One might think that nature would not lie, but it can sometimes be difficult to discern truth from what is essentially falsehood in nature. The reason for this is obvious: A bluff can be as successful in avoiding predation as in winning a poker hand.
The ability to deter a predator can sometimes be obtained cheaply by looking as if you are venomous or toxic, without possessing the necessary poisons or delivery system. The evolutionary reason for the common occurrence of such mimicry is that it is probably easier in terms of genetics, physiology, biochemistry and morphology to “talk the talk” than to “walk the walk.”
But this poses a huge dilemma for predators such as birds: How do they tell the difference? We do know that birds are quite discerning in picking out insects among foliage. The degree to which some insects are camouflaged is quite remarkable, and presumably due to the capture of any insects that stand out a little bit more than others.
Yet there are numbers of insects that are brightly colored — likely advertising their toxic and/or poisonous nature. Birds may learn by experience: Does this food item sting or make them sick? Or, in some cases, they may be genetically programmed to recognize colors that identify potentially dangerous prey.
So we have an interesting conundrum that is presented to birds which prey on insects. Insects that are toxic to eat or possess venoms generally advertise this fact with bright colors and characteristic shapes and behaviors that birds recognize as dangerous. Yet a number of other palatable and harmless insects have taken advantage of this fact to protect themselves in a clear case of false advertising.
What is a bird to do: Take a chance or not? Obviously they find it very difficult to distinguish among the the real deals and the imposters. Try this yourself when you next see an insect advertising itself with bold colors and behavior, and you will develop a better appreciation of the difficult choices that can face birds in their daily quest for food.
Bill Dunson is Professor Emeritus of Pennsylvania State University, thanks to a career spent entirely at that institution, teaching and doing research. Always curious about nature, Bill has dedicated his life to learning and sharing his knowledge with others. Contact him at WDunson@comcast.net.