Backstreet Bellows


The Blue Mountains’ koala population is growing and on the move – but you’re more likely to hear them than see them. And that’s where Blue Mountains locals can help.

By Julie Miller

 During the bushfires of 2019, the wildlife conservation organisation Science for Wildlife made the bold move of rescuing a dozen koalas from the line of the approaching inferno in the Kanangra-Boyd National Park, temporarily relocating them to Taronga Zoo’s Wildlife Hospital.

Three months later, 13 were returned to the recovering forests, with one surprise joey born in captivity amongst those released. Since then, these koalas – a crucial population, being amongst the most genetically diverse in Australia, as well as chlamydia-free – have thrived; but due to habitat loss, appear to be travelling further in search of better quality food.

According to Science for Wildlife’s Dr Kellie Leigh, this is a trend across the whole of the Greater Blue Mountains World Heritage Area, which boasts several small but important koala colonies including ones in the Hawkesbury-Wollemi area, Newnes Plateau, the Lower Mountains and Kanangra-Boyd.

“When we first started the Blue Mountains Koala Project, the general concept was that koalas don’t occur in the Blue Mountains, or are low density due to the sandstone soils,” Dr Leigh says. “There’s no doubt the fires had a really big impact on numbers, but they are bucking the trend, and certainly bouncing back since the the fur trade days. There’s enough of them to find each other and mate; we’re finding really good numbers wherever we look.”

Locating these colonies and identifying their habitat boundaries is an important part of Science for Wildlife’s ongoing studies. “If you’ve got a growing population, it will just naturally expand into nearby habitats,” Dr Leigh says. “The records show they can travel over 40 kilometres. If they decide to go on the move, they certainly can.”

Which is where the support of Blue Mountains’ locals comes in. One of the current surveys being conducted is Backstreet Bellows – a citizen science project using acoustic devices to record the distinctive roar of male koalas during mating season.

“From early September through to December is peak bellowing season,” Dr Leighs says. “Mating season can go right through to March, but most of the male bellowing is going on right now.”

During the first survey, nearly 100 residents of the Lower Mountains signed up to have a small recording device placed on their properties for seven days. The next round will take place on the western edge of the Greater Blue Mountains World Heritage Area, incorporating Lithgow, Clarence, Hartley, Kanimbla and the Upper Mountains where, as recently as November 4, a koala was sighted crossing Darling Causeway.

“These citizen science projects are critical. Koalas are famous for living around developed areas, where habitat loss, domestic dog attacks and vehicle strikes are all very real and known threats. We want to build local stewardship in the community; we want people to be aware if there are koalas around, so they can help conserve them.”

Future projects that will involve volunteers include tree planting and habitat restoration; while experienced bushwalkers can sign up for koala spotting, helping to radio track and monitor the health of known populations in remote areas. There are also online monitoring projects, while donations are always welcome.


For more information, or to report a koala sighting in the Blue Mountains region, visit

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