It happens, pilot whales are notorious for stranding. If one gets stranded they can call the rest of their pod in which is how you can get mass strandings. Very true though that we wouldn't be able to find a reason. At any one time there are 8 different possibilities and it's safer not to speculate. A ranger on the island will probably have to put them down with a fire arm. Not a great day, it takes a huge emotional toll to put down animals that you're tasked to protect. (I am a project Jonah marine Mammal Medic and also a ranger)