Island Extinction Research Articles

Can 30 × 30 targets stop island extinctions?

Can 30 × 30 targets stop island extinctions?

Late Pleistocene heather vole, Phenacomys, on the North Pacific Coast of North America: environments, local extinctions, and archaeological implications

Phenacomys cf. intermedius, the heather vole, is known from three late Pleistocene and early Holocene localities on Vancouver Island, British Columbia, Canada, where they are absent today. This study reports the heather vole specimens from one of these sites, P2 Cave, and provides a human behavioural context for its presence and eventual extirpation as a consequence of changing environments. Heather vole is a cold-adapted rodent. The early Holocene thermal maximum and subsequent development of coastal western hemlock forests contributed to its Vancouver Island extinction without an apparent corresponding range restriction in higher elevation habitats as has been noted elsewhere in Western North America. Tendency for low population densities in closed-canopy forests, antisocial intraspecies behaviours, and limited immigration across fragmented habitats supported local extinction. The absence of heather vole in the modern environment elsewhere along the coasts of British Columbia, Southeast Alaska, and Washington is probably due to similar factors as are highlighted here. Toward environmental reconstruction and the archaeological setting this study suggests that humans are unlikely to have occupied the Vancouver Island area during a hiatus in the vertebrate faunal record including the cold-adapted heather vole from about 19 700 to 14 700 years ago when the Cordilleran Ice Sheet extended west to the continental shelf. Improved environmental conditions for humans occurred both before and after this time. It also suggests that the glacial conditions in which the heather vole occupied Vancouver Island diverge from the Holocene interglacial setting that has seen an expansion of a human presence and of the corresponding archaeological record.

Sinking Paradise? Climate change vulnerability and Pacific Island extinction narratives

The extinction narrative of the ‘sinking island states’ is well known and discussed extensively in the climate change institutions, academic literature, and media accounts of climate change. This article questions the theoretical basis upon which this narrative has developed, asking how it became so embedded in climate change politics, and what implications this narrative has both for islands and for action on climate change. Focussing on the Pacific, this article uses the insights of racial capitalism and critical feminism to historicise the sinking islands extinction narrative. This historical analysis shows that underlying these extinction narratives of doomed islands and islanders is a colonial logic of disposability that has developed over time, shifting to naturalise changing forms of violence and exploitation in the Pacific. This argument has implications for climate change politics where extinction narratives are widespread, including in justice arguments. The racialised and gendered colonial logics that underlie vulnerability discourse means it does not function to strengthen arguments for mitigation, but instead to naturalise the suffering and loss of those deemed vulnerable. Questioning how discourses of vulnerability impact on capitalist accumulations and dispossessions is therefore important, as the solutions to vulnerability are different if it is understood not as inherent, but as an actively reproduced condition that is being resisted by vulnerabilised communities.

Island Mammal Extinctions are Determined by Interactive Effects of Life History, Island Biogeography, Mesopredator Suppression

Island Mammal Extinctions are Determined by Interactive Effects of Life History, Island Biogeography, Mesopredator Suppression

Niche differences may reduce susceptibility to competition between native and non‐native birds in oceanic islands

AbstractAimFew bird extinctions on oceanic island have been attributed to competition with non‐native species, even though it might be an overlooked driver of biodiversity loss. We evaluate the potential competition between native and non‐native island bird species, identifying species and island characteristics that enhance it and may promote future extinctions.LocationSeventy‐three (>100 km2) oceanic islands worldwide.MethodsWe compiled a species list for each island and used single‐trait meta‐analyses to assess differences between native and non‐native species. Then, we used single‐trait beta regression models to identify species traits linked to potential competition. Finally, we used a trait‐based approach to calculate the potential competition between native and non‐native species on each island and identify island characteristics linked to potential competition.ResultsNative bird species tended to be smaller forest dwellers, that were either carnivore, frugivore or insectivore, and that foraged in flight, in the canopy or at mid‐height. In contrast, non‐native birds tended to be open habitat granivores, that were either ground or unspecialized foragers. Potential competition tended to be higher for native species with typical non‐native traits and forest‐dwelling unspecialized non‐native species. Potential competition between native and non‐native birds was consistently higher in islands that were larger, had more non‐native birds or were drier.Main conclusionsNiche differentiation of native and non‐native species may explain the scarcity of reported competition‐driven extinctions since non‐natives clearly tend to favour and are better adapted to anthropogenic environments. However, the few non‐native birds that occur in native ecosystems may be problematic. The loss of native ecosystems coupled with the introduction of species that might outcompete native species may enhance the relevance of competition in future island extinctions.

