.
By observing what fish the birds catch and bring back to the island to feed their pufflings, and combining that with the GPS data, researchers hope to get real-time information about fish populations in the region.
"We're both trying to understand the environment to benefit seabirds and also use that information to help people manage fish populations," says Lyons.
Kress believes that as the oceans warm, the survival of puffin chicks is a good indicator of how well fisheries are managed. "A chick that's healthy means that we have a healthy ocean. If the chick is starving in the burrow or underweight or losing weight, it means the parents are not able to bring home enough food," he says.
Kress is still hopeful for the future but warns that we cannot be complacent. "Nature is resilient," but it requires "a lot of care," he says. His Project Puffin shows how much can be achieved when a determined group of people give nature a nudge in the right direction.