[GuySonic]

Originally Posted by soundgeezer

One question remains as I want the best possible sound quality in my nature recordings: which external stereo mics would you recommend ?

So far we have the DPA 4060 which do sound good for sure (can't really say anything about the noise floor but will try to get a pair for testing).
One problem might be the stereo setup as they are super small and I would like to exclude any phase issues from the beginning.

What other mics are used in profession nature recordings ?

While some do use 4060 for nature recordings, these are actually highly colored and a bit harsh, not giving true natural sound. But hard to tell this as nature sounds have little actual as-heard references as opposed to the natural as-heard sound of acoustic instrument were mic's uneven response is more easily identified.
Here is the (highly smoothed) spectrum graph of DPA frequency response showing artificial mic-high bandwidth emphasis:

Here is a not so smoothed wider bandwidth 4060 verses 4006 comparison showing jagged mid-high frequency response of 4060 causing harshness and unnatural response not so prevalent in the 4006 models.

Also uncolored windscreens are difficult to find as foam types also color sound reaching the mics.

My company makes custom windscreen configured microphones with lower noise, even and more extended frequency bandwidth than 4060 capsules.
Here is a photo of the DSM-1S/H windscreen headband configured microphone used for recording amateur and professional natural sounds.

Here are two recordings out of hundreds available made with this mic configuration:
Rock'n Rolling Thunder and light rain recorded in my driveway. Sounds of the afternoon with retired logger neighbors tending garden and a logging yarder sounding off in the near distance (the beep-beep sound) enhances the reality of living in a small once very scenic Oregon community that's clear cutting the surrounding forest for profit and real-estate.http://74.208.10.48/mp3/thunder5.mp3

It's early evening at Plat I, and a nearly constant breeze is blowing in the trees.

Canadian geese leave the water shortly before another westward overhead flock is heard. Small Plat I birds discuss pending nightfall as distant sound of a very high flying tanker plane paints the sky (with chemtrails).
http://74.208.10.48/mp3/platievg.mp3
Very low noise raw recording (~13 minutes) of mostly nature sounds. Played for best effect at moderate low volume in a relaxing quiet space.