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The fossil birds of Henderson Island, Pitcairn Group: natural turnover and human impact, a synopsis
Abstract
Recent studies of island biotas have suggested that the impact of man on indigenous flora and fauna is much greater than previously suspected. This impact resulted in the introduction of many new species and the extinction of many unique life-forms. Henderson Island, in the Pitcairn Group, has been found to be an excellent laboratory for the study of natural faunal turnover and the impact of people on the natural environment. This was principally due to the island's remote location and its limestone structure, which resulted in the excellent preservation of fossil remains. During the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands, extensive excavations were undertaken resulting in the collection of 42213 bird bones. It was possible to identify 31%. Of the 31 taxa identified, four seabirds appear to be vagrants, a surprisingly high number illustrating that the uncritical evaluation of fossil bird lists from other islands risks over-estimating the number of indigenous species. As a result of the arrival of Polynesian people during the first half of this millennium, half of Henderson's endemic landbirds became extinct, as did most of the small ground-nesting seabirds. The lower sea level during cold stages creates many temporary limestone ‘high’ islands. This results in many ‘former-atolls' developing geological and ecological similarity to Henderson. Hence lower sea-level greatly facilitates the movement of flora and fauna between currently isolated oceanic ‘high’ islands.
... Given extinction has resulted in the loss of many breeding colonies of petrels since human colonisation, it is likely that more than one taxon each of small and medium petrels formerly bred in the Gambier Group, and certainly several would have and still do forage in the group. As noted by numerous authors, identification of petrels to genera based on skeletal elements is straightforward, but specific separation of congeneric similar-sized species, is often not possible on morphology alone (Wragg, 1995;Olson and Rasmussen, 2001;Tennyson et al., 2015). For example, Murphy and Pennoyer (1952: 1) noted that many of these species are so similar skeletally as to preclude their separation, stating "We have compared, for example, skulls of the species neglecta, arminjoniana, and ultima and can find no detail that would distinguish one from another." ...
... For example, Murphy and Pennoyer (1952: 1) noted that many of these species are so similar skeletally as to preclude their separation, stating "We have compared, for example, skulls of the species neglecta, arminjoniana, and ultima and can find no detail that would distinguish one from another." Identification is even more difficult with post cranial bones and is compounded by breakage as typifies archaeological deposits, and so specimens are often grouped into large, medium and small size groupings within genera (e.g., Murphy and Pennoyer, 1952;Walker et al., 1990;Wragg, 1995;Olson and Rasmussen, 2001;Cooper and Tennyson, 2008;Tennyson et al., 2015). ...
... However, as detailed above, these are likely to mainly include three taxa with widely overlapping size known to breed in the Gambier Group (Herald Petrel P. heraldica, Murphy's Petrel P. ultima, and the Kermadec Petrel P. neglecta), although bones of vagrant individuals of further similar-sized taxa, such as Phoenix Petrel P. alba and Henderson Petrel P. atrata could also be present as well . It is not considered feasible to distinguish any of these taxa on the basis of the morphology of postcranial remains (Murphy and Pennoyer, 1952;Marchant and Higgins, 1990;Walker et al., 1990;Wragg, 1995;Cooper and Tennyson, 2008;Tennyson et al., 2015). ...
This paper analyses 647 bird bones identifiable at least to family-level collected from archaeological sites in 2005, 2012 and 2014 by P. Kirch, in the Gambier Group,French Polynesia. The bones derive from Onemea Site (TAR-6) on Taravai Island,Nenega-Iti Rock Shelter (AGA-3) on Agakauitai Island and Kitchen Cave (KAM-1) on Kamaka Island. Eighteen bird species, four newly recorded in this archipelago, are rep-resented among the bones from archaeological layers dating from human arrival in the tenth century to the late pre-European contact period in the early nineteeth century.They reveal that the original avifauna from the Gambier Group minimally included 37 species. These include six now extinct taxa, a species of Pseudobulweria petrel, two columbids (Bountyphaps obsoleta, Ducula tihonireasini n.sp. described herein) and three other land birds that were recorded historically. Minimally, a further six species have been extirpated from the Gambier Group. These archaeological avifaunas are strongly dominated by seabirds (89.4% Minimum Number Individuals) but differences in species representation and dominance suggest the composition of breeding seabird faunas differed between islands. Columbidae were the dominant land birds (58.9% MNI), although no species of this family currently exist on this archipelago.
... ) (Wragg 1995, Steadman 2006, Worthy & Bollt 2011). These islands offer a wide range of niches and indeed the available data suggest that the Polynesian sandpipers occupied several habitats, including open areas with low vegetation, forest edge and beaches around lagoons on atolls (Holyoak & Thibault 1984, Pierce & Blanvillain 2004, J.-C. ...
... Distribution of the Polynesian sandpipers: Aechmorhynchus (light grey) occurred on the Tuamotu and Gambier Islands (Aechmorhynchus parvirostris) and on Kiritimati, Line Islands (Aechmorhynchus cancellatus), whereas Prosobonia (dark grey) occurred in the Society Islands, on Tahiti (Prosobonia leucoptera) and Mo'orea (Prosobonia ellisi). Crosses indicate subfossil remains of unknown species or remains that are tentatively attributed to A. parvirostris (data from Wragg 1995, Steadman 2006, Worthy & Bollt 2011). ...
With only a single extant representative, endemic to the Tuamotu Archipelago, the Polynesian sandpipers (Aechmorhynchus and Prosobonia) may have had a larger distribution in Eastern Polynesia in the past, with four endemic taxa. Although these aberrant sandpipers' membership to the Scolocapidae has been well supported, finding their closest living taxa has proved difficult and the phylogenetic relationships of these taxa have remained unresolved. We present the first molecular analysis of the Polynesian sandpipers, including sampling of the only known specimen of the extinct Prosobonia leucoptera, collected in 1773. Based on mitochondrial and nuclear gene sequence data, the phylogenetic analyses demonstrate that the Polynesian sandpipers were sister taxa and belonged to the clade that included the other sandpipers (Calidris and allies) and turnstones (Arenaria), although without a close relative among extant genera. Divergence time estimates suggested that the lineage leading to Prosobonia diverged from the other extant sandpipers during the Oligocene and that either the Line Islands or the Tuamotu Archipelago were probably the first archipelagos colonized by the Prosobonia lineage. On the basis of these results, we suggest that Aechmorhynchus parvirostris and Prosobonia leucoptera be regarded as related species within the same genus, and thus that the senior name Prosobonia be used for both taxa.
... Henderson Island, with an area of about 37 km 2 and a maximum height above sea level of 33 m is a raised atoll whose outer rim is the ancient reef, and the lower inner region, the elevated floor of the lagoon. Henderson Island was discovered by the Spaniard Pedro Fernandes de Quiros in 1606 and it was then uninhabited and has not been settled since that time (Benton and Spencer 1995; Wragg 1995a). The island has attracted many scientific investigations, beginning as early as 1825 with HMS Blossom, but the most significant in terms of duration of investigation and scope of studies was the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands 1991–1992 (Spencer and Benton 1995). ...
... and D. galeata from Henderson Island, while admitting that the taxonomy of the extinct columbids was unresolved. The excavations by Weisler and Wragg during the Pitcairn Islands Scientific Expedition of 1991 – 1992 resulted in a collection of some 42,213 bird bones (Wragg 1995a). About 421 m 2 test pits were excavated in 11 sites of the 28 identified archaeological sites and one natural site. ...
A new species of extinct Ducula pigeon is described from abundant fossil material excavated from late Quaternary deposits on Henderson Island, Pitcairn Group, South Pacific Ocean. Tarsometatarsi that are longer than any extant Ducula and relatively reduced wing elements separate this species from all other extinct and extant Ducula. The description of this species adds another large endemic columbid to the suite that has become extinct since the arrival of man on one of the more isolated islands and island groups in the Pacific.
... Therefore, Raivavae, with no less than six Pterodroma gadfly petrels breeding in sympatry, is special-the only other island in the world with six Pterodroma species breeding in sympatry is Motu Nui (Rapa Nui; Plaza et al., 2021Plaza et al., , 2023. However, some petrel species have already gone extinct on these islands, e.g., Henderson Island (Wragg, 1995) and Rapa (Tennyson & Anderson, 2012). This means that what we see today is only an indication of past species diversity, so it is difficult to make any biogeographic comparison. ...
Raivavae is a small island in the Austral Islands of French Polynesia that is surrounded by a lagoon with 28 islets. Its marine avifauna is one of the least known and least studied in French Polynesia. Overall, seabird surveys in the various Austral Islands have been extremely sparse. This study addresses this need, using both historical and recent findings. The results show high species richness, with 10 breeding procellarid species, though none are numerous. We also update the knowledge on breeding petrels from other Austral Islands (except Rapa) and discuss the consequences of these findings in terms of their conservation on an island with cats Felis sp. and rats Rattus sp.
... However, we found no significant effects of human population density on species richness, which suggests that seabird colonies are more sensitive to specific human impacts, such as habitat destruction and the introduction of F I G U R E 4 CAP ordination depicting changes in the species composition of nesting seabirds across islands of the south-eastern Pacific Ocean. Each point represents an island, with the colours reflecting their geographical position (similar colours indicate geographical proximity as indicated in the colour key predators (Bourne, Brooke, Clark, & Stone, 1992;Thiel et al., 2018;Varela, Luna, & Luna-Jorquera, 2018;Wragg, 1995) than human population density per se. ...
Aim
For seabirds, food supplies and nest sites are largely driven by oceanographic gradients and island habitats, respectively. Research into seabirds’ ecological roles in insular ecosystems is crucial to understanding processes that structure seabird nesting assemblages. We examined the influence of island physiography and oceanographic factors on the spatial variation in α‐ and β‐diversity of nesting seabird assemblages.
Location
South‐eastern Pacific Ocean.
Taxon
Birds.
