More Than 100 Herons Die in Toyama Park, Japan; Causes of Deaths Are Unknown

The Yomiuri Shimbun

18:10 JST, July 21, 2025

TOYAMA — More than 100 herons have died at Toyama Joshi Koen park in the center of Toyama City since late last month.

So many herons dying in such large numbers at around the same time is unusual, and the Environment Ministry has begun an investigation in the cause at the request of the city.

The number of dead birds totaled 104 by July 18.

The avian influenza tests conducted by the ministry were negative, and it is conducting another test.

According to the city’s division in charge of parks, six pine trees were cut down at the park and the water in the moat was replaced between June 23 to 27. The water was drained over the course of about two days and chemicals were added to prevent the growth of algae, but it is unclear if these factors were related to the mass deaths.

The number of herons in the park has been increasing over the past three years, and about 100 birds were confirmed to be nesting at the park this spring.

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