There are a bunch of varients of this one including a Canucks/Seahawks one which can be looked at here... http://pobiak.com/item.php?cat=silkscreen&pid=631
I finally got me one of these the other day. Also in the tube a drawing of a guy that looks shockingly similar to me, thrashing your tombstone with a beer in his hand.
seems you have the same trouble Nate Duval used to have matching the proper heads to the proper animals, though your's seems to be restricted to birds. You may want to get in touch and ask him how he worked through that one.