Unlike humans, chickens and other birds cannot move their eyes to adjust their vision as their bodies move. Therefore, chickens must keep their heads still to ensure their vision. The eye correction system that automatically stabilizes your vision while you run Chicken save gas ride my cock shirt, jump, or dance is simply lacking in chickens. Chicks grown with prosthetic tails actually changed their posture, and had an upright femoral structure, confirming that there was "a shift from hip to knee adjustment to move. Hens reject sperm from low-status roosters based on selection criteria. The researchers found that, if the roosters were of low rank, the hens were more likely to reject sperm from them.