Have you ever been near a power tower whose lines are hissing? We can hear the electrical discharge but we can’t see where it’s coming from. Reindeer can see it!
You’ve probably experienced hissing power lines and wondered about the source of that noise. Sometimes the sound is so bad that it makes us worry. I remember hiking through a power line cut in Pennsylvania’s Laurel Highlands(*) where the lines were crackling. The sound was so spooky that I practically ran to the other side of that clearing!
The hissing is a corona discharge, the ionization of the air surrounding the high voltage conductor (wire). As electricity leaks into the air it creates hissing and crackling sounds and flashes in a spectrum we cannot see.
Since 2011 scientists have known that reindeer can see ultraviolet light. They’ve also noticed that reindeer avoid power lines by as much as 3 miles (5km). At that distance there’s no way the animals can hear the lines hissing so what is it? It’s flashing ultraviolet light!
Power companies use UV cameras to see the faults in their power lines so they can fix the leaks.
p.s. It turns out that most mammals can see some level of ultraviolet light. Humans and monkeys cannot.
(photos from Wikimedia Commons; click on the captions to see the originals. *NOTE: The tower photo shows a typical power line cut in Pennsylvania, not the one I ran across!)
Reindeer eyes are very funky. They change color (and structure) from summer to winter, for protection in the summer to being able to see better in the dark in the winter. Here are 2 interesting articles on their eyes. The UV adaptation lets them find their preferred food, as well.
https://www.livescience.com/40813-reindeer-eyes-turn-blue-in-winter.html
https://www.newscientist.com/article/dn20519-reindeer-gained-uv-vision-after-moving-to-the-arctic/