when recording nature sounds and ambiences I often setup and get out of the way . . . literally! How many folks going into record and get out the way when overlapping your recordings is a high risk.
It makes for a much longer mastering session later, but I really enjoy this method of capturing sounds. Once you enter a space it takes a good 10-15 minutes for nature to settle back down into its normal rhythms (I suppose the same could be said for most human environments as well!). Once everyone forgets that the mic is there, things return to normal and you can record what you originally intended. And when I leave my gear I normally don't go far; maybe retreat to my car or a nearby house, or even just around the corner from where I've set up, so I don't need to worry about my gear getting stolen or damaged.
In this issue of The Wire http://www.thewire.co.uk/issues/318/ Chris Watson discusses how he runs long cables to his mic/s, so he can be a safe distance but still listen.... and I'd tend to agree with him - I always prefer to monitor the recording...
I totally walk away for long takes. I am a fidgety mo'fo' - too much darn coffee. :-) I sometimes get great surprises, such as when other hikers come upon my gear and start talking about it, all captured pristinely! (Not usable for sound design, but super cute to hear in the edit!)
I never do this in any other circumstance, mostly due to the ability to monitor (and therefore no need to use limiters or similar techniques on the raw material) or fear or theft. I resort to long cable runs with some line of sight but ideally some objects between my position and the mics.
It depends sometimes on the ambiance- like a night ambiance in the country- if it is a field, I set up and the walk about 10m away and sit quietly and record for about 10 minutes. In a forest or wooded area, I will walk away completely so that whatever I have disturbed will slowly come back to normal. I am able to stand quite still but I always move away at least 10m. In cityscapes, recording can be difficult sometimes because people become curious so I try to hid myself or be discrete which can be difficult.
I do both. Sometimes animals make different sounds when you are right there with the mic pointed at them then in their natural state. Squirrels for instance tend to taunt me and get chatty with a mic in their face. Birds and many other animals on the other hand are often hard to get close to with out them flying/running away.
I generally will walk away and it doesn't bother me if I am monitoring while recording or not. I am always going to edit the recordings later so I often use the recording time as an opportunity to scout the next location (with my ears) that I will set up at. I've only done this at remote locations and odd times when I am pretty confident no one is out there but me so my gear stays safe.