I made a video showing one way to get to that ledge, but I suspect there is supposed to be an easier way.

 

I remember that nest. When i first came upon it (while cussing at how lost I was in Paititi) I went "this is high up here"  lol

Drat. I thought I replied to this, but I guess my post never...um, posted.
Anyway, I was able to get up there by scrambling up the interior wall of the building. It's temperamental but seems to work best if you aim for the left side of the opening, like so:

 

That is how I found it on my first play file, Stella lol

5 hours ago, Stellalune said:

Anyway, I was able to get up there by scrambling up the interior wall of the building. It's temperamental but seems to work best if you aim for the left side of the opening, 

 

I think I was trying to use the grapple jump instead of the scramble jump after the scramble jump didn't work after a few tries.