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City Weekend

Ecologists left hopping mad after Hong Kong politician calls for tadpole cull because ‘frogs are too noisy’

Scientists point out declining amphibian population contributing to an increase in pests such as mosquitoes

PUBLISHED : Saturday, 28 July, 2018, 10:05am
UPDATED : Saturday, 28 July, 2018, 10:03am

A Hong Kong politician has spawned a furore by calling for tadpoles in a public housing estate pond to be exterminated before they become “noisy frogs”.

Ecologists were quick to point out Yuen Long district councillor Ma Shuk-yin was jumping to the wrong conclusion in calling for a cull on the Tin Yiu Estate – as this could result in an increase in mosquitoes.

“Tadpoles compete with mosquito larvae for algae, so by removing them you’re likely to see an increase in the number of mosquitoes,” says Sung Yik-hei, an assistant research professor at the School of Biological Sciences with the University of Hong Kong.

Sung adds Ma’s views are worrisome and reflect a need for greater education in the city.

In a Facebook post on Wednesday, Ma wrote: “I am worried that when these tadpoles grow into frogs, the noise they make will disturb the neighbours.”

She urged the estate manager to “deal with it properly as soon as possible”.

Following a barrage of criticism, Ma doubled down with a second post, saying she was concerned that “too many creatures of a single species will influence the biodiversity of the pond”.

Sung explains the importance of the animals to the ecosystem.

“When tadpoles metamorphose into frogs, they become predators for a large number of insect pests, from mosquitoes and flies to termites.” he says.

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“Tadpoles and froglets [small frogs] are a food source for birds, fish and insects. They’re a really important part of the food chain.”

Only a small number survive to reach adulthood during which males begin making noise to attract others.

“Many people would agree that the noise made by humans is much more of a problem in Hong Kong. If we cannot tolerate frogs in a pond, how can we live on Earth?” Sung says.

Ma meanwhile is keen to allay fears that the tadpoles had already been removed.

“There has been a misunderstanding caused by my wording,” she says. “I have told residents we can accept the noise in the future, because we should not interfere with nature.”

She says her initial comments had been spurred by past complaints from residents, especially in summer, about the amphibians’ mating calls.

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But no action has so far been taken, she adds.

“The only advice I gave the estate manager was to include more creatures, such as fish and turtles, in the pond to make it more lively,” she says.

Chu Lee-man, an associate professor at the School of Life Sciences at Chinese University, was surprised residents would complain about the frog calls.

“I find it ridiculous,” he says. “All life has some intrinsic value. If you’re going to kill all the tadpoles because you’re worried about noise, would you also consider killing dogs because they bark? Or birds because they sing?

“More importantly,” Chu stresses, “these animals are not pests.”

If residents had indeed complained, it would be a good opportunity to educate them, he says.

“As a councillor, you can help teach people. Most of the frogs’ habitat in Hong Kong is being removed for development.

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“The consequence is we have more pests – especially mosquitoes, which are coming back, partly because there has been a decline in amphibian populations. And then, we have more diseases carried by mosquitoes.”

Chu adds that even in a concrete jungle like Hong Kong, there was close interaction between species, and these intricate relationships had a huge impact on humans.

“If we upset this balance, it can be disastrous, so getting rid of tadpoles because you’re afraid the frogs will make a noise is illogical.”

Greater ecological education and awareness was needed about these “ecosystem services”, Chu says, which indirectly contributed to human health.

“It’s important to tell people we’re not separate from the ecosystem – we’re in it – so tolerance is really important,” he says. “If they understand that, they might appreciate life more.”