No evidence for widespread island extinctions after Pleistocene hominin arrival

The arrival of modern humans into previously unoccupied island ecosystems is closely linked to widespread extinction, and a key reason cited for Pleistocene megafauna extinction is anthropogenic overhunting. A common assumption based on late Holocene records is that humans always negatively impact insular biotas, which requires an extrapolation of recent human behavior and technology into the archaeological past. Hominins have been on islands since at least the early Pleistocene and Homo sapiens for at least 50 thousand y (ka). Over such lengthy intervals it is scarcely surprising that significant evolutionary, behavioral, and cultural changes occurred. However, the deep-time link between human arrival and island extinctions has never been explored globally. Here, we examine archaeological and paleontological records of all Pleistocene islands with a documented hominin presence to examine whether humans have always been destructive agents. We show that extinctions at a global level cannot be associated with Pleistocene hominin arrival based on current data and are difficult to disentangle from records of environmental change. It is not until the Holocene that large-scale changes in technology, dispersal, demography, and human behavior visibly affect island ecosystems. The extinction acceleration we are currently experiencing is thus not inherent but rather part of a more recent cultural complex.

Environmental correlates of reptile variation on the Houtman Abrolhos archipelago, eastern Indian Ocean

AbstractAimTo examine the relationships between island environmental attributes, both biotic and abiotic, and three measures of reptilian variation—species assemblage, species richness and body size distributions.LocationHoutman Abrolhos archipelago, Western Australia.TaxonReptiles.MethodsNineteen islands were sampled from 2002 to 2012 using foraging and trapping. Body size (snout‐vent length) was measured on first capture. Island size varied from 0.3 to 587 ha, encompassing the three geomorphic island types, the three bathymetric groups and a range of other environmental attributes.ResultsFrom about 1,500 captures, 24 reptile species were recorded, including three previously undocumented on the archipelago, and 54 records of species not previously recorded on specific islands. Four significantly different reptile assemblage groups were identified. These were highly correlated with geomorphological composition—two groups encompassing the three large aeolianite islands; another the high rock islands and the largest composite island; and a fourth consisting of the remaining composite islands with one very small high rock island. Both assemblage and richness on islands were significantly correlated with island area, geomorphology and native plant species richness. Of the 13 species captured frequently, 11 showed statistically significant inter‐island variation in body size, and two exhibited sexual dimorphism. In three species, size was also correlated with environmental attributes, including reptile species richness, native plant richness, geomorphology and island area. Six of the eleven species captured on the two largest islands (both aeolianite) differed in size on these adjacent islands.Main ConclusionsHigh inter‐island variation in body size and assemblage composition suggest strong differential selection since the most recent isolation event at 6,500 bp. Anthropogenic disturbances over the last 150 years have resulted in several island extinctions. Species assemblage and richness are strongly associated with environmental attributes. Inter‐island body size variation in three species revealed idiosyncratic responses to environmental pressures. Results provide guidance for effective conservation and management strategies, and evidence for the extinction debts inherent in more recently fragmented mainland habitats.

Update on the Desecheo Island Flora

The introduction of non-native organisms has caused changes in island ecosystems world-wide. Two of the main drivers of island extinctions and ecosystem changes are goats and black rats. These organisms alter considerably the flora of island ecosystems by limiting propagule production and dispersal as well as constant herbivory. Even so, island floras can still be diverse if human contact is limited and removal of non-native organisms is carried out. This can start regeneration of the damaged ecosystem and begin the process of ecosystem restoration. The goal of our research was to update the flora of the island from the last 16 or more years. Plants were opportunistically observed, and some collected along trails, ridges, coastal areas, and in the most accessible valleys where other restoration efforts were taking place. Each collected plant was identified in the field, photographed, described, and its GPS coordinates were recorded. A total of 69 species were observed in the field, 17 of which were collected and vouchered in the UPR-Mayagüez Herbarium. Populations of some native plants, such as Harrisia portoricensis Britton (Cactaceae) seemed to be abundant while others, such as the Mammillaria nivosa Link. (Cactaceae) were found in marginal areas with a highly-restricted population. New populations of previously unknown non-natives Spathodea campanulata P. Beauv. (Bignoniaceae), Cenchrus ciliaris L. (Poaceae), and Leucaena leucocephala (Lam.) de Wit (Fabaceae) in Desecheo are of conservation concern. Control or quick removal of these invasive species would help the restoration process of the island.

