How does this help migrating cranes?

Photo AltaLink

Cranes can't see electrical transmission lines because, to their eyes, endless wires appear to have no beginning and no end. The small spiral device on the wire is called a bird deflector device, or BFD. Do you also see a reflective tag (named Firefly) hanging from the power line? How are these helpful to migrating cranes?

Think... then link

Journey North is pleased to feature this educational adventure made possible by the
Whooping Crane Eastern Partnership.