"It is the chaffinch, however, that provides an illuminating example of the open instinct. In Denmark the chaffinch begins to sing about February 15. Poulsen raised males in isolation. By the middle of January they were beginning to twitter and in two weeks were producing an abbreviated chaffinch song, imperfect of pitch, imperfect of rhythm.  When Chaffinch Day came in the middle of February, he freed them but allowed them at first to mix only with linnets. They imitated the linnet and succeeded in producing some of its notes. But then they heard a chaffinch. Immediately they perfected their chaffinch song, nor did they imitate the linnet ever again."
The Territorial Imperative
If the study above was done with a large enough group of chaffinches I wonder if there would be an occasional bird that would either stay stuck in the linnet song or unable to process the chaffinch song. Would we then have an autistic bird?
How to create an autistic monkey