Island extinctions: processes, patterns, and potential for ecosystem restoration

SUMMARYExtinctions have altered island ecosystems throughout the late Quaternary. Here, we review the main historic drivers of extinctions on islands, patterns in extinction chronologies between islands, and the potential for restoring ecosystems through reintroducing extirpated species. While some extinctions have been caused by climatic and environmental change, most have been caused by anthropogenic impacts. We propose a general model to describe patterns in these anthropogenic island extinctions. Hunting, habitat loss and the introduction of invasive predators accompanied prehistoric settlement and caused declines of endemic island species. Later settlement by European colonists brought further land development, a different suite of predators and new drivers, leading to more extinctions. Extinctions alter ecological networks, causing ripple effects for islands through the loss of ecosystem processes, functions and interactions between species. Reintroduction of extirpated species can help restore ecosystem function and processes, and can be guided by palaeoecology. However, reintroduction projects must also consider the cultural, social and economic needs of humans now inhabiting the islands and ensure resilience against future environmental and climate change.

Island extinctions weren't inevitable.

During the ice age, human colonizers often coexisted with vulnerable island fauna.

Effects of Damming on Long‐Term Development of Fluvial Islands, Elbe River (N Czechia)

AbstractDamming and water impoundment have fundamental influences on the geomorphology and ecological processes of lotic systems. Although these engineering projects affect all segments of the river channel, fluvial (mid‐channel, river) islands are among the most threatened features because of their link to both hydrostatic and hydrodynamic effects of damming. In this study, we used historical maps (1843, 1852) and aerial photos (1954, 2014), as well as other written and iconographic documentary sources, to document the long‐term development of the fluvial islands and channel planform in the Lower Labe (Elbe) River area (Northern Czechia) over the past ~170 years. Our results indicate the decrease of fluvial islands from 16 (1843), resp. 20 (1852) in the mid‐19th century to eight in 1954, and finally to five in 2014. Most islands have disappeared because of the construction of dams and lock chambers for the purpose of river navigation in the first half of the 20th century. The possible processes responsible for island extinction in individual river segments include sediment starvation (downstream of the dam), erosion by overflow (near upstream of the dam) and decreased flow in inter‐island branches (far upstream of the dam). The islands most susceptible to extinction are those with a smaller size and elliptical or irregular shape. Based on visual evaluation of historical photos and survey of present day temporary islands, the medium and fine sedimentary fraction and absence of a vegetation cover seem to be another predictor of island extinction. Finally, we stress the relevance of our findings for the current discussion on the construction of new lock chambers downstream of the study area. Copyright © 2016 John Wiley & Sons, Ltd.

A low frequency persistent reservoir of a genomic island in a pathogen population ensures island survival and improves pathogen fitness in a susceptible host

SummaryThe co‐evolution of bacterial plant pathogens and their hosts is a complex and dynamic process. Host resistance imposes stress on invading pathogens that can lead to changes in the bacterial genome enabling the pathogen to escape host resistance. We have observed this phenomenon with the plant pathogen Pseudomonas syringae pv. phaseolicola where isolates that have lost the genomic island PPHGI‐1 carrying the effector gene avrPphB from its chromosome are infective against previously resistant plant hosts. However, we have never observed island extinction from the pathogen population within a host suggesting the island is maintained. Here, we present a mathematical model which predicts different possible fates for the island in the population; one outcome indicated that PPHGI‐1 would be maintained at low frequency in the population long term, if it confers a fitness benefit. We empirically tested this prediction and determined that PPHGI‐1 frequency in the bacterial population drops to a low but consistently detectable level during host resistance. Once PPHGI‐1‐carrying cells encounter a susceptible host, they rapidly increase in the population in a negative frequency‐dependent manner. Importantly, our data show that mobile genetic elements can persist within the bacterial population and increase in frequency under favourable conditions.

Retraction: Predation selectively culls medium-sized species from island mammal faunas.

