Morgan Worthy The following is offered not as a formal theory, but only as a framework or illustration to show how different skills or traits related to eye darkness may lead to different hunting strategies. Among land vertebrates, those predators most skilled at catching mobile prey tend to have either yellowish eyes or eyes that are dark brown or black. Their hunting strategies differ. A yellow-eyed predator’s first response to mobile prey is to wait without moving; that is the first step in a successful ambush. A black-eyed predator’s first response to mobile prey is to move without waiting; that is the first step in a successful direct pursuit. Predators with eye colors near the midrange between yellow and black (e.g. red or light brown) appear to be unskilled at either ambush hunting or direct pursuit hunting; they tend to find prey that is immobile or ignored by other predators for some reason (noxious, toxic, deep underwater, etc.). To expand on that and include the full range of eye-darkness, the hunting behavior may change as species eye color (or average eye-darkness for subfamilies, families, etc.) changes from yellow to orange to red to brown to black. The numbers below each color are estimates of relative eye-darkness on a scale from 0 to 1.      .00 .25 .50 .75 1.00 Predator Eye Color Hunting Technique Black Immediate direct pursuit from a moving start (e.g. aerial flycatching as seen in swifts, swallows, and evening bats) Brown Immediate direct pursuit from a standing start (e. g. aerial flycatching from an exposed perch as seen in tyrant-flycatchers) Red Foraging for immobile prey (e.g. gleaning dormant insects or larvae as seen in woodpeckers) Orange Delayed ambush from a moving start (e. g. active looking for prey which is then stalked or surprised as seen in harmless snakes, some hawks, and civets/mongooses) Yellow Delayed ambush from a standing start (e.g. lying-in-wait or very slow stalking as is often seen in frogs, true vipers, herons and cats) To repeat, the above is offered only to illustrate some of the ways that gradations in eye darkness may be related to subtle differences in hunting behavior. The true picture is much more complex and includes special hunting strategies such as taking toxic prey avoided by other predators or swimming underwater to find prey.
Sep 21, 2008
 Eye Color and Predator Behavior
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