A scientist has been trying to find out whether animals reacted differently just before the Canterbury earthquake.
Dr Neil Whitehead has worked for the DSIR and has spent some time in Japan where he studied the same issue.
Dr Whitehead told Country Life that only a minority of animals react in any way before an earthquake, but the exception appears to be animals such as cattle or sheep, which gather in groups.
He says more than 500 people have responded to his survey about the 4 September quake, including farmers who reported unusual clustering of sheep and cattle, cows "going berserk", and an abnormal number of cattle and sheep lying down all at once.
He says there were reports of flocks of birds flying away in almost migratory numbers in the days before quake.
Dr Whitehead speculates that low frequency electro-magnetic waves which can be generated by pressure on rock might be involved, or sub-sonic noises well below the human hearing.