An intelligent creature is the crow
they know that the type of humans which "live" in a graveyard
won't disturb them high in their trees
and that the other sort
the ones that just pop by
don't seem to stay long anyway!
the crow knows a graveyard is a long established
and secure environment
and as such is well stocked
with many tasty creatures
so they know there'll be lots of their favourite food to eat - which is basically anything!
they also know there'll be places to shelter and roost and discuss the latest topics with mates on nearby branches
and social gatherings aren't likely to be interrupted by the residents below
so the chances of finding a mate are high
which makes it a fantastic place to start a family!
and seeing that crows are a symbol of death
and have been seen gathering 'round dead members of their flock,
as if to learn about potential dangers...
well
...a graveyard seems an appropriate place to find crows in - doesn't it?