I switched majors once, from pre-med psychology to a general business degree, oddly never choosing the area in which I might actually have had some talent - English or perhaps journalism. I then went on to have jobs in science, banking and law. I think I absorbed the idea that you don't want to be constrained (by a boss) in an area you wish to pursue with passion and abandon - like perhaps an artist wouldn't want to pursue a degree in fine arts, fearing being constrained by a career in marketing. Later in life I found this attitude depressing, I came to see it as betting against myself - maybe I could have had a career as a writer that wasn't based on someone else's demands, and in any event I think it would have been easy to feel competent and possibly more assertive if I picked something I actually had confidence about. If ornithology is the passion, I'd say pursue it!