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Since the 1990s, Greening Australia has worked with landholders and other partners on revegetation projects throughout the South-Eastern Highlands and South-Western Slopes of NSW and the ACT, often in areas that once supported grassy Eucalypt woodlands.

To confirm whether revegetation in these farm landscapes created quality bird habitat, in 1999 we started the BirdWatch program to monitor as many sites as possible.

Longitudinal studies of avifauna in Australian revegetation plantings are rare. The unique insights shared here, from 20+ years of surveying, confirm the importance of such long-term, standardised monitoring.

We gratefully acknowledge the dedicated efforts of volunteers from the Canberra Ornithologists Group, who’ve been supported by Greening Australia and other intermittent funding to undertake surveys over the years.

Stats at a glance

70%

Historic woodland bird habitat lost to grazing and cropping

1990s

Most of the surveyed revegetation sites established

142

Sites surveyed

1,502

Separate bird surveys conducted from 2000-2024

139

Bird species found in revegetation sites

20+

Bird species found at some reveg sites within 5 years of planting

Habitat loss and declining bird numbers

There is genuine concern about the status of entire bird communities that depend on habitats in our over-cleared agricultural landscapes, with many species and ecological communities nominated or listed as threatened.

In southern Australia, woodland birds have lost an estimated 70% of their historic habitat to grazing and cropping. Many landscapes have native vegetation cover well below 30%, which is the minimum considered necessary to support biodiversity and maintain ecological processes.

The South-Western Slopes and South-Eastern Highlands bioregions of ACT and NSW contain some of the most heavily altered landscapes, with less than 5% of vital habitat remaining in some parts. And what’s left is often fragmented or degraded, needing active management.

Habitat loss and declining bird numbers

There is genuine concern about the status of entire bird communities that depend on habitats in our over-cleared agricultural landscapes, with many species and ecological communities nominated or listed as threatened.

In southern Australia, woodland birds have lost an estimated 70% of their historic habitat to grazing and cropping. Many landscapes have native vegetation cover well below 30%, which is the minimum considered necessary to support biodiversity and maintain ecological processes.

The South-Western Slopes and South-Eastern Highlands bioregions of ACT and NSW contain some of the most heavily altered landscapes, with less than 5% of vital habitat remaining in some parts. And what’s left is often fragmented or degraded, needing active management.

From ‘Birdwatch’ beginnings to now

Most of the revegetation sites included in this study were established in the 1990s, funded through a variety of sources, primarily in areas that were once home to the now critically endangered Yellow Box – Blakely’s Redgum grassy woodland. Addressing salinity and erosion were prime objectives, as well as providing shade and shelter for livestock.

Creating habitat for native wildlife was also considered an important objective, but was perhaps an assumed outcome. To turn this assumption into evidence-based science, the ‘Birdwatch’ project was born. Remnant woodland and open paddock sites, as well as revegetated sites of various sizes and ages, were surveyed. Monitoring expanded from this project and continues at a range of sites through to the present day.

“At the end of the Decade of Landcare in the 1990s, with countless hours and dollars spent on revegetation in the ACT and southeast NSW, we took a step back and asked ‘Are we making a difference?’ There was little information available to assess whether revegetation did, in fact, provide habitat.”

Nicki Taws, Greening Australia Program Specialist

What did we find out?

Birds observed

One hundred and forty-two bird species were observed between 1999 and 2024 from more than 1,500 separate bird surveys at 142 different sites: 

  • 139 species observed in revegetation sites (103) 
  • 98 species observed at remnant sites (n=29) 
  • 48 species observed at paddock sites (n=10).
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Revegetation benefits woodland birds

Revegetation benefits woodland birds significantly over time, compared to passive restoration (grazing exclusion) or no revegetation [1].  

Direct seeding and tubestock revegetation sites supported a woodland bird community similar to that of remnant patches and significantly greater condition than that of paddock sites. 

Woodland bird communities responded quickly to revegetation, with some sites supporting more than 20 woodland species within five years of planting. 

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The bigger, the better - but some better than none

Generally, the bigger the replanting area, the better the community condition and richness of woodland bird species, but even very small sites supported a diverse range, with some sites < 1 ha supporting more than 30 different species. 

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Grazing exclusion plus revegetation works

Grazing exclusion plus revegetation had a strong positive effect on woodland bird species richness, abundance, and community condition relative to sites where no actions had occurred [1]. These effects strengthened over time as revegetation matured and exclusion of grazing allowed the understorey to recover.  

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Time changes revegetation structure for the better

The revegetation projects had a diverse mix of native trees and shrubs, including Acacia species, due to their importance in the vegetation community composition, their reliable germination in direct seeding, and fast growth rates. Over time, the dense growth gave way to the decay of some plants and the accumulation of leaf litter and dead wood, benefitting small insectivores and ground-foraging bird species. Patchiness and edges also provided for ground foragers and aerial feeders. 

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More vegetation nearby = better habitat

Landscape context – that is, the proportion of vegetation within a 100m radius of the planting site – was positively related to woodland bird community condition.  

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Paddock trees add value

Paddock trees were important for increasing bird species richness, total abundance, and community condition when associated with replanting sites.

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Bird species observed in revegetation

The 20 species most commonly recorded in revegetation during surveys were all native and many were small insectivorous birds. Although common across the region, not all are found in the typical grazed woodland remnant sites.

Some of the larger more aggressive native species such as the Noisy Miner and Pied Currawong were recorded less frequently in revegetation sites (27% and 38% of sites, respectively).

