OSHA 1926, Subpart N- Cranes, Derricks, Elevators- does not appear to DIRECTLY address dunnage under outriggers. However- the standards DO require that a piece of equipment be operated as the maker...
Because it look a bit like the bird, which is tall and slender.
A crane is a vehicle used to lift things usually with a hook.
A crane is either a type of bird or it is a machine that can dig, move, create, or destroy, depending on their type.