At the easternmost edge of our yard grows a tree covered in thorns.
It yawns unassumingly against the fence during the damp, heavy heat of spring and summer and summer’s dog days, imitating the yard’s other, friendlier trees. Still, even when it is inconspicuous to us on the ground, the squirrels never leap onto its trunk to escape the panting, eager predator who flushes them from her yard, mouth open, tail whirling, legs flinging her into the air with a springiness that rivals that of any Tigger. Birds don’t perch on it. No cat has climbed it. And Nala, who will put her paws on anything to get a stronger whiff of a squirrel, has never stretched up to grip its trunk.
At the end of each autumn, the tree shakes, and shudders, and sheds all its leaves in one fell swoop. At the end of each leaf is a slender, pliant twig, and each and every twig is studded with thin, sharp thorns.
Every year, they take us by surprise.
Nala, trotting her circuit of the edge of the yard, will take a step and stop, paw in the air, face expressing her totally pathetic brokenness. I will cross the yard and speak soothingly to her as I extract a thorn from her paw. It will happen again and again for a few days, as we humans desperately attempt to rake the twigs away, or to mulch the down to miniscule pieces, to reclaim that eastern edge of the yard.
The twigs and their thorns defy our attempts to remove them. They slip between the teeth of the finest rake we can find; they evade the lawn mower’s blades even as, ground up, they permeate the yard with a sweet, sharp, peppery smell. The only tool in the world that can consistently pick them up is a certain puppy’s paws.
Before a week has passed, the tree’s punishment has done its work, and Nala has picked out a new way to circuit the yard. Watching her trot, I can measure the tree’s canopy without even looking up; it is a nearly perfect semi-circle, extending nearly halfway into the center of the yard but not quite reaching the rotting fenceline at the southern edge of the yard (that fence is vine and peachtree territory). Nala’s new track lays a perfect map of where the tree and its thorns have affected her behavior; she won’t set foot under the tree again until the spring rains have washed every thorn away.
But that isn’t quite true.
Here’s what happens when Nala flushes a squirrel out of a tree on the north side of the yard and it bolts for cover in its nest in the vines:
Once, when a squirrel charged along the fence right in front of her and past the thorn tree, Nala gave chase. She flew, her feet barely hitting the ground before suspending her completely–she launched at the fence–she launched herself up the fence, over six feet in the air–she came crashing down, and jumped again, and again.
And then the squirrel was gone, and Nala froze, paralyzed, as the adrenaline deserted her and left her feeling all the pain and misery of four thorns embedded in a single paw pad. She would not, could not, move for the pain and discomfort. Seconds before, she had been totally oblivious.
I pulled the thorns out, and I comforted her, and I escorted her gently back to the safe part of the yard.
And that video, the one above, of her bouncing in pursuit of a squirrel right under the toothache tree? It was taken a few days later (and she managed to escape unscathed, that time).
Behavior is so much more complicated than merely what has been punished, or even what has been reinforced–behavior comes from emotions, from inherent drives, from motivation, from arousal levels, and, yes, from reinforcement or punishment history, and all of these things can be influenced by genetics, by experience, and by training. And even though nature itself can’t seem to keep Nala from chasing the squirrels, I–and a handful of chicken–can.