Research identifies value of river red gum hollows


Erin Westerhuis inspects the hollow of a river red gum near Alice Springs.

Erin Westerhuis inspects the hollow of a river red gum near Alice Springs.

New research undertaken by Charles Darwin University in Alice Springs confirms the importance of river red gums in providing habitat for more than 30 species of Central Australian wildlife.

Research Institute for the Environment and Livelihoods PhD candidate Erin Westerhuis said up to 37 species of inland Australian birds and microbats depended on tree hollows for breeding or roosting.

“These include the tiny inland forest microbat, which at 3.6 grams weighs less than a teaspoon of sugar, the red-tailed black cockatoo, which can weigh 7 kg, as well as Major Mitchells, boobooks, kestrels, barn owls and others,” Ms Westerhuis said.

“The river red gum (Eucalyptus camaldulensis subsp. arida) is the only tree in our region that grows in sufficient density and with distribution broad enough to provide widespread and predictable hollow resources.”

Reporting her findings in a co-authored article in “Austral Ecology”, Ms Westerhuis assessed river red gums across the rivers and creeks in the MacDonnell Ranges, finding that about 35 per cent contained hollows, mostly on branches and mostly among dead wood.

She said most hollows had small entrances with a diameter of less than 10cm, with just 13 per cent having an entrance diameter greater than 20cm, which could have negative implications for larger hollow using species such as owls and large parrots.

Ms Westerhuis said the older and larger river red gums were critical for animals that use hollows.

“These trees are also potentially the most prone to destruction from fires. But we will need to undertake further research on the effects of fire, in addition to tree hollow use by birds and bats in the arid zone, to best manage these resources,” Ms Westerhuis said.

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