In an attempt to entice and mate with females, male bowerbirds (Ptilonorhynchidae) have complex displays including dancing, vocal features, and courtship bowers. Bowers are areas that are cleared and decorated for mating purposes only. Depending on the species, the style of the bowers range from simple leaf arrangements to extravagant structures decorated with bright objects, and female viewpoints. There has been some scientific research to try and elucidate aspects of bower evolution. In this paper I will consider how female choice of bowers may have evolved through bower ornamentation as well as bower location. I will also investigate how bower design has evolved as a highly varied trait across species. I will highlight one study that has attempted to clarify this aspect of bowerbird development by suggesting that the evolution of bower complexity is connected to the evolution of brain size.
Female choice of bowers is highly swayed by the male’s ornamentation technique. It has been debated as to how this female attention evolved to focus on the bower. Bowerbirds that have plain plumage usually have elaborate bowers, and the birds with ornate and brightly colored plumage generally have simple bowers with few decorations. This observation led to the hypotheses that female choice has been switched from male ornamental plumage to bower design. This shift allowed for more extravagant ornaments, geared male aggression toward other males attempting to steal their ornaments, and helped to make males more cryptic to predators.1
Female choice of bowers may not only be influenced by decorations, but also by bower location. The marker hypotheses explains that female bowerbirds favor dominant males that reveal their genetic quality by competing for territory. Male bowerbirds gather in groups called leks to present their sexual displays. In a given mating season, success is usually achieved by only a few of the males. Female choice is correlated to
Bibliography: 1) Diamond J. 1986: Biology of birds of paradise and bowerbirds. Ann.Rev.Ecol.Syst. Vol. 17: pp. 17-37. 2) Borgia G. 1985: Bower quality, number of decorations and mating success of male satin bowerbirds (Ptilonorhynchus violaceus): an experimental analysis. Anim. Behav. 33, 266-271. 3) Day LB, Westcott DA, Olster DH. 2005: Evolution of bower complexity and cerebellum size in bowerbirds. Brain.Behav.Evol. 66:62-72. 4) Endler JA. Endler LC. Doerr NR. 2010: Great bowerbirds create theaters with forced perspective when seen by their audience. Current Biology 20. 1679-1684.