Inter-island Movements Research Articles

First Description of a Double Clutch, and Interisland Movements of a Pueo (Hawaiian Short-Eared Owl; Asio flammeus sandwichensis) in Hawaii, USA

First Description of a Double Clutch, and Interisland Movements of a Pueo (Hawaiian Short-Eared Owl; Asio flammeus sandwichensis) in Hawaii, USA

Correction: Behavior and inter-island movements of satellite-tagged humpback whales in Hawai’i, USA

Correction: Behavior and inter-island movements of satellite-tagged humpback whales in Hawai’i, USA

Population estimate and inter-island movement of sperm whales, Physeter macrocephalus, in the Eastern Caribbean Sea

When a population extends across international boundaries, management becomes more complex. This is especially true within a confined multinational area such as the Caribbean Sea. The population size of sperm whales in the Eastern Caribbean is estimated and the inter-island movements of individuals are quantified using a database of 1,394 photographic identifications taken between 1984 and 2006 by several research groups. A total of 194 individual sperm whales were identified off the leeward coasts of the islands of Dominica, Guadeloupe, Grenada, St. Lucia and Martinique. Population size was estimated using two-component finite mixture models. About 145 (95% CI=94- 219) sperm whales used Lesser Antillean waters in 1995 and this population appears to be growing slowly. There are differences amongst the individuals in their probability of identification. Of all individuals, 57 (29.4%) were identified during more than one year between 1995 and 2006. Long-term reidentification of associated females suggests that social units may be using the area for periods of at least 11 years. Twenty seven confirmed matches were made between islands, the majority (92.6%) of which were between Guadeloupe and Dominica, although there were two longer movements by single individuals between Dominica and the islands of St. Lucia and Grenada. High reidentification rates within the Lesser Antilles and no matches with identifications from nearby seas suggest the population in the Eastern Caribbean Sea is small and quite isolated. As such, we recommend that management actions be taken on a multi-island basis for the Eastern Caribbean, by encouraging the ratification of the SPAW protocols and that the current stock classification for the North Atlantic be reconsidered.

The territorial dimension of transactions in the Canary Islands’ grape market

The territorial dimension of transactions between grape growers and wine producers in the Canary Islands’ grape market is examined. This is a market fragmented into different wine-grape zones and institutionally organised through protected designations of origin (PDOs) which, except in the case of one that is regional in scope, restrict the spatial mobility of grapes. We use information from the harvest declarations submitted by grape growers, which indicate the location of the vineyard plots, and production declarations submitted by the wine producers, which indicate the grape grower who supplies grapes to their winery, as well as from harvest reports, which contain a record that facilitates the traceability of the grape's journey from the plot of origin to the winery of destination. The results obtained show that there are hardly any inter-island movements of grapes and that inter-zone transactions were selectively intensified between the wine-grape zones of the island of Tenerife following the creation of a regional PDO.

Back on the Rat Trail: Analyses of ancient mitochondrial genomes of Rattus exulans from the Western Solomons

The Solomon Islands, first settled c.30,000 years ago, sits on the boundary of Near and Remote Oceania. The archipelago played a significant role in major prehistoric Pacific mobility and interactions: such as the Lapita expansion, and settlement of the Polynesian Outliers and Micronesia. Previous genetic studies of commensals have inferred large-scale human migrations across the Pacific, but few samples from the Solomon Islands were included. Here, we present the analysis of ancient DNA from twelve Rattus sp. bones excavated from Sikopo Island in the Western Solomons, dated between 850 – 500 cal. BP. Mitochondrial DNA from nine Rattus exulans (Pacific Rat) specimens were successfully sequenced and thus more than doubled the number of commensal animals sampled from the Solomon Islands. Phylogenetic analyses identified the Sikopo Island rats as more closely related to Polynesian than Near Oceanic samples and showed them to be of a different mitochondrial DNA haplogroup than previously detected in the Solomon Islands. The results are consistent with current hypotheses for multiple introductions of these rats (and therefore human movements) across the Near and Remote Oceania boundary. With consideration of archaeological and other lines of evidence, we propose three scenarios to explain how the Sikopo Island rats may have been introduced into the Western Solomons – two of which involve different long-distance connections with Remote Oceania and the other involves inter-island movements within the Solomon Islands. Overall, our results highlight the potential for further genetic commensal studies in the Solomon Islands to reconstruct prehistoric Pacific population mobility and interaction spheres.

