The case of the roosters is interesting because scientists put them in the dark and they still crowed at dawn.

I think all birds sing at sunrise and sunset. This is because they have a condition called "night blindness," where they can't see at all in dim light.
They communicate by singing before they go blind. They sing more loudly at sunrise because their blindness is passing, and they feel a great sense of relief, as if they're returning to life.

orto

The pre-dawn “cock-a-doodle-doo” is closely linked to social hierarchy and dominance.

“Cock-a-doodle-doo” at sunrise is heard around the world as nature’s alarm clock, but roosters don’t just do this morning ritual out of duty or tradition. As shown by several scientific studies, roosters crow at dawn to assert their dominance and signal their social status to others.

 are social animals with a surprisingly strict hierarchy – that’s why it’s called a “pecking order”. Much of their behavior, from who gets to eat first and who gets to mate, to how territory is claimed, is governed by their hard-earned place in the social structure. Understanding their rank is essential for maintaining harmony within the flock.

For male roosters, dominance is established by aggression and certain cues, such as the size of their head’s comb and crowing ability, all of which are 

 levels of testosterone. It turns out, the timing of rooster calls offers valuable insight into the flock’s social ladder too.

 by the National Institute for Basic Biology in Japan found that the highest-ranking rooster has priority to squawk the first “cock-a-doodle-doo” of the day.

science

Animal_World

> **The pre-dawn “cock-a-doodle-doo” is closely linked to social hierarchy and dominance.**
>
> “Cock-a-doodle-doo” at sunrise is heard around the world as nature’s alarm clock, but roosters don’t just do this morning ritual out of duty or tradition. As shown by several scientific studies, roosters crow at dawn to assert their dominance and signal their social status to others.
>
> [Chickens](https://www.iflscience.com/tags/chickens) are social animals with a surprisingly strict hierarchy – that’s why it’s called a “pecking order”. Much of their behavior, from who gets to eat first and who gets to mate, to how territory is claimed, is governed by their hard-earned place in the social structure. Understanding their rank is essential for maintaining harmony within the flock.
>
> For male roosters, dominance is established by aggression and certain cues, such as the size of their head’s comb and crowing ability, all of which are [influenced by](https://academic.oup.com/endo/article-abstract/23/1/53/2772385?redirectedFrom=fulltext&login=false) levels of testosterone. It turns out, the timing of rooster calls offers valuable insight into the flock’s social ladder too.
>
> ## Why do roosters crow in the morning? 
>
> A [2015 study](https://www.nature.com/articles/srep11683) by the National Institute for Basic Biology in Japan found that the highest-ranking rooster has priority to squawk the first “cock-a-doodle-doo” of the day.
>
> [**...read more at iflscience.com**](https://www.iflscience.com/why-do-roosters-crow-at-dawn-78821)

Why do roosters crow in the morning? Why do roosters crow in the morning?