This is a very interesting way to look at defining leadership.  It is definitely something that is hard to nail down-- there are so many different types of leadership.  I do believe that there are some attributes that can be regarded as universal for all leaders, however. I wrote a blog post on this same topic (and also used an image of waterfowl!) -- http://360degreefeedback.blogspot.com/2010/06/so-what-is-leader-anyway.html

Thanks for the thought-provoking content!