An Inca Tern in the Hawaiian Islands: First Record for Hawaii and the United States

An Inca Tern (Larosterna inca) was observed and photographed at several locations in the Hawaiian Islands from 10 March 2021 to 8 January 2022, constituting the northernmost and westernmost record for this species, which breeds on the Pacific coast of South America, and the first for the United States. Here I provide details about the appearance and inter-island movements of this individual, along with evidence indicating that only a single individual was involved in all sightings. The Hawaiian Islands occurrence, along with recent documentation of the Inca Tern in Central America north to Guatemala, points to yet another South American seabird moving north with increasing frequency in the Pacific Ocean.

Port performance factors and their interactions: A systems thinking approach

Indonesia’s inter-island movement of goods relies heavily on sea transportation because it can transport large volumes of goods at a reasonable cost. However, it is challenging to meet the same pricing standards everywhere, particularly for regions located far from the production centres. The government initiated the Motorways of the Sea Program to tackle this issue. Stakeholders in Indonesia’s maritime logistics should be involved in the implementation processes, including the port operators, the shipping industry, and the government as a regulator and infrastructure enabler. However, the democratic, decentralised, and pluralistic nature of Indonesia’s government, culture, and bureaucracy has challenged the implementation of the Motorways of the Sea Program. Based on a systematic map of each stakeholder’s interests, barriers, and expectations, the study used a systems thinking approach to capture the interactions among stakeholders’ activities and policies in the maritime logistics system. A causal loop diagram and a stock and flow diagram were developed to provide a holistic view of the system. Several systemic forces that became the leverages of the system’s performance were identified. The most important factors are infrastructure development, both physical and non-physical infrastructures that include information and communication technology, service procedures, and human capital supporting the service system.

Insights on the residency status and inter-island movement patterns of pantropical spotted dolphins Stenella attenuata in the Agoa Sanctuary, Eastern Caribbean

The pantropical spotted dolphin (PSD, Stenella attenuata) is the most common cetacean species observed within the Agoa Sanctuary, located in the Lesser Antilles, Eastern Caribbean. These dolphins are easily observable and are the main target of whale-watching activities along the leeward coasts of Guadeloupe and Martinique islands. Because PSD is common within the sanctuary it is considered a resident species, however, no research has been carried out to estimate its population status and movement patterns between islands. Previous unpublished work found the sighting of an individual in Martinique and Guadeloupe, suggesting potential exchange of individuals between these islands. To test this hypothesis a photo-ID survey in 2018 and 2019 was conducted, resulting in 54,298 photographs. With no matches of individuals between islands, our findings do not support regular exchange of PSD individuals between Martinique and Guadeloupe. However, given previous re-sighting data, it is possible that movement of individuals between islands exists but at lower frequencies than expected, which can only be detected through long-term surveys. Additionally, populations from both islands showed relatively high site fidelity. We found that in Guadeloupe the PSD population is homogeneously distributed along the coast. In contrast, in Martinique the PSD population was composed of two resident groups concentrated in one area. Moreover, 70 new individuals were identified in Guadeloupe and 54 in Martinique while POPAN modelling estimated the number of marked individuals in the study area during 2018 and 2019 at 89 in Guadeloupe and 90 in Martinique. This research provides the first insights on the residency and movement patterns of S. attenuata in the Agoa Sanctuary and can inform future efforts in management and conservation.

Modelling the persistence and control of Rift Valley fever virus in a spatially heterogeneous landscape

The persistence mechanisms of Rift Valley fever (RVF), a zoonotic arboviral haemorrhagic fever, at both local and broader geographical scales have yet to be fully understood and rigorously quantified. We developed a mathematical metapopulation model describing RVF virus transmission in livestock across the four islands of the Comoros archipelago, accounting for island-specific environments and inter-island animal movements. By fitting our model in a Bayesian framework to 2004–2015 surveillance data, we estimated the importance of environmental drivers and animal movements on disease persistence, and tested the impact of different control scenarios on reducing disease burden throughout the archipelago. Here we report that (i) the archipelago network was able to sustain viral transmission in the absence of explicit disease introduction events after early 2007, (ii) repeated outbreaks during 2004–2020 may have gone under-detected by local surveillance, and (iii) co-ordinated within-island control measures are more effective than between-island animal movement restrictions.

