For the wild soundscape recordist, fieldcraft is primarily about being insignificant in the landscape, so the creatures we wish to record remain undisturbed by our presence. It's also about our own safety, and the more remote the places we record in, the more important that becomes.
One of the things most of us find difficult to accept is the extent to which our perceptions are degraded by urban living. But most of the time we're actually ferociously unobservant.
There's a lot of mythology about the extreme acuteness of animal senses. Some animals, particularly lone predators such as eagles, do indeed have extremely acute individual senses.
Animal perception is a much more difficult subject than our own as we can never really get inside the mind of another species. We can only infer perceptual capacities from a creature's responses to observed or experimental stimuli.
The two senses we mostly rely on are vision and hearing. Normally, hearing is the first to be engaged when both audible and visual information is present - it's an attention attracter, which is why we find audible fire alarms work and why our phones and computers bleep.