Whenever a horse is being ridden near Luca (my gelding), he pins his ears and charges at the horse. This only happens when Luca is not being ridden, just when he's on the paddock.
For example, about a week ago, my sis was riding one of the geldings on a paddock right next to the paddock that Luca was grazing on. Whenever the gelding would trot past, Luca would pin his ears back and charge at the fence. I was scared that he was going to jump it!
Luca does it when: a horse is being ridden on the same paddock as him.
When a horse is being ridden on a paddock next to him.
Luca doesn't do it: when the ridden horse is near and Luca is tied up. When he is too far away to charge properly. When he's being ridden as well.
When Luca is being ridden while another horse is being ridden, he only pins his ears a little when it comes past, but it depends on the horse. He's fine with his best buddy (an older gelding called Syd) but with Fleet (TB gelding) he gets grouchy. But I can easily control Luca when that happens.
So what I'm asking is:
-why is Luca doing this?
-what can I do to stop it?
Thanks in advance!