And, since we haven't gotten into tread and variations other than the treadle machine, there's also the treadmill.
And, speaking of treading, did you realize that that's the verb for copulation by a male bird? wwh, there really is a lot of fun to be found in reading the dictionary, in spite of its occasionally bitchiness...

Also, treading water, or walking in water...

And then there's those who tramp and those who trample...
(When you think of tramping around, betcha' never thought of tramping on the trampoline! Which, for some odd reason, reminds me of a kindergartner I once taught. I held up a tambourine and asked, "What is the name of this instrument?" All the hands went up; in kindergarten all the hands always go up. I called on a particularly vigorously waving hand, and the child to which it was attached answered confidently, "A tangerine!")

Edit: I just found another bird foot word:
zygodactyl - ( )
Having two toes pointing forward and two backwards

http://www.islandnet.com/~egbird/dict/z.htm


...still looking for an ornithologist