The British Divers Marine Life Rescue charity (BDMLR) said 55 of the animals washed up on the Isle of Lewis in the Outer Hebrides.
Police alerted the BDMLR to the beached pilot whales on Sunday morning. The responders came to administer first aid and managed to refloat two animals, but one of them become restranded and died, and only one of the whales got away safely.
Saving Scotland's pilot whales
Despite their name, pilot whales belong to the same family as dolphins. They can grow up to six meters (20 feet) in length and weigh a metric ton.
In their statement, BDMLR said it was "currently suspected that the whole pod stranded due to one female giving birth."
According to the rescuers, pilot whales are "notorious for their strong social bonds, so often when one whale gets into difficulty and strands, the rest follow, leading to more of them stranding."
The group was founded in 1988 and has 20 whale rescue pontoons at strategic locations across the UK to help stranded whales and dolphins.
Between 2011 and 2015, it responded to a series of mass pilot whale strandings in Scotland, including one incident that involved a pod of more than 70 pilot whales.
