Steps to reproduce:
- 1. Be riding a horse, with a rope in inventory.
2. Go to a thicket with a sufficiently long cliff passing through it.
3. Dismount the horse. (The horse should now be leashed.)
4. Climb the cliff and walk away, so that the horse will path to you.
5. Notice that the horse will first try to path directly to you. If there is no thicket between you and the horse, it will move to the thicket, where it will then cross the cliff (over thicket terrain) just as a bird would.
So far, I have only seen this happen with domesticated horses. Not wild ones. But I have no reason to believe that it wouldn't work with a clovered wildhorse.
I would post a gif if I could, but the person that told me of this is a fellow villager, and I don't want to doxx our location. Thanks for taking a look!