The Indian Myna has been named one of the world’s worst invasive pests – and with good reason.
The common or Indian myna (Acridotheres tristis) is one of the top pest birds in Australia. Often confused with native miner birds (probably to the similarity in the name and equally noisy habits!), it has been included by the International Union for Conservation of Nature (IUCN) as one of the 100 world’s worst invasive pests. It is one of only three birds on the list; the other two are the red-vented bulbul (invasive in the Pacific Islands) and the common starling (which we also have in Australia).
Introduction and current distribution
Indian mynas were first brought into Australia in 1862 to help with pest control – to target caterpillars and other pests in the Melbourne market gardens. As with all the early attempts of biological control, it was done with the best of intentions but little understanding about the potential unintended impacts. The Indian myna is popular in its native range (India and southern Asia) for feeding on a wide range of crop pests. It was also introduced to north Queensland to tackle locusts and cane beetles in sugar cane (sound familiar?).
The Indian myna is now common across the east coast of Australia, where it is firmly established. However, it is listed as an invasive pest in the ACT, Tasmania, South Australia and Western Australia where it is already present, but not considered fully established.
Biology and behaviour
Indian mynas pair for life and although highly territorial with regards to their nest sites, they do come together in communal roosts and will form flocks, typically between 4-80 birds, but sometimes large flocks of several thousand. Non-nesting birds will still stay close to nesting sites and congregate in communal roosts.
They are open woodland birds in their native range and readily adapt to a wide range of environments including urban areas, where they prefer to nest in roof and wall voids. The breeding season is from August to March (varying depending on climate), often producing three clutches per year, with up to six eggs in each clutch. They are omnivores eating a wide range of foods, including insects, seeds, fruit and garbage.
The Indian myna is a pest in urban and rural areas, not only impacting human activities but also native wildlife.
In urban areas they represent a health threat as they prefer nesting in houses, providing the opportunity to pass on diseases such as Salmonella, as well as parasites, such as bird mites. Their nests can also block gutters and downpipes, causing water damage. With their loud and frequent calls, regular squabbling and congregating in flocks, their presence can create significant noise pollution issues. In rural areas, Indian mynas damage fruit crops, such as apple, pear, strawberry, mango and grape, as well as cereal crops. As an aggressive, territorial bird it will often out-compete native birds and other animals for nesting sites in trees and food sources. It is also a carrier of a range of fatal bird diseases, such as avian influenza.
The Indian myna is now fully established along the east coast but is still a reportable pest in South Australia, Tasmania and Western Australia in an attempt to prevent its spread. Although its range only expands by around one kilometre a year (as the birds tend not to disperse far from the area in which they were raised), preventing its westward expansion into South Australia will be difficult. However, preventing establishment in Tasmania (where it can only really enter by boat) and Western Australia (where it can only really enter by road or train to cross the Nullabor Plain) should be possible. Reporting, trapping and euthanising is the key to control.
The ACT is an interesting case study as although the Indian myna is fully established, it was subsequently declared a pest species in 2021 by the ACT Government. However, in the absence of a government-led myna management plan, the Canberra Indian Myna Action Group (CIMAG) has taken the lead.
Before CIMAG started in 2006, researchers had established that the Indian myna was the third most common bird in the ACT, with around 250 birds per square kilometre. Over the following ten years, the group had trapped some 57,200 Indian mynas (as well as 8,700 starlings), reducing the status of the Indian myna from the third most common bird in the ACT to the eighteenth most common.
The key element in the group’s control strategy is the use of traps by community members and the subsequent euthanising of birds. A range of traps, both self-made and commercial (such as the Myna Magnet from PestIT), are utilised, using grain-based pet food/bird seed as bait. Interestingly, red-coloured food works particularly well (unlike insects, birds see and are attracted to red). It’s important that the traps should only be approached at night when free birds are not watching as, if they associate the traps with humans or danger, they will quickly learn to avoid them.
Members of the public can euthanise the birds themselves, as long as they do so in a humane manner. CIMAG’s recommended euthanising technique for nonprofessionals is through gassing by carbon dioxide or carbon monoxide. Specifically, connecting an airtight box, which contains the trapped birds, to a pipe from the car exhaust and running the engine (cold car) for 90 seconds. For those not comfortable euthanising the birds themselves, many councils and community groups around Australia, who have an active program to reduce Indian myna numbers, will also list vets or other professionals that provide Indian myna euthanising services.
In terms of bird management products, bird spikes have limited effect in preventing Indian mynas roosting or building nests, so more robust exclusion techniques such as netting are required.
To make an area less attractive to Indian mynas, preventing access to seed, grain and animal feed is a good start. If they are established in an area, exclusion through the installation of suitable bird management products provides excellent results. Bird nests in roof voids should be removed while wearing protective clothing and entry points blocked.