Oriole by age

When I came across this juvenile Black-naped Oriole, it reminded me of how I wanted to sort out some images of the juvy at different growth stages.
This one is a recently fledged bird, and true enough, it kept very much to one part of the tree.

This one too, although it looks older with more developed eye mask and darker black bill.

This one is also a juvy, with an interesting look at its back feathers.  It is definitely easier to differentiate the age by looking at the bill, black nape and eye mask.

Going by the eye mask, this one is also a juvy.

I suppose this one should be a young adult, with a pretty developed eye mask.

 Here's an adult with a juvy.

A couple more images of an adult bird.  It is observed that the irises  of the Oriole will change from "grey-brown, to brown, then brown-red to blood-red".