The Indian myna (Acridotheres tristis) chick is eating rice from its mother on the day of Mother's Day at Tehatta, West Bengal India on 08/05/2022. (Photo by Soumyabrata Roy/NurPhoto via Getty Images)
They’ve been shot in South Africa and New Zealand, caught in traps in Australia where they’re called “flying rats”, and poisoned in the Cook Islands.
Around the world, countries have tried to control one of the world’s most successful invasive bird species — the common myna. It is among only three bird species listed in the top 100 of the world’s worst alien species, alongside the red-vented bulbul and common starling.
These highly adaptable birds compete aggressively with indigenous species, and tend to replace them in areas where myna populations are well established, according to Invasives South Africa.
They eat the eggs and attack the fledglings of other birds. Common mynas have now been spotted nesting in the Kruger National Park.
How winged invaders took off in South Africa
The gregarious, feisty brown bird, with its distinctive yellow beak, eye patch, feet and legs, is native to southern and southeastern Asia and is now found on all continents except South America and Antarctica.
In South Africa, it is thought that escaped birds established the initial population in Durban in 1902, with a second potential introduction occurring during the 1930s in Johannesburg, when people released them.
After an initial lag, their rate of spread has increased, and they have become established throughout most of Southern Africa. This is according to Invasive Birds: Global Trends and Impacts, a 2021 book written by Colleen Downs, of the University of KwaZulu-Natal, who is a core team member of the DSI-NRF Centre of Excellence for Invasion Biology at Stellenbosch University, and Lorinda Hart, of the University of Namibia.
The South African National Parks (SANParks) has described how a few individuals introduced into KwaZulu-Natal “multiplied into millions”.
Here to stay
Brian van Wilgen, also of the Centre for Invasion Biology, said: “They’ve reached the Kruger National Park, they’re spreading down the East Coast, I think they’ve got past East London now. The time will come when they will reach Cape Town and be all over the place.”
He said mynas generally prefer urban areas. “So, if they’re in the Kruger Park, they’ll be in all the rest camps, not so much out in the veld.”
Visitors would get annoyed because they’ve gone to Kruger to see indigenous birds and mynas are noisy and roost in trees in their hundreds in the evenings.
Keeping the birds out of the Kruger needs to be a priority, he said. But they are here to stay in South Africa “for the next few million years”.
“It is too late. If you had caught them when they were still a small population you could have possibly eradicated them.”
Targeted control
Van Wilgen cited efforts by the eThekwini municipality to eradicate the house crow, another invasive alien bird species from Asia.
“It was confined to Durban for quite a while and then it arrived in Cape Town, on ships probably, and they had had a huge campaign to get rid of them … then they took their foot off the pedal and they bounced right back again.”
He said the house crow was now in Richards Bay and East London.
Finding an eradication method that will only address targeted species is another hurdle, explaining that they cannot be poisoned because other species would also be killed.
Research has shown how common mynas have developed evolutionary traits to help enable their spread. Once they settle in that area, they lose these features.
“What has been found is that the ones on the leading edge [of the invasion] have got bigger wings, stronger wings, than the ones that have been sitting in Durban for 100 years.”
How countries are tackling them
According to Downs and Hart’s book, controlling mynas by shooting them has been used in South Africa, New Zealand, the Cook Islands and Tokelau.
“Wide-scale eradication on continental countries is probably not possible, but problem birds and groups are controlled as needed,” it said.
“Control in Australia has mostly been using live traps, but trapping did not remove individuals faster than the replacement rate in Canberra.
“On Atiu Island, a bounty of NZ$2 per bird and live trapping further assisted the eradication of nearly 13 000 birds. In total, more than 26 000 birds have been culled, ridding the Cook Islands of this species using poisons, shooting and live trapping.”
Common mynas were eradicated from Kiribati by shooting, because numbers were low. The Seychelles has also eradicated mynas from some islands using trapping techniques, nest disturbance and shooting. “On Fregate Island, 745 birds and 42 eggs were removed to achieve total eradication.”
Using Starlicide poisoned baits on St Helena and Ascension islands, as well as live trapping on Ascension Island, has reduced myna numbers.
Irreparable damage
A 2017 position statement by BirdLife South Africa supports the legal eradication of myna in the country’s protected areas.
“BirdLife South Africa notes that large, communal common myna roosts that are situated in close proximity to humans can result in unwanted impacts (noise, odour, parasites). If it is considered that the only viable option for removing such populations is eradication, the provincial government authority must be consulted with to ensure legislative compliance, as regulations vary between provinces.”
But the statement said the potential displacement of indigenous species is believed to be limited to the local scale in South Africa. It noted that the adverse effects of mynas on biodiversity was not well documented and “most descriptions are of an anecdotal nature”.
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