warning coloration

:  conspicuous markings or bright colors possessed by an animal that serve as a warning to potential predators that it is toxic or distasteful The vivid orange, red, black and white color patterns on the wings are a monarch's advertisement to potential predators. This warning coloration enables a bird such as a blue jay, which might eat one poisonous monarch and become ill, to recognize and avoid the butterfly by sight alone in the future. — Marcia Davis