Oshima Park Zoo on Izu Oshima moved its Aldabra giant tortoises into outdoor enclosures this Wednesday to mark the start of the summer season.

This annual transition is critical for the health of the tortoises, as the species is highly sensitive to cold temperatures and requires specific thermal conditions to thrive. The move allows the animals to engage with their environment and provides educational opportunities for the local community.

Zoo Director Hitoshi Suzuki said the decision to move the tortoises is based on specific temperature thresholds. The facility generally looks for a minimum temperature of 15°C [1] as a guideline for the transition. Because temperatures can fluctuate, the zoo waits until the cold weather consistently eases before moving the animals outdoors.

This process occurs every year in early June [2]. To maintain their health during the winter months, the tortoises are kept in indoor housing from October through May [3].

During the move on June 10, the zoo organized an event where local children participated by feeding the tortoises ashitaba, a type of celery-like leaf vegetable. The interaction served as a public introduction to the giant tortoises, which are among the largest land-dwelling tortoises in the world.

"We generally use a minimum temperature of 15 degrees as a guideline," Suzuki said. "Because these tortoises are sensitive to the cold, we move them once the chill gradually eases."

“The facility generally looks for a minimum temperature of 15°C as a guideline for the transition.”

The strict adherence to a 15°C threshold demonstrates the specialized husbandry required for mega-fauna in non-native climates. By synchronizing the tortoises' outdoor access with specific meteorological markers, the zoo mitigates the risk of respiratory infections and metabolic dysfunction associated with cold-induced stress in reptiles.