Pick out the predators (2 eyes) and the prey (1 eye)
Now ever since I had learned Boyle's law in a grade nine science class I wanted a law named after me. As I matured however I realized that most good laws had already been taken and started to lean towards perhaps postulating a good theorem. Theorems are by definition a lot less stringent than a law and should have been easier to come up with. Now I have come upon something a little more attainable - a maxim, which by my understanding is a step above "some guy I know told me" or "a friend of a friend says".
So I am now presenting the following maxim to biologists and naturalists the world over. The Ritcey Maxim or the One-Eye Maxim states that if you have a picture of a bird or a mammal and you can only clearly see one eye, then the animal is most likely a prey species. Two eyes clearly visible in the photo and the animal is most likely a predator.
Try it out with your own photos. And yes there will be exceptions to the rule, even I have photos of a rabbit with both eyes clearly visible - but I would estimate that this maxim holds true over 78.6% of the time.