The reason why a mallard’s head appears green is due to the phenomenon of structural coloration. Unlike other animals that obtain their colors from pigments, the vibrant green color of a mallard’s head is a result of the interaction of light with the microscopic structure of the feathers.
Feathers are made up of keratin, a protein found in the outer layer of the epidermis. In the case of mallards, the feathers on their head have a unique structure that causes light to scatter and reflect in a way that produces the green color. This structural arrangement is known as iridescence.
When light hits the feathers at a certain angle, it undergoes a process called interference. This occurs when the light waves interact with each other, either reinforcing or canceling each other out. The specific structure of the feathers on a mallard’s head causes certain wavelengths of light, particularly in the blue and green range, to reinforce each other, resulting in a vibrant green color.
The iridescent green color of a mallard’s head can be further enhanced in bright light conditions. This is because the intensity of the light affects the angle at which it strikes the feathers, leading to a more pronounced reflection of green light.
Interestingly, the color of a mallard’s head can change depending on the viewing angle. When observed from different positions, the intensity and hue of the green color may vary. This variation is due to the way light interacts with the feather structure at different angles.
It’s important to note that not all ducks have green heads. The green coloring is specific to male mallards, known as drakes. Female mallards, or hens, have more subdued coloration, with mottled brown feathers for camouflage purposes.
The green color of a mallard’s head is a result of structural coloration caused by the unique arrangement of feathers. This iridescent green hue is a captivating characteristic of male mallards, contributing to their visual appeal and recognition.