About 60 animals have been stranded along 25 miles of Cape Cod coastline since Thursday, according to the International Fund for Animal Welfare (IFAW).
She said the pattern this year is unlike past years, when just one dolphin or a group would be found on a single beach.
"It feels like stranding after stranding after stranding," she said. "It's definitely out of the ordinary."
The dolphins began beaching themselves on Thursday, with a single dolphin stranded near the town of Wellfleet, Massachusetts, said Kerry Branon, a spokeswoman for IFAW.
On Saturday, the busiest day for rescuers, at least 37 dolphin were found spanning five towns along Cape Cod, Branon said.
January through April is the typical season for multiple beaching of dolphins, Branon said.
Cape Cod is among the top locations for the phenomenon worldwide, she said. Beaching of dolphins has been happening for centuries, but researchers are still trying to determine what brings the dolphins to Cape Cod Bay this time of year.
The group actions tend to happen, in part, because dolphins operate with a group mentality, where many others may follow one animal toward shallow water, IFAW said.