You have accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Biology Letters Editorial Team 2016Retraction: Predation selectively culls medium-sized species from island mammal faunasBiol. Lett.122016066120160661http://doi.org/10.1098/rsbl.2016.0661SectionYou have accessRetractionRetraction: Predation selectively culls medium-sized species from island mammal faunas Biology Letters Editorial Team Google Scholar Find this author on PubMed Search for more papers by this author Biology Letters Editorial Team Google Scholar Find this author on PubMed Search for more papers by this author Published:01 August 2016https://doi.org/10.1098/rsbl.2016.0661This article retracts the followingResearch ArticlePredation selectively culls medium-sized species from island mammal faunashttps://doi.org/10.1098/rsbl.2013.1066 Emily Hanna and Marcel Cardillo volume 10issue 4Biology Letters01 April 2014Biol. Lett.10, 20131066 (Published online 2 April 2014). (doi:10.1098/rsbl.2013.1066)Following publication of the article ‘Predation selectively culls medium-sized species from island mammal faunas’ in Biology Letters (Biol. Lett.10, 20131066, doi:10.1098/rsbl.2013.1066), the publisher was made aware of errors in the database. The authors constructed a new database that corrected all of the known errors, removed records from an unpublished Northern Territory Government source, and added a number of new records from the literature. The new database, with a full description of its construction, will be published in a forthcoming correction article in Global Ecology andBiogeography. On repeating the analyses using the new data, a new conclusion was reached that indicates island extinction patterns are more biased towards larger sizes, rather than intermediate sizes. Given that the main conclusion of the original paper is no longer supported, the editors have decided to retract the article. The new analyses and results will be published elsewhere.The errors in the original database resulted from honest mistakes, and there is no suggestion of any author misconduct.Despite numerous attempts to contact Emily Hanna, she could not be reached. This retraction is therefore signed by Marcel Cardillo on behalf of both authors.Dr Marcel CardilloMacroevolution and Macroecology Group, Research School of Biology, Australian National University, Building 116, Daley Road, Canberra, Australian Capital Territory 0200, Australiaemail: [email protected]Prof. Richard Battarbee FRSEditor-in-Chief, Biology LettersSurayya JoharPublishing Editor, Biology Letters Previous Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsRelated articlesPredation selectively culls medium-sized species from island mammal faunas01 April 2014Biology Letters This IssueAugust 2016Volume 12Issue 8 Article InformationDOI:https://doi.org/10.1098/rsbl.2016.0661PubMed:27576525Published by:Royal SocietyOnline ISSN:1744-957XHistory: Published online01/08/2016Published in print31/08/2016 License:© 2016 The Author(s)Published by the Royal Society. All rights reserved. Citations and impact Subjectsecology Large datasets are available through Biology Letters' partnership with Dryad

Reducing uncertainty based on model fitness: Application to a reservoir model

Sensitivity and uncertainty analysis are important tools in the modelling process: they assign confidence to model results, can aid in focusing monitoring and preservation efforts, and can be used in model simplification. A weakness of global sensitivity and uncertainty analysis methodologies is the often subjective definition of prior parameter probability distributions, especially in data-poor areas. We apply Monte Carlo filtering in conjunction with quantitative variance-based global sensitivity and uncertainty analysis techniques to address this weakness and define parameter probability distributions in the absence of measured data. This general methodology is applied to a reservoir model of the Okavango Delta, Botswana. In addition to providing a methodology for setting prior parameter distributions, results show that the use of Monte Carlo filtering reduces model uncertainty and produces simulations that better represent the calibrated ranges. Thus, Monte Carlo filtering increases the accuracy and precision of parametric model uncertainty. Results also show that the most important parameters in our model are the volume thresholds, the reservoir area/volume coefficient, floodplain porosity, and the island extinction coefficient. The reservoir representing the central part of the wetland, where flood waters separate into several independent distributaries, is a keystone area within the model. These results identify critical areas and parameters for monitoring and managing, refine and reduce input/output uncertainty, and present a transferable methodology for developing parameter probability distribution functions, especially when using empirical models in data-scarce areas. Keywords : sensitivity analysis, uncertainty analysis, Monte Carlo filtering, reservoir model, Okavango Delta

Radiocarbon evidence for the presence of mice on Madeira Island (North Atlantic) one millennium ago

Owing to the catastrophic extinction events that occurred following the Holocene arrival of alien species, extant oceanic island biotas are a mixture of recently incorporated alien fauna and remnants of the original fauna. Knowledge of the Late Quaternary pristine island faunas and a reliable chronology of the earliest presence of alien species on each archipelago are critical in understanding the magnitude and tempo of Quaternary island extinctions. Until now, two successive waves of human arrivals have been identified in the North Atlantic Macaronesian archipelagos (Azores, Madeira, Selvagens, Canary and Cape Verde Islands): 'aboriginal', which is limited to the Canary Islands around two millennia ago, and 'colonial', from the fourteenth century onwards. New surveys in Ponta de São Lourenço (Madeira Island) have allowed us to obtain and date ancient bones of mice. The date obtained (1033 ± 28 BP) documents the earliest evidence for the presence of mice on the island. This date extends the time frame in which the most significant ecological changes occurred on the island. It also suggests that humans could have reached Madeira before 1036 cal AD, around four centuries before Portugal officially took possession of the island.

