One would think they would install the spreaders when they erect the line. Perhaps the spreaders deteriorate with time. Or maybe the vultures steal them.

There have been places here in California where they have had to erect bird perches above the cross arms on the poles. Seems the condors have a wingspan large enough to bridge between the wires on the extremities of the cross arm. I'll forgive whoever designed the utility poles. Would you think to consider bird wingspans when designing power distribution systems?