“The decision has been made to withdraw this category for this year to avoid further backlash at this time,” the competition’s organizers said in a statement posted on Facebook. “We are disappointed and apologize for those who were excited to be involved in something that is about protecting … native birds, and other vulnerable species.”

Conservation authorities say feral cats are a significant threat to the South Pacific country’s unique wildlife, including native birds such as the flightless kiwi. Unlike stray cats, which typically remain reliant on humans and scavenge for food in urban environments, these cats are wild — roaming miles of countryside and preying on birds, bird eggs, bats, lizards and native insects, according to officials.

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The first cats arrived with early European explorers on ships in the 1700s, and wild cat populations grew around the country. These cats are often larger than their house cat counterparts. New Zealand has set an ambitious goal of eradicating by 2050 all nonnative pests — including feral cats, weasel-like stoats, possums, rats and mice — that have decimated much of its unique fauna.

But the idea of enlisting children, armed with air rifles, in an effort to kill feral cats set off alarm bells among animal rights groups, which worried they could easily mistake house cats for wild animals and would struggle to kill them humanely.

“It is very difficult to tell the difference between a feral cat and a pet cat,” Will Appelbe, a spokesman for the animal rights group SAFE, said over the phone on Wednesday.

Many New Zealanders let their cats roam freely outdoors and “the boundaries can be blurred,” Appelbe said. “I spoke to someone yesterday whose cat used to be a feral cat, and it was trapped and tamed and subsequently re-homed.”

New Zealand has one of the highest rates per capita of cat ownership, and relatively lax rules around registration and breeding have seen house cat populations rise in urban areas bordering native animal habitats.

The competition stated that any cat found to be embedded with a microchip would be disqualified, which Appelbe said wasn’t a good deterrent, “because the cat is already dead by that point.”

“The problem with competitions like this is that they tend to attract novices, in this case children,” he said.

“To place a killing shot on a cat is quite difficult,” he added. “So if they shot a cat and it didn’t kill it, that cat is likely to suffer for a long period of time.”

The North Canterbury Hunting Competition did not immediately respond to a request for comment on the decision to cancel the children’s component of the competition, which is held annually to raise funds for the rural South Island community and village school.

The organizers said on Facebook that the school had been receiving “vile & inappropriate messages and emails” since the new prize category was unveiled on Saturday, and the decision to withdraw it was made partly over safety concerns.

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Craig Gillies, principal scientist at the Department of Conservation, declined to take an official position on the event but said in an email that feral cat control “should be undertaken by skilled and experienced people using the right equipment and methods.”

He said the department uses “humane and approved methods to control feral cats to minimize the animals’ suffering,” mostly through trapping, but sometimes with lethal toxins and firearms.

Christine Sumner, a science officer at SPCA New Zealand, the animal welfare organization, acknowledged that “sometimes feral cats may be killed as part of an overall strategy to protect biodiversity.” But it requires a “coordinated response,” she said.

“Instead of organized killing events, humane education can better prepare young people to appreciate and protect the biological heritage of New Zealand,” she added.