@longgone Of course they could be ‘communicating’. Why even put that in quotes? Well, communication tends to imply intentionality. Like: I have a thought, want to share it with you, choose to do so, and speak. Now let’s try to apply this sequence to animals.
Thinking: well, maybe. My joke-response above to flip was a bit hasty and reactionary to being called ignorant and to my exasperation over his unconstructive observation that I neglected to write “non-human animals”, but he does in fact make a good point. It does seem that some animals may have mental events similar to human thoughts. It also seems apparent that others probably do not. Self awareness though, that’s a doozie – very hard to observe or quantify. Yes, some birds and apes have been observed to recognize themselves in a mirror, but whether this indicates self-awareness is a much larger and more opaque issue. This leads us to whether animals can have desires – as opposed to needs – and whether they make choices – as opposed to following the dictates of instinct.
Here’s an example. When my cat goes to drink water, is she realizing she’s thirsty? Surely the sensation of “thirsty” is something we both experience similarly…right? Of course, we cannot know this – but let’s take it as a given for now. How does the sensation register for her? How does her “decision” to go drink water then get enacted? From my point of view, all I can empirically verify is that she is taking a series of actions that end with her drinking water.
The point being: if we cannot know how another mind works, we cannot attribute intentionality to it.
This, I would venture, is why the OP put “communicate” in quotes. I understand that your point was that the word can be taken in another way, where it does not imply intentionality but only bare signifying. I agree that we can attribute this limited form of communication to horses and to animals in general.