The first of the giant right whales to be spotted offshore here this winter were a mother and calf pair, an early Christmas season delight for the aerial survey team in charge of monitoring the critically endangered species.

Four days later, two days before Christmas, the team got another surprise off Hilton Head — a different calf and mother; the mother had been seen off Georgia only a few days earlier, not having given birth.

The sightings give more support to the growing realization among researchers that the whales are giving birth here, well north of the waters off Florida where they were long thought to calve.

“It does appear (the two mothers) could have given birth here in South Carolina,” said Melanie White, Sea to Shore Alliance aerial survey team leader. With the Lowcountry coast still not necessarily thought of as a critical breeding habitat, she said, “that’s something good to know.”

The team flying from Charleston is part of a network trying to keep track of the whales, partly so ships know when they are around.

The right whale is the mammoth of the Atlantic, a 40-ton sea mammal longer than a bus.

The species was nearly wiped out by whalers in the 19th century. Only about 400 are known to exist today, so few that researchers consider every whale vital to the survival of the species.

Ship strikes are considered a leading threat to the animals. Despite their size, they are difficult to see because of their coloring, and tend to swim near the surface, said Barb Zoodsma. She is the coordinator of the federal National Oceanic and Atmospheric Administration right whale recovery program in the Southeast.

Each year, females and at least a few males head south from off New England to give birth and winter in warmer waters off the Southeast.

Their route is heavily trafficked, and an NOAA rule requires that large ships slow to half-speed within 23 miles of the coast in months when the whales are present.

Dozens of whales are spotted in waters off South Carolina nowadays, some with newborn calves. But until recently, the whales were thought only to pass through, and spotting one was considered a freak occurrence.

Indications that that might not be true led to the aerial survey flights.

The first mom and calf seen this year were spotted Dec. 19 less than 10 miles offshore in the Santee River delta area, and they didn’t appear to be on the move, White said. “They were just hanging out.”

Just beyond them out to sea, the team spotted a single right whale moving north.

On Dec. 23, the whale nicknamed “Millipede” was spotted eight miles off Hilton Head after being spotted without a calf in Georgia. The two were swimming determinedly south.

“Mom was on the move. She definitely had someplace to go,” White said.

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