Birdwatching Tower Sketches

I have been going through old piles of drawings and scanning some of them. Here is an interesting sketch of a birdwatching tower project in which I was experimenting with Santiago Calatrava's technique of using human form to inspire structural form:

Eventually the tower manifested itself as something like this:

with small landings on each level, so as to view the surrounding tree canopy from many different heights.