I found this question on The Equus Ink from another blog, Pony Tail Club.
As you may know, with my two horses, it can be different things on different days.
Lena thinks tarps and jackets are horribly sinister things. Bar thinks jackets are things that have treats in them, even when they are hanging on a fence, and was unconcerned enough with a flapping tarp to stomp on it on his way to some grass.
Lena hates things that are yellow - will skirt spray painted diamonds on pavement very delicately, as a matter of fact.
Bar spooked at crows flying over the arena one afternoon, but hasn't been bothered by birds since then. Lena, who has been known to chase birds, spooked at one just the other day. Short spook, but a spook nonetheless.
Bar once spooked in the indoor arena at shadows through the inside door and the sound of Peter's voice up in the hay pile next door. (He's actually not particularly fond of the way the indoor arena echoes in any case.)
Lena spooked at horses on the bike path and tore around the arena like her tail was on fire.
They have both spooked at the sun shining off a giant puddle in the outdoor arena.
Neither of them seem particularly bothered by dogs or bicycles in general, but on some days, bikes will cause much consternation for reasons and star alignments I cannot fathom. Lena has had one experience with the pod bicycle that runs silently along our bike path here and while she didn't bolt, it was pretty clear she thought it was a freak of nature. I did want to point out to the guy that riding something predator height and coming up behind a horse with no warning and almost completely silently was a good way to end up with a big, fat hole in his fiberglass pod.
Sometimes I know it's coming, or can at least sense what might set them off, and other times I'm just glad I'm still in the saddle when they are done.
I would actually hope that their instincts would cut in if a lion crossed our path, then hope I had the wherewithal to hang on tight as we got the heck out of there. I do think that a horse and rider would be an awfully large target, at least for a mountain lion, though perhaps not for an African lion. Yowza.