"Birds" represent rational concepts in the external man and intellectual concepts in the internal man.

861. Verse 6 And it happened at the end of forty days that Noah opened the window of the ark which he had made. 'It happened at the end of forty days means the duration of the former state, and the beginning of the one that followed. 'Noah opened the window of the ark which he had made' means a further state when the truths of faith appeared to him.