New Zealand’s annual Bird of the Year competition has been hit by foreign interference after 300 fraudulent votes, traced to Australia, were all cast in favour of the shag.

The humorously-named seabird – also known as the kawau in New Zealand and as the black cormorant in Australia – received a flood of votes on Wednesday night that organisers said was “potentially someone’s idea of a joke”.

The popular poll, now in its 14th year, is run by Forest & Bird New Zealand to raise awareness of the country’s rare and endangered birds, and attracts celebrity endorsements, heated debate and tens of thousands of votes from around the world every year.

This year, prime minister Jacinda Ardern has backed the black petrel, which she called “the bogan of the birds”, and Stephen Fry has endorsed the kākāpō.

Last night, we had 310 dubious votes for the shag from an I.P. address in Australia. Thankfully, @dflydsci are on the case as our official scrutineers. They picked up the votes and shut them down. #BirdOfTheYear pic.twitter.com/pVyTRjMzTE — Forest & Bird (@Forest_and_Bird) October 4, 2018

For the first time in the competition’s history, a data scientist has been hired to protect the integrity of the poll, after a series of ugly voting scandals in recent years.

In 2017, ecologist Yvan Richard personally foiled one Christchurch resident who used a random email address generator to vote 112 times for the white-faced heron.

In 2015, two 15-year-old girls created fake emails to rig the vote in favour of the kōkako. The then-Labour leader, Andrew Little, who was running a campaign for the kārearea, bemoaned the fact that “the campaign’s turned dirty”.

And in a copycat attack, Guardian Australia’s own inaugural Australian Bird of the Year poll was marred by automated voting for the powerful owl.

“I think people get really passionate about their favourite bird, and some are prepared to do whatever it takes to get their bird over the line,” said a spokeswoman for Forest & Bird on Friday. “Perhaps people want to test our systems and have a bit of a laugh.”

But she also issued a stern warning to fraudsters to stop.

“There are better ways to show your love for New Zealand’s native birds. We’re pretty confident nothing will get past our scrutineers, so there’s not much point trying.”

Someone in Australia was so desperate for a shag that they tried to hack #BirdOfTheYear. https://t.co/GqGHIt9BfE — Kimberley Collins (@kimi_collins) October 4, 2018

As of Friday afternoon, the kererū, or woodpigeon, was in the lead, with the kākāpō in second and the critically endangered kakī, or black stilt, in third.

Despite running every year for the past 14 years, no bird has ever won the competition twice.

Guardian Australia asked whether this was due to organisers influencing the vote to ensure that a new bird won every year, but Forest & Bird denied the charge.

“There’s absolutely no internal interference,” the spokeswoman said.

“There are so many wonderful and unique native birds in New Zealand, and the ones that have won before just don’t seem to do as well in subsequent years. The public obviously feels it’s time for another bird to shine.

“Partly I think it’s because campaign managers are more likely to back birds that haven’t won before, so those are the birds that tend to have the most visible and active social media campaigns.”

As well as the shag scandal, this year’s scrutineers also struck out 28 fake votes for the blue duck, and five for the orange-fronted parakeet. 20,000 votes have been cast in five days, and this year’s competition looks set to outpace the record 41,000 votes cast last year.

The shag or cormorant group of birds is made up of 36 species found across the world, and eight are endemic to New Zealand.

The name “shag” is thought to reference their shaggy plumage, and historically, the bird was hunted by fishers who erroneously thought they ate trout and depleted fishing stocks.

Voting closes on 14 October and the winner will be announced the next day.