Lion situation (final report)

In July 2026, several Lion at Tama Zoo 's Lion enclosure were found to be unwell, and subsequently, three of them died (announced on August 3, 2026). We have conducted an investigation into the cause of this incident and compiled measures to prevent recurrence, which we would like to report to you.

I would like to once again sincerely apologize for causing everyone concern.

1. Response after an accident

(1) Treatment of Lion

On July 18, two Lion were found to be suffering from symptoms such as loss of appetite, so medication was started. Subsequently, several other lions showed similar symptoms, so treatment was provided to them as well. As of August 3, the three lions that were recovering had all recovered by August 29.

(2) Strengthening measures against heat

Since heat stress was suspected as the cause of several lions' poor health, we strengthened heat countermeasures, such as installing spot coolers in Lion enclosure, in parallel with treatment.

(3) Investigation of the cause and compilation of measures to prevent recurrence

Tokyo Zoological Park Society established a crisis management committee, which sought expert opinions from director metropolitan zoos and aquariums, as well as veterinarians from each facility.

Subsequently, we reviewed the circumstances of the incident and the test results, and compiled a report on the cause and measures to prevent recurrence.

2. Consideration of the cause of the accident

Based on the circumstances at the time of onset and the results of various tests conducted by external organizations, the most likely cause of death is thought to be heatstroke resulting from the accumulation of heat-related effects without sufficient heat acclimatization (the body becoming accustomed to the heat), and multiple organ failure due to severe heatstroke.

While we carried out breeding and management as usual, the temperature rose sharply after June and early July, when it was relatively cool. We believe that insufficient acclimatization to the heat was a contributing factor to the accident.

3. Preventing recurrence of accidents

(1) Facility measures

Within the large enclosure, by next summer, we will make it easier for the animals to utilize the shade under the trees and install shading equipment to increase the amount of shade. In addition, we will create airflow by installing large fans and proceed with improvements to the watering holes.

In the medium to long term, we plan to renovate Lion enclosure, install permanent air conditioning, improve insulation and airtightness within the enclosure, and install power supply equipment. We will also consider installing air conditioners in existing shaded areas such as the scaffolding within the large enclosure.

(2) Measures for breeding management

We will introduce equipment that can remotely measure the temperature inside the enclosures and the body temperature of the animals, allowing us to take measures before the risk of heatstroke increases. In addition, if any abnormalities are observed, we will revise our system to ensure that information is quickly shared within the park and with relevant departments, leading to appropriate medical care or the suspension of exhibits.

In the future, we will formulate criteria for suspending exhibits that take into account the heat index (WBGT) published by the Ministry of the Environment and any signs of abnormality in Lion, in order to manage the health of animals while considering the risk of heatstroke due to climate conditions.

4. Animal care status at Tama Zoo (as of October 29, 2026)

13 individuals (5 males, 8 females)

Lion that was recovering (after recovery)

Regarding the reopening of Lion exhibit

Lion exhibit will reopen on (Fri), October 30, 2026.
Please see the link below for details.