Bulletin

Issue: March 2004

Research in Action

GANG WAR IN BUSHLAND: THAT'S FOR THE BIRDS

Mobile phones are causing a serious debt problem amongst youth as telecommunications companies target young people's financial and consumer inexperience.

They have muscled their way to control large tracts of Melbourne and Sydney suburbia, and increasingly larger slices of the east coast rural landscape.

Like bandits, they wear a black 'mask' over their eyes, forehead and chin and operate in gangs.

But easily identified by their bright yellow bill and legs, pale grey back and white belly, they are Noisy Miners-one of the few native birds to have become serious pests in their own country.

They do this by forcing other native birds from their leafy suburban areas and Eucalyptus woodland habitat and in doing so damage and potentially destroy it by upsetting the balance between flora, insects and other fauna. To compound the damage, some birds like the Grey-crowned Babbler and Regent Honeyeater whose habitat Noisy Miners have usurped, are becoming rare or endangered.

They may also cause more broad-scale ecological problems. The birds the Noisy Miners have replaced also ate insects in the few eucalypts left in our rural landscapes. Among insect-eating birds in decline are the Hooded Robin and the Jacky Winter.

The concern is that the Noisy Miners may not be eating the range or numbers of insects previously consumed by the displaced birds. This has the potential to lead eventually to the death of trees from insect damage, and the loss of whole woodland communities of plants and animals.

La Trobe University associate professor in Zoology and miner expert, Dr Michael Clarke, has received a Large Australian Research Council Discovery Grant of $60,000 per year over three years to investigate ways to lessen the Noisy Miners' dominance.

Dr Clarke explains that the Noisy Miner (Manorina melanocephala) is one of four species of native Australian miner. They are different again from the exotic Common Myna from India and southern China which is also increasing its range and also becoming a serious pest in many urban and some rural areas.

'We have tipped the ecological balance in favour of the Noisy Miner which thrives in eucalyptus woodland that is surrounded by cleared land on which short grasses now grow,' Dr Clarke said.

'For example over the years they have come to ?own? the car parks and other parts of the Bundoora campus to the detriment of other local native birds. Typically, between 20 and 200 Noisy Miners will ?colonise? a territory of up to 10 hectares. They operate as ?team-based? collectives based on families with breeding pairs helped by non-breeding close relative males.

'They have become the ?mafia? or ?brotherhood? of the east coast bird world by relentlessly attacking intruders in their territory-even tackling much larger birds like kookaburras and herons which are unable to ward off their ?massed? attacks. Persistently they chase off other birds-native and exotic-until they have virtual sole occupation of their territory.'

Dr Clarke said that Australians have to wrestle with the philosophical challenge of accepting that a native species could be a pest and that something must be done. 'To do nothing is to relegate other native species to extinction,' he said.

'Our reluctance to acknowledge that native species can become pests shows how easily we confuse concern for the welfare of an individual animal, with conservation. They are not necessarily the same thing. Conservation has broader goals of preserving whole populations, species, communities and ecosystems.

'Sometimes this involves making hard choices that have serious implications for individual animals. We need to appreciate that to do nothing also has serious implications for other individual animals, and potentially the persistence of entire species and ecological communities.'

Dr Clarke's new research will build on work carried out in the mid 1990s by La Trobe PhD candidate, Ms Merilyn Grey, on the effects of removing Noisy Miners from habitat near Benalla and Violet Town.

'We monitored the habitat after removing most of the Noisy Miners and found that other species moved back in immediately. When they did not have large numbers on their side, remnent Noisy Miners were content to cohabit with other species. Like most bullies, they stopped attacking others when they found themselves in a minority.'

'I will be working to determine what makes areas attractive or unattractive to Noisy Miners. One factor may be the height of grasses surrounding the woodland in which the birds nest. We feel confident that they like their woodland to be surrounded by short rather then long grass-but we don't know why.

'Part of my research will be to examine the relatively rare sites such as the Barmah Forest, and others in northern Victoria and in Gippsland where Noisy Miners live but do not dominate and try to ascertain why.

'One hypothesis I hope to test is that it is only through flying in loose flocks that other species-like Musk Lorikeets-can infiltrate the defences of the Noisy Miner and gain access to resources on their territories. The other species need to be in good numbers if they are to gain a foothold in a Noisy Miner territory, but many species are, themselves, in low numbers due to loss of habitat.

'The goal of my research is to come up with recommendations for land management practices that tip the balance back in favour of the other birds in our woodlands and parks, without creating more habitat for Noisy Miners.'•

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