Publications
Birds of Oeno Atoll, Pitcairn Islands, in September 2025
A 2025 survey of Oeno Atoll, Pitcairn Islands, reveals significant seabird population recovery following the eradication of invasive Polynesian rats in 1997. The study highlights asynchronous breeding patterns and high reproductive success across multiple species, with colony sizes surpassing pre-eradication estimates. In contrast, Henderson Island's ground-nesting seabirds continue to face predation pressures. The research emphasizes the importance of long-term monitoring to understand breeding phenology and population trends, underscoring Oeno Atoll's role as a critical seabird stronghold in recovery.
Low and steady: Minimal change in plastic exposure in Kermadec Petrels in the remote South Pacific
A study on Henderson Island reveals that plastic ingestion in Kermadec Petrels (Pterodroma neglecta) has remained consistent at low levels over more than 30 years, with only 23.1% of fledglings sampled in 2025 containing small quantities of microplastics (mean ± SD: 0.0113 ± 0.0061 g). This finding contrasts sharply with plastic ingestion rates in closely related species, suggesting that Kermadec Petrels may selectively avoid plastic or forage in areas with lower pollution densities. The research, conducted on uninhabited Henderson Island and Oeno Atoll, highlights the potential for these birds to serve as sentinels for pollution in remote South Pacific regions, offering valuable insights into species-specific vulnerability to marine debris.
Assessing strategies for remote island beach cleanups: Lessons from the Pacific and Alaska
Effective remote island beach cleanups require careful planning, local engagement, and innovative technologies to balance benefits with potential harms. A study comparing Henderson Island in the South Pacific and Kruzof Island in Southeast Alaska identified key strategies for managing plastic pollution in isolated regions. Using a six-step cleanup framework, researchers evaluated approaches based on feasibility, cost-effectiveness, and co-benefits. The findings highlight that while downstream cleanups are necessary, they must be executed with caution to avoid ecological disruption or unintended consequences. This research provides actionable insights for marine debris management in remote locations.
The Henderson Island microcosm: plastic pollution accumulation in the South Pacific
A significant reduction in plastic accumulation on Henderson Island, a remote UNESCO World Heritage Site in the South Pacific, was observed following a 2019 cleanup. Annual accumulation rates dropped from 284.75 g/m² (2015–2019) to just 16.8 g/m² (2019–2024), though litter density remains high at 53 items/m², primarily maritime debris. This study leverages decade-long longitudinal data to demonstrate the effectiveness of large-scale cleanups while highlighting persistent pollution challenges. It underscores Henderson Island's role as a microcosm for monitoring oceanic plastic dynamics, emphasizing the need for ongoing community-led efforts, larger sample sizes, and stricter maritime regulations to address lingering debris. Seasonal variability and methodological differences in data collection were also identified as key factors influencing results.
New distribution records of the coconut crab (Birgus latro) in eastern Polynesia on Oeno Atoll, Henderson Island, and Ducie Atoll, Pitcairn Islands
Researchers have extended the known eastern range of coconut crabs (Birgus latro) by over 600 kilometers, documenting their presence on Oeno Atoll, Henderson Island, and Ducie Atoll in the Pitcairn Islands. This discovery challenges previous assumptions about the species' distribution limits in the Indo-Pacific region. While populations remain sparse, suitable habitat and prey suggest larger numbers may exist, particularly on Henderson Island. The study relied on narratives and occurrence records to identify these new distribution points. Edge-of-range populations are often vulnerable, but the remoteness of the Pitcairn Islands may provide protection from threats affecting other regions.
Confirmation of a new breeding area for humpback whales (Megaptera novaeangliae) in the central South Pacific
Research confirms the waters around Henderson Island and nearby Pitcairn Island as a new breeding ground for humpback whales (Megaptera novaeangliae) in the central South Pacific. Observations from 2019 to 2021 revealed small, mixed groups of adult males, mothers with calves, and escort whales, exhibiting behaviors such as surface-active movements and unrecorded singing, indicative of mating and calving. Calves were estimated to be newly born, suggesting these islands serve as critical habitats during the austral winter and spring. While the study did not track individual whales, it hints at a possible connection between these isolated breeding groups and larger populations in French Polynesia, though further research is needed to establish this link.
