The first time we witnessed this act, we were taking her for a walk in Creve Coeur Park. It was a beautiful fall morning. The air was crisp with with scent of freshly fallen leaves. The sun was shining, keeping the chill away. As we meandered along, Kuma kept her nose to the ground, intently sniffing everything in her path. When we approached a cluster of trees, she began to pull toward it, needing to investigate. As soon as she reached her destination, she promptly LIFTED HER LEG AND PEED ON THE TREE! Did I just see that? That did NOT just happen! Holy crap! Okay, so she actually propped her leg up on the trunk in order to pee on the tree, but seriously! Once she was finished, she put her leg back down and proceeded on as if she didn’t do anything out of the ordinary. Her mommy and daddy, on the other hand, were not so lucky. We are now scarred for life.
It’s an expression of dominance. In a wolf pack, the alpha members (male and female) lift their legs to pee. All others squat.