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It was sudden when the humpback whale popped out of the water at the Hawaiian Island Humpback Whale National Marine Sanctuary near a crew of filmmakers. The large adult, a female, seemed curious.

She began slapping the water with her tail, then swishing it back and forth above the water's surface. The unusual behavior went on for just over an hour. The film crew thought, and hoped, she might be having contractions. Then, as if nothing happened, it ceased. And the whale swam away.

“It just sort of happened out of the blue,” says filmmaker and National Geographic grantee Chris Cilfone. “But that's exactly what we're looking for.”

Cilfone had hoped it would be the moment he would finally film something no one has ever captured on camera: a humpback whale birth. Together with a crew of filmmakers, marine naturalists, and humpback whale experts, Cilfone spent this past winter season trying to catch a female in the act.

View Images A humpback whale swims off the coast of Maui. Photograph by Flip Nicklin, Minden Pictures/Nat Geo Image Collection

Since the behavior has never been documented, Cilfone's team isn't quite sure what to look for. While they weren't successful this year, they say they won't give up until they achieve their goal, even if it takes years.

“In this day and age when everything is so connected there's still something that no one knows,” says Cilfone. “People are shocked that no one has ever seen a birth. They think you can go on YouTube and look it up, but it's a huge mystery.”

Sitting, Watching, Waiting

Actually getting that elusive glimpse on camera will be no small feat. Humpbacks migrate from Alaska to Hawaii during the fall. They spend their winters in these warmer waters, mating and giving birth before returning to their northern feeding grounds. All the while, humpbacks fiercely protect their calves. They may even minimize the risk to their newborns by giving birth at night or in quiet, remote waters—difficult areas to find, let alone film.

“For as well as we think we understand these animals, and as many people as there are looking at them around the world, witnessing a birth is extraordinarily challenging,” says Ari Friedlaender, a marine ecologist from Oregon State University and a National Geographic explorer.

Filming a humpback whale giving birth would answer scientists' many questions about how and when calves enter the world. For Cilfone, having the footage means he'd be able to fully tell humpback whales' story: a near-death experience.

Until the 1960s, it was legal to hunt humpback whales, and the animals were consumed as meat or made into oil. By 1970, their population numbers were precipitously low, numbering only 1,200 in the northern Pacific, and the U.S. government officially classified them as endangered. But by 2016, those numbers rebounded so dramatically that some populations near the eastern Pacific were taken off the endangered species list.

“I realized you can't tell this success story without talking about the next generation,” says Cilfone. “The calves that will be the next chapter of this story.”

Cilfone and his crew live in Maui, which they say gives them an advantage in filming the rare sight. Since they're locals, they can put in more hours searching for whales than researchers who visit only seasonally.

It's one of the few advantages Cilfone has. Unlike programs at well-funded universities or research institutions, Cilfone's effort is more grassroots, with funding cobbled together from a National Geographic grant and a GoFundMe page. Local shops donate gear and equipment, and Cilfone bought his research vessel—an 18-foot inflatable boat—off of Craigslist. It's powered by a decades-old engine.

“It's older than I am,” he says. “We definitely get a lot of looks—but hey, whatever works.”

Knowing Where to Look

Usually, Cilfone says that his crew is out on the water by 7:00 a.m., and in the afternoon, they leave for their day jobs. To get just a few seconds of video, Cilfone's team must put in hours and hours of watching and waiting.

The team's biggest challenge? The sheer lack of precedent for what a humpback whale birth looks like. Cilfone and his crew have ideas of what to look for—a large female thrashing her tail around, for example—but they aren't sure what the exact signs will be.

“We think a lot of circling happens,” says Cilfone. “A couple whales circle around [the pregnant female]. Anything with the tail coming up out of the water.”

As a result, they regularly run across false alarms. They often see clusters of whales, which turn out to be multiple males vying for a female's affection. But Cilfone finds even the most casual encounter with a humpback whale awe-inspiring—an awe he says he wants to instill in others.

“It is unreal to be in the water with an animal that's 50 feet long and almost a hundred thousand pounds,” says Cilfone. “All of a sudden, out of the blue haze of darkness, this massive animal appears—you can look into the eyes.