Entering the following command to kill all parrot entities will not kill any parrots that are perched on the player's shoulders:
/kill @e[type=minecraft:parrot]
If the only parrots in the game are those currently on the player's shoulders, an error is displayed:
No entity was found
Killing all non-player entities has no effect on them either:
/kill @e[type!=player]
Killing all entities detaches the parrots from the player's shoulder as the player dies, but leaves the parrots alive:
/kill @e
Hey there!
This looks to be a duplicate of MC-114967.