Traditional portents of spring, humpback whales are already discreetly present in local waters.

Residents along Astwood Park in Warwick spotted the spouts of whales off the South Shore on Sunday, telling The Royal Gazette: “Springtime is almost here.”

Humpbacks are skittish when sightseeing boats intrude, but researcher Andrew Stevenson, now in his 11th year of studying the animals, has struck gold with his drone, which he operates under a research permit courtesy of the Department of Environment and Natural Resources — plus a licence from the Bermuda Civil Aviation Authority.

“It’s been a game-changer,” Mr Stevenson said, surveying aerial footage on his computer screen showing whales cavorting far off Bermuda’s shores.

Humpbacks are not easy to find, and aside from their spouts and flourishing tails, the 50ft giants merge into the depths with surprising ease.

But, the drone, which can skim quietly just above the whales, catches humpback behaviour in “incredible” detail, Mr Stevenson noted — including the animals lolling on their sides or “spy hopping” to observe the machine following from above.

“I start looking in December,” said Mr Stevenson, who puts in an average of 40 painstaking days a year panning the seas for whales.

Earlier this month, the filmmaker happened upon a young calf with its mother, plus an escort.

The whales, which pair up in sanctuaries like the Silver Bank off the Dominican Republic, were probably heading south — but Mr Stevenson believes the calf was born here.

He cautioned that it was “premature to say that Bermuda is becoming a birthing ground again”.

“The calf itself could have been premature birth, or a one-off.”

Humpbacks used to congregate off Bermuda to give birth, but stopped calving here after local whalers exploited that vulnerability.

“On four of the last five years, reliable fishermen have told me that they saw a calf,” Mr Stevenson said.

“Perhaps it’s starting to form a pattern.”

Aside from breeding down south, humpbacks feed far in the north, and by tracking the distinctive fluke patterns on their tails, Mr Stevenson finds the same wheels keeping a schedule over vast distances.

The animals do not linger year-round in Bermuda, but the island lies smack-dab in the middle of their migratory route, affording a unique window on to their behaviour.

In his research, Mr Stevenson has identified 1,250 individual whales in Bermuda alone — enough for five catalogues of fluke identifiers, which he compiles with the help of sharp-eyed colleagues such as Judie Clee

“The database I have is completely unique, and the behaviour we see here is extraordinary.”

The drone was initially hampered by its inability to launch from a moving surface, making it impossible to take off from a boat.

But the equipment has been retooled, allowing Mr Stevenson to cut his boat engines and unobtrusively scan for whales from above.

While he seldom presumes to guess, Mr Stevenson speculated that Bermuda served as a meeting spot for whales to socialise and regroup.

“We have the best opportunity here to unlock the complex secret lives of these incredibly intelligent animals,” he said.