>There are too many questions for such a simple man to understand, let alone answer.

I've got one answer for you at least

https://www.washingtonpost.com/news/style/wp/2018/07/23/feature/the-crane-who-fell-in-love-with-a-human/

Apparently, Walnut was bred and raised at a time where conservation efforts were staffed by volunteers. Back in the late 80's, the consequences of imprinting were not fully observed or understood among many bird species, especially endangered species like the white-naped crane, whose interaction with humans are not well documented. Due to the fact that she was raised by volunteers, it would be impossible to know just who raised and fed her, but whoever it was, they must have treated her with a lot of love, because she imprinted hard on humans. She barely recognizes other cranes as her conspecifics, leading to the two alleged killings attributed to her, and her falling for Mr. Crowe here.

200% yandere.