A new extinct species of Polynesian sandpiper (Charadriiformes: Scolopacidae: Prosobonia ) from Henderson Island, Pitcairn Group, and the phylogenetic relationships of Prosobonia
Researchers have identified a new extinct species of Polynesian sandpiper, Prosobonia sauli, from Henderson Island, Pitcairn Group. This discovery, based on Holocene fossil bones collected during an expedition in 1991–92, extends the record of known extinct Polynesian sandpipers to four. The species is distinguished from the extant Tuamotu Sandpiper by notable differences in leg and bill morphology, suggesting adaptations to distinct ecological niches. Phylogenetic analyses using newly sequenced genetic data, including mitochondrial genomes of related species, confirm Prosobonia's close relationship with turnstones and calidrine sandpipers, providing insights into the evolutionary timeline and sedentary lineage development within the highly migratory Scolopacidae family.
Records of Brown Booby Sula leucogaster in the Pitcairn Islands with additional observations during 2015–19
A comprehensive review of the avifauna of the Pitcairn Islands, including Henderson Island, reveals that while Henderson supports five endemic bird species, Ducie and Oeno lack any endemic species. The study highlights the significant scientific attention given to Henderson's birds since the early 20th century, with notable expeditions such as the Sir Peter Scott Memorial Expedition (1991–92) providing extensive data on the island's avian life. Recent studies have also focused on the impact of introduced Pacific Rats on Henderson's native fauna and the abundance of various species. The avifauna of the Pitcairn group has been described in key works, including those by Williams (1960), Brooke (1995b), Thibault & Cibois (2017), and a review by Bourne & David (1983).
Air temperature trends, variability and extremes across the Solomon Islands: 1951-2011s
A significant warming trend has been observed across the Solomon Islands from 1951 to 2011, with mean annual temperatures rising by 0.14 to 0.39 °C per decade at seven weather stations. This shift is marked by an increase in warm days (2.2 days/decade) and warm nights (0.8 nights/decade), alongside a decrease in cool days (0.4 days/decade) and cool nights (1.4 nights/decade). The study, utilizing daily minimum and maximum temperature data from all operational stations, reveals that Taro has the highest mean temperature due to its equatorial proximity, while Henderson Island, part of UNESCO World Heritage Sites, recorded the lowest average at 26.9°C. Honiara's elevation contributes to its warmest temperatures during June through October. Overall, the Solomon Islands' climate has warmed significantly, with implications for regional ecosystems and heritage sites.
Entrapment in plastic debris endangers hermit crabs
Plastic debris on Henderson Island and the Cocos (Keeling) Islands poses a severe threat to strawberry hermit crabs, with an estimated 61,000 and 508,000 crabs becoming entrapped annually on these islands. The study highlights that beach debris creates significant barriers for crabs during their daily activities, leading to mass mortality. This research underscores the urgent need to understand the link between debris interactions and population persistence, as hermit crabs play a crucial role in maintaining tropical ecosystems. The findings suggest that accumulating plastic debris could seriously impact crab populations globally, with implications for countless other islands where crabs and debris overlap.
Recovery of introduced Pacific rats following a failed eradication attempt on subtropical Henderson Island, South Pacific Ocean
A failed eradication attempt of Pacific rats (Rattus exulans) on Henderson Island, a UNESCO World Heritage Site in the South Pacific, led to rapid population recovery within two years. The study found annual per capita growth rates ranging from 0.48 to 5.95, with rat numbers rebounding from 60–80 individuals to two-thirds of pre-eradication levels before stabilizing around carrying capacity. Seasonal fluctuations in trapping rates—peaking at 36.6 rats per 100 trap-nights and dropping to 12.6—were observed, alongside density variations (20.4 to 42.9 rats/ha) in embayment forests and lower densities (0.76 to 6.08 rats/ha) on coral plateaus. These findings highlight the challenges of rodent eradication in tropical environments, where reduced seasonality and resource pulses complicate population dynamics. Understanding invasive species behavior is critical for future eradication success.
