Another for the 'gosh, isn't this beautiful?!' files: the Himalayan Monal (the national bird of Nepal).
(Image via Facebook: Tambako the Jaguar; Flickr — with Robin Subba, Sarvesh Wangawad,Jeriko Angue, Roberto Delapisa, Jonas Mgr, Neelesh Suryavanshi, Shashank Asai,Sushant Bhujel and Pabitra Lamichhane.)
This stunning bird (Lophophorus impejanus) is a type of pheasant, and like other pheasants the species is strongly sexually dimorphic: the males are dressed in gorgeous irisdescent plumage, while the females' plumage is dark brown apart for white patches on throat & rump, & the same bright blue circle round the eyes.
Such marked differences between the sexes are often due to intersexual selection, with females acting as the agents of selection & choosing their mates on the basis of physical appearance, or other attributes that give information on the male's quality. The monal is a stand-out example of the eventual outcome.
Strongly dimorphic species are often polygamous - more usually polygynous, with dominant males mating with several females during the breeding season; phalaropes, however, are polyandrous, with the more brightly-coloured female laying eggs in the nests of several males and leaving them to incubate alone. In species where there's little dimorphism, it's often associated with monogamous breeding patterns, & as a general rule the type of breeding pattern in a given species is linked to the species' ecology.