Symptoms - A common symptom of a chicken crowing will be a loud boisterous call. Often generalized as a "cock-a-doodle-doo" sound. Can vary quite a bit.
1. Highly associated with maleness in a chicken, though not required.
2. Colourful plumage on the animal, though not a requirements,
3. Daybreak, though not required.
All kidding aside, I notice that our roosters crow at various triggers:
1. The sound of the garage door opening. Might the expectation that someone might wander by with some treats
2. Sunrise - but I get the sense that for the most part it is more about being let out of the coop.
3. Kids and their usual high activitiy
4. Nervousness such as an adult approaching the run or walking away from the run
Others can comment on this as well. It is just my observation.
The point I am trying to make is that if you are concerned about your rooster crowing you might want to look at what is triggering the crowing.