Highly mobile seed predators contribute to interisland seed dispersal within an oceanic archipelago

Long‐distance dispersal (LDD) is an essential event for species colonization and expansion in oceanic island ecosystems. Endozoochory by birds is an important factor promoting the LDD of plant seeds, but its contribution to interisland seed dispersal is still unclear. Here, we show possible seed dispersal by a seed predator pigeon, the Japanese wood pigeon Columba janthina, among oceanic islands in the Izu archipelago, Japan. Although some previous studies showed that most seeds swallowed by this pigeon are crushed, intact seeds were found in 44.5% of pigeon feces, indicating the contribution of these birds to seed dispersal. Seasonal population fluctuations and movements by pigeons between neighbouring islands which are 4 km apart by pigeons can promote interisland seed dispersal. We found seeds from fruiting trees not located on the islands where the pigeon feces were collected, which could have been transported from another island. Although many tree species overlap their fruiting phenology with pigeon movement between islands, the seeds of only six species were dispersed by pigeons, and most of the dispersed seeds were from species with small seeds less than 1.5 mm in diameter. Fruit consumption and frequent interisland movement of Japanese wood pigeons might homogenize the distribution of plants with small seeds among neighboring islands. In contrast, their intensive seed consumption might disturb the recruitment of plants with large seeds and make their expansion to other islands difficult. Such effects of mutualistic (dispersal) and antagonistic (predation) interactions with highly mobile seed predators may modify plant distributions and gene flow in oceanic archipelagos.

Diversity and Geographical Structure of Xanthomonas citri pv. citri on Citrus in the South West Indian Ocean Region.

A thorough knowledge of genotypic and phenotypic variations (e.g., virulence, resistance to antimicrobial compounds) in bacteria causing plant disease outbreaks is key for optimizing disease surveillance and management. Using a comprehensive strain collection, tandem repeat-based genotyping techniques and pathogenicity assays, we characterized the diversity of X. citri pv. citri from the South West Indian Ocean (SWIO) region. Most strains belonged to the prevalent lineage 1 pathotype A that has a wide host range among rutaceous species. We report the first occurrence of genetically unrelated, nonepidemic lineage 4 pathotype A* (strains with a host range restricted to Mexican lime and related species) in Mauritius, Moheli and Réunion. Microsatellite data revealed that strains from the Seychelles were diverse, grouped in three different clusters not detected in the Comoros and the Mascarenes. Pathogenicity data suggested a higher aggressiveness of strains of one of these clusters on citron (Citrus medica). With the noticeable exception of the Comoros, there was no sign of recent interisland movement of the pathogen. Consistent with this finding, the copL gene, a marker for the plasmid-borne copLAB copper resistance that was recently identified in Réunion, was not detected in 568 strains from any islands in the SWIO region apart from Réunion.

Behavior and inter-island movements of satellite-tagged humpback whales in Hawai’i, USA

Humpback whales Megaptera novaeangliae encountered off the island of Kaua’i, Hawai’i, USA, in 2017, 2018, and 2019 were photo-identified, and 19 whales were equipped with satellite telemetry tags to track their inter-island movements and use their movement behavior to estimate when and where the whales changed their behavior from breeding to migration. Fluke photographs were matched in the online photo-ID repository HappyWhale to track individual observation histories and movement records within the islands and on their way to their feeding grounds. Tag attachment periods were relatively short, with transmissions lasting 1.6-12.5 d. Movement behavior models were developed using hidden Markov models; whales in proximity to land were found to remain in area-restricted search or an intermediate behavior state, while whales that moved between islands or offshore tended to transition into directed travel behavior. Movement patterns and routes were similar between animals and across years, particularly when they transited between Kaua’i and O’ahu and began migrating from Ni’ihau to the first seamounts of the northwestern Hawaiian Islands. Dive data were also analyzed in association with the movement behavior. Whales that transited between Kaua’i and O’ahu as well as those in offshore waters conducted repeated series of deep (>100 m) dives only at night, whereas whales that remained in nearshore waters conducted less frequent and less deep dives day or night. These results provide insight into the inter-island movements and behavior of humpback whales while on the Hawaiian breeding grounds as well as where and how their behavior transitioned into migration.

Connecting the dots in databases of endangered species: a Bayesian hierarchical imputation strategy for missing Peary caribou (Rangifer tarandus pearyi) population data

