A vibrant forest clearing filled with colorful butterflies in the Pilliga Forest.

Pilliga Forest Butterflies: Unveiling a Hidden World & What It Means for Conservation

Nico Varela in Climate & Environment August 2025 • 4 min read.

"Discover the surprising diversity of butterfly species in the Pilliga Forest and why this makes it a critical hotspot for biodiversity conservation in Australia."

Australia's western slopes have undergone significant transformation over the past two centuries, evolving from vast temperate woodlands into extensive agricultural landscapes. This shift has left native vegetation highly fragmented, primarily confined to small remnants on less productive soils unsuitable for agriculture. As a result, a wide array of native vertebrate species faces serious decline, highlighting the urgent need for conservation efforts.

Invertebrate species' impact remains less understood. Many invertebrate species have disappeared from the agricultural matrix, now confined to remnant woodland areas. Even small remnants, often overlooked in vertebrate conservation, support diverse woodland invertebrates. However, disturbance-sensitive species may have already vanished, emphasizing the importance of studying and preserving these habitats.

Located in northern inland New South Wales (NSW), between Coonabarabran and Narrabri, the Pilliga Forest stands as the largest surviving temperate woodland remnant in the western slopes bioregions. This makes it an invaluable resource for understanding the original invertebrate fauna of the western slopes before landscape-scale agricultural development. This study describes the butterfly fauna of the Pilliga Forest, documenting local species diversity's spatial and temporal patterns.

Why the Pilliga Forest's Butterfly Diversity Matters

A vibrant forest clearing filled with colorful butterflies in the Pilliga Forest.

The Pilliga Forest's butterfly fauna is exceptionally rich, with 63 species representing five families recorded. This makes it one of the richest butterfly faunas recorded on the New South Wales western slopes and adjacent plains. This high diversity reflects the Pilliga Forest's location in a biogeographic overlap zone between northern and southern faunal assemblages, close to both the western plains and outliers of the mesic eastern highlands.

The study found no narrow-range endemic species or species of state or national conservation concern. However, half the recorded species have patchy, discontinuous distributions within their broad range due to specific habitat requirements. The study also documented some minor western range extensions and two hilltopping sites, further highlighting the Pilliga Forest's ecological importance.

Biogeographic Overlap: The forest's location makes it a meeting point for species from different regions.
Habitat Diversity: Varied landscapes within the forest support a wide range of butterfly species.
Range Extensions: The presence of certain species indicates a potential expansion of their known habitats.
Hilltopping Sites: Specific locations within the forest serve as gathering points for butterflies, crucial for mating and genetic diversity.

The most frequently recorded species included Belenois java, Junonia villida, Vanessa kershawi, Danaus petilia, Zizina otis, and the introduced Pieris rapae. These six species made up 65% of all field survey records. Interestingly, almost half the species (48%) had 10 or fewer records each, and ten species (18%) were represented by single records. This suggests that many species are present but not abundant, highlighting the need for ongoing monitoring and conservation.

Protecting the Pilliga Forest for Future Generations

The Pilliga Forest stands as a vital refuge for butterfly diversity in a landscape increasingly dominated by agriculture. Its unique biogeographic location, combined with varied habitats, makes it a crucial area for conservation efforts. Ongoing monitoring, habitat protection, and climate change mitigation strategies are essential to ensure the survival of these butterfly populations and the overall health of this invaluable ecosystem.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1071/pc18002, Alternate LINK

Title: The Butterfly Fauna Of The Pilliga Forest, A Large Woodland Remnant In The Brigalow Belt South Bioregion In Northern Inland New South Wales, Australia

Subject: Nature and Landscape Conservation

Journal: Pacific Conservation Biology

Publisher: CSIRO Publishing

Authors: Michael J. Murphy

Published: 2019-01-01

Everything You Need To Know

Why is the Pilliga Forest considered an invaluable resource for understanding invertebrate fauna in Australia?

The Pilliga Forest is significant because it represents the largest remaining temperate woodland in the western slopes bioregions of northern inland New South Wales. This makes it invaluable for understanding the original invertebrate fauna before widespread agricultural development. Its butterfly diversity, with 63 recorded species, reflects its unique position as a biogeographic overlap zone and a refuge in an agricultural landscape. The forest gives insight into the spatial and temporal patterns of local species diversity.

What factors contribute to the high butterfly diversity observed within the Pilliga Forest?

The high butterfly diversity in the Pilliga Forest is due to several factors. Firstly, its location is a biogeographic overlap zone between northern and southern faunal assemblages, near both the western plains and the mesic eastern highlands. Secondly, the varied landscapes within the forest provide diverse habitats supporting a wide range of butterfly species. Lastly, the documented minor western range extensions indicate the forest's role in potentially expanding species' known habitats.

Are there any butterfly species of conservation concern in the Pilliga Forest, and what does their presence indicate about the forest's ecosystem?

While no narrow-range endemic species or species of state or national conservation concern were identified in the Pilliga Forest, about half of the recorded species have patchy, discontinuous distributions due to specific habitat needs. Ongoing monitoring is crucial because nearly half the species had very few records, with some represented by single records. This suggests that although many species are present, their populations may not be abundant or stable, thus require careful monitoring and conservation.

Which butterfly species are most commonly observed in the Pilliga Forest, and what does their prevalence suggest about the local ecosystem?

The most frequently recorded butterfly species in the Pilliga Forest are Belenois java, Junonia villida, Vanessa kershawi, Danaus petilia, Zizina otis, and the introduced Pieris rapae. These six species account for 65% of all field survey records. Understanding the population dynamics and ecological roles of these common species can provide insights into the overall health and stability of the forest's ecosystem. Monitoring these species helps track changes and implement appropriate conservation strategies.

What measures are necessary to ensure the Pilliga Forest continues to serve as a vital refuge for butterfly diversity in the future?

Protecting the Pilliga Forest involves several key strategies. Ongoing monitoring is essential to track butterfly populations and identify any declines or threats. Habitat protection ensures that the diverse landscapes within the forest remain intact and suitable for various species. Climate change mitigation strategies are needed to address the potential impacts of changing environmental conditions on butterfly habitats and populations. Effective strategies ensure the survival of butterfly populations and the health of the Pilliga Forest ecosystem.