Methods
We compiled data from 53 seabirds breeding on 41 coastal and oceanic islands using different sources: our field records, online databases, environmental reports and literature. We used generalized linear models (GLM) to describe the effect of island physiography (area, elevation and isolation) and oceanographic factors (surface temperature, salinity and primary productivity) on seabird species richness (α‐diversity). We applied multivariate GLM to test the effects of physiographic and oceanographic predictors on species composition (β‐diversity). We used Jaccard dissimilarities on species occurrences per island to calculate β‐diversity partitioned into turnover and nestedness. Polynomial models allowed us to model these metrics against geographical and environmental gradients and so analyse patterns in seabird β‐diversity across spatial scales.
Results
Species richness was highest in Galápagos, Pitcairn and Rapa Nui. Changes in seabird α‐diversity across islands were determined by island area and distance to South America but not by oceanographic variables. Physiographic and oceanographic factors were significant in determining β‐diversity. Changes in β‐diversity were mostly due to species replacement (β‐turnover) across three major island Systems (Galápagos Archipelago, Chilean coastal islands and oceanic islands of the south‐eastern Pacific). The contribution of β‐nestedness was restricted to small scales (within archipelagos).
Main conclusions
Physiographic and oceanographic factors explain species diversity of seabird assemblages on islands of the south‐eastern Pacific. Oceanographic variables did not affect species richness but significantly influenced species composition. Change in species composition reflects gradients across three marine biogeographical realms: Temperate South, Eastern Indo‐Pacific and Tropical Eastern Pacific. The low degree of species nestedness may reflect multiple evolutionary origins.
... Pacific rats Rattus exulans were introduced during the period of Polynesian expansion around 1100-1400 CE (Weisler 1995), and have negative effects on Henderson's avifauna through predation of chicks and eggs, and competition for food resources (Wragg and Weisler 1994, Brooke 1995a, Brooke et al. 2010. At least four bird species, including three doves (Columbidae) and a sandpiper (Scolopacidae), have become extinct on Henderson Island over the past 500 years since Polynesian colonisation, partly due to human consumption and the detrimental effects of introduced rats (Steadman and Olson 1985, Wragg and Weisler 1994, Wragg 1995. The high biodiversity values place Henderson Island among the top priorities for restoration among the UK Overseas Territories (Dawson et al. 2015). ...
Invasive rodents detrimentally affect native bird species on many islands worldwide, and rodent eradication is a useful tool to safeguard endemic and threatened species. However, especially on tropical islands, rodent eradications can fail for various reasons, and it is unclear whether the temporary reduction of a rodent population during an unsuccessful eradication operation has beneficial effects on native birds. Here we examine the response of four endemic land bird species on subtropical Henderson Island in the Pitcairn Island Group, South Pacific Ocean, following an unsuccessful rodent eradication in 2011. We conducted point counts at 25 sampling locations in 14 survey periods between 2011 and 2015, and modelled the abundance trends of all species using binomial mixture models accounting for observer and environmental variation in detection probability. Henderson Reed Warbler Acrocephalus taiti more than doubled in abundance (2015 population estimate: 7,194-28,776), and Henderson Fruit Dove Ptilinopus insularis increased slightly between 2011 and 2015 (2015 population estimate: 4,476–10,072), while we detected no change in abundance of the Henderson Lorikeet Vini stepheni (2015 population estimate: 554–3014). Henderson Crake Zapornia atra increased to pre-eradication levels following anticipated mortality during the operation (2015 population estimate: 4,960–20,783). A temporary reduction of rat predation pressure and rat competition for fruit may have benefitted the reed warbler and the fruit dove, respectively. However, a long drought may have naturally suppressed bird populations prior to the rat eradication operation in 2011, potentially confounding the effects of temporary rat reduction and natural recovery. We therefore cannot unequivocally ascribe the population recovery to the temporary reduction of the rat population. We encourage robust monitoring of island biodiversity both before and after any management operation to better understand responses of endemic species to failed or successful operations.
... Cats Felis catus are also present in low numbers following a failed eradication attempt in 1997. The presence of these introduced predators has resulted in a severely depauperate avifauna (Wragg 1995), and many seabirds are now restricted to breeding on offshore rocks and stacks (Williams 1960, Brooke 1995b. Indeed, introduced rodents are found on many oceanic islands and cause considerable damage to native ecosystems (Atkinson 1985, Croll et al. 2005. ...
... Tous, à l'exception de Morane, abritent des populations de rats polynésiens, au moins sur une partie de leurs terres émergées. Les études archéologiques menées à Temoe n'ont pas apporté beaucoup de renseignements sur les oiseaux, mais il est vrai que les ossements se conservent mal sur les îles basses, contrairement aux îles volcaniques ou aux atolls soulevés de la région qui ont révélé la présence de nombreux restes [Henderson : Wragg & Weisler (1994), Wragg (1995) : Gambier : Worthy & Tennyson (2004), Steadman (2006)]. ...
Only a few of the 76 atolls in the Tuamotu Archipelago have a monograph summarizing their fauna and flora. The classics are for Raroia Atoll (Morrison, 1954) and for Moruroa Atoll (Chevalier et al. 1968). This type of synthesis is important, plus its accessibility via published journals or "online" is indispensable. Of primary importance is building onto the general knowledge of the surrounding archipelago's ecosystems, as the data can be used as a basis for comparisons with neighboring atolls, or even other parts of the Pacific. They also allow the general public who are interested in Temoe’s heritage, to discover its biodiversity.
Our objective is to inventory the vascular plants and birds of Temoe Atoll by gathering historical information on the number of species, including their status as indigenous plants and reproductive or migratory birds. Then, we put this information in a more general context - that is to say in the geographical area comprising the southern Tuamotu to the north and Oeno Atoll (in the Pitcairn Group) to the east. Searching for information in historical texts and collections of natural history museums allows us to present the natural history of Temoe and follow its changes over the past 150 years.
... The determination of ecological baselines is an essential step toward restoring native fish populations to pre-industrialised fishing levels, and as fisheries catch records generally only provide information from the last hundred years or so, otoliths, along with other fish remains, hold vital information frequently used for establishing knowledge of ancient fish stocks. There are some issues intrinsic to using anthropogenically compiled assemblages (Reitz, 2004), and Indigenous populations often had notable impacts on faunal populations (Holdaway and Jacomb, 2000; Mannino and Thomas, 2002; Wragg, 1995); however, it is undeniable that impacts experienced after the industrialisation of fishing have been unparalleled in human history. Otoliths also provide a wide range of information regarding the past occupants of a site; human subsistence strategies, fishing methods and technologies, trade routes, seasonality of site usage, and past human responses to environmental changes can all be examined through the analysis of these small carbonate structures. ...
... The black-winged petrel was by far the most abundant seabird represented by bones found at the Tangatatau site in 1989. Evidence from archaeological sites on two widely-separated islands in the South Pacific -Mangaia (Steadman & Kirch 1990) and Henderson (Wragg 1995) -indicates that, over recent centuries, the breeding range of this species has contracted significantly, no doubt as a result of human-induced habitat alteration, human exploitation, and mammalian predation. However, the black-winged petrel now appears to be making something of a comeback, by either reoccupying former breeding grounds, or expanding its former breeding range as appears to be the case, e.g., at Norfolk Island (Holdaway & Anderson in press), in northern New Zealand (Pierce & Parrish 1993), and at the Chatham Islands (Tennyson 1991). ...
A species of small procellariid known locally as titi, probably the black-winged petrel (Pterodroma nigripennis), nested into the historic period in burrows in the volcanic soil ofthe uplands of Mangaia in the southern Cookgroup. The demise ofthis titi as a breeding bird on Mangaia was probably caused by a combination of the detrimental effects of human harvesting and various introduced mammalian predators which were present on Mangaia after the arrival of missionaries in the early nineteenth century. Medway, D. G. 2001. Causes of the demise of a breeding population of titi on Mangaia, Cook Islands. Notornis 48 (3):137-144.
... Eleven radiocarbon age determinations bracket occupation from ~1100 to 400 BP, making the basal deposits amongst the oldest in southeast Polynesia. All excavations recovered more than 150 000 well-preserved bones of mostly fish, rats, pigs, turtles and humans (Collins & Weisler, 2000; Stefan et al., 2002) but also elements of extinct birds (Wragg, 1995). Fish bone reported here came from TP (test pit) 12 situated towards the west end of the site and about an equal distance from the beach and base of the cliffs (Weisler, 1998: Figure 4 ...
Three fish bone identification protocols used for determining taxa composition for Pacific island archaeofaunal assemblages are evaluated. The protocols include using the following: (1) the most commonly identified five paired cranial bones and ‘specials’ or unique elements; (2) an expanded number of cranial bones; and (3) the less common inclusion of all vertebrae. Explicit identification and quantification protocols are outlined for systematically incorporating all vertebrae which, predictably, increases the number of identified specimens for an assemblage, thus providing more bones useful for reconstructing live fish biomass (weight and length). Significantly, a range of unique archaeological vertebrae are useful for calculating minimum number of individuals. Using a well-preserved assemblage from Henderson Island, Pitcairn Group, southeast Polynesia, numbering 6480 fish bones (concentration index = 21 580 m3), we demonstrate differences in rank-order abundance from three taxon identification protocols. For example, when using all vertebrae grouper (Serranidae) and surgeonfishes (Acanthuridae) are more numerically equivalent than when relying mostly on cranial bones for identification for minimum number of individuals and number of identified specimens. This has important implications for making comparisons between sites or across regions where different identification protocols were used. This pilot study demonstrates that using all vertebrae for taxon identification and quantification, not just unique hypurals (terminal vertebrae) or those from sharks and rays (Elasmobranchii), should be standard practice for identifying a greater number of bones to taxon and thereby providing better reconstructions of prehistoric fishing and subsistence practices in the Pacific. Copyright © 2013 John Wiley & Sons, Ltd.
