How long can a chicken live without its head?

Because most of the basic behaviors of a chicken are controlled by the brainstem and not its brain, and because of automatic nerve responses, a headless chicken can live for a long time. They can continue living for anywhere from a few minutes to a record of 18 months.

Usually, the chicken only lives for a few minutes, because, though its brain function has ceased, its automatic nerve and muscle responses continue, and it runs as an instinctive way to flee and escape danger. According to Stuff You Should Know, there was a chicken who lived 18 months after beheading because the ax missed its brain stem.