In one of those studies where researchers find out that the sun is hot and water is wet, they have finally understood that cockerels crow in the morning because they are regulated by their internal clock.
The study found out that they can sense the crack of dawn even when they are in a windowless sound-proof enclosure. This suggests that something more than external cues are at work. The cockerels which were studied in an enclosure could still crow at the same time even when the environment was manipulated and controlled.
The biological clock suggests that cockerels do not need cues of the rising sun, increased honking of vehicles, other animals that may wake up early or just about anything that we thought was enough to give cockerels clue that the sun is about to rise. Instead, they have a circadian rhythm which tells them that it is time to wake up and crow, just like they have been doing for thousands of years. What I fail to understand is, why researchers sometimes have to prove what is already obvious.
I did not do a review of available scientific literature before writing this post, but I bet there must be some study that had already proven that animals have circadian rhythms and they sense which part of the day it is at a particular moment. Dr Takashi Yoshimura, a professor of animal physiology at Nagoya University revealed that he led the research in order to find out of the crowing was regulated by a bodily rhythm or because of external stimuli. I guess he finally found out what we all knew already for hundreds of years.
If you like animals and hate it when people are being cruel to them, you might want to take a look at these 9 Video Games that Promote Animal Cruelty.