... Bones (still undescribed) of Gallirallus also have been found in archaeological sites on four islands in the Marquesas (Steadman 1989a, Steadman and Rolett 1996). Gallirallus apparently never made it as far northeast in Oceania as the Hawaiian Islands or as far southeast in Polynesia as Henderson Island, both of which have good Holocene fossil bird records ( James and Olson 1991, Olson and James 1991, Wragg 1995, Steadman in press). ...
We examined 50 bones previously assigned to ''Gallirallus new sp.'' from the prehistoric (1,250-750 yr B.P.) Fa'ahia archaeological site on Huahine, Society Islands. Most of these specimens ðn ¼ 47Þ, representing nearly all major cranial and postcranial skeletal elements, belong to a medium-sized flightless rail that we name Gallirallus storrsolsoni. Three femora represent a second species of extinct rail that we name Porphyrio mcnabi. With the description of these two species of rails, the total number of extinct species of land birds from the Fa'a- hia site stands at seven, consisting of two rails, two doves, two parrots, and a starling. Fa'ahia also has yielded bones of six other species of land birds that no longer exist on Huahine but survive elsewhere in Oceania.
... Evidence of North Atlantic Miocene to Pleistocene extinctions (Warham, 1996; Brooke, 2004) suggests that these may have contributed to the latitudinal asymmetry observed. Additionally , prehistoric anthropogenic extinctions on Pacific islands (Steadman, 1995; Wragg, 1995; Kirch, 1996) are evidence of extinction also operating at lower latitudes. However, since these are thought predominantly to have been local extinctions of island breeding populations (Steadman, 1995) with few entire species extinctions (Milberg & Tyrberg, 1993; Gaston, 2004), any absolute latitudinal bias in influences on species foraging ranges remains uncertain. ...
Aims Tests of the energy hypothesis for the large‐scale distribution of species richness have largely been concerned with the influence of two alternative forms of environmental energy, temperature and energy from primary productivity, both of which (at least in terrestrial systems) peak within the tropics. Taxa showing extra‐tropical diversity peaks present a potential challenge to the generality of species–energy theory. One such group are pelagic seabirds of the order Procellariiformes that show not only an extra‐tropical diversity peak but one confined to the Southern Ocean, hence a highly asymmetric one. They are distinct in being exceptionally adapted to take advantage of wind energy, which they may rely on for long‐distance ocean foraging for the patchy resources needed to meet their energetic needs. Wind represents a readily available source of kinetic energy, shows a strong latitudinal gradient, and has been largely omitted from species–energy theory. Moreover, maximal benefits of wind are likely to be afforded in areas of greatest available contiguous ocean extent. We compare the relative importance of wind speed, ocean productivity (chlorophyll concentration), air temperature and available ocean extent (distance) in explaining large‐scale global distribution of procellariiform species richness across the world's oceans.
Location Global, oceanic.
Methods Hierarchical partitioning, model selection, ordinary least squares (OLS) and spatial generalized least squares (GLS) regression.
Results Hierarchical partitioning of non‐spatial regression models indicates that ocean distance is the most important predictor of procellariiform species richness followed by wind speed and then temperature. In contrast, that of spatial regression models indicates the roughly equal importance of ocean distance and temperature, followed by wind speed. Although contributing additional model fit, ocean productivity is consistently the weakest predictor. Best‐fit models include all four predictors and explain 67% of observed variation. The species–productivity relationship is negative overall, while the species–temperature relationship is hump‐shaped. In contrast, ocean distance and wind speed are positively associated with species richness.
Conclusions Large‐scale procellariiform species richness distribution may represent a trade‐off in the use of different energy forms, being highest in Southern Ocean areas where productive energy and temperature are relatively low, but where available ocean foraging extent and wind energy required to utilize it are near‐maximal.
... Phytogeographical model for south-eastern Polynesia 1319 Approximately 40 birds have been recorded from either the islands of the Pitcairn group or crossing the ocean area between the islands, and at least four landbirds became extinct during the period of Polynesian habitation (Brooke, 1995; Wragg, 1995). Most of the sea birds and migrants are opportunists, feeding primarily on fish or squid, but the landbirds are commonly either omnivores or frugivores (Brooke & Jones, 1995; Imber et al., 1995; Jones et al., 1995; Trevelyan, 1995). ...
Aim To identify how the Pitcairn group relates biogeographically to the south-eastern Polynesian region and if, as a subset of the regions flora, it can then be used as a model for biogeographical analyses.
Location The Pitcairn group (25°4′ S, 130°06′ W) comprises four islands: Pitcairn, a relatively young, high volcanic Island; Henderson, an uplifted atoll, the uplift caused by the eruption of Pitcairn; and two atolls, Ducie and Oeno. The remote location, young age and range of island types found in the Pitcairn Island group makes the group ideal for the study of island biogeography and evolution.
Methods A detailed literature survey was carried out and several data sets were compiled. Dispersal method, propagule number and range data were collected for each of the 114 species that occurs in the Pitcairn group, and environmental data was also gathered for islands in Polynesia. Analyses were carried out using non-metric multidimensional scaling and clustering techniques.
Results The flora of the Pitcairn Islands is derived from the flora of other island groups in the south-eastern Polynesian region, notably those of the Austral, Society and Cook Islands. Species with a Pacific-wide distribution dominate the overall Pitcairn group flora. However, each of the islands show different patterns; Pitcairn is dominated by species with Pacific, Polynesian and endemic distributions, with anemochory as the dominant dispersal method (39.5%); Henderson is also dominated by species with Pacific, Polynesian and endemic distributions, but zoochory is the dominant dispersal method (59.4); Oeno and Ducie are dominated by Pantropic species with hydrochory as the most common dispersal method (52.9% and 100%, respectively).
Main conclusions • Habitat availability is the most significant factor determining the composition and size of the flora.
• South-east Polynesia is a valid biogeographical unit, and should include the Cook, Austral, Society, Marquesas, Gambier, Tuamotu and Pitcairn Islands with Rapa, but should exclude Easter Island, Tonga and Samoa.
• Regionalization schemes should take island type into consideration.
• The Pitcairn Island group can serve as a useful model for Pacific biogeographical analyses.
... Instead attention was focused on the much rarer bones of land birds that would be free from this complication. Several of the bird species chosen for dating were themselves extinct species and direct dates on their bones would obviously be of considerable interest (Wragg 1995). These dates fall into two groups. ...
... Comparison of feather barbule morphology and size with published keys and photographs (e.g. Chandler 1916; Brom 1986) suggests that the feather residue is from one of the Procellariformes, Pelecaniformes, or Charadriformes; however this still leaves a range of some 25 possible species from Henderson Island including endemic land species and sea birds (Wragg 1995:407). At this stage we do not possess a large enough comparative reference collection to further restrict the possibilities. ...
The causes of population divergence in vagile groups remain a paradox in evolutionary biology: dispersive species should be able to colonize new areas, a prerequisite for allopatric speciation, but dispersal also facilitates gene flow, which erodes population differentiation. Strong dispersal ability has been suggested to enhance divergence in patchy habitats and inhibit divergence in continuous landscapes, but empirical support for this hypothesis is lacking. Here we compared patterns of population divergence in a dispersive clade of swallows distributed across both patchy and continuous habitats. The Pacific Swallow (Hirundo tahitica) has an insular distribution throughout Southeast Asia and the Pacific, while its sister species, the Welcome Swallow (H. neoxena), has a continental distribution in Australia. We used whole-genome data to demonstrate strong genetic structure and limited introgression among insular populations, but not among continental populations. Demographic models show that historic changes in habitat connectivity have contributed to population structure within the clade. Swallows appear to exhibit evolutionarily labile dispersal behavior in which they reduce dispersal propensity after island colonization despite retaining strong flight ability. Our data support the hypothesis that fragmented habitats enhance population differentiation in vagile groups, and suggest that labile dispersal behavior is a key mechanism underlying this pattern.
We describe a new species of Polynesian sandpiper from Henderson Island, Prosobonia sauli sp. nov., based on multiple Holocene fossil bones collected during the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands (1991–92). Prosobonia sauli is the only species of Prosobonia to be described from bone accumulations and extends the record of known extinct Polynesian sandpipers to four. It is readily differentiated from the extant Tuamotu Sandpiper P. parvirostris in several features of the legs and bill, implying ecological adaptations to different environments. The geographically nearest Prosobonia populations to Henderson Island were found on Mangareva, where it is now extinct. A previous record of a species of Prosobonia from Tubuai, Austral Islands, is here shown to belong to the Sanderling Calidris alba. Our analyses of newly sequenced genetic data, which include the mitochondrial genomes of P. parvirostris and the extinct Tahiti Sandpiper P. leucoptera, confidently resolve the position of Prosobonia as sister-taxon to turnstones and calidrine sandpipers. We present a hypothesis for the timing of divergence between species of Prosobonia and other scolopacid lineages. Our results further provide a framework to interpret the evolution of sedentary lineages within the normally highly migratory Scolopacidae.
Avifaunas derived from Lapita archaeological sites excavated between 2004 and 2014 from four sites in the Vava'u Group and two on Tongatapu, Kingdom of Tonga are described, revealing birds encountered by the first human arrivals. A total of 741 identifiable bones revealed 24 avian taxa, among which terrestrial birds, especially rails, pigeons and parrots, were the most abundant. At a minimum, eight taxa, or 50% of the original non-passerine land bird diversity in the sample, are globally extinct. These include two megapodes (Megapodius alimentum and a larger unnamed megapode), three pigeons (a large Caloenas sp. indet., Didunculus placopedetes and Ducula shutleri sp. nov.), two rails (Hypotaenidia vavauensis sp. nov. and an unnamed one) and the parrot Eclectus infectus. The rail H. vavauensis was restricted to Vava'u and was flightless, with reduced wings, and larger than Hypotaenidia woodfordi of the Solomons, the largest congener hitherto found in the Pacific. The pigeon Du. shutleri was volant, but was the largest species in its genus and was widespread in the Kingdom. The evolution of Tongan avifaunas is related to varying ages (Pliocene to Pleistocene) of the island groups, where geological youth apparently precluded true giantism in the fauna.
