Re: How do roosters know when to crow when it’s dark?

Roosters crow during pre dawn hours.

There are similar events occurring through the life of
various plants and animals including human.
Even though you/we love to sleep, we cannot. Even before we
wake up in the morning our biological clock sends signals to
appropriate centers in the brain so as to prepare our body
to wake up and do our morning tasks. For example, our body
temperature which drops by 1 to 2 degrees centigrade when we
sleep, begins to raise an hour before we wake up. This is
because of the biological clock (others names: head clock,
circadian clock, endogenous clock).

Before the sun rises, water lilies start closing their
petals - a endogenous clock controlled phenomena.

The biological clock in roosters initially send signal which
triggers a cascade of activation of different centers in the
brain. One of the resultant activation leads to the crowing of ROOSTERS.