Conservation lessons from the Pacific Islands

THE Pacific Islands have long been at the vanguard of the battle for our planet’s ecological sustainability, including biodiversity in this time of the Anthropocene. It was on these islands that the world began to understand the devastating impacts of invasive species, direct or indirect passengers on our invasion waves, on endemic animals, maladapted to avoid predation (Elton 1958). Devastating statistics on island extinctions are the frontispiece of any textbook on conservation biology. Further, the standout general rule for ecology, the relationship between biodiversity and natural habitat area, the species’ area curve, was underpinned by our understanding of the bird communities of Pacific Islands (Diamond and Mayr 1976). These are the conservation lessons of the past, an ever present reminder of the legacy of the impact of our species on natural environments and the other organisms with which we share this earth. Ultimately we all depend on the ecosystem services provided by our environments. Today, conservation in the Pacific Islands continues to teach us important lessons for focussing scientific research, implementing best practice management, disseminating educational material, and developing legislative and policy mechanisms. These are tied to ongoing acute and chronic threats, burgeoning human populations and the relatively poor capacity, compared to wealthy nations, to apply available conservation tools for effective change.

Island mammal extinctions are determined by interactive effects of life history, island biogeography and mesopredator suppression

AbstractAimUnderstanding extinction on islands is critical for biodiversity conservation. Introduced predators are a major cause of island extinctions, but there have been few large‐scale studies of the complexity of the effects of predators on island faunas, or how predation interacts with other factors. Using a large database of island mammal populations, we describe and explain patterns of island mammal extinctions as a function of introduced predators, life history and geography.LocationThree hundred and twenty‐three Australian islands.MethodsWe built a database of 934 island mammal populations, extinct and extant, including life history and ecology, island geography and the presence of introduced predators. To test predictors of extinction probability, we used generalized linear mixed models to control partially for phylogenetic non‐independence, and decision trees to more fully explore interactive effects.ResultsThe decision trees identified large mammals (> 2.7 kg) as having higher extinction probabilities than small species (< 2.7 kg). In large species, extinction patterns are consistent with island biogeography theory, with distance from the mainland being the primary predictor of extinction. For small species, the presence of introduced black rats is the primary predictor of extinction. As predicted by mesopredator suppression theory, extinction probabilities are lower on islands with both black rats and a larger introduced predator (cats, foxes or dingoes), compared with islands with rats but no larger predator. Similarly, extinction probabilities are lower on islands with both a mid‐sized (cats or foxes) and a larger (dingoes) predator, compared with islands with cats or foxes only.Main conclusionsIsland mammal extinctions result from complex interactions of introduced predators, island geography and prey biology. One conservation implication of our results is that eradication of introduced apex predators (cats, foxes or dingoes) from islands could precipitate the expansion of black rat populations, potentially leading to extinction of native mammal species whose remaining populations are confined to islands.

Update: The (often ignored) role of vicariance in evolutionary diversification on oceanic islands