Peary caribou (Rangifer tarandus pearyi) is listed as Endangered under Canada's Species at Risk Act. Studying rare and endangered species can be particularly challenging due to the constraints posed by incomplete datasets owing to poor weather conditions, lack of technology, organizational deficiencies, and high survey costs in remote areas. A defensible way to remedy data gaps and thus improve the robustness of any given modelling exercise is through imputation schemes, which are typically selected on the basis of missing data patterns. In this study, we develop a regression-based imputation method aiming to identify the linkages among available population records in time and space. One of the fundamental assumptions of our imputation model is that there is a subset of primary islands that act as the core areas from where the Peary caribou populations migrate to secondary or satellite islands. Specifically, we delineated six distinct geographic clusters (Banks, Axel Heiberg, Bathurst, Boothia, Melville and Mackenzie King) across the Canadian Arctic Archipelago, and within each cluster Peary caribou seasonal inter-island movements take place in any given year. Parameterized with Bayesian inference techniques, our imputation modelling strategy has a flexible structure that can accommodate non-monotonic spatiotemporal patterns, and was thus able to capture more than 65% of the variability in our dataset. The two islands (Banks and Northwest Victoria) of the Banks island complex exhibited an average decline rate of 6% per year over the past four decades, which collectively reflects the dramatic population decrease from the early 1970s until the late 1990s, as well as the distinct recovery after the early 2000s. Similar “wax-and-wane” cycles characterize the Peary caribou population patterns on Melville and Bathurst island complexes. Our analysis provides evidence of positive rate of change of the population trends on Axel Heiberg and Ellesmere Islands, which likely stems from pockets on those islands, where favorable climatic/geomorphological conditions, and rich vegetation prevail. In stark contrast, overharvesting, higher predation, adverse climatic conditions, and human-induced forage shortage have led to a dramatic decline, nearing their extirpation, on the Boothia island complex.

Risk Modeling of Bat Rabies in the Caribbean Islands.

Rabies surveillance and control measures vary significantly between Caribbean islands. The Centers for Disease Control and Prevention currently recommends certain groups of U.S. travelers to any Caribbean island receive pre-exposure rabies immunization. However, most islands self-declare as “rabies free”, and have never publicly released data to support rabies-free claims. We used the Analytic Hierarchy Process to create pairwise comparison values among five risk factors determined by subject matter experts. Risk factor weights were calculated and used in a geospatial analysis to calculate a risk value for each island nation (higher values indicate higher risk). Risk values ranged from 8.73 (Trinidad) to 1.57 (The Bahamas, Turks and Caicos Islands). All four countries that have documented occurrences of laboratory confirmed rabid bats were ranked highest (Trinidad and Tobago, Grenada, Cuba, Dominican Republic), as well as Haiti. The top five highest risk countries that currently have no reports of bat rabies include St. Vincent and the Grenadines, Jamaica, Puerto Rico, the Cayman Islands, and Dominica. This study reviews the inter-island movement potential of bats, designates areas of high risk for bat-associated rabies within the Caribbean islands, and demonstrates a need for further surveillance efforts in bat populations within islands that self-declare as rabies free.

Dispersal out of Wallacea spurs diversification of Pteropus flying foxes, the world's largest bats (Mammalia: Chiroptera).

Islands provide opportunities for isolation and speciation. Many landmasses in the Indo-Australian Archipelago (IAA) are oceanic islands, and founder-event speciation is expected to be the predominant form of speciation of volant taxa on these islands. We studied the biogeographic history of flying foxes, a group with many endemic species and a predilection for islands, to test this hypothesis and infer the biogeographic origin of the group. Australasia, Indo-Australian Archipelago, Madagascar, Pacific Islands. Pteropus (Pteropodidae). To infer the biogeographic history of Pteropus, we sequenced up to 6169 bp of genetic data from 10 markers and reconstructed a multilocus species tree of 34 currently recognized Pteropus species and subspecies with 3 Acerodon outgroups using BEAST and subsequently estimated ancestral areas using models implemented in BioGeoBEARS. Species-level resolution was occasionally low because of slow rates of molecular evolution and/or recent divergences. Older divergences, however, were more strongly supported and allow the evolutionary history of the group to be inferred. The genus diverged in Wallacea from its common ancestor with Acerodon; founder-event speciation out of Wallacea was a common inference. Pteropus species in Micronesia and the western Indian Ocean were also inferred to result from founder-event speciation. Dispersal between regions of the IAA and the islands found therein fostered diversification of Pteropus throughout the IAA and beyond. Dispersal in Pteropus is far higher than in most other volant taxa studied to date, highlighting the importance of inter-island movement in the biogeographic history of this large clade of large bats.

Grouper (Epinephelidae) spawning aggregations affect activity space of grey reef sharks, Carcharhinus amblyrhynchos, in Pohnpei, Micronesia.

