Zealand Offshore Islands Research Articles

A taxonomic re-evaluation of Pittosporum roimata Gemmill & S.N. Carter (Pittosporaceae, Apiales)

Pittosporum roimata Gemmill & S.N. Carter (Pittosporaceae, Apiales) was established in 2018 as an endemic species confined to the Poor Knights Islands group, off the eastern coastline of Northland Aotearoa / New Zealand. The new species was distinguished from P. cornifolium A. Cunn. on the basis of vegetative characters (leaf length, width, petiole length), floral characters (pedicel length, flower colour), and numbers of fruit per stem. The new species was also reported as differing from P. cornifolium by a single substitution within the nrITS cistron, with that data obtained from a paper that did not provide a phylogenetic interpretation of this result, nor specify whether the cultivated plants used were derived from seed obtained from multiple individuals or from cutting grown plants from a limited wild-sourced selection. In this paper the same morphological characters used to separate P. roimata are examined using a much wider sampling of P. cornifolium, and the specimens available for P. roimata. There are very slight differences in leaf width and length, petiole length, and pedicel length in Poor Knights Islands P. roimata specimens seen also in some collections from other northern Aotearoa / New Zealand offshore islands and some mainland stations. Flower colour is not a useful character as this is variable in P. roimata and P. cornifolium, as it is also in many other Aotearoa / New Zealand Pittosporum. On the basis of our morphological assessment we conclude that to maintain the segregation of P. roimata from P. cornifolium at the species rank is impractical, as there is a grading of characters between both species. As plants corresponding to P. roimata occur throughout the range of P. cornifolium, already a variable species, we suggest that, in line with other treatments of Aotearoa / New Zealand Pittosporum, it is better to reduce P. roimata into synonymy of P. cornifolium.

Functional traits explain non-native plant species richness and occupancy on northern New Zealand islands

Plant functional traits can greatly influence invasion success on islands. However, interrelationships between traits and invasion success are rarely integrated with the island biogeography theory. Here, we explored relations between functional traits and plant distributions to assess which traits are associated with invasion success (i.e. high island occupancy), test whether non-native richness and seed mass of species with distinct growth forms and dispersal modes vary differently with island characteristics (e.g. area, isolation, exposure to ocean-borne disturbances, distance from the nearest urban area, and whether islands were managed for conservation), and whether results differ from native species. We assembled a database of 264 northern New Zealand offshore islands, amalgamating species lists from field surveys and previously published data, and comprising 822 native and 855 non-native species. Non-native graminoids occurred on islands more frequently than forbs and woody species, and long-distance dispersal modes (wind, animal, unspecialized) more than species with short-distance dispersal modes. Most differences among trait categories of non-native species were associated with human-related variables (i.e. distance from the nearest urban area, and whether islands were conservation areas). Non-native plant species with high island occupancy were less commonly associated with human-related variables than non-native species with low island occupancy. Instead, they were more similar in their distributional patterns to native species within the same trait category, suggesting comparable processes regulate both sets of species. Our results illustrate that integrating trait-based approaches in the island biogeography framework can be a useful tool in understanding and predicting plant invasions.

SEABIRDS AS POSSIBLE RESERVOIRS OF ERYSIPELOTHRIX RHUSIOPATHIAE ON ISLANDS USED FOR CONSERVATION TRANSLOCATIONS IN NEW ZEALAND.

