I am always amazed by the prowess of herons and egrets as they successfully catch fish in the shadows of the early morning or evening hours. How do they see the fish and react with such accuracy? For this photo essay, I decided to do some basic research to help understand the amazing vision exhibited by these birds.
Herons and Egrets are highly effective hunters and when I watch them in the shallows of the wetlands, I am struck by their slow and deliberate patience as they gaze beneath the surface of the water looking for prey. Like us, these birds have binocular vision unlike some other bird species. Because their eyes are positioned far enough forward, both eyes can focus on a single object. This dramatically improves their depth perception and the ability to accurately locate a moving fish.
Refraction, or “bending” of light when it hits the water causes a visual distortion of the fish below the surface. To correct this distortion and determine the exact location, these birds have adapted certain techniques to adjust. They often strike from close to a 90-degree angle. Sometimes they tilt their heads to minimize glare, and I have seen them shade a sunny area with their wings. Because they have an abundance of photoreceptor cells in their eyes, they are better adapted to hunting in low light. Most of the images in this essay were taken in low light conditions. One thing is clear, when they strike – it’s very fast, and most often successful.
It is an absolute delight to sit and observe these graceful and highly adapted birds.
