[Skybird]

We sometimes notice that animals become nervous or swarms of birds fly up suddenly, hours, even days before a volcanic erruption, an earthquake, or a flooding event takes place. Of birds we know now that they can navigate by the magnetic field of the Earth, and that this is inheritable.

I wonder what kinds of hums these anmials maybe can hear, or what sensory input they perceive that we cannot imagine. Maybe us few hummers amongst the humans have just touched the tip of an iceberg, and we do not even know it.