Fish spawning aggregations (FSA) act as biological hotspots that concentrate food and nutrients across a broad trophic spectrum. In Pohnpei (Federated States of Micronesia), 20 female grey reef sharks (Carcharhinus amblyrhynchos) were acoustically tagged at two multi-species grouper (Epinephelidae) FSA to examine the likelihood that these mesopredators utilize FSA as a seasonal food source. Both FSA sites are within small-scale MPAs, thus providing a secondary opportunity to examine their conservation potential during these ephemeral events. Shark movement and residency was gauged against known spatial and temporal grouper reproductive patterns using an array of 15 and 50 acoustic receivers at Ant Atoll and Pohnpei (Island), respectively. Activity space was investigated using Kernel Density estimates of individual sharks, and residency indices (RI) were analyzed based on daily and monthly occurrence at the array. Three distinct residency patterns were identified: transient, semi-transient, or resident (Daily RI <0.40, >0.40 to 0.80, or >0.80, respectively). Generalized linear mixed models (GLMMs) were used to identify biological and environmental factors influencing shark activity space, including month, temperature, shark size, spawning month, and residency pattern. Findings revealed significant changes in average monthly residency indices and kernel densities during spawning months in support of an opportunistic foraging strategy around FSA. Monthly residency was higher during spawning months among semi-resident and transient sharks, while average monthly activity space was concentrated around FSA. Best-fit models for the GLMM indicated that activity spaces were most influenced by month and grouper spawning month. Seven of 20 sharks demonstrated inter-island movement and wide variations in individual movement and spatial requirements were shown. The concentration of sharks and groupers at unprotected FSA sites increases their vulnerability to fishing and supports the need for combined area and non-area management measures to effectively protect these species.

More than just SIDS: local solutions for global problems on small islands

Small islands are often taken as poster children for climate change vulnerability, and their status as hotspots of climate change impacts has been widely acknowledged in the scientific literature. In many cases, however, individual studies as well as reviews and global assessments, generalise small islands as a whole—often with a strong focus on Small Island Developing States (SIDS)—and lack a thorough understanding of island specificity, relationality, and context dependency. Looking at small islands’ issues beyond SIDS implies the recognition of topics such as asymmetrical governance structures, archipelagic centre-periphery relationships, as well as intra- and inter-island movements in various types of island territories and geographies worldwide. This special thematic section of Island Studies Journal features contributions from the Atlantic, Indian, Pacific Ocean, and Caribbean dealing with the locally specific challenges and opportunities of adaptation to environmental and climate change.

Interisland genetic structure of two endangered Hawaiian waterbirds: The Hawaiian Coot and Hawaiian Gallinule

ABSTRACT Most of Hawaii's endemic avifauna are species of conservation concern. Some of Hawaii's endangered waterbirds, however, have increased in number as a result of intensive management of wetlands. To inform these conservation efforts, we examined interisland genetic structure and gene flow within 2 Hawaiian endemic waterbirds, the Hawaiian Coot (Fulica alai) and the Hawaiian subspecies of the Common Gallinule (Gallinula galeata sandvicensis), using microsatellite and mitochondrial loci. Hawaiian Coots and Hawaiian Gallinules occupy coastal wetlands and exhibit similar life history characteristics and generation times, although they may differ in dispersal propensity. Mark–resight data for Hawaiian Coot indicate interisland movements, whereas Hawaiian Gallinules are sedentary. Genetic diversity is partitioned across the landscape differently for Hawaiian Coots and Hawaiian Gallinules; patterns of variation are likely influenced by behavioral and ecological mechanisms. Hawaiian Coots exhibit low level...

Inter-island movement of Japanese Wood Pigeons Columba janthina between Hachijo-jima and Hachijo-kojima in the Izu Islands

Inter-island movement of Japanese Wood Pigeons <i>Columba janthina</i> between Hachijo-jima and Hachijo-kojima in the Izu Islands

Cryptic diversity in Black rats Rattus rattus of the Galápagos Islands, Ecuador.

Human activity has facilitated the introduction of a number of alien mammal species to the Galápagos Archipelago. Understanding the phylogeographic history and population genetics of invasive species on the Archipelago is an important step in predicting future spread and designing effective management strategies. In this study, we describe the invasion pathway of Rattus rattus across the Galápagos using microsatellite data, coupled with historical knowledge. Microsatellite genotypes were generated for 581 R. rattus sampled from 15 islands in the archipelago. The genetic data suggest that there are at least three genetic lineages of R. rattus present on the Galápagos Islands. The spatial distributions of these lineages correspond to the main centers of human settlement in the archipelago. There was limited admixture among these three lineages, and these finding coupled with low rates of gene flow among island populations suggests that interisland movement of R. rattus is rare. The low migration among islands recorded for the species will have a positive impact on future eradication efforts.