Discovering the Climate Threat to New Zealand's Unique Alpine Grasshoppers

New Zealand's alpine ecosystems are home to a remarkable radiation of flightless grasshoppers, endemic species adapted to the harsh conditions of the Southern Alps and other mountain ranges. A pivotal study from Massey University's Wildlife Ecology Group has sounded the alarm: approximately a quarter of these alpine grasshopper species are at high risk of extinction due to ongoing climate change. Led by PhD researcher Emily Koot alongside Professors Mary Morgan-Richards and Steven Trewick, the research utilized advanced ecological niche modeling to project future habitat suitability under various global warming scenarios. This work not only highlights the vulnerability of these insects but also underscores the critical role of university-led research in understanding and mitigating biodiversity loss.

These grasshoppers, belonging primarily to the genera Sigaus, Alpinacris, Brachaspis, and Paprides, are flightless and rely on specific high-elevation habitats characterized by cool temperatures, seasonal precipitation patterns, and open tussock grasslands. As global temperatures rise, their low-elevation ranges are already contracting, forcing populations upslope where suitable habitat dwindles to nothing at the peaks.

The Evolutionary Marvel of New Zealand's Alpine Grasshoppers

New Zealand's alpine grasshoppers represent a classic example of adaptive radiation, where a common ancestor diversified into multiple species each occupying distinct ecological niches across the archipelago's mountains. There are 12 key species studied, all short-horned (Acrididae family, Catantopinae subfamily), with elevation ranges from lowland extensions up to over 2,000 meters above sea level. For instance, Sigaus villosus thrives between 1,370 and 2,130 m.a.s.l., while Sigaus childi is more restricted to lower elevations around 160–420 m.

These insects are freeze-tolerant, capable of surviving intracellular ice formation during winter, a remarkable adaptation to alpine life. However, their flightlessness limits dispersal, making them particularly susceptible to habitat fragmentation. The study compiled 949 georeferenced occurrence records from museum collections, literature, and field surveys spanning 1967–2016, providing a robust dataset for modeling.

• Sigaus australis: Widespread, 285–2,020 m, key model species.
• Brachaspis collinus: High alpine, 1,000–2,000 m, severe loss predicted.
• Paprides dugdali: 400–1,160 m, at extreme risk.

This biodiversity hotspot in Aotearoa's alps is under siege, with implications for ecosystem engineers like these herbivores that shape tussock grasslands.

Massey University's Wildlife Ecology Group Leading the Charge

At the forefront of this research is Massey University's Wildlife and Ecology Group, based in Palmerston North. Emily Koot's doctoral work formed the backbone, supported by senior academics Mary Morgan-Richards and Steven Trewick, experts in invertebrate evolution and phylogeography. Funded by a Massey doctoral scholarship and the Miss E. L. Hellaby Indigenous Grasslands Research Trust, the study exemplifies how New Zealand universities drive conservation science.

The group's ongoing Phoenix Lab blog, including a 2025 post on 'Climate Squeeze', documents real-time observations of upslope shifts and local extinctions at lower elevations, validating model predictions. Such research positions Massey as a hub for ecology students and professionals. Aspiring researchers can explore opportunities via higher ed research jobs or career advice at AcademicJobs.com higher ed career advice.

Unpacking the Methods: Ecological Niche Modeling Explained

Ecological niche modeling (ENM) predicts species distributions based on environmental variables and known occurrences. The team calibrated 10 algorithms—Generalized Linear Models (GLM), Generalized Boosted Models (GBM), Generalized Additive Models (GAM), Classification Tree Analysis (CTA), Artificial Neural Networks (ANN), Surface Range Envelope (SRE), Flexible Discriminant Analysis (FDA), Multivariate Adaptive Regression Splines (MARS), Random Forest (RF), and Maximum Entropy (MAXENT)—using the R package biomod2.

Data included 19 WorldClim bioclimatic variables (e.g., annual mean temperature, precipitation of driest month), refined to seven uncorrelated via variance inflation factor (VIF), plus soil and vegetation layers. Models were trained on 80% data, tested on 20%, with ensemble projections under RCP2.6 (+1°C) and RCP8.5 (+3.7°C) for 2061–2080. Fragmentation assessed via FRAGSTATS, considering dispersal limitations.

Step-by-step: 1) Collate presences/absences; 2) Select variables; 3) Train/evaluate models (ROC >0.9, TSS >0.8); 4) Ensemble forecast; 5) Analyze patches.

Startling Findings: Species-Specific Habitat Losses

Results reveal nuanced but dire outcomes. With unlimited dispersal, some species gain habitat under mild warming, but realistically, no dispersal shows universal contraction. A quarter—three species (Brachaspis collinus, Sigaus childi, Paprides dugdali)—face 96–100% range loss, spelling likely extinction.

Climate variables like mean diurnal temperature range and isothermality dominate predictions.

Understanding Climate Scenarios and Their Global Context

RCP2.6 represents aggressive mitigation (+1°C global rise), while RCP8.5 is business-as-usual (+3.7°C). New Zealand's alps amplify effects: warmer lows become unsuitable, squeezing species upward. Fragmentation metrics show declining patch sizes (e.g., Sigaus australis mean patch shrinks), increasing isolation risks like inbreeding.

This mirrors global alpine insect trends, as noted in a 2025 review citing NZ grasshoppers' upslope shifts into suboptimal habitats.

Real-World Evidence: Observed Declines in the Southern Alps

Beyond models, field data confirms: low-elevation populations of Sigaus villosus extinct, with contractions noted since the 1990s. A January 2025 report highlights 'local extinction' events, aligning with 'climate squeeze'. Massey's longitudinal monitoring reveals upslope migration but no compensatory gains.

Conservation Strategies and Protected Species

Species like Sigaus childi are protected under the Wildlife Act 1953, one of few grasshoppers so listed. Efforts include predator control (e.g., for Brachaspis robustus, related endangered species) via DOC fences and monitoring. Recommendations: assisted migration, habitat corridors, emissions reduction. Universities like Massey train conservation biologists for these roles—check NZ university jobs.

• Predator exclusion fences.
• Population translocations.
• Climate-resilient reserve design.

Broader Implications for Aotearoa's Biodiversity and Ecosystems

Loss of these grasshoppers disrupts alpine food webs: herbivores influence plant succession, prey for birds/spiders. Signals wider invertebrate crisis; NZ has high endemism but few protections. Ties to Māori values of taonga species and whenua care.

University research informs policy, e.g., via Crown Pastoral Lease reviews.

Future Research and Opportunities in NZ Higher Education

Massey's team continues with genetic studies on divergence (e.g., 2024 phenotypic paper). PhDs in wildlife ecology offer hands-on fieldwork. Explore rate my professor for insights on Massey faculty, or faculty positions.

Photo by David Trinks on Unsplash

Call to Action: Support Research and Conservation Careers

This Massey study calls for urgent action. Students, rate your experiences at Rate My Professor, seek higher ed jobs in ecology, or get career advice. Engage with NZ universities to safeguard alpine taonga.