Some souls that stand closer to the borders of other dimensions, birds and other young souls can go through these gates without difficulty.
When kids disappear into thin air, most of them get pulled into realms beyond our believes. Too never be heared from again. Birds however understand this extra sense and make use of dimensions all the time. They are true masters. There was a time when there where so many birds that they formed a elite clan, they offered a high quality and secure messaging/guiding service. A huge black blue raven was the leader and each kind of bird had it own specialty.
Kings and Queens used the birds for sending messages to other kingdoms through dimensions. But things have changed and there are dark forces that influence souls for evil purposes. They can use birds as spies or they serve as a nice snack.
If a bird is caught by a witch, she can bind her vision with the bird to see it from up above. She does loose one eye herself as sacrifice.
Other creatures seem either care less or hungry for the poor feathered friends.
Birds don’t harm other creatures unless attacked.