page_title: Warning colouration
hierarchical_section_title: Warning colouration
caption_attribution_description: English: Nymphs of Lygaeus kalmii on Asclepias subulata in Phoenix, Arizona, USA
context_page_description: Animals that are dangerous, or foul to eat, usually advertise the fact. This is called warning colouration or aposematism. It is the exact opposite of camouflage. Warning colours tend to be some combination of red, yellow, black and white.
  Alfred Russel Wallace, a British naturalist, explained it this way, in 1889:
  "The animals in question are possessors of some deadly weapons, as stings or poison fangs, or they are uneatable, and are thus so disagreeable to the usual enemies of their kind that they are never attacked when their peculiar powers or properties are known.
  It is, therefore, important that they should not be mistaken for defenceless or eatable species... since they might suffer injury, or even death, before their enemies discovered the danger or uselessness of their attack. They require some signal or danger flag which shall serve as a warning to would-be enemies..."
  Wallace predicted that birds and other predators would reject conspicuous prey whilst accepting cryptic prey. Later reports confirmed this.
  Animals with warning colours move slowly and expose themselves to sight. The sluggishness and exposure helps to advertise their defence.
context_section_description: Animals that are dangerous, or foul to eat, usually advertise the fact. This is called warning colouration or aposematism. It is the exact opposite of camouflage. Warning colours tend to be some combination of red, yellow, black and white.
  Alfred Russel Wallace, a British naturalist, explained it this way, in 1889:
  "The animals in question are possessors of some deadly weapons, as stings or poison fangs, or they are uneatable, and are thus so disagreeable to the usual enemies of their kind that they are never attacked when their peculiar powers or properties are known. 
  It is, therefore, important that they should not be mistaken for defenceless or eatable species... since they might suffer injury, or even death, before their enemies discovered the danger or uselessness of their attack. They require some signal or danger flag which shall serve as a warning to would-be enemies..." 
  Wallace predicted that birds and other predators would reject conspicuous prey whilst accepting cryptic prey. Later reports confirmed this.
  Animals with warning colours move slowly and expose themselves to sight. The sluggishness and exposure helps to advertise their defence. Along with the colour and behaviour often goes the foul smell of their chemical weapons. Noxious caterpillars often have thick, leathery cuticles which help them to resist young birds making a 'test'. When the bird takes a peck, disgusting fluid seeps out from special glands on its back. The caterpillar (or other larva) will often survive such an attack, and the young bird has learnt a lesson it will never forget. All in all, the predator is given good warning. Tests show that warning colours definitely do deter predators.
  Some individual animals will die or receive damage while birds or mammals on the attack learn about the connection between colour and taste. However, if warning costs less than hiding, the animal benefits. And the advertising traits such as colours may serve other functions as well. The patterns may help mate identification within the species, for instance.
  Warning colouration is the basis of two different kinds of mimicry: Müllerian mimicry and Batesian mimicry.
caption: Gregarious nymphs of an aposematic milkweed bug, Lygaeus kalmii: by keeping together they make their warning more visible
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