Seasonal variation in movements and survival of invasive Pacific rats on sub-tropical Henderson Island: implications for eradication
A study on Henderson Island revealed that Pacific rats exhibit significant seasonal variation in survival, with the highest monthly survival probability (0.950) observed in late August and the lowest (0.352) in late July. This temporal pattern suggests resource limitations that could influence the success of eradication efforts. The research used a spatially-explicit Cormack-Jolly-Seber model to estimate movement distances, home range sizes, and survival rates over five months. Rats displayed varied movement behaviors, with some exhibiting 'territorial' (median radius: 134 m) and others 'roaming' (median radius: 778 m) patterns. The proportion of roaming rats fluctuated seasonally, peaking at 23% in October. These findings imply that timing eradication efforts to align with periods of lower survival probability could enhance success.
Divergent foraging strategies during incubation of an unusually wide-ranging seabird, the Murphy’s petrel
Murphy's petrels exhibit two distinct foraging strategies during incubation, with one group traveling up to 4800 km around the South Pacific Gyre while another forages closer to home. Birds on longer trips gain more mass and encounter prey more frequently during directed movement, suggesting that in unproductive waters, covering larger areas increases foraging success. Analysis of long-term data reveals consistency in these strategies across years, with lighter birds benefiting from tailwinds and reduced competition. The study used GPS tracking and salt-water immersion loggers to differentiate between directed movement and area-restricted search behavior, providing insights into the adaptive foraging tactics of this wide-ranging seabird.
Population status of four endemic land bird species after an unsuccessful rodent eradication on Henderson Island
An unsuccessful rodent eradication on Henderson Island, a UNESCO World Heritage Site in the Pitcairn Group, revealed that even temporary reductions in invasive rat populations can benefit some endemic bird species. The study found that the Henderson Reed Warbler and Henderson Fruit Dove showed significant population increases post-eradication attempts, likely due to reduced predation pressure and competition for fruit, respectively. However, natural factors like a prolonged drought may have also influenced these trends, complicating definitive attribution of recovery to rodent reduction alone. Researchers used point counts at 25 locations over four years (2011–2015) and binomial mixture models to account for detection probabilities, emphasizing the need for robust pre- and post-management monitoring to clarify species responses in such operations.
Escaping the oligotrophic gyre? The year-round movements, foraging behaviour and habitat preferences of Murphy’s petrels
Murphy's petrels, breeding on Henderson Island, exhibit unprecedented foraging ranges among seabirds, traveling over 4800 km during incubation to escape the nutrient-poor South Pacific Gyre. This study reveals their year-round movements and habitat preferences using geolocators, showing they migrate seasonally to the Subarctic Gyre in the North Pacific for more productive waters. Unlike many seabirds, Murphy's petrels do not show strong preferences for oceanographic or topographic features, instead favoring deep, unproductive waters. Their high activity levels, particularly during incubation, suggest a reliance on mesopelagic prey that undergo diel vertical migration. Conservation efforts should prioritize eliminating invasive threats at breeding sites while recognizing the challenges of protecting such wide-ranging species.
Henderson Island’s Plastic: An Explanation
Henderson Island, a pristine UNESCO World Heritage Site, has become a significant repository for plastic waste due to the accumulation of debris transported by a broad, permanent surface current. This current, characterized by its high temperature, shallow depth (around 100 meters), and sluggish speed (10-20 cm/sec), flows southeastward past the island, which is located at the midpoint of this extensive warm current spanning over 5000 km along 28 S. The study suggests that understanding the origin of this plastic waste more precisely could potentially mitigate its accumulation on Henderson Island's beaches, offering a path to preserve this unique environment.
