A giant stack of sticks on display in the Freycinet National Park demonstrates the time and energy that white-bellied sea eagles put into building the structure that forms their nests.
The pile has another function – to encourage walkers not to fashion walking sticks from woody debris they find under trees.
An information panel with the title “not just a stick” explains the debris not only forms the building blocks of eagle nests but is a vital ingredient for the health of the broader forest eco-system.
The stick pile at the start of the trail to the Wineglass Bay lookout has, in fact, been created by parks staff gathering up makeshift walking sticks discarded by walkers on their way out of the park.
The sticks, along with fallen leaves and bark, form what is known as coarse woody debris, which has many natural functions. When it rots it provides food for insects which in turn provide food for insect-eating mammals and birds. The debris also stops soil erosion and protects seeds and young plants from heavy rain and grazing animals. And when the debris is broken down by fungi it helps build rich soils in which trees, shrubs and grasses flourish.
The stick pile at Freycinet is designed to represent a well-established nest, one reaching this size after 30 years of stick-gathering. The nests grow huge because nesting sea eagles add sticks each season as part of a general refurbishment. Sea eagles live for more than 30 years so it is possible for huge nests to be built by a long-lived pairs, or successors taking over nest sites.
The sea eagle is an apt symbol for the woody debris initiative. These magnificent birds are a common sight over the Freycinet peninsula and it did not take long for me to spot one on a recent trip. It was easy to separate the raptor from the other large bird of prey seen in Tasmania, the wedge-tailed eagle. Grey and white in colour, the sea eagle soared like a giant white butterfly on broad, raised wings. The sea eagle has a short tail which also aids identification over the “wedgie”.
Both the eagles might look fearsome in appearance but they are shy nesters, easily disturbed. The sea eagle nests in trees overlooking water but favoured nesting areas have come under increasing threat from coastal development in recent years. In the Freycinet National Park, however, they do not have a problem looking for nest sites, if such trees are not already occupied by other eagles. It is only the sticks to build the nests that can be in short supply.
Although the eagles take three decades to build a nest of this size, the mock nest took parks staff only three months to construct, such was the volume of discarded sticks at just one site.