Woodland biodiversity is declining on Adelaide’s doorstep

With the plight of threatened fauna normally obvious, researchers are finding it can take decades to detect subtle changes in the abundance of many species.

Since 2001, the woodland birds of the Mount Lofty Ranges near Adelaide have been monitored every year at over 150 sites from Victor Harbour in the south to near Gawler in the north. This one-of-a-kind dataset now paints a troubling picture of an ecosystem experiencing inexorable declines in many once common woodland species.

Researchers at the University of Adelaide's Environment Institute considered 65 South Australian bird species and found in their latest paper in Journal of Applied Ecology, that 75% of the abundance of these species had declined since 2001. These woodland specialist birds were more likely to be declining, including many small species such as crescent honeyeaters, golden whistlers, mistletoebirds and thornbills.

In contrast, many medium to large birds like magpies, ravens, corellas, sulphur-crested cockatoos and rainbow lorikeets are increasing in these woodlands. These are the same species that tend to thrive in relatively open urban landscapes.

[caption id="attachment_15573" align="alignleft" width="300"] Image: Peter Day. Musk lorikeets feed on pollen and nectar in the woodland canopy and are declining in the Mount Lofty Ranges[/caption]

While this research shows woodland biodiversity is declining right on Adelaide’s doorstep, Dr Thomas Prowse says it also suggests a solution.

"We need to modify the management of our woodlands to promote the development of complex understorey and canopy habitats that are required by woodland specialist birds. This means controlling grazing pressure from native and feral herbivores, as well as planning fuel-reduction burning to preserve some long-unburnt habitat within the landscape."

Often constrained by funding and organisational capability and commitment, monitoring programs need to be optimised to maximise ecological and economic efficiencies, as part of sound future management.