The Frog with Self-Cleaning Feet by Michael Bright

Author:Michael Bright
Language: eng
Format: epub
Publisher: Skyhorse
Published: 2012-12-31T16:00:00+00:00

The male great bowerbird Chlamydera nuchalis in northern Australia uses an optical illusion to impress a female. He builds an ‘avenue’ type of bower, about 1m (about 3ft) long, out of sticks, the sides of which face east and west, and decorates the courtyard between the walls with coloured trinkets called ‘gesso’—anything from stones to bones, sticks and shells, but always with a preference for things that are white, grey or green. As part of his courtship routine, the male bird picks up objects from the gesso to show to a potential mate. This is where the illusion is created: large objects are placed at the rear of the gesso and small objects at the front. Large objects appear smaller with distance, so the overall effect is that everything in the gesso is roughly the same size, a phenomenon known to photographers as ‘forced perspective’. And research at James Cook University has showed that females are, indeed, impressed with males who produce the best illusions. It’s not yet clear why, but it could be that the more uniform displays better hold a female’s attention and might well demonstrate qualities in the male that impress the female. It’s the first time a non-human animal has been known to alter a visual perspective to be viewed by other individuals; put another way, that’s ‘art’!

Nerds, don’t despair. Clever boys get the girls, at least in bowerbird society. Male satin bowerbirds Ptilorhynchus violaceus build avenues of sticks and decorate the ground in between with mainly blue objects, from feathers to flowers and even shotgun cartridges and ballpoint pen tops. Researchers from the University of Maryland tested how clever these males are by introducing red objects into their nests. The birds had to work out how to remove them—remove a transparent cover to get at the red object in order to throw it away or cover up a red object that had been screwed to the floor using leaves. Some birds were able to solve the problems, but others didn’t seem to have a clue. It turned out that the smart males attract-ed the most females, the cleverest individuals mating with twice as many females as the slowest problem-solvers. Whether females were selecting males on the basis of their braininess or whether it was some other element of the courtship display, such as a sexy dance, is not clear, but the brainy birds undoubtedly won the most hearts.

Many male animals make themselves bigger and bulkier to intimidate their rivals in order to win the right to mate with females. Ducks, however, just grow bigger penises. Two species have been studied—the lesser scaup Aythya affinis and the ruddy duck Oxyura jamaicensis. During the mating season, the penises of lesser scaup drakes grow about 4cm (1.6in.) longer, and those of ruddy ducks grow 15cm (6in.) longer than normal. It’s the first known example in vertebrates of social competition being driven by the size of male genitalia.

The golden-collared manakin Manacus vitellinus is a small, mainly yellow, bird that lives in the tropical rainforest of South and Central America.

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