Stimulus controlled fighters

At temperatures above 30 degrees Celsius, an increased humidity of 80% and in the presence of females, adult males in the territory easily get into a tournament mood. Especially dominant males jostle their conspecifics and drive away subadult animals. But if two equally strong rivals meet, it comes to a spectacular showdown. The opponents try to lift the rival's carapace with their gular shields and turn it onto its back. With their heads tucked in and their hind legs bent, the males hammer each other, but there is practically never any biting. If both males follow the same fighting style and try to lift their opponent from the side, a dance-like circular movement occurs. Sometimes, males in threes or fours are also involved in such a round of fighting. These circular fight tracks are visibly marked in the sandy ground of tournament grounds. To demonstrate dominance, males also ride up on smaller males and attempt to mate with them.

Inferior males in the comment fight are driven away from the show grounds, but not really pursued further. When the heat decreases, inferior males are tolerated by the current dominant alpha without any problems. The males of the same size in our breeding group sometimes beat each other up for hours, but are on good terms again the following day. Nevertheless it is very important that the animals can avoid each other at any time and that too aggressive conspecifics can be separated. The winner of a fight has the mating privilege. The alpha male, which is highly tuned in the commentary fight, also increasingly successfully proceeds to mating. Interestingly, these ritualized comment fights are carried out again and again, and the alpha male can be replaced after days by another equally large and strong male.

Sometimes also sexually mature females show an aggresive behavior during the mating season and drive away smaller conspecifics or try to ride up on them. It is conceivable that this dominant behavior is associated with an active oviposition cycle and is triggered by certain hormones.

In behavioral biology, a commentary fight is a ritualized fight in which the risk of injury to the opponents is relatively low. Commensal fights have a precisely defined ? and therefore largely predictable ? sequence of behaviors for the opponents. They are widespread in the animal kingdom, for example in connection with the determination of rank within a group of animals or in the course of a courtship ritual. The characteristic feature of the commentary fight is that during the fighting action mechanisms of aggression inhibition are active at the same time, so that the fighters avoid serious injury of the opponent. Usually, the fight ends as soon as one of the two signals its inferiority and thus triggers an inhibition of aggression in the superior.

In Astrochelys radiata, comment fights are mainly triggered by external stimuli, such as an increase in daylight, temperature, and humidity. But also the presence and smell of adult conspecifics can stimulate a comment fight.