news and update ISSN 1948‐6596 update The (often ignored) role of vicariance in evolutionary diversifica‐ tion on oceanic islands Elucidating the evolutionary history of diversifying lineages in space and time remains a major chal‐ lenge in biology. The value of islands and island‐ like systems for studying this question has been long recognized by professional and amateur bi‐ ologists alike. First, many islands are young and thus have relatively low species diversity; this natural simplicity makes them easier to study. Second, most islands are geographically isolated, which means that insular lineages are often on an evolutionary track independent of external influ‐ ences from other areas. Finally, if part of an archi‐ pelago, islands can be viewed as replicates or snapshots in time of a natural experiment occur‐ ring at a spatial scale and a temporal scale of which experimental biologists could only dream. The considerable scientific attention devoted to island biotas has resulted in an increasingly com‐ plete picture of the geographical distribution of insular species. In addition, with the more recent advances in genetics and phylogenetics, it is now possible to infer the evolutionary processes re‐ sponsible for generating these observed bio‐ geographical patterns. Indeed, by combining infor‐ mation about the current geographical location of populations or species with a description of their genetic or phylogenetic relationship, it becomes possible to reconstruct the evolutionary history of diversifying lineages in their specific geographical contexts, a key step in evaluating the relative im‐ portance of determinism and contingency in evo‐ lutionary diversification (Losos and Ricklefs 2009). However, despite the relative simplicity of island systems, the study of their diversifying line‐ ages poses its own set of challenges. First, al‐ though island biogeographical studies often as‐ sume that islands are fixed in time and space, they are rather dynamic entities that might change in size, location, elevation, etc. over time. Oceanic islands in particular go through a series of predict‐ able “life” stages that are likely to influence their carrying capacity via changes in island area, topog‐ raphy, etc. (Whittaker et al. 2008). Furthermore, over time, geological forces combined with sea‐ level changes might create or eliminate land con‐ nections between islands, which could facilitate or hinder the dispersal and colonization of the geo‐ graphical areas involved. Second, island biotas often are at greater risk of extinction. This greater risk stems from a combination of factors. Impor‐ tantly, island species have limited ranges and as‐ sociated smaller population sizes, and they also are more susceptible to changes in their environ‐ ment caused by introduced species or habitat de‐ struction by human activities. Extinction events are difficult to detect and, if ignored, might lead researchers to draw erroneous conclusions from the observed patterns of biodiversity. Finally, not necessarily specific to island systems, the evolu‐ tionary history of any diversifying lineage might be blurred by human‐mediated dispersal. This effect is exacerbated on islands where dispersal can be quite limited between islands, and where humans might artificially increase the rates and/or modify the trajectories of organisms’ natural dispersal. These three sources of variation—island dynamics, extinction, and introduction—most of‐ ten are ignored, or in the best‐case scenario sim‐ ply assumed to add noise to the diversification patterns observed. However, in a recent study of giant Galapagos tortoises, Poulakakis et al. (2012) tackled these three challenges by incorporating information about the dynamic geography of Galapagos, genetic data from extinct species, and information regarding human‐based dispersal of individuals in this group of species – highlighting their influence on the diversification patterns ob‐ served and reaching a better understanding of the diversification process in this lineage. In their study, Poulakakis and colleagues integrated DNA data from all known extinct and extant species, past information about inter‐island dispersal of giant tortoises by humans, and newly available data on the dynamics of the islands themselves. Overall this results in an updated and more com‐ prehensive picture of the diversification patterns © 2012 the authors; journal compilation © 2012 The International Biogeography Society — frontiers of biogeography 3.4, 2012

Historical bird and terrestrial mammal extinction rates and causes

AbstractAim Conservation of species is an ongoing concern.Location Worldwide.Methods We examined historical extinction rates for birds and mammals and contrasted island and continental extinctions. Australia was included as an island because of its isolation.Results Only six continental birds and three continental mammals were recorded in standard databases as going extinct since 1500 compared to 123 bird species and 58 mammal species on islands. Of the extinctions, 95% were on islands. On a per unit area basis, the extinction rate on islands was 177 times higher for mammals and 187 times higher for birds than on continents. The continental mammal extinction rate was between 0.89 and 7.4 times the background rate, whereas the island mammal extinction rate was between 82 and 702 times background. The continental bird extinction rate was between 0.69 and 5.9 times the background rate, whereas for islands it was between 98 and 844 times the background rate. Undocumented prehistoric extinctions, particularly on islands, amplify these trends. Island extinction rates are much higher than continental rates largely because of introductions of alien predators (including man) and diseases.Main conclusions Our analysis suggests that conservation strategies for birds and mammals on continents should not be based on island extinction rates and that on islands the key factor to enhance conservation is to alleviate pressures from uncontrolled hunting and predation.

Why tropical island endemics are acutely susceptible to global change

Tropical islands are species foundries, formed either as a by-product of volcanism, when previously submerged seabed is thrust upwards by tectonics, or when a peninsula is isolated by rising sea level. After colonisation, the geographical isolation and niche vacancies provide the competitive impetus for an evolutionary radiation of distinct species-island endemics. Yet the very attributes which promote speciation in evolutionary time also leave island endemics highly vulnerable to recent and rapid impacts by modern people. Indeed, the majority of documented human-driven extinctions have been exacted upon island endemics. The causes include over-exploitation, invasive species brought by people and destruction of island’s naturally constrained habitats. Imminent threats include inundation by rising sea levels and other adaptive pressures related to anthropogenic global warming. We review recent work which underscores the susceptibility of island endemics to the drivers of global change, and suggest a methodological framework under which, we argue, the science and mitigation of island extinctions can be most productively advanced.