Mooshrooms overcrowded in a single block cow crusher teleport instead of dying

Put the summary of the bug you're having here

What I expected to happen was...: 

for newly spawned calf to kill older mobs**

What actually happened was...:
They tend to teleport across nearby area in herds

Steps to Reproduce:
1. build a basic cow crusher for Java by Wattles (https://www.youtube.com/watch?v=QnH2-vlBU2s)
2. breed mooshroms to max capacity, then start breeding some more
3. log in and out, excess cows will scatter accross nearby area, sometimes teleporting move is visible live