The extinct Kiritimati Sandpiper Prosobonia cancellata is known from a single contemporaneous illustration by William Wade Ellis and a description by William Anderson. We reproduce Ellis' illustration for the first time, and we consider the illustration as almost in line with Anderson's description. Further, using both Anderson's work and Ellis' illustration, we prepared a description of the bird to replace Latham's interpretation of the depiction. Finally, we show that Kiritimati Sandpiper possessed several unique morphological characters.
Supporting Information
Human translocation as an alternative hypothesis to explain the presence of giant tortoises on remote islands in the south-western Indian Ocean
Lucienne Wilmé, Patrick O. Waeber, Joerg U. Ganzhorn
Appendix S1 Systematics of the Testudines
Appendix S2 List of references compiled
The petrels (Procellariiformes), although regarded as the most successful of the seabirds with a near global distribution, are facing a crisis with almost half of the species threatened with extinction, yet many lack the basic biological data important for their conservation, due to the difficulty of studying these species which spend most of their lives at sea, only returning to land to breed annually. This thesis focuses on the IUCN-listed Vulnerable Westland Petrel (Procellaria westlandica), one of the largest burrowing seabirds, which breeds only in a relatively small area in the Paparoa National Park in Westland, New Zealand, during the austral winter. The major goals were to test specific hypotheses related to the behavioural, migratory, and foraging ecology of this species with critical relevance for its conservation. The major aims were to identify the annual distribution of the Westland Petrel, its migratory dynamics, how these vary between the sexes and seasons, to characterise sex differences in morphological characteristics, and to study the temporal variation in the social and vocalisation behaviours of a nocturnal colonial seabird. Two separate year-long tracking studies using miniature archival light loggers (geolocators) identified Westland Petrels use coastal shelf waters to the west, north and east of New Zealand‟s South Island during the breeding season, followed by a rapid trans-Pacific outward migration to southern South American waters usually in November and taking approximately 6 days. Most birds remained in the productive Humboldt Current, although a few birds remained off Southern Argentina. Birds began their return migrations to New Zealand waters usually in April, taking several days longer in comparison to the outward migration. A morphological analysis and molecular sexing revealed sexual size dimorphism through the use of linear discriminant function analyses of seven commonly measured morphometric characters, with males having larger bill depths, longer head lengths, and heavier body weights. However, no sex differences were found in migration timing dynamics and habitat use, but individuals showed positively correlated patterns of departure dates from breeding and from non-breeding ranges and females were found to travel faster during the migration than males, which may be related to the increased wind velocities they experienced. Birds spent the greatest time immersed in the ocean during the nonbreeding season, followed by the breeding and the least time during the outward migration. A three-behavioural state model was developed using K-means clustering, and the resulting classifications were assigned to each location, revealing seasonal, but not sexual, variation in behavioural state. Stable isotope analyses of blood samples indicated dietary sexual differences during the breeding season, with males feeding on higher trophic-level prey. Extensive behavioural observations on the colony across different temporal scales (over nights, seasons, years) were carried out to characterize the temporal dynamics of at-colony behaviours for the first time in this petrel genus. Our analyses show consistent temporal variation in several behavioural attributes (e.g. social interactions, vocalizations, eyes closed, body movements) with little or no variation in others (e.g. self maintenance or stationary behaviours). This thesis expands our knowledge of the distribution of a threatened species, the Westland Petrel, identifies the core areas that should be monitored for potential threats (e.g. fisheries bycatch) to this species both during the breeding and non-breeding seasons, identifies behavioural rhythms on the breeding colony, reveals sex differences in this species and provides critical data and new implications for the conservation management of this species, identifying critical behavioural and ecological variables to take into consideration when developing mitigation and management plans.
Plumage states of the long-tailed cuckoo (Eudynamys taitensis) are reviewed and summarised from examination of museum study-skins. Besides the distinctive adult plumage (barred above, white background colour below) and immature plumage (spotted above, pale brown below), some birds (13% of those in the wintering grounds, plus 1 bird from New Zealand) show a "transitional" plumage presumed to be intermediate between the immature and adult condition. Also, some pale birds found in New Zealand may represent a hitherto-unrecognised juvenile plumage. A review of distribution records (museum specimens plus published sight-records) in both the summer and winter ranges of the cuckoo confirms a vast fan-shaped distribution extending 6,000 km north from New Zealand to the tropical Pacific, and 11,000 km from east to west in the tropics. Wake Island (19.3°N) in the north, Palau (134.5°E) in the west, Henderson Island (128.3°W) in the east and the Snares Islands (48.0°S) in the south are the extreme records in this range. Records of museum specimens reveal that almost all long-tailed cuckoos returning to New Zealand in October are in adult plumage. Autumn records show a gradual northward retreat of cuckoos within New Zealand, with a stronger-than-average bias in North Island records from March to May. There is no equivalent North Island bias for the spring influx in September and October. Museum specimens from eastern Polynesia exhibited an uneven sex ratio biased towards males (74%), whereas the sex ratio elsewhere was more even. Our study confirms the vast total range of the long-tailed cuckoo and provides age-specific details of the seasonal waxing and waning of the migratory patterns of the breeding population within New Zealand.
More than 50 species of flightless rails (Gruiformes: Rallidae) have been discovered on islands throughout the world, including members from most of the tribes and genera of the family. In the present study, qualitative and morphometric analysis of 3,220 study skins, more than 1,200 associated (complete and partial) skeletons, approximately 4,000 disassociated subfossil elements, and pectoral dissections of 41 fluid-preserved specimens formed the primary basis for investigation. Analyses emphasized statistical comparisons of flightless species with closest flighted relatives, augmented by analyses of data on body mass, wing areas, wing lengths, clutch sizes, egg dimensions, and ecophysiological parameters. These were integrated with a companion cladistic analysis and current evolutionary theory. Flightless members of the Rallidae span more than two orders of magnitude in body mass. Univariate comparisons of skin specimens confirmed a repeated pattern of relatively or absolutely shortened wings and (with a few exceptions) tails in flightless taxa. Greatest reductions in relative wing size were evident in Habroptila wallacii, Gallirallus australis-group, Tricholimnas spp., Habropteryx insignis, Amaurornis ineptus, and Tribonyx mortierii. These shifts were confounded by diverse changes in body size; most flightless species were characterized by increases in body size of various magnitudes (greatest in Porphyrio mantelligroup, Nesotrochis debooyi, Gallirallus australis-group, Tricholimnas lafresnayanus, Aphanapteryx bonasia, Erythromachus leguati, Diaphorapteryx hawkinsi, and Amaurornis ineptus), whereas a minority showed substantial decreases (Cabalus modestus), modest decreases (Dryolimnas aldabranus, Rallus recessus, Gallirallus wakensis, Atlantisia rogersi, most flightless Porzana, and Tribonyx hodgenorum), or virtual stasis (Porzana palmeri) in directly measured or estimated body masses. Sexual dimorphism was significant in virtually all external dimensions, although magnitudes of these differences were substantially less than within-sex differences between congeners. Although confounded by subspecific variation in some taxa, indications were found of inflated variance in some external dimensions (e.g., tail length) of flightless species relative to flighted relatives (e.g., Amaurornis ineptus). Limited data on wing loadings--ratios of body mass divided by area of wings--confirmed that two flightless species had significantly higher values than flighted relatives of similar size. Only the estimate for bulky Porphyrio hochstetteri exceeded the "threshold of flightlessness" of Meunier, whereas the value for tiny, flightless Porzana atra was roughly one fourth of the threshold value. The latter indicates the inapplicability of this criterion in taxonomic groups (e.g., Rallidae) in which reductions of the pectoral musculature are critical to flightlessness. Principal component analyses (PCAs) and canonical analyses (CAs) of studyskins provided multidimensional discrimination of species and sexes within key clades with respect to both size and shape. These not only confirmed the variably pronounced reductions in relative wing length and overall size in flightless species indicated by univariate analyses, but revealed that corresponding multivariate shifts were exceptionally great in Porphyrio hochstetteri, Porzana sandwichensis, and Amaurornis ineptus, and that sexual dimorphism was exaggerated in P. hochstetteri, Habroptila wallacii, Gallirallus owstoni, and Cabalus modestus. PCAs of lengths of extracted remiges revealed that flightless species, in addition to differences in overall size, were characterized by disproportionately short (in extreme cases, absent) distal primary remiges (i.e., had more rounded wings). Remiges displayed several important trends associated with flightlessness: reductions in length relative to body size; variably pronounced changes in shape; disproportionate shortening of the distalmost remiges, resulting in comparatively rounded wings; losses of the distalmost one or two remiges primarii and several remiges secundarii (a minority of taxa); and microanatomical reductions in the integrity of margins of vanes ("fringing"). Univariate comparisons confirmed the relative and (in some cases) absolute reductions in lengths of wing elements, and also quantified the reductions in dimensions of elements of the pectoral girdle and widths of appendicular elements. These shifts were accompanied by increased size of the cranium and pelvic apparatus in a number of flightless taxa (e.g., Porphyrio hochstetteri, Gallirallus australis-group, Amaurornis ineptus, and Tribonyx mortierii). Subfossil coots (Fulica chathamensis-group and F. newtoni) largely qualify as allometrically enlarged versions of typical congeners, comparable to two large Andean coots (Fulica cornuta and F. gigantea). Univariate sexual dimorphism was significant in most rallids. However, intersexual differences in bill lengths of several subfossil rails (Diaphorapteryx hawkinsi, Aphanapteryx bonasia, and possibly Cabalus modestus) were exceptionally great and suggestive of intersexual differences in feeding niche. Bivariate correlations within flightless species differed from those for flighted species, notably in the low correlations between most sternal measurements and other osteological variables, a pattern indicative of the virtual disjunction between sternum and other skeletal elements in flightless species. Comparisons of proportions within the pectoral limb revealed that the antebrachium, carpometacarpus, and (to a generally lesser degree) the phalanges were disproportionately short and the brachium was disproportionately long in flightless species. These patterns and the disproportionately robust alulae in flightless rails are consistent with the effects of two largely perpendicular