A Literal Bird

A Literal Bird

Geoffrey Giller
Published: 07/25/2013

A male peacock shows off its full display. Photo by Koshy Koshy / CC BY 2.0

Peacocks have some of the most ostentatious (and famous) feathers in the animal kingdom. When in full display mode, the males are a sight to behold, their grand fan of feathers reaching heights of over five feet, with shimmering greens, blues, and coppers forming the distinctive “eyespot” patterns.

But as it turns out, peahens (the females of the species) don’t pay too much attention to the impressive height of those flamboyant feathers. A study, published yesterday in the Journal of Experimental Biology, found that peahens directed their gaze at the lower part of the display, including the denser feathers at the very bottom of the fan. The upper parts of the display, which includes most of the eyespots as well as the distinctive “fishtail”-shaped feathers at the end (see photo above), were mostly ignored. “It was definitely surprising when we initially saw that most of the gaze was directed at the lower portion of the peacock’s train,” says Jessica Yorzinski, the lead author of the study.

A peahen shows off her eye-tracking system while a peacock displays in the background. Photo by Jessica Yorzinski.

The researchers outfitted 16 peahens with small helmets that use a high-tech vision-tracking system to see exactly what the birds are looking at. The system, adapted from similar ones used in psychological studies of humans, uses infrared light reflections to pinpoint where the birds are looking. The researchers analyzed the footage from the setup (see an example here) and calculated the amount of time each peahen spent looking at the various parts of the males’ displays.

A peahen (foreground) and displaying peacock (background). The "backpack" housing part of the eye-trackign system can be seen on the peahen. Photo by Jessica Yorzinski.

For Yorzinski, the most intriguing part of the research was seeing the peacock displays through the females’ eyes. She says she could essentially “ask [each peahen] what visual signals she’s using when she’s choosing a mate.”

The researchers were also curious why the peacocks would evolve such tall displays if the females were only looking at the bottom part. They suggest that females may use the top of the display to find the males in the dense vegetation of their native habitat. But once they locate the males, the females turn their gaze away from the towering heights of the feathers, focusing solely on the lower feathers.

Yorzinski says that this is the first time anyone has used this eye-tracking technology to find out exactly what catches a peahen’s fancy. The technique could be expanded to other species, offering bird’s-eye views like never before.

 

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