Sleepy hollows

Eucalypt tree hollows

eucalyptus tree hollow, showing signs of use, Edward Hunter Heritage Bush Reserve

Tree hollow, showing signs of use

Eucalypts support a great diversity of life in Australia, providing food, shelter and habitat. They are also an important source of shelter for animals in the form of hollows.  It can take quite a long time for hollows suitable for shelter and breeding to form in eucalypts. Fire and practices such as cutting down dead trees in a stand for firewood has had the effect of reducing the availability of tree hollow habitat. And this has a flow-on effect for the animal life that depends on these eucalypt hollows to shelter and raise the next generation.

Diversity of animal life

Animals such as brush tailed possums use hollows in trees.

Shows image of brush-tailed pssum in tree hollow, sourced from Our communities images

A brush-tailed possum hiding in his tree hollow
Photographer: Paul Smith for Koroit Wildlife Shelter
Creative Commons Attribution-Noncommercial 2.5 Australia License

And so do bats, insects, mammals, amphibians, birds, reptiles and invertebrates.

The presence of eucalypt hollows in a forest is an indicator of the ability of that forest to support a diversity of animal life. One of the aspects that affects which animals can be supported is the sizing of the hollows. For cockatoos, for example, the hollow needs to be quite large. Hollows of these sizes can take up to 150 years to form, depending on the eucalypt species. In the Edward Hunter Heritage Bush Reserve, most hollows that can be seen from the ground seem to be on the smaller side.

Crimson rosellas

The crimson rosella (platycercus elegans) uses eucalypt hollows for their clutches of eggs. An adult can be seen here in the Reserve shifting in and out of the nesting hollow.

Shows crimson rosella using tree hollow, Edward Hunter Heritage Bush Reserve

Tree hollow habitat: crimson Rosella, early March

Shows crimson rosella using tree hollow, Edward Hunter Heritage Bush Reserve

Tree hollow in use: crimson rosella

The breeding season is from September to January and the female incubates the eggs (usually five). Both male and female birds care for the young, looking after the chicks for a further month once they leave the nest. Young rosellas gradually attain their red adult plumage over 18 months.

Bees

Both native bees and the exotic honeybee use tree hollows, too. These two examples from the Reserve were taken in April. It’s a little hard, though, to tell what kind of bees, pictured here, are using these particular hollows – whether native or exotic.

eucalyptus tree hollow, bees in residence, Edward Hunter Heritage Bush Reserve

Bees in residence

eucalyptus tree hollow, bees in residence, Edward Hunter Heritage Bush Reserve

Tree hollow: bees in residence

In situations where tree hollows are in limited supply, competition from exotic bees can put a great deal of pressure on native animals.

Other users

Animals can be selective about their choice of hollow. Whether it is a useful hollow or not can depend on depth, entrance size, location in the tree and shape. It can also depend on which part of the landscape it is in and how close predators or the same species might be.

Whilst it hasn’t been possible to always see and photograph the animals that use hollows in the Reserve – especially if they are nocturnal or simply not arround when the viewer is – the rubbing marks around these hollows below show they may be good ones.

This one below shows nesting materials, possibly of the common ringtail possum, which uses ferns in its nesting materials.

eucalyptus tree hollow, showing signs of use, Edward Hunter Heritage Bush Reserve

Tree hollow, with nesting material: perhaps ringtail possum?

In this case below, the only way to know if it is in use would be to see inside…

Showing eucalypt tree hollow, Edward Hunter Heritage Bush Reserve

Tree hollow: potential habitat

Sources and further information

Birds in Backyards (2013) Crimson rosella Basic information. http://www.birdsinbackyards.net/species/Platycercus-elegans

Gibbons, P. & Lindenmayer, D. (2002) Tree Hollows and Wildlife Conservation in Australia. CSIRO Publishing: Collingwood.

Goldingay, R. (2012) Trees and non-flying mammals: a hollow understanding. ECOS Science for Sustainability. http://www.ecosmagazine.com/paper/EC12338.htm

Koch, A. Forest Practices Authority (2009) Tree hollows in Tasmania: A guide www.crcforestry.com.au/downloads/hollows-booklet-241109.pdf

NSW National Parks and Wildlife Service (2002) Threatened Species Information: competition from feral honeybees as a key threatening process – an overview. http://www.environment.nsw.gov.au/resources/pestsweeds/feralHoneybeesFactsheet.pdf

Parks Victoria (n.d.) Park Notes: Crimson Rosella http://parkweb.vic.gov.au/__data/assets/pdf_file/0012/322203/rosella4.pdf

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