Very interesting, but I didn't see much in regards to how you made that nest which in itself I think is very neat!
You have to look into "1st step" group, then inside "nest" group. You will find 2 groups, "nest master 1" and "nest master 2" groups... everything is there.
Just put those 2 groups visible. The group "master 1" is some "copy & paste" parts of the source.
For the group "master 2", I used a simple tin brush, opacity & size control with pen pressure and medium hardness, with bevel & emboss effects on it. I draw those details for making nice edges to the nest.
For the eyes I used 1 external that I blew up, cleaned and modified.
I used 2 eggs for the egg, and you can see another external that started the nest but we can't see it because it's covered by the source... it was just for giving a direction on size and perspective.
Sorry for the big mess with layers & groups, usually I make it cleaner!
I hope it's helping!