Gorgeous Gorget

[Donkees]

3. Anna's Hummingbird (Calypte anna)

The male has a striking reddish-pink crown and gorget, which are strongly iridescent and dependent on the angle of illumination and observation by female or male competitor birds.[8] The iridescence results from large stacks of melanosomes in the feather barbules, occurring as layers separated by keratin.[8] The barbules reflect incident light in the manner of partially-opened Venetian blinds, enabling the iridescence – which varies the head and gorget coloration with the changing angle of light – as a coloration advantage for courtship attraction and territory defense.[8]

Male birds with elevated levels of protein in their diet have more colorful crowns and higher iridescence in their head feathers compared with male birds with low protein intake.[9]

https://en.wikipedia.org/wiki/Anna%27s_hummingbird