Last weekend’s flight was the first of the right whale season, which typically runs from early January to May. Each week of the season, Mayo and his team board a small plane once used for reconnaissance during the Vietnam War and fly over the bay’s waters to observe the whales.

“These are extraordinarily rare animals, but we seem to have the mother lode of them,” said Charles “Stormy” Mayo, senior scientist at the Provincetown Center for Coastal Studies, who led Sunday’s survey.

A dozen right whales were spotted by researchers Sunday in an aerial survey of Cape Cod Bay, an occurrence that would have made headlines five years ago but is now commonplace.


Of the estimated 500 right whales still in existence, Mayo’s team reported spotting at least half of them every year for the past four years.

“The numbers that come to Cape Cod Bay are tracking well above the increased estimate in population, but my colleagues in the rest of the Atlantic are saying they can’t find them,” Mayo said.

Researchers at the Provincetown center are working to identify what draws the endangered mammals to the area in such large numbers. Answers so far have pointed to the increasingly rich food source available in Cape waters.

The whales need to eat more than 150 pounds of plankton an hour to maintain their protective layer of blubber.

Right whales were once plentiful, but centuries of whaling have decimated the population.

“My family has been in the Cape since the 1600s, and my ancestors were whale hunters,” Mayo said. “Now, generations later, I’m studying them. We’re a lot friendlier.”

Catalina Gaitan can be reached at catalina.gaitan@globe.com. Follow her on Twitter at @catalina_gaitan.