Summary: Bonato et al. (2009)

Female birds invest more in reproduction than males, due to egg production. Therefore, females should change their investment in any one breeding attempt in relation to the probability of it succeeding. Females of many species favour mating with males that show elaborate ornamentation, possibly because ornamentation is an indicator of male quality. Thus, females should invest more in more ornamented males. Egg size is a good indicator of maternal investment and chicks hatched from larger eggs growth faster and have a higher chance of survival. Bonato et al. (2009) investigated the relationship between male colouration (measured using UV-visible range spectrophotometry) and egg mass in male ostriches (Struthio camelus). They assessed paternity of eggs using microsatellite markers. Female ostriches discriminate between males on the basis of ornamentation and some features of male colouration (neck colour, white and black body feathers and brightness of black feathers) are good predictors of egg mass. Bonato et al. (2009) suggest that these visual cues influence female perception of male quality and females adjust their level of maternal investment as a result. Their study has important implications for the ostrich farming industry, where hatching success is notoriously low.