Why am I not getting any bows from my mob grinder?

enter image description here

I have a really simple grinder set up in my base. Mobs fall about 30 blocks on top of a hopper, which feeds to another hopper and finally to a chest.

But I'm not getting any bows from the skeletons! Any ideas why?


Bows only drop when the skeleton is killed by the player.

Your mob grinder kills them by fall damage, so the bows would not drop.