That's what succulent little morsels like grasshoppers, frogs and salamanders try to avoid. Some small critters arm themselves with stings, slime or sickening flavor and often advertise their repulsive characteristics by being brightly colored. This poison-arrow frog advertises to predators that a good meal lies elsewhere. Coupling flashy colors with noxious characteristics lets animals go about their business with impunity.
Birds do it, bees do it, even monarch butterflies in trees do it.
Biologists have long wondered how such advertising developed. Their study is one of two papers in this week's issue of the journal Nature that begins to explain how warning colors could evolve. Not all predators may realize that a yellow jacket isn't an easy meal. But the insects also rely on their numbers to allow for some clueless predators to learn the hard way. The great tit, a European bird related to North American chickadees, generally eats both seeds and insects.