I give up. Who's Whicker?

To me, "whicker" is a gentle noise that a horse makes.

Have you ever read anything by the man called "The Horse Whisperer?" Most interesting. He wrote that wild horses are totally silent - afraid of predation. It's domesticated horses that neigh, whinny, and whicker, because they have less fear.

Of course, when they do whicker, they always have nice coats on.