Bird Brained Illusionist and Illusions Promote Mating Success in Great Browerbirds
A new study suggests that male browerbirds, who are known for arranging rocks (fig 1), organize them to utilize a forced perspective (fig 2). Larger rocks placed further away make the projected texture appear more uniform. Males are arranging rock gradients so that female birds perceive a larger nest from a vantage point. Females choose mates from those who produce the best illusion. The scientists are exploring whether the birds construct these illusions intentionally.
Kelly, LA and JA Endler. 2012. Illusionist and Illusions Promote Mating Success in Great Browerbirds. Science 20, January 2012. Vol. 335 no. 6066 pp. 335-338