Peacocks are renowned for their striking and elaborate tail-spreading display. This impressive exhibition is a central part of the male peacock’s strategy to attract a mate and ensure reproductive success.
The Peacock’s Grand Fan
The male peacock’s “tail,” more accurately termed a “train,” is a magnificent structure composed of exceptionally long upper tail covert feathers, not the true tail feathers. When fully spread, this fan can reach up to 1.5 meters (60 inches) in length, making it longer than the bird’s body. This expansive display features between 100 to 175 specialized feathers, each adorned with prominent, iridescent “eyespots.” These eyespots typically have a dark purple-black center, surrounded by concentric rings of blue-green and bronze-gold.
The brilliant, shimmering colors are not due to pigments alone but arise from structural coloration. Microscopic structures within the feather barbules, consisting of precisely arranged melanin rodlets and air channels within a keratin matrix, interfere with light. This intricate nanostructure reflects and refracts light, creating the vibrant, iridescent hues that change with the viewing angle. The complex design ensures that the display remains visually dynamic.
Courtship and Mate Selection
The primary reason peacocks spread their elaborate feathers is to attract peahens for mating. During the breeding season, from late February to early August, male peacocks engage in a ritualistic courtship dance. This display involves strategically fanning out their train into a large, upright fan shape behind them. As part of this display, the male vibrates his tail feathers, a behavior known as “train-rattling.” This rapid vibration, occurring at an average of 25.6 hertz, creates a shimmering visual effect and a rustling sound.
The male often angles his body, sometimes at a 45-degree angle to the sun, to maximize the iridescent appearance of his eyespots. Peacocks may also circle the peahen, shaking and adjusting their tail feathers to enhance the visual impact. Beyond the visual display, loud, piercing vocalizations often accompany the fanning, serving to announce the male’s presence and attract distant females. This combination of visual, auditory, and behavioral cues is designed to capture and hold the peahen’s attention.
Signals of Fitness
The peacock’s display serves as an honest signal of the male’s health, genetic quality, and overall fitness to potential mates. Peahens evaluate various features of the train as indicators of a male’s suitability. The number and quality of eyespots are significant; males with a higher quantity of well-formed eyespots are often preferred. Experiments have shown that offspring of males with more eyespots tend to be larger at birth and have better survival rates.
The vibrancy of the colors and the iridescence of the eyespots, particularly the blue-green portions, are also important factors that correlate with mating success. The symmetry of the display is another trait peahens assess, with studies indicating a preference for males with more symmetrical patterns. While the overall size of the train is considered, recent research suggests females may assess a complex trait combining eyespots and train size, along with the male’s vigor. These elements collectively provide information about the male’s genetic quality, influencing the peahen’s choice.