Chickens were put in a 2x2x2 hole in the ground with a ladder in the corner going up. When the player character is positioned on the block with the ladder the chicken will get lifted/jump up on the player and then to the surface.

This works in both creative and survival.

What I expected to happen was...:
Chicken should stay in the hole when I stand on the block with the ladder.

What actually happened was...:
However it got lifted/jumped up on the player character and then was able to jump out of the hole.

Steps to Reproduce:
1. Dig a 2x2x2 hole (in my case in dirt)
2. Put ladders in a corner of the hole going up.
3. Put chickens in the hole.
4. Have the player stand on the block with the ladder.
5. Chickens should jump/get lifted up on the player and then out of the hole.

Pushing a chicken into the corner with the ladders seems to help this process, but it will also happen without player movement.