What to do with the invasive understorey shrub Acacia paradoxa? Sorting the avian winners and losers

ABSTRACT Woody shrub encroachment into the understorey of grassy eucalypt woodland in temperate southern Australia is changing ecosystem processes and impacting associated biodiversity. We investigated the impact on avian species richness and abundance caused by the perennial native wattle Acacia paradoxa invading three woodland vegetation communities (Eucalyptus arenacea/E. baxteri, E. camaldulensis and E. leucoxylon). Identification of avian winners and losers in these developing novel ecosystems can guide land managers seeking appropriate management options when faced with insecure funding for ongoing and expensive on-ground actions. Changes in avian species composition and abundance were determined at 56 sites, stratified into four A. paradoxa cover categories, in three open eucalypt woodland habitats across four localities. A total of 1251 birds/71 species were recorded in 209 surveys in spring 2022. Avian species richness and abundance varied significantly among the four localities and three grassy woodland vegetation types, with 34% of species found in only one vegetation type. Invasion by A. paradoxa altered bird community structure, increasing local species richness but reducing landscape-level richness – especially in E. leucoxylon woodlands. Threatened and open-woodland specialist species declined with higher shrub cover, while shrub-nesting birds flourished. Differing avian community responses to increasing A. paradoxa cover were evident with similar numbers of flourisher, user and avoider species. Over 70% of species either used or benefited from shrub invasion, but 19 species declined in abundance. Effective management should prioritise early intervention in low-to-moderate shrub cover areas to support threatened species and maintain avian diversity.

• Publication year

  2025

• Venue

  Transactions of the Royal Society of South Australia

• Publication date

  2025-07-03

• Fields of study

  Not labeled

• Identifiers
  DOI 10.1080/03721426.2025.2582103
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar

• No claims are published for this paper.

• No concepts are published for this paper.

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