Erysipelothrix rhusiopathiae, the causative agent of the disease erysipelas, is a gram-positive bacillus, and an opportunistic pathogen in diverse species of animals. In New Zealand, E. rhusiopathiae has killed endangered birds on offshore islands, including Kākāpō (Strigops habroptilus), Takahē (Porphyrio hochstetteri), and Kiwi (Apteryx spp.). The source of infection is uncertain, and the prevalence of E. rhusiopathiae among wild birds is currently unknown. During October 2018 to December 2018, we surveyed dead and live seabirds that visit two of New Zealand's offshore islands used for Kākāpō conservation with the goal of determining the prevalence of E. rhusiopathiae. Bone marrow from dead birds was cultivated on selective agar, and organisms cultured were identified using matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry. The prevalence of E. rhusiopathiae was calculated in different species for each island. We surveyed live birds using PCR with Erysipelothrix spp.-specific primers on blood samples. The prevalence of E. rhusiopathiae in dead seabirds on Whenua Hou and Te Hauturu-o-Toi was 3.4% (3/86) and 11.4% (5/44), respectively. On Whenua Hou, E. rhusiopathiae was detected in Sooty Shearwaters (Puffinus griseus; 5.9%, 2/34) and Mottled Petrels (Pterodroma inexpectata; 2.7%, 1/36) while it was detected only in Cook's Petrels (Pterodroma cookie; 13.5%, 5/37) on Te Hauturu-o-Toi. Blood samples were collected from two seabird species; only one of 50 Mottled Petrels (2.0%) was positive for the presence of Erysipelothrix spp. Our findings confirm that burrowing seabirds are possible reservoirs of E. rhusiopathiae on both islands studied and may be the source of spillover to other species on the island. The differences in observed prevalence suggest the species composition of the reservoir of E. rhusiopathiae may vary geographically.

Fine-Scale Distribution, Abundance, and Foraging Behavior of Salvin's, Buller's, and Chatham Albatrosses in the Northern Humboldt Upwelling System1

Three albatross species occur in Perú that nest in New Zealand offshore islands: Salvin's (Thalassarche salvini), Buller's (T. bulleri ssp.), and Chatham albatross (T. eremita). To determine their spatial distribution, relative abundances, and foraging behavior in Perú, we conduct two surveys coinciding their wintering time in the austral autumn and spring 2019. The study area was from 06° S to 18° S and from the coastline to 100 nautical miles (nm) offshore. We recorded 483.7 hours of observation while surveying 7,678 km2, recording 249, 200, and 22 individuals of Salvin's, Buller's, and Chatham albatrosses, respectively. Salvin's occupied shallower waters along the continental shelf-break in the northern and central regions (07°–12° S), while Buller's and Chatham's preferred oceanic waters in southern regions (12°–17° S). Salvin's greatest abundance was during autumn (April–June) when adults dominated (85.7%) and shifted to the north. In spring (October–December), the Salvin's abundance was lower and dominated by subadults (62.5%) shifting to the south. Conversely, Buller's greatest abundance was in spring, with similar age-classes to those of Salvin's, while in autumn a lower abundance was observed and adults dominated (>85%). Chatham's adults (80%) were abundant in autumn, while in spring Chatham's were very few (n = 3 total observations). According to a Principal Component Analysis (PCA) and Correspondence Analysis (CA), Salvin's were positively associated with higher sea temperature and salinity, lower latitudes, and shallower depths. Buller's and Chatham's were associated with greater shelf-break distance and wind velocity. Salvin's presence in Perú could primarily originate from birds coming from the Western Chain in The Snares. We suggest that adult Buller's seen in autumn, probably originate from the Chatham Islands, while those in spring probably originate from The Snares. Salvin's were spatially associated with cephalopods and Buller's and Chatham's with fishes. The two latter species were attracted to offal discards of small-scale fisheries.

Biogeography and anthropogenic impact shape the success of invasive wasps on New Zealand's offshore islands

