[examplary_cable]

Parrots can't use sign language, but some great apes can(koko)[0]!

Even thought monkeys don't have the vocal complexity to generate all the vowels(a,e,i,o,u) I think "great ape language" communication is more complex and nuanced than a fricking parrot repeating some phonemes after some form of stimulation.

Fascinating.

[0]: https://en.wikipedia.org/wiki/Koko_(gorilla)

[faitswulff]

I think you are underestimating avian intelligence. Despite the term "parroting," if I recall correctly, they're estimated to grow to about the intelligence of a 3 year old human child:

> ...parrots demonstrate sophisticated problem solving abilities, they can communicate their desires, they can count, add and subtract, and remarkably, they even understand the concept of zero

- https://www.forbes.com/sites/grrlscientist/2018/07/12/what-m...

[falsaberN1]

It's not uncommon for people to underestimate avian intelligence, for some reason I never quite understood.

At times I wonder if it's some sort of tiny vendetta from humans themselves. You know, like how (Eurasian) magpies are considered pests, even bad omens, despite being intelligent and crafty...only because they are able to get past human-made traps. I guess a lot of humans are sore losers, heh.

But corvidae are legitimately intelligent, specially crows and magpies. The behaviors of crows in Japan are well-known, and magpies were proven to not only being able to recognize themselves in a mirror, they also used the view from the mirror as a tool (in the controlled experiment, to try to remove a sticker put on them by researchers). They can also remember humans visually (and therefore being able to hold grudges, or consider individuals "safe"), use and/or make rudimentary tools to achieve goals.

Not to mention that a bunch of birds can go literally (and visibly) insane in captivity. You can't have insanity without sanity.

[baja_blast]

It's difficult to use sign language without hands/arms.