I get so used to the idea that humans, compared to other animals, are superior only in the brain and opposable thumbs areas (and things which derive from them, like language, problem solving, tool use, civilization, and knowing how to use digital watches) that I just expect to be inferior in all other regards. And that goes double for the senses. We just take for granted that other animals beat us on all factors, except we make an exception for how colorblind most animals with whom we are most familiar are, compared to us, but that seems almost trivial.
Intellectually, I know I have better eyesight than a dog, and not just in terms of color, but also distance, acuity, and ability to see things before they move. But on some level I just always imagine that anything I'm aware of, my dog is already aware of, and lots of things I'm not aware of, too.
A few times recently when I've taken Socks for a ride with the Springer, I have had hammered home that that's not the case. There are a fair number of deer that prance around near here, even on the roads, and a few times as we headed down the hill toward the lake, I could see a few of them, usually does, on the side of the road. Each time, the does don't seem to notice me and Socks, nor does Socks notice them, for a good fifteen seconds of travel, when we've closed about half the distance. Then all of a sudden everyone else is aware of what I've been noticing for a while, and the deer are off into the woods, and Socks is pulling me along.
Yesterday, this happened in an even more interesting way. I saw the deer, but they didn't see me, and Socks didn't see them. They moseyed along on their way which took them into the woods and out of my sight. I thought Socks might not have noticed at all and the trip would go by without any reaction, but then a little ways on, she suddenly perked up and lunged forward. By this point the deer were so thoroughly into the woods that had I not seen them earlier I would have had no idea whatsoever they were nearby. And Socks certainly wasn't seeing their motion; I knew where to look and didn't see anything. But she got a scent of them some distance into a thick wood, and whoosh, we were off at a run. By time we got to where they'd gone into the woods they were long gone and Socks lost the scent soon after (pulled along by the bike leash).
On the one hand this certainly shines a light on all the times she pulls for no reason I can fathom. It's easy to make fun of how she's reacting to a squirrel in New Jersey being impudent, and imagine she's imagining things, but this was a very tangible lesson that she's really reacting to stuff completely outside my ability to be aware of. And on the other hand, it's even more striking to me that there was a whole interaction between me and several other animals in which I was the only one who had the faintest clue of what was going on. Not because of being smart, or having an infrared sensor, or even having studied the movement of wildlife and knowing how to read the signs, but because of a basic biological advantage I have over dogs and deer. Hard to get used to thinking of not being the idiot-savant of the animal kingdom in all respects.