Among Birds-of-Paradise, Good Looks Are Not Enough to Win a Mate
GW: And, may this bird not fly up your nose
Study suggests key physical traits & behaviors evolved in tandem
November 20, 2018
Ithaca, NY—Male birds-of-paradise are justly world famous for their wildly extravagant feather ornaments, complex calls, and shape-shifting dance moves—all evolved to attract a mate. New research published in the open-access journal PLOS Biology suggests for the first time that female preferences drive the evolution of physical and behavioral trait combinations that may also be tied to where the male does his courting: on the ground or up in the trees. There are 40 known species of birds-of-paradise, most found in New Guinea and northern Australia.
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| Lesser Bird-of-Paradise during courtship dance. Photo by Tim Laman. |
Study lead author Russell Ligon, a postdoctoral researcher at the Cornell Lab of Ornithology, suggests females are evaluating not only how great the male looks but, simultaneously, how well he sings and dances. Female preferences for certain combinations of traits result in what the researchers call a “courtship phenotype”—bundled traits determined by both genetics and environment.
Study authors examined 961 video clips and 176 audio clips in the Cornell Lab’s Macaulay Library archive as well as 393 museum specimens from the American Museum of Natural History in New York City. They conclude that certain behaviors and traits are correlated:
- As the number of colors on a male increases so do the number of different sounds he makes.
- The most elaborate dancers also have a large repertoire of sounds.
- Males that display in a group (called a lek) have more colors to stand out better visually amid the competition.
Because female birds-of-paradise judge male quality based on a combination of characteristics, the study suggests that males may be able to evolve new features while still maintaining their overall attractiveness to females—there’s room to “experiment” in this unique ecological niche where there are few predators to quash exuberant courtship displays.
The researchers found that where a bird-of-paradise puts on his courtship display also makes a difference.
Graphic shows which types of displays are most common at varying heights in the rainforest. Birds-of-paradise illustrations by Szabolcs Kókay; background illustration and graphic design by Jillian Ditner. Graphic courtesy of the Cornell Lab of Ornithology. Click image for full-size version. Read more
