The knowledge that chickens will watch one another on television inspired one of us (Smith) and her colleagues to create a 3-D animated rooster using the same rendering technology employed in movies such as Skyfall and Titanic. This virtual rooster allowed the team to test the meaning of the birds' displays and their perceptions of one another. It also solved the age-old question of why roosters have wattles.
The wattle is that dangling flap of skin that hangs loosely from a rooster's beak. When a male performs his tidbitting display—a series of head movements that he uses to tell potential mates that he has found food—the wattle swings back and forth, even smacking him in the side of the head if he gets too enthusiastic.
Decades of research had failed to find any benefit to the male's having a wattle. Smith suspected that the flap of skin might make a male's tidbitting display more obvious and give him an edge in attracting the females, but she could not test her idea by cutting off the appendage and seeing how a female reacted. Instead she created an animated rooster that would tidbit on command for a live hen and then altered the flexibility and size of the wattle on her animated bird to test how the females would react.
The wattle, it turned out, acts like a red flag to the females, making it easier for a hen to spot the male who has the food. For the male, the ornament may cost him a bit in terms of his health because a bigger wattle comes with more testosterone, which weakens the immune system, but the cost is worth it in the long run because it gets him the girls.
Sometimes the chickens' intelligence made studying them challenging. On multiple occasions a bird would subvert an experiment by answering a different question than the one the researcher was posing. In a test of the tidbitting display, Smith had created a setup in which a hen got a chance to watch a video of a male with food. To do so, the female had to wait behind a door that had been rigged with a remote-controlled servo stripped from a toy car. One hen that wore an orange band with the numbers 07 (and thus affectionately dubbed “007”) was notorious for getting into trouble. While waiting for the researcher to open the door via remote control, 007 grew impatient and began examining the release mechanism closely, turning her head from side to side. After a few moments, she carefully plucked the wire that controlled the latch. The door opened, and 007 got what she wanted: to be close to the guy and his food. After that single trial, she would never wait again. Although the researchers changed the latch configuration several times, 007 was always able to solve the puzzle and escape before her turn. —C.L.S. and S.L.Z.
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