A blistering stretch of summer heat in Japan has proved deadly for three lions at a Tokyo-area zoo, where officials say the animals are believed to have succumbed to heatstroke as oppressive humidity gripped their enclosure.
Japan sweltered through its hottest summer on record last year and parts of the country have hit 40C in recent weeks, qualifying for the new designation “cruelly hot day”.
Tama Zoological Park said that since mid-July, 10 of its 16 lions have shown signs of distress, including “loss of appetite and decreased activity”, and three lionesses have died.
The zoo said one lioness died today, following another death last Friday, and a third on Sunday.
“According to our veterinarian, the cause of the deaths is suspected to be heatstroke” after dehydration and multiple organ failure were observed, a spokeswoman told AFP.
She said staff had been reinforcing safeguards in recent years despite the common assumption that lions can withstand high temperatures.
“Even though lions are thought to be resistant to heat, zookeepers have been strengthening countermeasures to cope with Japan’s summer heat in recent years. Heat here comes with high humidity; that is different from heat with dry air in Africa,” she said.
One of the lions, named Ichigo, which died at the park (Image: Tokyo Zoological Park Society)
The spokeswoman said the situation worsened when temperatures spiked quickly at the end of the rainy season.
“But this summer, heat arrived suddenly after the rainy season was over” in late July, she said.
“We are strengthening measures against the heat (further), sprinkling water, improving ventilation and installing spot air conditioners,” she said.
Several lions remain under treatment, she added.
The lion deaths come as heat-related illness rises across the country. Close to 18,600 people were taken to hospital for heatstroke between 20-26 July, with 45 of them pronounced dead on arrival, according to the fire and disaster management agency.
Japan experiences about 1,300 heat-related deaths annually and is aiming to halve that number by 2030.
Scientists say human-induced climate change is increasing the frequency and intensity of extreme heat events in Japan and elsewhere.
Its highest recorded temperature was registered on 5 August 2025, at 41.8C in Isesaki, north of Tokyo.
Authorities have adjusted the timings of a string of cultural and sporting events in recent years because of the heat, including the World Cosplay Summit in Nagoya, which held its last summer edition last weekend.
