Invasive species can come in pretty guises. Take mynas

30 Juli 2019

Mynas are expert mimics capable of reproducing various kinds of sound from human voices to animal calls to engine rattles. Common mynas, also called Indian mynas (Acridotheres tristis), are native to Asia, but they have spread across much of the world.

That is not entirely a good thing.

Common mynas feed on insects and some countries have imported mynas as a means of pest control at farms. Over time, however, the birds have turned into pests themselves, negatively impacting native birds.

“Because they’re very opportunistic, they are very social, they form large groups, they also form lifelong bonds, so they have a partner they hang out with for their lifetime,” explains Dr. Andrea Griffin, a scientist at the School of Psychology at the University of Newcastle.

They may look pretty, yet these little birds are also aggressive. Coupled with their ability to adapt to a wide range of geographical conditions, they are true survivors. But that can be bad news for native birds whose territory they invade. They often drive other birds away from their nesting sites and roosting areas.

Common mynas are now thriving in many parts around the world. In Israel, after escaping from a zoo two decades ago, the birds have become abundant. A study conducted in Tel Aviv’s Yarkon Park affirms the aggressiveness of these birds.

Researchers put up nesting boxes with different entrance sizes on trees in Yarkon Park. Boxes with larger openings could be utilized by bigger bird species, including mynas. By contrast, ones with smaller entrances could be used only by smaller species such as songbirds.

Mynas could not make use of the boxes with small openings as they could not fit into them. Not so with the other boxes. The results showed that most of the nesting boxes with larger openings ended up being occupied by mynas. In many cases native birds were evicted from their nests by these aggressive invasive birds, which meant that the eggs and chicks of these ousted birds died during these “hostile takovers.”

Thanks to such unscrupulous survival techniques, common mynas have been remarkably successful in various climates worldwide. The IUCN now lists the myna as one of the only three bird species (alongside the European starling and the red-vented bulbul) that are ranked among the 100 worst invasive species globally.

Similarly to Israel, native bird species in Australia have been suffering from the presence of common mynas. The invasive birds were brought into the country to curb insects at flower farms in Melbourne. Their numbers have since risen so high, however, that the country needs to take action to control Indian myna populations so as to protect native species increasingly at risk.

“The myna was introduced in 1868 in Melbourne because they make amazing pets who can talk and it was thought they could deal with pests like grasshoppers. But the experiment has been a disaster. They breed fast in summer, steal food from other birds and, when they hollow in trees, they’re so aggressive they even take on kookaburras and cockatoos,” said an ecologist, Stefan Hattingh.

“They’re the bigger threat to our native wildlife,” he continued.

Hattingh’s findings line up with those done in Yarkon Park: common mynas will oust native species once they move into a new area. “In one tree, there are many hollows but, as soon as a myna moves in, it’s so extremely aggressive that it won’t let any native birds nest and breed there, which means we’re seeing less of them and more mynas,” Hattingh explained.

The post Invasive species can come in pretty guises. Take mynas appeared first on Sustainability Times.