developmental axes acting on both the skeletal and muscular derivatives of the mesoderm in the avian pectoral limb: a primary, proximal-distal growth axis; and a secondary, cranial-caudal growth axis that principally affects the manus. Proportions within the pelvic limb showed a diversity of shifts associated with the loss of flight, one of the most marked being a disproportionate elongation of the pedal digits in highly aquatic Fulica. Ratios of humerus length divided by femur length provided a remarkably robust indicator of flight capacity of rallids (with the exception of natatorial Fulica), with ratios for flighted taxa averaging above 0.90, whereas those for flightless taxa averaged below 0.90. A PCA of detailed matrices of skulls displayed the diversity of size and bill manifested by species of the Rallidae, among which the most extreme bill shapes (and probably foraging modes) were those of several flightless species (e.g., Capellirallus karamu, Diaphorapteryx hawkinsi, Aphanapteryx bonasia, and Erythromachus leguati). Pectoral allomorphosis (intraspecific allometry) displayed higher slopes in many flightless species, consistent with termination of pectoral growth at an earlier stage of skeletal development through heterochrony. CAs of skeletal measurements within clades confirmed relative magnitudes of shifts related to loss of flight that were broadly consistent with those apparent in PCAs, and confirmed significant increases in sexual dimorphism in most flightless lineages. Qualitative changes associated with flightlessness were found in most pectoral elements (especially the humerus and sternum), with many extending to the extinct adzebills (Gruiformes: Aptornithidae), and corroborated homoplasy among flightless species. Tallies of these apomorphies indicated that the most-derived flightless lineages were Porphyrio hochstetteri, Habroptila wallacii, Gallirallus australis-group, Cabalus modestus, Capellirallus karamu, and Diaphorapteryx hawkinsi. Comparisons of the pectoral musculature of rails revealed that reductions in bulk and cranial extents of mm. pectoralis et supracoracoideus were the most conspicuous myological changes. As a percentage of mean body mass, these underwent reductions among flightless taxa as high as 15% (Gallirallus australis and Tribonyx mortierii) and as low as 5-6% (Dryolimnas aldabranus and Gallinula comeri). Also typical of most flightless rails was an increase in the prominence of m. cucullaris capitis pars clavicularis (associated with the caudal regression of the apex carina sterni), attenuation of mm. biceps brachii et humerotriceps, greater distal extent of m. pronator superficialis relative to the underlying (foreshortened) radius, and a corresponding increase in the impressio m. brachialis relative to the ulna. A minority of flightless rails also showed variably pronounced weakening of fibrous portions of m. rhomboideus profundus, m. flexor digitorum superficialis, and m. ulnometacarpalis ventralis, and increased conformational variation in several muscles of the manus (mm. abductor alulae capita dorsale et ventrale, and m. extensor brevis alulae). PCAs of mean muscle measurements indicated greatest morphometric shifts in Gallirallus australis, G. wakensis, Atlantisia rogersi, Porzana palmeri, and Gallinula comeri, patterns not entirely congruent with reductions in breast muscles. A correspondence analysis of ecomorphological variables principally discriminated three groups: small crakes on small, extremely isolated islands (Porzana palmeri and P. atra), large terrestrial species from New Zealand (Porphyrio hochstetteri and Gallirallus australis), and robust, aquatic species from moderately large islands (Habroptila wallacii, Amaurornis ineptus, and Tribonyx mortierii). Most flightless rails manifest variably pronounced increases in size, and in accordance with the substantial literature on giantism, these shifts appear to confer selective advantages related to thermodynamics, procurement of mates, territoriality, capacity for fasting, and interspecific competition. These gains were accompanied by negative implications, including greater total energetic requirements, diminished capacity for stealth, and vulnerability to selected environmental and predatory agents, with the latter contributing to the minority of flightless rails showing dwarfism. Changes in body size are accompanied by allometric changes in numerous, fundamental ecophysiological parameters, among which are several critical to flight capacity. Departures from familial isometry in relative wing size accompany flightlessness in most cases, but in rails reductions in pectoral musculature (and the associated skeleton) appear to be paramount, changes that were associated with variably pronounced changes in the integument, modifications in bill shape, increased sexual dimorphism, energetically efficient reductions in basal metabolic rates, and changes in reproductive and dietary parameters. The latter are consistent with r-K shifts in life histories, and most of the ecological changes are typical of insular birds. Heterochrony, combining pectoral paedomorphosis with (in most taxa) peramorphosis of the axial and pelvic complexes, appears to underlie most anatomical apomorphies related to flightlessness in rails. Morphological and ecological changes in flightless rails provide a strong qualitative analogy with those of vertebrate and invertebrate endemics of caves (troglomorphs). Phylogenetic reconstructions of rallids are replete with morphological homoplasy, apparent irreversibility of the apomorphy associated with flightlessness, and only a few candidates for speciation following the loss of flight. Many rails show metapopulational demographic characteristics, and a number of migratory species show high vagrancy and qualify as consummate colonists of islands. These qualities suggest that a number of flighted rails, especially a core group with high fecundities and longdistance migratory patterns, may maintain dispersal polymorphisms in which a minority of progeny are predisposed to vagrancy and colonization of insular habitats. Insular colonizations occasioned thereby essentially represent "permanent migratory stopovers" followed by evolutionary refinements for year-round residency. The highly convergent morphology of flightless rails indicates a shared, readily triggered, canalized bifurcation in ontogeny that leads to the morphological and physiological changes that result in flightlessness. Conditional advantages of resources redirected in flightless lineages (e.g., conversion of investments in musculature, pectoral skeletons, and metabolic characteristics) are substantial, as indicated by the exorbitant anatomical and physiological requirements of the primary capacity surrendered, migration. The potential for this transformation may be preserved through dispersal polymorphisms and bethedging against overdependence on ephemeral, variable, natal breeding locales. Alternative patterns of dispersal also may be accelerated in some rallids through selectively maintained, environmentally induced plasticity through threshold traits or developmental reactionnorms within small demes subject to founder effects, genetic drift, and population bottlenecks. Distributions of flightless rails are explainable by a complex history of colonizations by flighted ancestors, a scant number of colonizations or nearisland expansions by flightless lineages, and extinctions related to small demes, marginal habitats, earthquakes, volcanoes, El Niño-La Nina events, and (especially) tsunamis of islands during recent millennia. Many flightless rails encountered ecological opportunities beyond those of continental confamilials. Selective advantages under these circumstances were accrued through decreased clutch size, increased egg size, and protracted developmental periods. Flightlessness in rails represents the selectively advantageous, ontogenetically mediated conversion of anatomical and caloric assets of the pectoral apparatus and associated metabolic parameters related to flight toward multiple evolutionary alternatives of intensified selective importance in insular habitats and the adoption of a nonmigratory lifestyle. The evolutionary scenario can be summarized as follows: migration-imposed anatomical and physiological requirements for migration preconditioned key rallids for a conversion of resources; vagrancy (possibly enhanced by polymorphism of dispersal and accelerated cladogenetic capacity maintained among metapopulations) provided opportunities for insular colonization; one or a suite of similar alternative, heterochronic, developmental avenue(s) retained by key rallids (perhaps triggered and hastened as threshold traits or by developmental reaction norms) facilitated the anatomical and physiological transformation to the local optimal, flightless phenotype(s) after colonization; successful colonization may have been advanced by differences in preferred stopover habitats between sexes and ages, and the acceleration of kin-selected altruism among close relatives migrating in concert; concomitant changes in size carried multiple allometrically related changes in physiology and metabolism; and despite a resilience to natural disasters (notably tsunamis), anthropogenic agencies ultimately led to extinction for most flightless lineages effectively by breaching key aspects of insularity essential to their provision of refuge. Accordingly, the "ideal avian colonist" would possess a combination of a capacity to modulate metabolic and physiological parameters; manifest dispersal polymorphism that includes long-distance, gregarious vagrancy as one component tactic; comparatively high sexual dimorphism or a potential for such; and expanded ontogenetic variance and cladogenesis that facilitates evolutionary changes in size and pectoral paedomorphosis.
Located in the South Pacific Ocean, the Gambier Islands are sometimes presented as an example, with Easter Island, of biodiversity collapse provoked by overexploitation of the natural resources by the Polynesian people during the course of several centuries. However, when comparing the list of bird bones obtained from archaeological sites with the data obtained and specimens collected by naturalists from the end of the eighteenth century to the mid-twentieth century, we show that land-bird extinction continued uninterrupted, mostly due to introduced predators and the continuous loss of wooded areas. Conversely, the list of breeding seabirds has remained relatively stable, but the number of breeding sites has decreased owing to introduction of predators, especially the cat and black rat. Today these sites are restricted to cliffs on the main islands and to remote islets.
People have lived on tropical Pacific islands over the past 30,000 years (Bismarcks, Solomons) or 3000 to 1000 years (the rest of Oceania). Their activities have led to the loss of many thousands of populations and as many as 2000 species of birds that probably otherwise would exist today. This extinction event is documented by avian fossils from archaeological (cultural) and paleontological (noncultural) sites from nearly 70 islands in 19 island groups. Extinction of birds in Oceania rivals the late Pleistocene loss of large mammals in North America as the best substantiated rapid extinction episode in the vertebrate fossil record. Some avian extinctions in Oceania occurred within a century or less after human arrival, while others required millennia or even tens of millennia. Any of these time frames is rapid in an evolutionary or geochronological sense. Inter-island differences in the speed and extent of extinction can be explained by variation in abiotic (A), biotic (B), and cultural (C) factors. Levels of extinction on large, near islands can be comparable to those on small, remote islands when C factors (such as high human population density and introduction of invasive plants and animals) override A factors (such as large land area or little isolation) or B factors (such as rich indigenous floras and faunas). An innovative, proactive conservation strategy is needed not only to prevent further extinctions of birds in Oceania, but also to restart evolution of some of the lineages that have suffered the most loss, such as flightless rails. This strategy should focus on islands with ABC traits that retard rather than enhance extinction.
