It has long been reported that animals act odd before earthquakes, I had never heard about before tornado's. Animals do seem to have some "6th sense" that we just don't understand.
I had an idea over ten years ago, that I hoped could save lives and make me money, but I'll never do anything with it, so here it is:
One animal acting strange (as in before an earth quake or whatever) is nothing, but a large number of animals in a specific area, could very possibly be a warning of impending danger. If there was a (well known) web site that you could report your animal acting "weird", or out of the ordinary to, you would have random reports from all over the place, but if you mapped results in real time and saw a lot of activity in a specific area, that could be an early warning. I don't see why it wouldn't work, assuming the "animals act weird before events" theory is correct.
Anyway, if this works and saves lives, remember you heard it here first.