I disagree on cows, I have had first hand experience lol. At my grandmaws, the field ligning there property they have cows, and i hunt in the ravine, with a field in front of me and behind me and those field's border woods. The deer do not come from the field infront of me from the woods, till the cows go behind me. I personally dont think they like each other. But that is just my experience.
Last year, on a particular property that bordered fenced cow pasture, I noticed that EVERY time I heard the cows mooing I would see deer movement within 5 or 10 minutes. I don't know if they were on the same eating/sleeping schedule or the movement was making the cows nerveous or what. But I hunted this property for a week during the rut and I'm telling you it happened every single time!
You will also notice in rural communities that the dogs will start barking when they sense/see the deer movement.
I think this time of year the squirrels are 'barking' for territory, food,or breeding (I'm no squirrel expert.)
There is a distinctly different sound they make when alerting to deer. It is more of a 'bitching' than a barking - as if the squirrel is chewing the deer out and warning the deer to stay away from his acorns.