I asked myself if the pilotwhale stranding at Stewart Islands was iniciated by the change of the earth magnetic field, which maybe was an early sign of the heavy earthquake around Christchurch, New Zealand (strength 6.3 in about 4 miles depth, which is very little!).
Quote from http://www.guardian.co.uk/science/2010/mar/31/toads-detect-earthquakes-study : "There could be several mechanisms for animals to sense the beginnings of an earthquake, wrote Grant in the Journal of Zoology. They could detect seismic waves directly or ground tilt (which can occur in the minutes before a quake). In addition there might be anomalies in the Earth's magnetic field."
Pilotwhales as well as other toothed whales and other animal species are possibly capable to navigate by the help of the magnetic field. Theories say that a sudden change in magnetic field lines may disturb the navigation. Result for the whales is navigating into dangerous waters of low depth.
What it makes NOT easy to verify this theory is, that also solar eruptions can change the earth magnetic field structure. We had a peak in solar eruptions in the last few days ...