That's hilarious! I have a mare who thinks EVERY stick on the ground is a snake... year round! It's particularly hilarious when I'm not riding her! hahaa
But really, she is so spooked at sticks that one time I actually got nauseous riding her... she was shying and baulking and going sideways so often I got seasick! We have one training trail that travels through a large area of eucalyptus trees (known for their shedding behaviour), and every piece of bark, branch, etc, is a potential horse-eating snake that is sure aiming at her legs.... it makes for an interesting ride.