Bird Vision

My wife is a naturalist and she recently went down a rabbit hole on the internet when researching "dimorphism" (male birds having a different appearance than females) and discovered that many bird species that don't at first appear to have dimorphism actually do.

That is because bird's eyes see a different visual spectrum than we do.

This article on bird vision (What Birds See) does a great job of illustrating how birds (and possibly some humans!) can sense things that most of us can't because their eyes are just a little different.

Rathar than elaborate on those differences here, I suggest you go down your own search rabbit hole. Or if you really want to dig deep, check out this Wikipedia entry on the subject: Bird Vision (Wikipedia) 

For those of you who have read any of my YA mystery-thriller Vox Oculis novels, you've probably recognized that the science of bird vision inspired many aspects of the storyline (ravens are involved) and bird-vision like abilities in humans play an important part. If you haven't read any of those books but are curious, you can read a sample of the first book, Not Alone, here.

-fm