Sometimes snippets of evidence turn up in the oddest places.
There are 30 videos of this foul-beaked parrot (all of them hilarious) on YouTube. Just search 'X-rated parrot'.
In this one, the parrot starts repeating the name 'Jill'. The owner is baffled, and explains that Jill was his sister, who died years ago. When he tells the parrot 'Jill died', the parrot responds 'Bye-bye' which is a heck of a coincidence for a bird with such an extensive vocabulary.
This particular parrot is an excellent mimic and picks up words quickly.
Coincidence? Well, the world is full of them, but this one clearly sends shivers up the parrot-owner's spine.
Watch the video and decide for yourself - but be warned, that parrot's vocabulary extends deep into the gutter!