I am quite startled by this plate; I wanted to do something with planets for this bird, but not realistic illustrated planets (maybe that comes later). So I looked at Astrolabes and sky maps as a starting point. Then I reinvented a completely fictitious night sky for this bird to rule over.
The astrolabe is a very ancient astronomical computer for solving problems relating to time. Then when you have sorted out the time you can use the astrolabe to show how the sky looks at a specific place at a given time. It was not usually used to navigate, but more as an instrument to find out a specific the time of a celestial event.
A very good explanation of the astrolabe here from Wikipedia