We report numbers and distributions of the breeding seabird community of the Gambler Islands (Eastern Polynesia, South Pacific Ocean), obtained in 1995 and 1996. Comparing these data with those collected in 1922, 1965-69 and 1971, we assess the extent of changes in distribution and numbers of seabirds. None of the 14 species recorded previously to 1995-96 has disappeared, but numbers and ranges of all the tern species have decreased. Breeding of three additional species (Pterodroma spp.) has been discovered or confirmed in 1995-96, though their numbers are very small. We also identified an unknown Cookilaria petrel, of which a wing was collected in 1922 on Mangareva, but which was not recorded later. Although seabird diversity on Gambler Islands is high, no species breeds in large numbers. Indeed, several species have tiny population sizes, and concern is therefore expressed for the future of this seabird community.
A vagrant Laughing Gull (Larus atricilla) from Pitcairn Island: A new record for southern and eastern Polynesia During mid-March 1992, I discovered the remains of a Laughing Gull (Larus atricilla) at Down Rope Beach, Pitcairn Island. It appeared to have been dead for approximately one month. The distance from Pitcairn Island to the wintering grounds of this North American gull is over 5,000 km (Figure 1) and the nearest vagrancy record to Pitcairn Island is Samoa (4,000 krn away). It was probably displaced to the south west by the cyclone strength winds associated with the 1991-1992 El Nino. This gull's skeleton (which I used for species identification) is now deposited at the Museum of New Zealand, Wellington (#24650).
Five bones, representing one adult of the Pacific Flying Fox, Pteropus tonganus, were recovered from an archaeological site on Rurutu (151°21′W, 22°27′S), Austral Islands, French Polynesia, making this the most eastern extension of the species. For the first time, flying fox bones from cultural deposits were directly dated by accelerator mass spectrometry, yielding an age of death between A.D. 1064 and 1155. Their stratigraphic position in an Archaic period archaeological site and the absence of bones in the late prehistoric to historic layers point to extirpation of the species. No flying fox bones were found in pre-human deposits and human transport of the species cannot be ruled out.
We examined 53 bones of rails (Rallidae), previously referred to Gallirallus n. spp., from archaeological sites on four islands in the Marquesas Islands, French Polynesia. We describe three new, extinct, flightless species of Gallirallus: G. roletti (Tahuata), G. gracilitibia (Ua Huka), and G. epulare (Nuku Hiva). Two bones from Hiva Oa, although probably representing another extinct species of Gallirallus, are regarded as an inadequate basis for describing a species. At first human contact, the genus Gallirallus probably included many scores if not hundreds of flightless species on islands from the far western Pacific (Okinawa, Philippines, Halmahera) eastward across most of Oceania. As currently understood, the Marquesas Islands represent the eastern range limit of Gallirallus.
Situated at the extreme margin of the Indo-West Pacific biotic province, the four islands of the isolated Pitcairn Group hold interest for biogeographers and archaeologists alike. Human settlement may have been as early as the 8th century AD for the uplifted limestone island of Henderson, the most pristine island of its kind. An archaeological survey of the Pitcairn Islands is provided, while Henderson is examined in detail. Recent extensive excavations provide a record of change during 600 years of human occupation. Adaptation to the ecologically-marginal conditions is documented by artefacts, more than 150000 vertebrate bones, molluscs and subfossil plant remains recovered from stratigraphic contexts. The effects of prehistoric human occupation on the pristine environment are revealed by Polynesian plant and animal introductions, bird extinctions and range reductions, possible over-predation of marine molluscs, exploitation of sea turtles, and large-scale burning for swidden agriculture. The origin of human colonists is documented by analysing imported artefacts by geochemical characterization (x-ray fluorescence analysis). The human abandonment of Henderson, by the seventeenth century, is viewed in the context of prehistoric regional dynamics.
Excluding the gadfly petrels Pterodroma spp. and the resident landbirds, this paper details the present status of bird species seen during an expedition to the Pitcairn Islands (Ducie, Henderson, Oeno and Pitcairn) in 1991 and early 1992. Ten species were recorded in the Islands for the first time. Several Southern Ocean petrels were recorded, most in the midwinter period of June and July. The populations of Christmas Island shearwaters breeding on Oeno and Ducie laid in synchrony every 9–10 months. The species is one of few with such a sub-annual, synchronized regime. The majority of other seabirds had an annual breeding cycle, laying between May and October. Around one percent of the world population of the bristle-thighed curlew passes the non-breeding season in the Pitcairn Islands.
The relationship between island biogeography and the vulnerability of island biota to extinction as a result of human activities was examined. In particular, this study analyzed whether island area, maximum elevation of an island, isolation from the nearest continental landmass, or date of human colonization had statistically significant relationships with the proportion of endemic island bird species that have become endangered or extinct. The study examined islands or island groups with endemic bird species, and which have never been connected to a continental landmass. Both modern and fossil bird species were incorporated into the analysis. Islands that were colonized by humans earliest had the lowest proportion of modern species alone, and modern and fossil species combined, that have gone extinct. However, date of human arrival was not correlated with the proportion of modern species that are endangered. Maximum elevation of an island was negatively correlated with the proportion of modern species that are extinct, and was positively correlated with the proportion of modern species that are endangered. Area was negatively correlated with the proportion of modern species that are endangered. Isolation of islands was not significantly correlated with the proportion of modern species extinct or endangered, but was positively correlated with the proportion of modern and fossil species combined that have gone extinct. These results indicate that the initial spasm of island bird extinctions due to human contact may have, in part, passed. They also indicate that bird species on islands colonized earliest by humans may have had more time to adapt to the presence of man and his commensal species, resulting in reduced extinction rates.
The UK has sovereignty over 16 Overseas Territories, which hold some of the world’s great seabird colonies and collectively support more endemic and globally threatened bird species than the whole of mainland Europe. Invasive alien mammalian predators have spread throughout most of the Territories, primarily since European expansion in the 16th century. Here we review and synthesize the scale of their impacts, historical and current, actions to reduce and reverse these impacts, and priorities for conservation. Mammalian predators have caused a catastrophic wave of extinctions and reductions in seabird colony size that mark the UKOTs as a major centre of global extinction. Mammal-induced declines of threatened endemics and seabird colonies continue, with four Critically Endangered endemics on Gough Island (Tristan da Cunha), St Helena and Montserrat directly threatened by invasive alien House Mice Mus musculus, Feral Cats Felis catus and rats Rattus spp. Action to reduce these threats and restore islands has been modest in comparison with other developed countries, although some notable successes have occurred and a large number of ambitious eradication and conservation plans are in preparation. Priority islands for conservation action against mammalian predators include Gough (which according to one published prioritization scheme is the highest-ranked island in the world for mammal eradication), St Helena and Montserrat, but also on Tristan da Cunha, Pitcairn and the Falkland Islands. Technical, financial and political will is required to push forward and fund the eradication of invasive mammalian predators on these islands, which would significantly reduce extinction risk for a number of globally threatened species.
Henderson Island, an uninhabited raised coral atoll in the Pitcairn group, has recently been designated a World Heritage Site because of its unique and relatively undisturbed ecosystem. The island is believed to have been uplifted and subaerially exposed during the last 275 kyr. This therefore provides the maximum age for the terrestrial biota that includes several endemic taxa. Henderson today supports 16 strictly terrestrial species of snails, about half of which are endemic. Analyses of sediments beneath Polynesian occupation horizons dated between the 11th and 17th centuries AD, have yielded 11 species of land snail present in the modern fauna, together with at least six (and possibly as many as eight) further species that no longer occur on the island. These extinct taxa are illustrated and formal descriptions provided for five (Pleuropoma hendersoni, Orobophana carinacosta, Minidonta macromphalus, Philonesia pyramidalis, P. weisleri); a sixth, known only from broken shells, appears to belong to the genus Hiona. The two remaining taxa are 'tornatellinids' that have not been recognized among the modern fauna. Radiocarbon dates from bones of associated extinct land birds confirm their occurrence on Henderson before the first signs of Polynesian settlement. The extinction of these taxa seems to coincide with the Polynesian occupation and evidence for large-scale burning, at least around parts of the plateau margin, suggests that their demise can be linked with habitat destruction. At least three species, Gastrocopta pediculus, Lamellidea oblonga and Pupisoma orcula, first appear in Polynesian occupation horizons. Their status as prehistoric introductions is therefore confirmed but G. pediculus no longer lives on Henderson. Pacificella variabilis, Tornatellides oblongus parvulus and Elasmias sp., all previously thought to have been other prehistoric introductions to Henderson, were recovered from pre-Polynesian levels and are therefore native.
The first wave of human colonists spread across the Pacific from 4000 to 1000 years ago. That they caused many extinctions is well known from fossil finds. We estimate how many fossil species were missed - the answer is roughly half - and so estimate the true extinction rate. The first colonists exterminated roughly half the species on each island group. Some of these extinctions are falsely attributed to the first colonists, because intensive collection often began a half century after the damage initiated by European discovery. Even taken at face value, these recent extinctions are too few. Many species are so critically endangered that we know neither whether they still survive or how to save them. Interestingly, there are fewer recent extinctions and currently endangered species in the islands of the western Pacific, which were the islands occupied first by humans. We suggest that the species sensitive to human occupation died out long ago in these areas. If so, these islands would have lost even more than half of their bird species.
