Suspected heatstroke kills 3 lions at Japan zoo

Three lions from the Tama Zoological Park in Tokyo have died from suspected heatstroke, while others are receiving treatment, according to a zoo spokeswoman. The big cats were experiencing high humidity levels, which compounded the effects of the extreme heat. Japan experienced its hottest summer on record last year, with temperatures soaring above 40°C in several regions.

Since mid-July, ten out of the sixteen lions at Tama Zoological Park have exhibited symptoms like loss of appetite and decreased activity. Decomposition and multi-organ failure were identified as the probable causes of death in the deceased lions, reported by the veterinarian. The deaths occurred on Tuesday, Friday, and Sunday, respectively.

Zoo authorities have been increasing their heat mitigation efforts, including water sprinkling, enhanced ventilation, and the installation of spot air conditioners. The sudden onset of heat, following the conclusion of the rainy season in late July, added to the challenges faced by the zoo keepers. Despite lions being considered heat-resistant, the zoo has been intensifying its preventive measures due to Japan's unique combination of heat and high humidity.

Several other lions are currently undergoing treatment. Approximately 18,600 individuals sought medical attention for heatstroke between July 20 and 26, with 45 of them succumbing to the condition upon arrival at the hospital. Japan records around 1,300 heat-related fatalities annually and is striving to cut this number in half by 2030.

Climate scientists attribute the rising frequency and intensity of extreme heat events in Japan to human-induced climate change. The country's all-time high temperature of 41.8°C was recorded on August 5, 2025, in Isesaki, north of Tokyo. In response to the heat, authorities have altered the schedules of various cultural and sporting events, such as the World Cosplay Summit in Nagoya, which last held its summer event last weekend.