What does it take to be a deer?
Our neighbor Diane told us a story that impressed me deeply. She was working in her garden one autumn when she heard an apple fall from one of Klaus’s trees across the road. Within seconds, she heard and then saw a deer running to get the apple. It makes perfect sense, and I’m sure I would do the same if I were a deer. But I’m not a deer, so a question arises about how it knew it was an apple that fell, and knew to get there fast.
Everyone knows the story about Sir Isaac Newton and the falling apple. Schoolchildren learn that the idea to work out the rules of gravity occurred to him when an apple fell while he was reading under a tree. According to the story, a light bulb went on in Newton’s head when the apple fell, and after that moment, everything was different for him.
If the light bulb of gravitational attraction went on for Newton when the apple fell, then what kind of light bulb goes on for deer to allow them to connect the sound of an apple falling to the promise of food if they get there first? Does it mean that they understand gravity as a scientist understands it? Probably not. For many kinds of reasons, they probably don’t understand it in anything like the way we humans do. But whatever their understanding of gravity, Diane’s observation tells us they know what to do when an apple falls.
You might assume that the deer was merely expressing an instinctive response to the sound of the apple, but I don't think so. For one thing, there were no apples in the woods while these deer were evolving. Nor was there any fruit at all within hundreds of kilometers that makes a sound anything like an apple when it falls. Apples have been growing on Quadra Island for at most only a few deer generations, and deer love them. (So do bears, but that’s another story.)
It makes most sense to me to think that deer learn to attend closely to apple trees at the right time of year, to listen carefully for the sound of apples falling, and to not waste time getting there when they hear it. Maybe they learn it by themselves, entirely through their own experience. Maybe they learn it by paying attention to their elders. But they they learn it, and they get more apples as a result. Maybe they have to learn it again each year when the apples are ripe, but that seems pretty unlikely to me. You remember as well as I do how good a good apple tastes, and you can at least imagine the sound of an apple falling on the ground. You might not know that that particular tree of Klaus’s has especially good apples, but I'll bet the deer know it. I’ll bet they learn these things only once, early in their lives, then reap the benefits for as long as they live.
The more I study the behaviour of wild animals, the less useful the concept of instinct is to me. Nearly everywhere anyone has looked closely enough, there is an abundance of strong, rich, clear evidence of learning and remembering by individuals of a very wide range of species including insects. The evidence is even more impressive that animals can put two and two together and that they apply that knowledge surprisingly intelligently to practical problems in their everyday lives.
Here’s another example. Deer love roses, and they also love kale, peas, strawberries, blueberries, and nearly everything else we grow in our garden. That’s why we have a high, deer-proof fence all around. Last year, Lucretia and I were both working in the garden one day when I noticed a young buck emerge from the alders to the south of the garden, where there is no gate. He moved very slowly to near the fence, then sneaked along the fence line to the east. (I had never seen a deer move that way, so I hope you’ll forgive me for suggesting he was sneaking. I also think territorial hummingbirds sneak, but that's another story.) When he rounded the southeast corner, he sneaked northward along the east fence, turned the next corner, and sneaked more and more slowly and carefully, as if on tiptoes, toward the gate by the northwest corner, which we had left standing open.
I watched the whole thing carefully, and was interested to see what would happen when the buck reached the gate. One careful step at a time, he entered the garden with his eyes glued to the kale, which was only 4 or 5 body lengths inside the gate. I was only a little farther away, and when he got about halfway to the kale, I said in a loud voice, “Now just a minute there, Buster! That is our kale and this our garden, and you’re not invited. You’re not even invited to come into the garden, so you can just turn around and get back out!”