Population status, breeding success and ecology of the Henderson Petrel after a failed rat eradication on Henderson Island
A study on Henderson Island, a critical breeding site for the endangered Henderson Petrel (Pterodroma atrata), found no evidence of population decline despite a failed rat eradication attempt in 2011. Researchers compared data from 1991 and 2015, estimating the current population size at 19,987 pairs—slightly higher than the previous estimate of 18,668. Nest survival was recorded at 28.5%, with most failures occurring within a week of hatching due to predation by rats or crabs. Breeding success appeared stable, suggesting the population may remain resilient despite ongoing threats. The study highlights the challenges of conservation efforts in subtropical island ecosystems and underscores the need for continued monitoring.
Rat eradication comes within a whisker! A case study of a failed project from the South Pacific
Despite efforts to eradicate invasive rats from Henderson Island, a UNESCO World Heritage Site in the South Pacific, the project fell short by a narrow margin. Genetic analysis revealed that only about 50–80 rats survived the initial baiting with brodifacoum, indicating a near-successful eradication attempt. The study excluded reintroduction as the cause for the rat resurgence and found no signs of resistance to the toxicant in the surviving population. This case study provides valuable insights into the challenges of large-scale invasive species control and offers lessons for future conservation efforts.
Reducing the primary exposure risk of Henderson crakes (Zapornia atra) during aerial broadcast eradication by selecting appropriate bait colour
Research indicates that Henderson crakes (Zapornia atra), a globally threatened island endemic, are significantly less likely to consume blue bait pellets compared to green ones. This finding suggests a potential strategy to reduce non-target mortality during rat eradication efforts on Henderson Island. The study involved 22 captive Henderson crakes, which were observed over five days in 2015, with consumption measured and analyzed using linear mixed models. Results showed that females consumed 24% less blue bait than green, while males consumed 77% less. Notably, the crakes did not consume dry pellets, highlighting the importance of wet bait conditions. The study recommends using blue baits during future rat eradication to minimize exposure risk for Henderson crakes.
Native plant species richness on Eastern Polynesia’s remote atolls
Native plant species richness on remote atolls in Eastern Polynesia is primarily influenced by atoll area and proximity to raised atolls or large volcanic islands, such as Makatea and Tahiti. These factors explain 47.1% and 36.9% of the variation in species richness, respectively, while isolation indices show no significant relationship. The study analyzed 49 remote atolls with complete botanical surveys, using Spearman’s rank correlation and linear regression to assess eight abiotic predictors, including area, elevation, shoreline length, and distances to potential refugia or stepping-stone islands. Findings suggest that larger atolls with closer proximity to raised landmasses support greater species diversity, indicating the role of these areas as dispersal hubs during sea-level changes.
Prioritizing islands for the eradication of invasive vertebrates in the United Kingdom overseas territories
A prioritization framework for eradicating invasive vertebrates from islands in the U.K. overseas territories identifies 25 high-priority islands, including two UNESCO World Heritage Sites—Gough (South Atlantic) and Henderson (South Pacific)—that would benefit 155 native species, 45 of which are globally threatened. The approach evaluates eradication feasibility and distinguishes between potential and realistic conservation value, considering the impact of removing all invasive species or only those with current eradication techniques. This study provides a strategic tool for allocating limited resources to maximize biodiversity conservation benefits, with the framework adaptable to future advancements in eradication methods.
Review of a Large-Scale Pacific Rat Eradication Attempt from an Uninhabited World Heritage Site: Project Approach, Lessons Learnt, and Future Directions
A large-scale attempt to eradicate Pacific rats from Henderson Island, a UNESCO World Heritage Site and near-pristine raised coralline atoll in the South Pacific, failed despite extensive planning and international collaboration. The operation, led by the Royal Society for the Protection of Birds (RSPB) and the Government of the Pitcairn Islands, involved a GBP£1.5m aerial bait dispersal in 2011 but resulted in rat sightings seven months later. Independent reviews identified gaps in planning and execution, emphasizing the need for rigorous yet flexible strategies that integrate international expertise with local knowledge. The study underscores the critical role of rat eradication in preserving the island's Outstanding Universal Value, particularly for the endangered Henderson petrel, and offers lessons for future conservation efforts on similar islands worldwide.
