Phasianus

Phasianus pheasants are a harem polygynous species that are a highly sexually dimorphic genus, where males are large and elaborately ornamented with brightly coloured plumage, ear tufts, wattles, spurs, and long tails, compared to females that are non-ornamented with a dull cryptic plumage.^[7][8][9] They have a polygynous mating system that is based upon males defending mating territories during breeding season in the early spring to control access to females with higher quality resources and defence against predation.^[7][10][11] Females are free to move between different male territories, allowing them to benefit from direct or indirect benefits by choosing high quality mates and areas with better resources for their offspring.^[11] Phasianus chicks are precocial so males provide no parental care for their young.^[7][10][11]

A male's ornaments and weaponry are a symbol of status that allow females and rivals to examine a male's fitness and fighting ability.^[7] During breeding season, males court females or challenge other males by enlarging their sexual traits, sloping their body towards their opponent or mate while spreading their tail and plumage, inflating the wattle and raising their ear tufts.^[11] Older males usually have more exaggerated ornaments and weaponry than younger males, and are more likely to mate and control larger territories.^[12] Submissive or juvenile males will conceal their wattle display from bigger males, reducing their chance of mating but minimizing their risk of injury by avoiding physical conflict with a more dominant male.^[11] The general brightness of the plumage may also be used to identify healthy males from unhealthy males.^[7] Only in cases where males exhibit similar characteristics, do males attack one another.^[13]

To display these traits throughout breeding season entails a physiological cost, leading to an endurance rivalry between males, where only males that can afford to display these breeding rituals will pass on their genes to their offspring.^[11][13] An example of this can be seen in the length of a male's spur and the wattle display that is enlarged during sexual displays; both are considered costly as they are highly dependent on nutrition and testosterone levels.^{[8][9][14][15][16]} Females generally prefer brighter wattles and longer spurs.^[8] The brightness in the wattle comes from storing a carotenoid pigment known as astaxanthin in their diet that is inhibited by an infestation of parasites.^[8] Only healthy individuals in good physical condition can afford to fully express bigger and brighter wattles, which may also be associated with disease resistance.^[8][16] Spurs function not only as weapons in combat between males but also as an important cue in female choice as the length of the spur signifies the male's phenotypic condition (age, weight, size) and viability.^[10][14] Studies have found that longer spurs resulted in bigger harem sizes compared to males with shorter spurs.^[15]

Females will benefit from choosing males with higher expressed ornaments, as her offspring will also inherit these genes, increasing their survival and chance for reproduction (sexy son hypothesis).^[11]

Media related to Phasianus at Wikimedia Commons