Astrochelys radiata is a gentle, sensitive and rather pacifistic tortoise. In captivity it behaves outside the mating season towards conspecifics of both sexes usually extremely tolerant and compatible. Hand-raised Radiated Tortoises become very trusting, like to be fed by hand and also to be cuddled on the head. Adult, tame Radiated Tortoises recognize their caretakers from afar and sometimes interfere with their curious, pushy and begging for food nature care and cleaning work in the enclosure so that they must be temporarily separated into a separate area. Females seem to be somewhat more sensitive and susceptible to stress in husbandry and care than males. Like all tortoises, radiated tortoises do not like to be picked up. However, tame animals will tolerate short lifting and transport maneuvers over time without immediately going into a stress or defense mode. Wild caught or very shy specimens react to being touched and lifted with immediate, jerky retraction of the limbs. A hissing sound is often heard, caused by the muscle pressure of the retracted limbs on the lungs and the rapid expulsion of air through the nostrils. If a suspected troublemaker does not leave, the animals urinate in a wide jet of defense and protest. A frightened or injured Radiated Tortoise may retreat so tightly and convulsively into its own shell that the limbs can hardly be pulled out of the shell by hand. This often makes examination and medical treatment impossible in Astrochelys radiata.

During the day, Radiated Tortoises spend most of their time foraging. They are most active in the morning and late afternoon. During the greatest midday heat, they like to doze in the shade of bushes and shrubs. During long periods of drought, the animals crawl into hiding places to conserve energy and resources in a kind of drought rigidity. Body functions and metabolism remain greatly reduced. This survival strategy is very effective during the winter season with cool night temperatures as well as during hot drought periods and is always initiated by extreme dryness of the environment. The drought rigidity is reversed by the approaching rainy season. The increase in humidity encourages the animals to leave their hiding places, mate and drink copiously. Warm-humid weather is the trigger stimulus to fully reactivate the organism of radiated tortoises. Water is a rare, precious commodity in southwestern Madagascar and is always greedily consumed by ray turtles when available. During the rainy season, the animals are particularly active, so that most mating also falls into this time. This particularly active behavior can also be observed in captivity in the outdoor enclosure before, during and after warm summer storms.

In case of strong and sudden excitement, Radiated Tortoises show a very special behavior. They lift their shells horizontally from the ground with their strong legs, stand stretched out on their legs and remain in this raised position for several minutes. Especially often and reflexively the animals show this behavior when it starts to rain or when you gently shower them with lukewarm water. The meaning of this striking and somewhat strange behavior is not known. We suspect that this reflexive movement may be spontaneously triggered by ground-level vibrations and low sound frequencies, such as those caused by approaching thunderstorms and falling raindrops. The sudden state of arousal allows the animals to quickly fill their lungs with lots of oxygen, increase blood pressure, and activate the entire organism more quickly, regardless of temperature. The tortoise could thus awaken more quickly from rigor mortis or another inactive state and, when rain begins to fall, absorb as much fluid as possible before it seeps back into the parched and water-permeable calcareous soil. This reflexive "power activation" of the organism could be an adaptation to a very dry habitat in order to be able to regulate the water balance again as quickly and efficiently as possible.