[Ruwan Rodrigo]

Ruwan Rodrigo asked the Naked Scientists:

My family used to raise chickens, in a small farm in Sri Lanka. We used to let them run free during the day and would close them up in a coop at night. On Fridays, we used to close them up a few hours before the sun went down. After many months, we noticed that all the chickens on Fridays would already be in their coop 2 hours before the sun went down, waiting for us to lock them up.

How did the chickens know how to keep track of time? It was quite amusing; I could never figure it out
What do you think?

[opus]

They use an egg-timer of course!