The bug
Whenever you try to climb a ladder or vines when you have a parrot on you shoulder it'll fall off. Since you are moving pretty slowly upwards you would expect it to stay on your shoulder.
MC-115088
Parrots dismount from shoulders when climbing ladders or vines
Resolved
Works As Intended
5
Andrew David Gronowski
migrated
Confirmed
ShoulderEntity, climb, climbing, ladder, parrot, vines
Minecraft 17w13a, Minecraft 17w16b
Retrieved
Jumping is intended, see MC-114890.
Climbing ladders (and very likely vines as well) might not be. Therefor I am changing this report to be only about ladders and vines.