Why Are Pilot Whales Beaching Themselves?

On a remote stretch of beach in New Zealand, hundreds of pilot whales recently beached themselves, resulting in over 400 dead pilot whales.  Volunteers worked round the clock to refloat as many whales as possible.  They were able to return about 200 of them to the water, but more pilot whales came the following day.  Why?  That has the scientists stumped.  There are theories that they may be following a food source, or taking care of sick whales in their pod.  Neither of those theories make much sense to me.

It's really tragic.  New Zealand has one of the highest rates of whales beaching themselves in the world.  This was the third largest whale tragedy in New Zealand history.  The largest was in 1918, when 1,000 pilot whales beached themselves.  The cause of this remains a mystery.