Cows yellow, tigers red

What - in my head or yours - are "well known facts" and what are not? When are we surprised by the knowledge of another and when are we surprised by an apparent gap in their knowledge?

This question came to me when reading Simon Baron-Cohen's review of Animals in Translation by Temple Grandin and Catherine Johnson (here).

I've read a little ( not very much around) about a few aspects of this the subject before. Temple Grandin's work on animal perception and behaviour and her theory of autism do look important, and Baron-Cohen's review is useful.

I didn't know that the reason cows are wary of yellow is because, like most mammals (monkeys? and primates among the exceptions) cows have dichromatic vision: they just see blue and green. As Baron-Cohen recounts:

"That means that a yellow object is very clear to them - it has the highest contrast. Humans have trichromatic vision - we see blue, green and red - while birds see four basic colours (blue, green, red and ultraviolet)".

I was vaguely but not precisely aware of dichromatic vision in many animals, but do not recall ever knowing that birds are quadro(?)chromatic - although I guess this is an obvious well known fact to some. [What can we imagine, and what can we reproduce in our mere three dimensions of a bird's vision?]

By contrast, I was surprised that Baron-Cohen, a distinguished scientist (with some talented brothers/relations including the guy who worked with the MST in Brazil and Ali Gee), writes:

"I was delighted to learn [from this book] that elephants use infrasonic and possible even seismic communication...And I was distressed to read that male chimpanzees wage territorial war in just the same way as humans do, resulting in many deaths. Or that the stereotypically friendly dolphin has been observed to engage in gang rape of an isolated female".

These three examples seem incredibly obvious and well known to me (is Baron-Cohen for real in this apparent ignorance?).

Talking of animals, Sara Wheeler makes a good case for reading Ruth Padel's Tigers in Red Weather, which examines the fate of the world's tigers. It looks a little like a book on another species vaguely forming in my mind (though in my case probably without the personal angst) . Probably, in my ignorance, there are already several good books of the kind I imagine writing already out there.