Don’t forget the middle: why shrubs are the most important plants you’re not planting

• A 2025 study found vegetation complexity, not tree cover or water, is the strongest driver of bird diversity in urban parks
• The 1–3m shrub layer is the most commonly missing layer in urban green spaces
• Pardalotes, Silvereyes, Scrubwrens, Fairy-wrens, the Eastern Spinebill, and certain honeyeaters (eg: New Holland, Regent) are among the species affected
• The fix is simple: add locally-native shrubs to plantings in your garden, street, or local park

Have you noticed a change in the type of birds you see in your neighbourhood over the years? Are there more Noisy Miners than anything else these days? Perhaps fewer Fairy-wrens? Why is that, and can we do something about it? (spoiler: yes!)

One study that set out to answer this question was recently (2025) published by Dr Nicola Sockhill and colleagues at The University of Queensland. Using eBird data and map files from various sources, they compared the complexity in vegetation with the diversity of bird species across a number of sites in Brisbane, QLD. The authors found that bird species richness within urban greenspaces strongly increased with vegetation complexity. That is, the more complex the vegetation, the greater the bird diversity. Interestingly, there was no significant association of bird diversity with tree cover or water cover.

These results are incredibly important because they prove that if urban greenspace revegetation focuses only on increasing tree cover, we’ll lose out on valuable biodiversity enhancement opportunities. And our special woodland birds would continue to be absent.

3D structure, physical mass in vertical space, is one aspect of forests that stands out as missing in new suburbs and urban areas. There is a distinct lack of vegetation complexity, but it’s something we can change. Planting trees is very popular among councils and revegetation groups, but too often shrubs and ground-cover are missing. In particular, the middle layer from 1m–3m is often forgotten about…with devastating consequences for our woodland birds in particular. Pardalotes, Silvereyes, Scrubwrens, and Fairy-wrens all lose out when the middle layer is missing.

Without the middle layer, bully birds like Noisy Miners gain strength in bold numbers, ruthlessly excluding many of our beautiful woodland birds. This process is well known and has even been listed in our national environmental laws (EPBC Act) as an official Key Threatening Process for our woodland birds. The perfect habitat for Noisy miners is scattered Eucalyptus trees in amongst lawn, so we’re selecting for this over-populated bully bird every time we over-mow or exclude ground cover and especially the middle shrubby layer in revegetation plans. Dr Ann Jones’ Brisbane Birds episode on Catalyst illustrates this well.

Many programs in Australia and globally, such as carbon credits, focus on the number of trees planted, rather than biodiversity outcomes. So, it’s up to us to change this norm and to push for better biodiversity outcomes in these schemes and programs. You can write to your council and ask about including shrubs wherever possible. Let’s get locally-native shrubs back into plantings.

And for National Tree Day on the 26 July, make sure to plant shrubs too!