Prescribed burning in numbat habitat under fire

Western Australian scientists petitioned their Premier this week for a full, independent scientific enquiry into the state’s prescribed burning practices, which they say have now killed some of the last remaining numbats (Myrmecobius fasciatus), or walpurti, a rare and endangered marsupial.

A fire was lit by the Department of Biodiversity, Conservation and Attractions (DBCA) on 25 March this year by dropping firebombs from a helicopter in Weinup block, south of Perth, next to Perup Nature Reserve – one of the numbat’s last two homes.

The drop was “catastrophic for the numbat and its habitat,” according to the Leeuwin Group of Concerned Scientists. “This very hot burn has killed mature trees and completely burnt the fallen logs housing the termites on which the numbats feed, leaving any surviving animals without cover and protection from predators.”

And it couldn’t have come at a worse time for the vulnerable little mammals, the group adds.

They say a spokesperson from the DBCA claimed the burn took place when numbats didn’t have young in their dens, and that “the younger animals were mature enough to access refuge areas during and after the fire”.

This is not true, according to the scientists. “Numbats mate in January and give birth to young two weeks later,” they write in their open letter. “The young remain with the mother and in the den until July and they are not weaned until late October or November.

“The fire…thus coincided with the time that all the females were carrying young, which would have been killed along with their mothers.”

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Credit: Bart Lebbing

Numbats are a cherished state fauna emblem, a unique species with a Family of their own. They have an exclusive diet of termites, are the only truly diurnal marsupial (active during the day), and have extraordinarily sharp vision.

They used to be spread across eucalypt forests in dry areas of South and West Australia and the Northern Territory. Habitat loss and introduced predators have now restricted them to two areas of southwest WA: Dryandra and Perup.

With a population of less than 1000 in the wild, numbats were listed in 2014 as endangered on the IUCN Red List of Threatened Species. The Perth Zoo has spent decades intensively breeding them to return to their native habitat.

They’re not the only animals likely to have been impacted by the burn, according to the Leeuwin group; they say it would have jeopardised other threatened species such as the Woylie and Western ringtail possum.

The group has previously expressed concerns about the state’s prescribed burning, one of Australia’s longest running programs that incinerates more than 200,000 hectares of the biodiverse southwest region of WA from autumn to early summer every year.

According to Kingsley Dixon, one of the group’s members and a distinguished professor at Curtin University, research has found that the “high intensity aerial incendiaries used to ignite these large and ferocious fires are the same intensity as wildfires, and because of the speed and gridding pattern for the ignition few animals are likely to survive”.

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Numbat in Dryandra Woodland, Western Australia. Credit: Auscape/Universal Images Group/Getty Images

This is not the traditional preventive burning that First Australians employed, Dixon adds.

“Our Noongar traditional custodians refer to what is happening in the southwest of Western Australia as ‘legal arson’ that is not the cultural burning undertaken for over 40,000 years.”

A Parks and Wildlife Service spokesperson from the DBCA says the department’s fire management program is based on evidence and strategic planning, aiming “to manage the risk to people, assets and the environment from the damaging impacts of bushfires and works to ensure the conservation of biodiversity values on the land it manages”.

The department has also invested resources into protecting numbats and their habitat over the past 20 years with a feral animal control program and numbat breeding in collaboration with Perth Zoo, along with managing numbat habitat through fire management.

The spokesperson says they do “not consider that this prescribed burn has impacted overall populations of the numbat but has provided a mosaic of burnt and unburnt patches across the landscape, leading to longer-term protection of their habitat from the occurrence of severe summer bushfires”.

They do acknowledge that soil dryness in parts of the March burn “may have been a contributing factor to patches of higher intensity fire than was planned”, and say they have undertaken an operational review to learn from this.

As far as prescribed burning more broadly, other scientists have analysed its benefits and found that it’s only warranted around housing and infrastructure.

The Leeuwin group’s convenor, John Bailey, emeritus professor from Murdoch University, acknowledges the importance of the burning to protect buildings, but is concerned that it’s “too often applied to environments remote from these assets and putting biodiversity and the natural environment at risk” – including conservation reserves.

“The solution is to burn in accordance with ecological principles informed by Indigenous burning practices,” he says. “This is no easy task, hence our call for an Independent Review based on the latest scientific findings.”

Dixon says the solution “is called ‘right way burning’, rather than the towering infernos of the European prescribed burning. Or to quote my Noongar friends, ‘if you can’t burn in bare feet you are burning too much’.”

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