Eucalypt plantings benefit declining bird species
From the October 2007 edition of Agriculture Today.
Species of woodland-dependent birds whose numbers have been declining are finding new homes in plantings of eucalypts and shrubs.
NSW Department of Primary Industries (DPI) forest biodiversity researchers have surveyed 120 eucalypt plantations in south-western NSW and northern Victoria and found they are providing useful habitat for at least 10 declining woodland-dependent bird species.
These include the Speckled Warbler, Red-capped Robin (pictured) and Rufous Whistler.
Most of the original forest and woodland cover in these areas has been cleared for agriculture, and what remains is fragmented and often disturbed.
However, over the last 30 years, eucalypts and native shrubs have been planted extensively to provide a range of environmental benefits.
NSW DPI forest biodiversity research leader, Dr Rod Kavanagh, said the survey was undertaken to determine the extent to which these plantings could improve biological diversity in agricultural landscapes.
"We sampled birds at 120 sites encompassing the range of patch sizes, stand ages and structural conditions for both planted areas and nearby forest remnants to assess their potential as habitat. These were compared with surrounding paddocks. "
Eucalypt plantings were found to provide significant improvements in bird population density, compared with cleared or sparsely treed paddocks.
"Mixed eucalypt and shrub plantings contained similar bird communities to remnant native forest and woodland in the region," Dr Kavanagh said.
Factors found to be important for the presence of birds included the size of the patch, its age and distance from remnant forest and woodland.
Larger remnants and plantings - those more than five hectares in area - had more species and more individuals than smaller patches of similar vegetation.
Older plantings, aged between 10 and 25 years, had more individuals and species than younger plantings.
‘Habitat connectivity’, which is the distance from remnant forest, is an important variable influencing bird species richness in eucalypt plantations.
A few species, including the Brown Treecreeper, were confined to remnant forest and woodland in the region.
Dr Kavanagh said eucalypt plantings of all shapes and sizes, but especially those larger than five hectares, were found to have an important role to play in providing habitat for many bird species.
Contact Rod Kavanagh, West Pennant Hills, (02) 9872 0160, rodk@sf.nsw.gov.au
