At a drainage pool near a popular hiking site in Hong Kong’s rural Tai Po district, a group of volunteers armed with snorkels, nets and gloves wade through the muddy water to find dozens of turtles left there by residents.

Thousands of animals are affected every year and scores are likely to be released in May leading up to the Buddha’s birthday on May 19, conservation experts said.

“It’s not suitable for these turtles to live in places like these catchwater drains or ponds because they are not local Hong Kong species,” said Sean Lai, who runs a concern group for abandoned turtles.