Courtship arena and the handicap principle

Animals are plagued by all kinds of parasites. Ticks, lice, worms, bacteria and viruses nest on and in animals. Animals with heavy parasite infestations have less chance of survival than animals that can somehow fend off the parasites.

Anyone looking for a sexual partner should give preference to parasite-free partners. How can animals without X-ray eyes recognize parasite infestation? Good signals are a smooth, shiny coat or smooth, shiny feathers. This criterion makes it easy to distinguish between sick and healthy mating candidates. That is good. But it only ensures beautiful camouflage-colored feathers, not brightly colored plumage.

The thing with the beautiful feathers is particularly important when many females only mate with one male (courtship arena). In this case, it is not enough to be a good guy. Only the one, the most beautiful one, will reproduce. But how does a camouflage-colored male become the most beautiful? Well, the camouflage colors must be somewhat stronger than the colors of the competing males. Because the competition in the mating arena is fierce, the colors of the males become more and more vibrant and eye-catching to the point of gaudiness. The females like it. So do the predators. Because the males are now colorful birds, many of them end up in predators‘ stomachs. Shouldn’t the females now start to prefer the camouflage-colored females again? What good is it to have children fathered by a brightly colored male?

If the gene switches ensure that the daughters remain camouflage-colored and only the sons are brightly colored, colorful males are beautiful and sexy. Because males that have survived brightly colored are really tough guys with really good survival genes (except those for coloration).

The preference for mates with hindering traits (as honest proof of fitness) is called the handicap principle.

More in the chapter: It’s election day – Who can crossbreed with me?