That lead to a discussion about the farm. I told them how we used to stand at the top of a field and make a long whistling yoohoo noise. The cows would look up and saunter on over, head up the road and turn into our yard. In retrospect, it's probably more remarkable that an entire herd of pea-brained cows were so well-trained that they even responded at all, let alone monitored themselves and automatically turned into the right yard than that it is that Swirl responds to Kyle's whistling.
I hadn't whistled that call for years, but as soon as I did, both Teelay and Kyle immediately groaned. Apparently, I used it a time or two when they were younger.