BIRDS ON FARMS
It is universally recognized that protecting natural ecosystems and maintaining biodiversity on farms are fundamental elements of sustainable agriculture. A healthy bird community removes between 50-70% of leaf-eating insects and plays a valuable role in keeping farm trees alive. Birds are, therefore, critical in maintaining tree health.
The Birds on Farms Survey found that in order to achieve sustainable farming practices, including approaches such as integrated pest management. A few simple guidelines can be applied. They are as follows:
Management of one-third of the farm should be sympathetic to the local vegetation, with native vegetation covering at least 30% of the total farm area.
Native vegetation cover should be in patches of 10 hectares and linked by strips at least 50 meters wide.
Manage at least 10% of the farm area for wildlife.
Maintain a range of tree ages.
Leave fallen trees to break down naturally.
Maintain shrub cover over at least one-third of the native vegetation area.
Maintain native vegetation around water bodies, dams, wetlands, and riparian zones.
Here are some interesting statistics that came out of the study:
Bird diversity increased by 30% for every 10 large trees present at a farm site.
A critical age for planted trees appears to be between 5 and 10 years, after which bird diversity is significantly greater.
For every 10 fallen trees present at a farm site, the diversity of ground-dwelling birds increased by 30%, and bark-foraging birds by 70%.
Total bird diversity was greater in farm sites with leaf litter, particularly when the litter was present in dense clumps.
In farm sites where understorey shrubs were present, there was a 31% increase in the diversity of woodland-dependent birds.
Ground-nesting birds were almost 3 times as diverse where understorey was present.
A river or creekline resulted in a 21% increase in the diversity of woodland-dependent birds.
Small birds were 28% more diverse, and ground-nesters were 29% more diverse when waterways were present. With the addition of features such as dense scrubby vegetation, shallow wet areas for birds to feed, islands or dead trees for birds to roost, or fencing to exclude stock, there was a 14% increase in waterbird diversity. The presence of 2 of these features resulted in a 28% increase, 3 resulted in a 42% increase in diversity, and so on.
Small foliage-gleaning birds were 26% less diverse in farm sites where exotic trees had been planted instead of native trees. By contrast, exotic birds were about 5 times more diverse in these sites.
Bird diversity is re-established about 15 years after the removal of stock from a heavily grazed site. This increase in diversity continues, reaching a maximum diversity after about 25 years.
It takes a minimum of 80 years for trees to start producing hollows. 1 in 5 Australian birds require nest hollows for breeding. If no large old hollow-bearing trees are available, then establish nest boxes for species such as the barn owl, the laughing kookaburra, sugar and squirrel gliders.
Other birds you may want to attract to your farm include the Eastern Yellow Robin, White-throated Treecreeper, Superb fairy-wrens, Brown Thornbills, Yellow-faced Honeyeaters, Bush Stone-curlew, Flycatchers, Golden whistlers, Speckled Warblers, Spotted Pardalote, Herons, Kingfishers, and Finches, etc.
The Birds on Farms book is available from Birds Australia, providing a fuller description of the guidelines mentioned above.