tulip-tree flower--gift of a squirrel

It's always been clear to me, when these tulip-tree flowers land on the ground, that they have been snapped off by something, and I guessed it was squirrels but didn't know for sure until---ta da--last week when Estelle Porter told me she had actually observed it. I'd love to know why they do it, because where they snip the flowers off--usually about 1/2 inch down the stem--doesn't seem to make sense, food-wise. Maybe that's a good spot for sipping sap?  

Marion David gave me the sweet little vase (which she made).