BOSTON (Reuters) - Animal welfare advocates are perplexed by dozens of dolphins swimming onto land along the scenic Cape Cod shores south of Boston beginning late last week, one of the largest cases of dolphins stranding themselves in years.
About 60 animals have been stranded along 25 miles of Cape Cod coastline since Thursday, according to the International Fund for Animal Welfare (IFAW).
So far, 19 dolphins have been rescued and released, with some of the 27 dolphins stranded alive unable to survive, said Katie Moore, manager for the group's marine mammal rescue and research. She estimated another 32 washed ashore already dead.
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.
The animals, which tend to get stuck on the bay side of the hook-shaped Cape Cod, are assessed by rescuers on site and then transported and released in deeper water on the ocean side.
Marine biologists check for signs of stress and body condition, among other factors, and tag the dolphins with an identifier before release.
A handful of animals have also been affixed with a tag to track movement and transmit data to researchers, Branon said.
Moore said this year's series of dolphins stranded on beaches reminded her of the 2005-2006 winter, when dolphins beached themselves over a 40-day period.
The IFAW team of six dedicated staff who respond to marine mammals and more than 300 volunteers will continue to monitor for additional stranded dolphins.
Editing by Greg McCune