Three lions whose ill health was confirmed at the Tama Zoological Park lion enclosure in July 2026 have died. Insufficient heat countermeasures are believed to have been the cause, and measures to prevent recurrence have been announced.
In July 2026, several lions at the lion enclosure of a metropolitan zoo were confirmed to be in poor health, and 3 of them died on 3 August. After treatment began, 3 lions had recovered by 29 August. Heat countermeasures, including the installation of spot coolers in the lion house, were strengthened. The cause was investigated by the Crisis Management Committee, and measures to prevent recurrence were compiled based on the test results.
Based on the circumstances at the time of onset and the results of tests by external organisations, heatstroke and multiple organ failure are considered most likely to have resulted from the cumulative effects of heat while the lions were insufficiently acclimatized to high temperatures. Relatively cool conditions prevailed from June through early July, but the subsequent sharp rise in temperatures is cited as a contributing factor.
To prevent recurrence, facility measures will be strengthened, including renovating the large outdoor enclosure, ensuring shade beneath trees, installing shading equipment and introducing large fans. Over the longer term, renovations to the lion house, installation of permanent air-conditioning equipment, improvements to power-supply facilities and the introduction of air-conditioning units in shaded areas will be considered.
In terms of animal management, the zoo will proceed with measures including introducing equipment capable of remotely measuring temperatures in the outdoor enclosure and the animals' body temperatures, and will establish a system linking the sharing of information, medical treatment and suspension of exhibits when abnormalities are observed. Going forward, criteria for suspending exhibits based on the Wet Bulb Globe Temperature (WBGT) heat index will be established.
As of 29 October 2026, Tama Zoological Park was keeping 13 lions (5 male, 8 female). Exhibits of lions that recovered after receiving treatment will resume on 30 October 2026.