Creating Koala Hubs
on your land
Koala Fact Sheet #2: Creating Koala Hubs on your land
Rivers and creeks wind across the Western Plains, with tight, forested bends that are pockets of biodiversity. These bends are often inaccessible to farm machinery, and can harbour weeds and feral pests. With sensitive revegetation and fencing, these bends can be perfect “Koala Hubs” – habitat for koalas and native birds.
What’s a Koala Hub?
Koalas need a lot of trees. A small koala home range in the You Yangs is 5 hectares of forest. A large one may be 50 ha (1). These home ranges are comprised of many thousands of trees of many species.
The shape of the home range is also important. One long single line of trees isn’t a viable habitat for a koala, no matter how long it is. They need blocks of habitat that are wide, with a mixture of tree and shrub species. (2,3)
This fact sheet was produced by Koala Clancy Foundation as a Melbourne Water Liveable Communities, Liveable Waterways Project.
Why are river bend Koala Hubs important to koalas?
Deep river bends are prime koala habitat – they are compact and biodiverse, on fertile soil, with water on three sides. The bends are cool in summer, and often hold water well into droughts.
The trees growing in the river bends are more sheltered from extremes, and tend to be better food trees for koalas. (4) Often the bends have more healthy trees than along the straight stretches.
Revegetation of the river bends is the cheapest, most effective way to get maximum benefit for koalas, with the smallest disturbance to the landowner.
Koalas need large blocks of forest, containing many hundreds or thousands of trees. Landscape configuration, soil fertility and proportion of primary tree species is also important. (7, 8)
How to create a Koala Hub
Rather than fencing that follows the curves (diagram B below), a river bend is fenced off across the neck, creating a wide block of habitat (diagram C). Fencing off a deep bend is up to 7 times cheaper than a long line of fencing that follows the curves of the river. This short, visible run of fencing is also easier to maintain.
Revegetation with native species inside a fenced-off bend is more likely to be successful than a long, narrow linear planting. Edge effects are reduced in a broad plantation, ensuring it will survive better, grow faster, suppress weeds more quickly, require less maintenance and is more likely to develop into a naturally regenerating ecosystem. Gaps in the plantation will be naturally filled, new seedlings will establish without constant maintenance.
For koalas, a fenced-off bend is somewhere to live, not just a movement corridor.
Why not make these river bends a win:win for wildlife, and landowners?
How wide should it be?
The wider the better! Anything is better than nothing, but traditional corridors 10m or 20m wide are expensive to revegetate. They will need constant replanting, will remain full of weeds and a refuge for ferals, and planted trees will have low survival rates.
A 50m wide corridor is a good starting point, especially when a couple of koala hubs of average 100m or 200m width are planned.
Remember: Koala home ranges start at 5 hectares for one young animal, and 20 ha for a breeding female. If your koala hubs are one hectare each, aim for at least 5 of them connected by corridors. Better still, plan a series of 2 or 3 hectare hubs.
Example 1:
Diagram A – A stretch of river with few trees, no fence, provides no effective habitat for a koala. Trees are in a single line, too far apart and too few for a koala to stay in the area for long.
Diagram B – shows an expensive revegetation scenario that is often employed. A lot more trees are planted, within a fence 20m from the river following the curves. This fence is very expensive, but still provides no effective koala habitat, and koalas don’t stay long. In addition the revegetation struggles to grow due to edge effects, fails to regenerate and fails to suppress weeds.
Diagram C – shows a much shorter fence that saves thousands of dollars. Two small river bends are fenced off koala hubs, and linked with a fence 20m from the river. With less cost, less maintenance, this delivers 4 x the koala trees in scenario B. The forest in the hubs is self-regulating, it regenerates, suppresses weeds and trees thrive.
Example 2:
Diagram A – A stretch of river at a creek junction, no fence, no habitat for a koala.
Diagram B – shows a very short fence that is inexpensive to install and easy to maintain. A large koala hub is created, potentially enough for a breeding female to occupy. The forest in the hub matures and thrives, an ecosystem forms, weeds are suppressed, beneficial insects thrive, water remains in the river longer.
What Trees to plant?
River Red Gum Eucalyptus camaldulensis: in the valley, right beside the water. Also on broad floodplains (lowest terrace) and sometimes on hills (eg You Yangs), particularly where there is underground water.
Manna Gum Eucalyptus viminalis: variable. On stony rises on the plains, and in forested gullies of the ranges (eg Anakie Gorge). Sometimes on rocky hills (eg Granite Road, Anakie).
Yellow Box Eucalyptus melliodora: in the valley, just upslope from Red Gum. Also scattered on the plains and slopes of the ranges (eg. Rowsley Valley).
Red Box Eucalyptus polyanthemos: on the plains, particularly east of the You Yangs. (eg Toynes Rd, Little River)
Grey Box Eucalyptus microcarpa: on the flat plains in clay soil, particularly north and west of You Yangs and in Balliang, Melton & Bacchus Marsh. Also on rocky slopes of the ranges (eg Reids Rd, Glenmore)
Black Wattle Acacia mearnsii: dry slopes, beside Yellow Box, Red Box and Grey Box. Hardy, fast-growing and grows its own crop of seedlings.
Blackwood Acacia melanoxylon: sheltered, moist areas, often beside Red Gum in the valley. Slow-growing and very long-lived.
Lightwood Acacia implexa: on the slopes, but also near the river. Hardy plant. Not as slow-growing as Blackwood, also long-lived.
Sweet Bursaria Bursaria spinosa: anywhere. Slow-growing and long-lived.
Tree Violet Melicytus dentata: anywhere from right beside the river, to the dry flat plains. Hardy, slow-growing and resistant to browsing.
Drooping Sheoak Allocasuarina verticillata: anywhere, including dry plains and slopes.
Buloke Allocasuarina luehmannii: has limited distribution around Balliang on the plains.
Hop Bush Dodonea viscosa: anywhere from right beside the river, to rocky outcrops on the dry flat plains.
This fact sheet was produced by Koala Clancy Foundation as a Melbourne Water Liveable Communities, Liveable Waterways Project.
REFERENCES:
(1) Koala Clancy Foundation, How Many Trees Does a Koala Need? https://koalaclancy.wordpress.com/tag/koala-home-ranges/
(2) McAlpine, C.A., Rhodes, J.R., Callaghan, J.G., Bowen, M.E., Lunney, D., Mitchell, D.L., Pullar, D.V. and Possingham, H.P., 2006. The importance of forest area and configuration relative to local habitat factors for conserving forest mammals: a case study of koalas in Queensland, Australia. Biological Conservation, 132(2), pp.153-165. https://www.sciencedirect.com/science/article/pii/S0006320706001455
(3) Rus, A.I., McArthur, C., Mella, V.S. and Crowther, M.S., 2021. Habitat fragmentation affects movement and space use of a specialist folivore, the koala. Animal Conservation, 24(1), pp.26-37. https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/acv.12596
(4) Wu, H., McAlpine, C. and Seabrook, L., 2012. The dietary preferences of koalas, Phascolarctos cinereus, in southwest Queensland. Australian Zoologist, 36(1), pp.93-102. https://meridian.allenpress.com/australian-zoologist/article-abstract/36/1/93/135034