An extinct species of fossil shearwater (Puffinus holei sp. nov.), referable to the subgenus Puffinus, is described from the sand dune complex of the Jandia Peninsula, Fuerteventura, Canary Islands. The material, consisting of adults, nestlings and partial eggshells, indicated that the collecting locality was once a breeding site of the species. A radiocarbon data of 32, 100 ±1, 100 BP, obtained from an eggshell, shows that the colony was still extant during the Devensian (Wünn) Stage of the Upper Pleistocene. Observations on the taxonomy and osteology of the Recent North Atlantic and Mediterranean shearwaters, P.p. puffinus, P.p. ntauretanicus and P.p. yelkouan are also made. It is recommended that these subspecies be elevated to full species status.
A vagrant Laughing Gull (Larus atricilla) from Pitcairn Island: A new record for southern and eastern Polynesia During mid-March 1992, I discovered the remains of a Laughing Gull (Larus atricilla) at Down Rope Beach, Pitcairn Island. It appeared to have been dead for approximately one month. The distance from Pitcairn Island to the wintering grounds of this North American gull is over 5,000 km (Figure 1) and the nearest vagrancy record to Pitcairn Island is Samoa (4,000 krn away). It was probably displaced to the south west by the cyclone strength winds associated with the 1991-1992 El Nino. This gull's skeleton (which I used for species identification) is now deposited at the Museum of New Zealand, Wellington (#24650).
Archaeological and palaeontological excavations were conducted as part of the Pitcairn Islands Scientific Expedition (January 1991 to March 1992). In this preliminary analysis of the subfossil bird bones from Henderson Island (24.22' S, 128.18' W) we identified 29 taxa, which were divided into five groups: (1) four endemic extinctions, (2) five local extinctions, (3) a minimum of 12 breeding residents, (4) three non-breeding migrants, and (5) five birds of uncertain status. Over half of the landbird species known from Henderson Island are listed here for the first time, including one new genus and at least three new species. New listings for Henderson Island include: Henderson Archaic Pigeon (Columbidae new genus), Henderson Ducula Pigeon (Ducula new species), Henderson Ground-Dove (Gallicolumba new species), Henderson Sandpiper (Prosobonia new species), Royal Albatross, Little/Audubon's Shearwater, Bulwer's Petrel, Black-winged Petrel, Sooty Tern, cuckoo (Eudynamys sp.), and a swallow (Hirundo sp.). Most of the bird bones collected were associated with prehistoric Polynesian occupation sites dating from ca. AD 1000 to 1600. Humans may have caused the extinction of at least four of the eight endemic landbirds, which equates with similar extinction rates on other Pacific islands.
The first wave of human colonists spread across the Pacific from 4000 to 1000 years ago. That they caused many extinctions is well known from fossil finds. We estimate how many fossil species were missed-the answer is roughly half-and so estimate the true extinction rate. The first colonists exterminated roughly half the species on each island group. Some of these extinctions are falsely attributed to the first colonists, because intensive collection often began a half century after the damage initiated by European discovery. Even taken at face value, these recent extinctions are too few. Many species are so critically endangered that we know neither whether they still survive or how to save them. Interestingly, there are fewer recent extinctions and currently endangered species in the islands of the western Pacific, which were the islands occupied first by humans. We suggest that the species sensitive to human occupation died out long ago in these areas. If so, these islands would have lost even more than half of their bird species.
The discovery and taxonomic history of fluttering shearwater (Puffinus gavia (Forster) and Hutton's shearwater (Puffinus huttoni Mathews) are reviewed. Taxonomic theory, where appropriate to this thesis, is discussed. The external morphology of P. gavia and P. huttoni is compared. No single external measurement or plumage character separates more than 60% of birds examined. The best system of identification is to compare the ratio of different body parts within an individual bird. The distribution of P. gavia and P. huttoni is compared. Hutton's shearwater feeds further out to sea and it is believed to be a migrant species wintering in north west Australian waters. The fluttering shearwater is believed to be a semi-migrant species with only the juveniles spending time in south east Australia. The red cell enzymes of P. gavia, P. huttoni and P. griseus are compared. There are differences in two esterase loci between gavia and huttoni, while P. griseus is more distantly related. Nei's genetic identity values are calculated. The systematic value of electrophoretic data is discussed. The relationship of an undescribed subfossil shearwater to P. gavia and P. huttoni is discussed. An outgroup analysis to other shearwater species is carried out according to phylogenetic (cladistic) theory. The subfossil shearwater is most closely related to the fluttering shearwater, and these two form a sister group to Hutton's shearwater. These three species are a sister group of P. opisthomelas. The relationship between the many P. assimilis subspecies, the black-backed Manx shearwaters, and the gavia, huttoni and opisthomelas group was not resolved. Puffinus nativitatis is more closely related to the Manx and the little shearwaters than to the P. griseus, P. tenuirostris group.
Bones deposited in caves show that, before the arrival of humans, at least 27 species of land birds lived on the Tongan island of 'Eua, where 13 indigenous species live today. Six of these 13 species were recorded from pre-human strata; three others probably occurred on 'Eua in pre-human times but were not in the fossil sample; and four others probably colonized 'Eua since the arrival of humans approximately 3000 years ago. Of the 23 species of extinct or extirpated land birds recorded from 'Eua, the nearest geographic occurrences of conspecifics or most closely related congeners are from the Solomon Islands (1 species), New Caledonia (2 species), Fiji and/or Samoa (9 species), elsewhere in Tonga (8 species), or unknown (3 species). The avifauna of West Polynesia (Fiji-Tonga-Samoa) is more closely related to that of Melanesia than that of East Polynesia. There was little pre-human turnover in Tongan land birds. The arrival of humans has influenced the Tongan avifauna more than any climatic, tectonic, or biological event of the past approximately 100,000 years.
Long thought never to have been inhabited and to be in a pristine ecological state, Henderson Island (southeast Pacific) is now known to have been colonized and then abandoned by Polynesians. Bones from an archaeological site on the island associated with (14)C dates of approximately 800 and approximately 500 years B.P. include specimens of 12 species of birds, of which 3, a storm-petrel and two pigeons (Nesofregetta fuliginosa, Ducula cf. aurorae or D. pacifica, and Ducula cf. galeata), no longer occur on Henderson, and two others (Puffinus nativitatis and Sula sula) still visit but are not known to breed. The vanished species were presumably exterminated by Polynesians and the biota of Henderson Island can thus no longer be regarded as being in an unaltered state. The prehistoric abandonment of various small, unarable islands by Polynesians may have been due to the depletion of seabirds and pigeons, the only readily available food source. The species of pigeons identified from Henderson are known historically only from distant archipelagos and have never before been found sympatrically. Distributional patterns resulting from man-caused extinctions may give rise to erroneous interpretations of the relationships and evolutionary history of insular organisms. Certain endangered species, such as Ducula galeata, might effectively be preserved by reintroduction to abandoned islands that they occupied before human intervention.
Archaeological and palaeontological excavations were conducted as part of the Pitcairn Islands Scientific Expedition (January 1991 to March 1992). In this preliminary analysis of the subfossil bird bones from Henderson Island (24022( S, 12S018( E) we identified 29 taxa, which were divided into five groups: (1) four endemic extinctions, (2) five local extinctions, (3) a minimum of 12 breeding residents, (4) three non-breeding migrants, and (5) five birds of uncertain status. Over half of the landbird species known from Henderson Island are listed here for the first time, including one new genus and at least three new species. New listings for Henderson Island include: Henderson Archaic Pigeon (Columbidae new genus), Henderson Ducula Pigeon (Ducula new species), Henderson Ground-Dove (Gallicolumba new species), Henderson Sandpiper (Prosobonia new species), Royal Albatross, Little/Audubon’s Shearwater, Bulwer’s Petrel, Black-winged Petrel, Sooty Tern, cuckoo (Eudynamys sp.), and a swallow (Hirundo sp.). Most of the bird bones collected were associated with prehistoric Polynesian occupation sites dating from ca. AD 1000 to 1600. Humans may have caused the extinction of at least four of the eight endemic landbirds, which equates with similar extinction rates on other Pacific islands.
Two radiocarbon dates on charcoal are 400 ± 60 and 870 ± 70 yr BP. 70% of the bird bones are of Pterodroma alba (phoenix petrel), which still nests on Henderson. A single bone of Gallicolumba sp. represents a new species for Henderson and the easternmost record for the genus. Other extirpated species of birds represented in the sites are Pterodroma externa (Juan Fernandez petrel), a smaller unknown species of Pterodroma, and Nesofregetta fuliginosa (white-throated storm-petrel). The resident avifauna of Henderson Island has lost 2-5 species of seabirds and 3 species of landbirds since the arrival of humans >800 yr BP. Hunting and habitat disturbance were primarily responsible. -from Authors
We propose a strategy for evaluating the contribution of human predation to the depletion of endemic birds on Pacific islands. Humans reduced avian populations indirectly through habitat alteration, for which there is much archaeological evidence. However, direct evidence of human predation and its role in avian extinctions has seldom been critically evaluated. Because many archaeological sites containing bird bones occur in nesting locales such as coastal dunes and rockshelters, distinguishing naturally from culturally deposited material is crucial. We address this problem by analyzing bird bones from nine archaeological sites on Moloka'i, Hawaiian Islands. Species composition, weathering, non-human predation, burning, element frequencies, and modification are considered. Similarity between archaeological and replicated breakage suggests human consumption of some extirpated bird species. We couple these results with converging, independent lines of evidence to identify human predation in avian assemblages from Moloka'i. We stress that determining the chronology of avian extinctions is best accomplished by directly dating bird bones with butchering marks and other evidence of human consumption.
