Wasn't too sure how delicate they would be once you got smaller. I just remember cracking them open as a kid.
Cutting them from paper should work well enough (at 10 mm scale...unless they are monstrous birds, they will be pretty small). However, it would likely try my patience. Might check one of the hobby stores to see if they have an appropriately shaped hole punch or something like that. I know that I have seen a punch that does the edges of paper and leaves a lace look to it that had some bird shapes in it (was for a First Communion invitation).