This guy was definitely taking in the scent of something or someone. This was the first time I have seen a Moose exhibit this behavior. Called the Flehmen response, many mammals will curl their lips and raise their head, inhaling deeply allowing them to get a better sampling of a particular smell that interests them – kind of like a human taking a big whiff to smell something. You most likely have seen horses do this and I have seen deer, elk and bison do it as well.