At least with tamed crows, when you tell them to stay they sometimes wander off a bit. Its nothing major, but cost me 2 crows.

Crows on shoulders don't return items if there is space in the inventory.
Also crows on shoulders sometimes glitch and try to fly even tho they are still on the shoulders and flap the wings in front of the face.

For some reason crows glitched and I lost 3 blocks of iron(tried to do the iron golem and decided to create him inside of the fenced perimeter; disassembled and was too slow to pick up - crows took 3/4 blocks))

P.S. Is there a way to force all of the crows to return every picked item except RMB everyone of them?
(didn't know that they will sit if you sit)