Playground Balls on Electrical Wires

Have you ever been driving along and looked up at the electrical wires, only to see what appears to be a reddish-orangish playground ball like the one you used to kick during kickball in gym class? These balls are just hanging on the wires and some places have a bunch and some have none.
I've always wondered what they were and now my kids are wondering. I really really really don't like giving an "I don't know" answer to a question that seems like it has an easy and logical answer.
So I googled it.

There seems to be one major reason and a bunch of uses that have come about. The first reason is to mark the wire for low flying planes. I guess the electrical lines are somewhat transparent when you are flying along in the sky. Crop dusters, helicopters, etc. find them necessary so they don't crash. Seems like a pretty reasonable reason for some areas, but there are other spots where I have seen them that I cannot believe a plane or helicopter would ever fly/land.

A benefit found out by using these is that it saves the lives of some birds. Birds don't crash into the wires and big giant playground balls let them know there is something there. OK.
Here is some info on bird strikes of the whooping crane:

"The number one problem of migrating cranes is collision with power
lines. Danger can be a huge string of transmission lines high in the
air or simply a single wire running into a farm house or irrigation
system in an isolated area where practically no one lives. The cranes
simply do not see the lines. Why should they even be looking since the
only natural danger they have are attacks from eagles? Transmission
lines are hard to see when you are looking into the sun, late in the
day when the light is dim, or in bad weather including blizzards or
foggy days. When we radioed 6 whooping cranes back in the early 1980's
and tracked them all the way to and from Canada, two of the six died
hitting power lines. To make power lines more visible, red plastic
balls or similar devices are placed on the lines near airports so
pilots can see any lines as they come in to land. When power lines are
built across wetlands, the U S Fish and Wildlife Service asks the
companies to mark the lines. This reduces bird strike mortality by 50%."

Another benefit is it prevents a vibration to the wire that can happen when there are strong winds. I don't really don't know much about wind speed, etc. Hopefully this one makes sense to someone besides myself.

Fun stuff!!! Who knew?!?!?