Large great white sharks are gathering off the South Carolina coast – for reasons scientists don’t quite understand.

Satellite tracking tags show five great whites were clustered between Charleston and the North Carolina state line as of Thursday. Some have lingered in the area since early December, data shows.

OCEARCH, which attached the tags, says the tagged sharks represent just a fraction of the white sharks prowling the region.

The five include males and females ranging in size from 8 to just over 12 feet. The largest, named Miss Costa, weighs more than 1,000 pounds.

OCEARCH has collected data proving North Atlantic white sharks have a habit of moving south for winter, but experts remain unsure of the motive.

The migration, which typically begins Dec. 1, sees the sharks move to an area between Cape Hatteras and Florida’s Gulf Coast. The sharks reverse course around May 15 and head north again, data shows.

It was initially assumed the apex predators preferred warmer water, but that doesn’t explain why some go as far west as the mouth of the Mississippi River, OCEARCH says.

Experts suspect it may be a combination of factors, including their hardy appetite.

“During the winter residency, temperature, current, prey and reproduction are likely the most significant drivers of white shark movements and habitat use in the region, with reproduction having more influence on mature animal movements in the spring,” OCEARCH told McClatchy News.

Patterns have been established in some cases, including a penchant for younger sharks to spend their first winter off North and South Carolina, studies show.

OCEARCH staged an expedition off the Carolinas Nov. 28 through Dec. 14 to study white shark migration in the area, but has yet to reveal its findings.

The researchers collected blood, fecal and muscle tissue samples from sharks caught in the area, and performed ultrasounds on mature females.