I really hate to nitpick such an adorable critter, but I can't help noticing that you have given your vampire bat a leaf-shaped nose, which is characteristic of several fruit-eating and insect-eating microbat species but not of vampire bats. Actually, the white facial markings suggest that your model may have been a Jamaican Leaf-nosed bat, which primarily eats fruit and the occasional insect: the nose "leaf" acts like a megaphone, allowing the bat to project its chirps through its nose so that it can echo-locate while carrying a chunk of fruit in its mouth. Vampire bats have flat noses. (Also, if I'm going to get technical, the li'l guy should really only have one thumb on each wing, not two.)
Don't get me wrong, though: I love your concept! It's witty and well-drawn, and the big sad eyes just kill me! I used to volunteer at a place that has a captive colony of vampire bats - they get cow's blood donated from a kosher slaughterhouse.