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Situated at the extreme margin of the Indo-West Pacific biotic province, the four islands of the isolated Pitcairn Group hold interest for biogeographers and archaeologists alike. Human settlement may have been as early as the 8th century AD for the uplifted limestone island of Henderson, the most pristine island of its kind. An archaeological survey of the Pitcairn Islands is provided, while Henderson is examined in detail. Recent extensive excavations provide a record of change during 600 years of human occupation. Adaptation to the ecologically-marginal conditions is documented by artefacts, more than 150000 vertebrate bones, molluscs and subfossil plant remains recovered from stratigraphic contexts. The effects of prehistoric human occupation on the pristine environment are revealed by Polynesian plant and animal introductions, bird extinctions and range reductions, possible over-predation of marine molluscs, exploitation of sea turtles, and large-scale burning for swidden agriculture. The origin of human colonists is documented by analysing imported artefacts by geochemical characterization (x-ray fluorescence analysis). The human abandonment of Henderson, by the seventeenth century, is viewed in the context of prehistoric regional dynamics.
The records of long-distance vagrancy in the Procellariiformes are listed and re-examined. Some are clearly valid, more are obviously doubtful, many are difficult to confirm. Some records from the last century have failed to be repeated in this, but others have been repeated, sometimes more frequently. Some of them suggest hitherto unrecognized migrations or post-juvenile or post-breeding dispersal. Otherwise in general it appears that the more migratory albatrosses and much less often perhaps the southern fulmars may cross the equator into the opposite hemisphere, shearwaters and storm-petrels may go astray on migration into the wrong ocean, and the gadfly petrels of the genus Pterodroma, though rarely recorded anywhere near land away from the breeding stations, are occasionally capable of prodigious feats of wandering across several oceans and continents. These last records are hard to explain, though some at least must be genuine; the best explanation appears to be that the birds are first displaced from their range by storms, and then have vast powers of endurance so that they are able to wander even further afield in attempting to return to it. They then often come to grief in circumstances where it may be very hard indeed to prove the manner of the appearance beyond all reasonable doubt, and there will always be a large element of uncertainty about many older records, including a number on current national lists, although many cannot be ignored entirely.
Plate tectonic theory accounts for the steady subsidence of mid-plate oceanic islands by cooling of the lithosphere and so provides a sound basis for Darwin's theory of atoll formation. Now it is evident that because the lithosphere behaves elastically in response to loads such as islands, more localized subsidence and uplift patterns can also be explained. Tectonically active areas, where one plate is subducted beneath another, are also likely to contain regions of marked uplift, but are less amenable to modelling. These processes together provide a background motion framework for most reef settings with rates of vertical movement of the order of a few millimetres per year.
Reef forms are greatly influenced by the configuration of their foundations. Holocene reef foundations were essentially moulded by processes of deposition and erosion during the Pleistocene when global sea level changes were often greater than 1 cm year-1.
We are now developing a sufficient understanding of the rates and nature of reef processes of growth and destruction to be able to see the manner in which the structural development of reefs responds to the complex interplay of tectonic uplift and subsidence plus changes of sea level and climate.
Excluding the gadfly petrels Pterodroma spp. and the resident landbirds, this paper details the present status of bird species seen during an expedition to the Pitcairn Islands (Ducie, Henderson, Oeno and Pitcairn) in 1991 and early 1992. Ten species were recorded in the Islands for the first time. Several Southern Ocean petrels were recorded, most in the midwinter period of June and July. The populations of Christmas Island shearwaters breeding on Oeno and Ducie laid in synchrony every 9–10 months. The species is one of few with such a sub-annual, synchronized regime. The majority of other seabirds had an annual breeding cycle, laying between May and October. Around one percent of the world population of the bristle-thighed curlew passes the non-breeding season in the Pitcairn Islands.
This paper reports the breeding biology and nesting seasons of the gadfly petrels which nest on the four islands of the Pitcairn group, Pitcairn, Henderson, Oeno and Ducie. The species currently breeding are Murphy's petrelPterodroma ultima, Kermadec petrelP. neglecta, Herald petrelP. heraldicaand Henderson petrelP. atrata. Of these, Murphy's petrel is the most numerous; an estimated 250 000 pairs bred on Ducie, which is probably the major breeding station of the species. Novel basic breeding data for Murphy's petrel are presented. Incubation spells, averaging 19.3 days, are exceptionally long for a petrel. Phoenix petrelP. albaappears to have ceased to breed on the Pitcairn Islands since the 1922 surveys of the Whitney Expedition. Nesting success was low on Henderson Island during the study. For all four breeding species, less than 20% of eggs laid yielded fledglings. Failure occurred at the early chick stage and observations indicated that it was due to predation by Pacific ratsRattus exulans.Although rats are present on Ducie, predation was apparently less severe there. The situation on Oeno may be intermediate. I consider how the populations of Henderson are maintained in the face of this intense predation. The Murphy's petrel population may be sustained by immigration from Ducie while the Herald and Henderson petrel populations could be undergoing a long-term decline on Henderson. It is not clear how the Kermadec petrel population is maintained. The conservation implications of these findings are discussed.
The land snails (and semi-terrestrial molluscs) of the four islands that comprise the Pitcairn group are reviewed and the indigenous species illustrated. The strictly terrestrial molluscan faunas from the two atolls (Oeno and Ducie) are poor, like many other atolls in the Pacific. Each supports less than six species with wide geographical ranges. In contrast, the terrestrial molluscan fauna from Henderson Island, an uplifted atoll, is more diverse with at least 16 species belonging to seven families. Over half these taxa appear to be endemic, at least at the level of sub-species. Two species of semi-terrestrial molluscs have also been found on Henderson. Analyses of archaeological deposits in caves near the North Beach have revealed that at least a further six species of land snail formerly occurred on Henderson. The volcanic island of Pitcairn, the only island in the group still inhabited, supports the greatest number of terrestrial molluscs. Twenty-six species of land snail (and one semi-terrestrial pulmonate) were found living there during the recent expedition and a further three taxa were recognized amongst museum material. At least seven of these species are thought to be recent adventives and a further three are likely to have been prehistoric introductions. One Henderson (Georissa hendersoni) and three Pitcairn endemics (Pacificella filica, Sinployea pitcaimensis and Diastole tenuistriata) are formally described as new species. Some of the Pitcairn endemics occur in very restricted areas (less than a hectare) and it is important that measures should be taken to prevent the spread of invasive plants, such as rose-apple, that would threaten their survival.
Many bird species were extirpated or became extinct when prehistoric man reached oceanic islands We list > 200 species of extinct island birds only recorded as sub-fossils and which probably vanished due to prehistoric man In addition we list c 160 cases where an extant species has been found as subfossil on islands where it no longer occurs Several species today considered endemic to single islands of island groups had a much wider distribution in the past Biogeographic analyses of insular avifaunas are almost meaningless it the extensive prehistoric extinctions are not taken into account
Most extinct species belong to Anatidae Rallidae and Drcpanididae while local extirpations are numerous among doves and seabirds Smaller birds are rare mainly due to sampling bias and taphonomic factors The bird populations were depleted mainly by overhunting predation by introduced vertebrates and alteration of the original vegetation
Prehistoric humans on islands although dependent on limited animal resources regularly failed to exploit these in a sustainable way Several cases where human populations disappeared from islands in the Pacific may have been due to over-exploitation of native animals
Prehistoric man reached most tropical and temperate islands and most of the few remaining island faunas have been severely depleted in historic times The prehistoric extinctions emphasize the extreme vulnerability and value of the very few pristine island faunas that still remain
The study of bones from archaeological sites in Eastern Polynesia has revealed much late Holocene extinction of birds. Because this extinction has been found in all Eastern Polynesian archipelagos where bird bones are part of the archaeological record (Marquesas, Society, Pitcairn, and Cook island groups), similar levels of extinction are likely to be found in other Eastern Polynesian island groups (Line, Tuamotu, Gambier, Austral, Easter), if the evidence is sought. Human impact is the most plausible explanation for these extinctions, which begin immediately after peopling of the islands about 2000 years ago and diminish only after the avifaunas are largely depleted.
Coral reefs drilled offshore of Barbados provide the first continuous and detailed record of sea level change during the last deglaciation. The sea level was 121 ± 5 metres below present level during the last glacial maximum. The deglacial sea level rise was not monotonic; rather, it was marked by two intervals of rapid rise. Varying rates of melt-water discharge to the North Atlantic surface ocean dramatically affected North Atlantic deep-water production and oceanic oxygen isotope chemistry. A global oxygen isotope record for ocean water has been calculated from the Barbados sea level curve, allowing separation of the ice volume component common to all oxygen isotope records measured in deep-sea cores.
The vegetation of the raised coralline Henderson Island and Oeno Atoll (Pitcairn Group, south-central Pacific Ocean) is described from cover-abundance values of the vascular flora sampled in 10 10 m quadrats. Exploratory data analysis by detrended correspondence analysis and two-way indicator species analysis was used to summarize the resulting data matrices for each island, and to aid definition of vegetation types. For Henderson, six major vegetation communities are described, which are often closely linked to geomorphology: beachfront, embayment forests, open limestone scrub, cliff and ledge, exposed cliff top, and plateau forests. For Oeno, four main vegetation communities are described: open sandy littoral,Argusiascrub, closed forest, and coconut grove. For each island, the main vegetation types were further subdivided into a number of communities depending on the proportions of various taxa. Brief qualitative descriptions of the vegetation of Ducie and Pitcairn are also given. Anthropogenic communities, some of which are highly invasive, are widespread on Pitcairn. Adequate conservation measures must be given to all islands in the Pitcairn Group; this will protect not only the endemic-rich and possibly unique plateau forests of Henderson, but also the species-poor and scientifically important analogues of vegetation types which occur elsewhere in the Pacific islands.
After volcanic explosions or tidal waves had defaunated several islands near New Guinea, bird species number rapidly returned to equilibrium on coral islets and rapidly returned to quasi-steady-state values limited by regrowth of vegetation in lowland forest of larger islands. However, reequilibration in montane forest has been limited by slow dispersal of the birds. Colonists have been drawn disproportionately from r-selected "supertramrip" species, which maintain much higher population densities than do K-selected faunas, perhaps due to selection for resource overexploitation by the latter.
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