Groundbreaking Research from University of Hawaiʻi at Mānoa

A recent study led by researchers at the University of Hawaiʻi at Mānoa (UH Mānoa) has sent ripples through the fields of ecology, historical biology, and conservation science. Published in the esteemed journal Ecosphere, the paper titled "The 'regime shift extinctions' hypothesis and mass extinction of waterbirds in Hawaiʻi" meticulously reviews decades of paleoecological data to challenge a persistent narrative. Lead author Kristen C. Harmon, a recent PhD graduate from UH Mānoa's College of Tropical Agriculture and Human Resources (CTAHR) Department of Natural Resources and Environmental Management, collaborated with Melissa R. Price, associate professor and head of the Wildlife Ecology Lab, and Kawika B. Winter, associate professor at the Hawaiʻi Institute of Marine Biology (HIMB). This interdisciplinary effort integrates archaeology, paleontology, climate records, and Indigenous knowledge systems to provide a fresh perspective on one of Hawaiʻi's most debated environmental histories.

The core revelation? There is no scientific evidence supporting the long-held belief that Native Hawaiians, or Kānaka ʻŌiwi, overhunted waterbird species to extinction following Polynesian settlement around 800–1000 years before present (B.P.). Instead, the study proposes that extinctions were driven by complex interactions including climatic regime shifts, invasive species introductions, and later land-use transformations—many predating or postdating active Indigenous stewardship periods.

Unraveling the 50-Year Myth of Indigenous Overhunting

For over half a century, a narrative originating from early 1980s publications—such as Storrs Olson and Helen James' work—has dominated discussions on Hawaiian avifauna losses. This 'overkill hypothesis' posited that Polynesian voyagers, upon arriving in the pristine Hawaiian archipelago, rapidly hunted flightless waterbirds like moa-nalos (extinct duck-like geese) and flightless ibises to extinction due to their naive behavior and lack of predators. Textbooks, museum exhibits, and conservation reports perpetuated this view, often framing Native Hawaiians as agents of ecocide without robust archaeological backing.

Kawika Winter articulates the bias succinctly: "So much of science is biased by the notion that humans are inevitable agents of ecocide, and we destroy nature wherever we go. This idea has shaped the dominant narrative in conservation, which automatically places the blame for extinctions on the first people—the Indigenous People—of a place." This framing not only lacked empirical support but also strained relationships between conservationists and Native Hawaiian communities, excluding traditional knowledge from decision-making processes.

Re-examining the Fossil Record: A Methodical Approach

The UH team employed a rigorous, multi-pronged methodology to reassess the evidence. They scoured databases like Google Scholar, Web of Science, and the AVOTREX (Avian Overkill Timing and Refugia Extinction) database for subfossil remains, radiocarbon dates, and direct observations of 18 extinct Hawaiian waterbird species. Key steps included:

• Determining the last known occurrence (LKO) in the fossil record for each species, categorizing them as pre-Polynesian (>1000 B.P.), Polynesian era, or post-European.
• Evaluating four competing hypotheses: overkill (hunting), deforestation, climate change, and species introductions.
• Searching for diagnostic evidence like cut marks, charred bones in middens, pollen/charcoal profiles for land clearance, paleoclimate proxies, and co-occurrence of invasives like Pacific rats (Rattus exulans).

Results were stark: Of the 18 species, 10 had LKOs before Polynesian arrival (e.g., Medium Kauaʻi Goose at 5145–6740 B.P.), 6 during the era (ambiguous timing), and 2 post-European (Hawaiian Rail, Laysan Rail). Critically, no extinct waterbird bones showed hunting modifications—only correlative midden proximity, undermined by dating inconsistencies.

The 'Regime Shift Extinctions' Hypothesis: A New Paradigm

Enter the study's novel contribution: the "regime shift extinctions" hypothesis. This framework posits that abrupt ecological transitions—triggered by climatic fluctuations or biological invasions—cascaded into biodiversity collapses. For instance, mid-Holocene droughts (5750–2190 B.P.) shifted vegetation from grasslands to ferns, stressing wetland-dependent waterbirds.

Polynesian-introduced Pacific rats exacerbated this by preying on eggs/chicks and depleting seeds of key plants like loulu palms, altering habitats indirectly. Post-contact, European cattle, pigs, and wetland drainage amplified losses. Read the full paper for detailed analysis: Ecosphere DOI: 10.1002/ecs2.70445.

Unlike simplistic blame on hunting, this model emphasizes systemic interactions, aligning with global patterns of Holocene extinctions (e.g., New Zealand moas).

Spotlight on Extinct Waterbird Species

Hawaiʻi's waterbirds were diverse and specialized. Notable extinctions include:

• Moa-nalos (Thambetochen spp.): Flightless, herbivorous geese browsing native plants; 7 species gone.
• Flightless Ibises (Apteribis spp.): Probing wetland for invertebrates; 4 species.
• Mole Ducks (Talpanas lippa): Burrowing Kauaʻi duck.
• Rails and Crakes (Porzana spp.): 10+ flightless species, vulnerable to rats.

These losses represent a significant trophic gap in island ecosystems.

Indigenous Stewardship: From Blame to Empowerment

Far from destroyers, Native Hawaiians actively managed wetlands via loʻi kalo (taro pond fields), fostering waterbird abundance. Historical accounts note thriving populations of endangered survivors like ʻalae ʻula (Hawaiian gallinule, Gallinula chloropus sandvicensis) and ʻaeʻo (Hawaiian stilt, Himantopus mexicanus knudseni) pre-1778. Melissa Price emphasizes: "Recent studies support what Hawaiians have always known—that restoration of loʻi is critically important... restore relationships between nature and communities."

Ulalia Woodside Lee of The Nature Conservancy adds that debunking the myth rebuilds trust, enabling collaborative recovery efforts.

Current Threats and Conservation Imperatives

Today, Hawaiʻi remains the "extinction capital of the world," with avian malaria (via invasive mosquitoes), habitat loss, and climate-driven sea-level rise threatening survivors. The study advocates loʻi restoration, invasive control, and biocultural integration. For more on UH's conservation work, visit the UH news release.

Success stories include successful nesting in restored sites, signaling potential for 'Recovery Capital' status.

UH Mānoa's Pivotal Role in Avian Research

CTAHR and HIMB lead globally, from AI-chant bird detection to malaria studies. This publication exemplifies UH's commitment to decolonizing science, blending Western empiricism with Native epistemologies for holistic solutions.

Broader Impacts on Global Conservation Narratives

Beyond Hawaiʻi, the study prompts reevaluation of Indigenous blame in Pacific extinctions, advocating evidence-based, inclusive approaches amid Anthropocene crises.

Future Directions: Research and Action

Next steps: Genomic analyses of subfossils, long-term loʻi monitoring, climate modeling. Policymakers should prioritize funding for stewardship-led initiatives to avert further losses.

Stakeholder Perspectives and Cultural Resonance

From graduate students challenging dogma (Harmon) to community leaders mending divides (Lee), voices converge on hope through partnership. Kristen Harmon notes: "Bringing together... knowledge systems can yield a more accurate picture of reality."

Photo by Jimmy Conover on Unsplash