Size really does matter to birds, scientists have shown...

22 January 2012
Posted by Hannah Critchlow.

A study in this week's edition of the journal Science shows that male bower birds, which live in Australia, use a visual trick to fool females into thinking the males - and the titbits they offer as part of their courtship rituals - are larger than they really are.

Laura Kelly and John Edler from Deakin University, Australia captured over 1600 hours of footage of the mating activities of 20 male birds. 

The filming revealed that the males construct 'courts', avian dance floors, decorated with an arrMale Satin Bowerbird, Ptilonorhynchus violaceusay of objects including stones, dried fruits and shells which are selected by the males during foraging flights. 

The arrangement of these objects is carefully coordinated by the male birds to produce an illusionary trick called forced perspective to make the overall court area look smaller.

He does this by arranging display objects with the largest items are farther away. The female surveys the spectacle from nearby.

During the courtship ritual the male picks up a large decorative item from the back of the court and pops it in his beak, and brings it forwards to the female as a wooing offering. Great Bowerbird bower

Compared with the smaller items at the front of the display, the offering in his beak, and the bird himself, now look much larger!

And the scientists showed that males who made the best use of this forced perspective effect  in their bowers were much more likely to attract a female and mate!

Using this illusion, the scientists think, helps to enhance the male bower birds assets......

So, is there a lesson to be learnt from the male bowerbird? Well guys, may I suggest perhaps pruning away the undergrowth to make your offerings look bigger than they actually are......

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