The Real Bounty: Marine Biodiversity in the Pitcairn Islands
A groundbreaking survey of the Pitcairn Islands, one of the most remote and least impacted marine regions in the Pacific, revealed extraordinary biodiversity with 51 new algal records, 23 coral species, and 15 fish species. The study, conducted in 2012, found significant variations in ecological communities across four islands (Ducie, Henderson, Oeno, and Pitcairn) based on age, isolation, and geomorphology. Ducie exhibited the highest coral cover (56%) and top predator dominance (62% of fish biomass), while Pitcairn was dominated by erect macroalgae (42%) and herbivorous fishes. The research also uncovered high regional endemism in fish assemblages (45%), peaking at 56% on Ducie. Additionally, deep-sea surveys using drop-cameras identified 57 fish species, including rare and undescribed ones, extending the known depth range for shallow reef sharks and other reef fishes down to 300 meters. These findings underscore the Pitcairn Islands' unique biodiversity value and emphasize the urgent need for protection.
Assessing Protocols for Identifying Pacific Island Archaeological Fish Remains: The Contribution of Vertebrae
Incorporating all vertebrae into fish bone identification protocols significantly enhances the reconstruction of prehistoric fishing practices in Pacific Island contexts. A study comparing three identification methods—using cranial bones, expanded cranial bones, and all vertebrae—revealed that including vertebrae increases the number of identifiable specimens and provides more accurate rank-order abundance for taxa like grouper (Serranidae) and surgeonfishes (Acanthuridae). This approach improves minimum number of individuals calculations and offers better insights into subsistence practices. The research, conducted on a well-preserved assemblage from Henderson Island, underscores the importance of standardizing protocols to ensure consistency in comparative studies across regions.
Distribution and age-specific plumage states of the long-tailed cuckoo (Eudynamys taitensis)
A comprehensive analysis of the long-tailed cuckoo (Eudynamys taitensis) reveals its vast migratory range, spanning 6,000 km from New Zealand to the tropical Pacific and 11,000 km east to west. The study identifies distinct plumage states—adult, immature, transitional, and a potential new juvenile plumage—using museum specimens. It also documents seasonal migration patterns within New Zealand, with nearly all birds returning in adult plumage by October. Additionally, the research highlights an uneven sex ratio in eastern Polynesia, favoring males (74%), while other regions show a more balanced distribution. This work confirms the species' extensive range and provides new insights into its age-specific migratory behavior.
Overcoming hermit-crab interference during rodent-baiting operations: a case study from Henderson Island, South Pacific
A successful rat eradication strategy for Henderson Island, South Pacific, is feasible despite high hermit-crab interference. Researchers determined that even with crab densities reaching 1370 crabs per hectare—where they consume up to 3.8 grams of bait daily—rats can still be effectively targeted using rhodamine-dyed cereal pellets. By adjusting bait application rates, the study achieved 100% bait consumption by rats across four plots, demonstrating that careful planning can mitigate crab interference. This insight provides a model for other eradication efforts facing similar challenges, though it also underscores the need to assess potential impacts on non-target species like hermit crabs. The findings were derived from distance sampling of crabs and mark-recapture studies of rats, combined with hand-applied bait trials.
An experimental test of the toxicity of cereal pellets containing brodifacoum to the snails of Henderson Island, South Pacific
An experimental test on Henderson Island found no significant toxicity of brodifacoum-laced cereal pellets to endemic snails. The study, conducted by Brooke et al. (2011), involved housing snails in captivity for up to 10 days with and without access to the poisoned pellets. Results showed no detectable differences in survival rates between the two groups, nor were there significant differences in brodifacoum concentrations among those that died or survived, with the toxin detected in only a few samples. This suggests that brodifacoum, commonly used for invasive rodent eradication on islands, does not pose a risk to Henderson Island's snails. While caution is advised before applying these findings to other sites due to potential variability, the study provides valuable insights into the ecological impacts of this anti-coagulant poison.
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