Also, females may be more likely to engage in extra-pair matings when they have a poor quality mate ("trade- up hypothesis") (Kempenaers et al. 1992).
What colors animals can detect will influence their ability to forage and hunt, avoid predators, and select quality mates.
Assortative mating may result from lower-quality individuals mating with each other due to the inability to attract or retain a high quality mate, rather than preferences for a particular phenotype [14], [43].
According to sexual selection theory, females should actively choose high quality mates, as determined by reliable indicators of male quality [8].
As a result, "high quality" (i.e., experienced) birds may choose high quality mates to avoid poor synchronization and reduce the need to compensate for a partner who requires more time at sea [66].
Another one of the main hypothesis suggests that QP in non-passerine birds is an insurance mechanism against the potential detrimental effect of inbreeding, or more simply, males' own low quality mate [31].
Second, G. gracilicornis females may delay intromission in order to carefully assess the male's "quality," and therefore may display more resistance to some males (physically and by delaying genitalia protrusion), and less resistant to others of better quality (Mate assessment hypothesis).
When both sexes show preferences [ 21] for high quality mates, irrespective of own quality, low quality mates may be unacceptable.
Courtship vigour may help females identify high quality mates when conspicuous colour signals were reduced [ 50].
Hence, by linking urine release with aggressive behaviour females can select high quality mates and enhance their fitness.