Particularly encouraging was the occurrence of threatened or declining woodland bird species in revegetation.

Case study

Direct seeding to increase midstorey cover has transformed this degraded remnant of Box-gum Grassy Woodland. Over the space of 12 years, it changed from being a Noisy Miner-infested remnant to a vibrant regenerating woodland of up to 30 bird species per survey.

2001

  • Australian Magpie
  • Common Starling
  • Eastern Rosella
  • Galah
  • Noisy Miner
  • Spotted Pardalote
  • Striated Pardalote
  • Superb Parrot
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2008

  • Australian Magpie
  • Black-faced Cuckoo-shrike
  • Buff-rumped Thornbill
  • Common Bronzewing
  • Crested Pigeon
  • Eastern Rosella
  • Galah
  • Golden Whistler
  • Grey Butcherbird
  • Grey Fantail
  • Grey Shrike-thrush
  • Noisy Friarbird
  • Noisy Miner
  • Pied Currawong
  • Red Wattlebird
  • Striated Pardalote
  • Superb Parrot
  • Weebill
  • White-winged Chough
  • Willie Wagtail
  • Yellow Thornbill
  • Yellow-faced Honeyeater
  • Yellow-rumped Thornbill
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2023

  • Australian Magpie
  • Black-faced Cuckoo-shrike
  • Buff-rumped Thornbill
  • Crimson Rosella
  • Double-barred Finch
  • Eastern Rosella
  • Grey Fantail
  • Grey Shrike-thrush
  • Laughing Kookaburra
  • Leaden Flycatcher
  • Noisy Friarbird
  • Olive-backed Oriole
  • Pied Currawong
  • Red-browed Finch
  • Rufous Whistler
  • Silvereye
  • Spotted Pardalote
  • Striated Pardalote
  • Striated Thornbill
  • Sulphur-crested Cockatoo
  • Superb Fairy-wren
  • Superb Parrot
  • Weebill
  • Western Gerygone
  • White-plumed Honeyeater
  • White-browed Scrubwren
  • White-winged Chough
  • Yellow Thornbill
  • Yellow-faced Honeyeater
  • Yellow-rumped Thornbill
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Lessons learned: revegetation for woodland bird habitat

Quality is key

The quality of revegetation as habitat for birds increases with age. This probably has less to do with age, and more to do with vegetation features that develop as revegetation matures. Either way, revegetation is an investment in the future.

The ‘matrix’ matters

The greatest influence on the number of woodland birds is the total amount of wooded vegetation in the landscape. By adding to or buffering remnant vegetation with revegetation, bird species richness is increased, especially for landscapes with little remnant vegetation present.

Revegetation vs remnant vegetation

The species richness for remnant and revegetated sites can be similar, but the actual composition of bird species will likely differ. Species richness in remnant and revegetated sites is shown to be 2-3 times greater than in pasture sites with scattered trees, and almost 5 times more than in open paddocks.

Paddock trees are precious

These ‘avifauna apartment blocks’ provide critical habitat and resources and should be retained at all costs. For example, paddock trees often contain hollows that are critical for hollow-nesting bird species and can take 200 years to form. The presence of paddock trees in revegetation significantly increases bird diversity, abundance and community condition.

Extent, structure and context are important

Bird species richness is greater in revegetation areas that are large, wide, structurally complex, mature and near remnant vegetation. Wider shelterbelts support more species than narrow shelterbelts. Structurally complex revegetation supports more and different bird species than simpler revegetation. Different revegetation strategies (e.g. direct seeding vs tubestock planting) will result in different woodland growth types and support different bird assemblages. Understorey-dependent birds will respond to an increase in shrubby vegetation, granivores require seeding grass, while bark-gleaning insectivores need mature trees.

How long until birds return? It depends

Bird species can rapidly recolonise revegetation plantings. Common bird species can recolonize revegetation within two to three years, and many declining and uncommon birds after eight years [2]. However, realising the full recovery potential of revegetation for woodland birds takes time – from 40-100 years. Some groups may remain absent until specific ecological components are restored, e.g. leaf litter, native forbs, mistletoe, logs, hollows, understorey, midstorey.

Cleared landscapes need active intervention

Native vegetation systems typically do not recover on cleared agricultural land without intervention. Excluding grazing is not sufficient on its own; active restoration is required to overcome degrading influences. Replanting or sowing seed is often the only means of restoring vegetation community structure.

Everyone loves a bird

Even the most hardened farmer can be encouraged to talk about birds. While the focus or funding for a project may be for another objective (addressing salinity, erosion etc.), incorporating the benefits to birds has proven to be a strong motivator for undertaking revegetation. Threatened bird species (e.g. Superb Parrot Polytelis swainsonii, Swift Parrot Lathamus discolor, Regent Honeyeater Anthochaera phrygia, Glossy Black-Cockatoo Calyptorhynchus lathami) have been a central focus for Greening Australia to receive funding and achieve revegetation across the grassy box-woodland region of the inland slopes.

References:

[1] Gibson, M. et al. (2022) ‘Use of citizen science datasets to test effects of grazing exclusion and replanting on Australian woodland birds’, Restoration Ecology, 30(7), p. e13610. Available at: https://doi.org/10.1111/rec.13610.

[2] Greening Australia (2007) ‘Bringing Birds Back: make a love box guide for bird identification and habitat restoration in the ACT and south-estern NSW’. Greening Australia. Available at: https://www.greeningaustralia.org.au/wp-content/uploads/2017/11/GUIDE_Bringing-back-the-birds_-a-glovebox-guide.pdf.