Ornaments are equally informative in males and females: a bivariate meta-analysis in birds

Abstract

Female ornaments are often reduced, male-like traits. Although these were long perceived as nonadaptive, it is now broadly accepted that female ornaments can be functional. However, it is unclear whether this is as common in females as it is in males, and whether ornaments fulfil similar signalling roles. To test this, we conduct a systematic review and apply a phylogenetically controlled bivariate meta-analysis to a large dataset of ornaments in mutually ornamented birds. As expected, female ornament expression tends to be reduced compared to males. However, ornaments are equally strongly associated with indicators of body condition and aspects of reproductive success in both sexes, regardless of the degree of sexual dimorphism. Thus, ornaments in birds provide similar information in both sexes: more ornamented individuals are in better condition and achieve higher reproductive success. Although limited by their correlational nature, these outcomes imply that female ornaments could widely function in a similar manner as male ornaments.

Annual molt period and seasonal color variation in the Eared Dove´s crown

“…Could this region of the body also be related to the selection process in females? In other birds, it is known that as in males, the ornamentation of females is linked to individual quality and is also subject to selection pressure [34][35][36][37]. The fact that the color of the crown in female Eared Doves changes from winter to spring perhaps indicates that this region of their body could be subject to selection pressure such as sexual selection or intrasex competitions.…”