Veteran And Stag Trees : A Valuable Resource - Going, Going, Gone!

Since European settlement in Western Australia millions of hectares of forest and woodland has been cleared for agriculture, cities, towns, timber production and mining, and millions of ancient trees that provided places where birds, reptiles and mammals could sleep, rear young, shelter from the weather and evade predators have been destroyed.

In the South-West of this State only about 10% of the original primary vegetation remains and urban, agricultural, forest and woodland landscapes now contain far fewer trees with hollows. Hollow formation in Jarrah, Marri, Karri, Wandoo, Tuart and Salmon Gum is an incredibly slow process reliant on fungi and invertebrates such as termites and other insects to decompose and excavate the wood.

How are hollows formed?

Hollows are formed when a branch or top of main trunk snaps off, or the tree is damaged by fire. This extremely slow process, combined with the fact that our hardwoods live up to 500 years, means that hollows can be quickly lost, but not easily replaced.

How old does a tree have to be to form a hollow big enough for a Black Cockatoo to nest in?

Recent studies have shown that hollows suitable for black cockatoos did not begin to appear in eucalypts until they are at least 230 years old. A number of nest trees used by Forest Red-tailed Black Cockatoos and Baudin’s and Carnaby’s Cockatoos are estimated to be between 300-500 years of age. This clearly shows that the large old and decaying trees used as nesting sites by our black cockatoos in the south-west began growing well before Captain Stirling sailed up the Swan River.

Why are Black Cockatoos losing their hollows?

Apart from the dwindling supply of hollows in some landscapes, hollow users are also in competition with other birds such as Galahs and Rainbow Lorikeets and feral swarms of the introduced European honey bee that is rapidly infesting hollows throughout the south-west region.

What about installing more artificial nest boxes?

Although some artificial nest boxes are being used successfully for breeding Glossy Black Cockatoos on Kangaroo Island and for Carnaby’s Cockatoos here in the Wheatbelt of Western Australia they can also attract introduced species (such as European honey bees) and are relatively expensive to erect and monitor. Also, further research into size, shape and placement of artificial hollows needs to be undertaken to discourage introduced species from using the hollows.

Cockatoo Care is supportive of habitat enhancement through the creation of native corridors linking remnants, revegetation of degraded areas and the protection of remnant bushland with large trees.

Hollows provided by veteran and stag trees are unique and irreplaceable and crucial for the long-term survival of much of our wildlife.

We must start growing the next generation of veteran and stag trees now.