The bower, built and decorated by the male bowerbird, is a site for sexual display and mating. This video illustrates the importance of the bower for the male Vogelkop bowerbird (Amblyornis inornatus). Being mainly olive brown in colour with no ornamental plumage, the Vogelkop bowerbird however, has one of the largest and most elaborate bowers. The bower substitutes the dull plumage, and act as an alternative form of mate attraction as contrasted with the conventional bright plumage of males in other bowerbirds such as the male Satin bowerbird.
In this video, two male Vogelkop bowerbirds constructed their bowers on the forest floor. The objects used to build and decorate individual’s bower, are dependent on the bowerbird’s preference; one prefers bright colored objects eg. orange flowers, while the other prefers dark colored objects eg. deer dung. When the female arrives to inspect each bower, the male struts and sings, convincing her to enter the bower for mating. Eventually, the female mated in the brightly colored bower, as she was less convinced with the darker colored bower perhaps because of the sprouting fungus from the dung! It is interesting to note the importance of visual display to the female bowerbird and truly, the prettier and ‘cleaner’ bower was chosen!
Sexual selection occurs in the Vogelkop bowerbirds. The sexual mechanisms displayed are inter-sexual selection (female choice of males) and intra-sexual competition (male competition for females). The females discriminate among their potential mates as males provide them only with sperm thus there is a need to ensure the health and vigor of their offspring (Borgia, 1986). Elaborate bowers and decorated display courts evolved as a result of female preference (Borgia & Albert, 2000). By the male’s ability to build, maintain, and display high-quality bowers, despite the attempts of other males to destroy bowers and steal decorations, males give females a means of assessing their dominance status and ultimately, their quality as mates (Borgia, 1985). Additionally, older males are preferred as females assumed that they tend to carry heritable traits promoting survival, such as diseases resistance or predator avoidance. The ability to survive to an old age but also has been able to maintain a high quality bower under the rigors of male competition enables the lucky male to be selected for mating!
1) Borgia, G. 1986. Sexual selection in bowerbirds. Scientific American 254: 92-101.
2) Borgia, G. 1985. Bower quality, number of decorations and mating success of male satin bowerbirds (Ptilonorhynchus violaceus): an experimental analysis. Animal Behavior 33: 266-271.
3) Borgia, G & Albert, J. C. U. 2000. Sexual selection drives rapid divergence in bowerbird display traits. Evolution 54: 273-278.
4) “Life – the Vogelkop Bowerbird: nature’s great seducer – BBC one,” by BBC. Youtube, 5 November 2009. URL:
http://www.youtube.com/watch?v=E1zmfTr2d4c (accessed on 1 April, 2010).