AbstractAimThe theory of island biogeography predicts that the susceptibility of an island to invasion is determined by its isolation and size. However, many island ecosystems have been intensely modified by humans. Here, we investigated the biogeographic, biotic and anthropogenic drivers of invasive social wasps on 36 offshore islands.LocationIslands off the east coast of New Zealand's North Island.TaxaVespula germanica(Fabricius, 1793),Vespula vulgaris(Linnaeus, 1758) andPolistes chinensis antennalis(Fabricius, 1793), Polistes humilis(Fabricius, 1781).MethodsWe used GIS software for in situ randomization of plots on each island (36 islands, 409 plots) and conducted 5‐min wasp counts to estimate wasp abundance. Wasp abundance and canopy cover were recorded at each plot. Island isolation was measured using GIS software. Data on island size, human settlement and the presence of introduced rats (Rattusspp.) were collated from the literature and island managers. The number of boat docks per island was counted from satellite images. A generalized linear mixed‐effect model (GLMM) was fitted to identify drivers ofVespulaandPolistesabundance on offshore islands.ResultsThe abundance ofVespulawas negatively correlated with island isolation and canopy cover, yet positively correlated with island size.Vespulawere also more abundant on islands that have been settled by humans. The abundance ofPolisteswas negatively correlated with canopy cover. Finally, results did not support the notion that invasive wasps were associated with introduced rats on New Zealand's offshore islands.ConclusionsOur findings highlight the importance of biogeographic factors, such as island size and isolation, for species invasions, and suggest that intact forest cover could contribute to biotic resistance to invasive wasps in island ecosystems. Studies of invasive species should consider the joint effects of biogeographic, biotic and anthropogenic factors to best inform conservation management.

Early tropical crop production in marginal subtropical and temperate Polynesia

Polynesians introduced the tropical crop taro (Colocasia esculenta) to temperate New Zealand after 1280 CE, but evidence for its cultivation is limited. This contrasts with the abundant evidence for big game hunting, raising longstanding questions of the initial economic and ecological importance of crop production. Here we compare fossil data from wetland sedimentary deposits indicative of taro and leaf vegetable (including Sonchus and Rorippa spp.) cultivation from Ahuahu, a northern New Zealand offshore island, with Raivavae and Rapa, both subtropical islands in French Polynesia. Preservation of taro pollen on all islands between 1300 CE and 1550 CE indicates perennial cultivation over multiple growing seasons, as plants rarely flower when frequently harvested. The pollen cooccurs with previously undetected fossil remains of extinct trees, as well as many weeds and commensal invertebrates common to tropical Polynesian gardens. Sedimentary charcoal and charred plant remains show that fire use rapidly reduced forest cover, particularly on Ahuahu. Fires were less frequent by 1500 CE on all islands as forest cover diminished, and short-lived plants increased, indicating higher-intensity production. The northern offshore islands of New Zealand were likely preferred sites for early gardens where taro production was briefly attempted, before being supplanted by sweet potato (Ipomoea batatas), a more temperate climate-adapted crop, which was later established in large-scale cultivation systems on the mainland after 1500 CE.

Chemical time capsules: bioactive volatiles in eighteenth century herbarium samples of mānuka, Leptospermum scoparium

ABSTRACTLeptospermum scoparium J. R. et G. Forst. (Myrtaceae), called mānuka or kahikātoa by Māori, shows distinct foliage chemotypes in different regions of Aotearoa New Zealand, including one with rare antimicrobial triketones. To extend knowledge of mānuka chemotypes geographically and historically, we have developed a miniaturised method for analyses of herbarium samples needing just a few small leaves analysed by headspace solid phase microextraction gas chromatography (HS-SPME-GC). This method was validated on herbarium samples of known chemotypes. Geographical knowledge was extended by analysing herbarium samples collected on New Zealand's offshore islands, ranging from the Manawa/Three Kings in the North to Rakiura/Stewart Island in the South. The chemotypes were generally similar to the nearest populations on the main North or South islands. Historically, volatiles were identified from herbarium samples collected by the first botanists from Europe in 1769, showing that the oil glands in mānuka leaves act as ‘chemical time capsules’.

Leonard Cockayne's surveys of New Zealand's offshore islands, 1901–1908

This article examines a series of extended botanical surveys conducted by the botanist Leonard Cockayne on several of New Zealand's main offshore islands between 1901 and 1908 and considers their implications for the country's ecological and conservation history. Three dominant features arising from the surveys are discussed: (i) Cockayne's examination of the ecology of the islands visited and his identification of biogeographical connections between island, mainland and more distant ecosystems; (ii) his conspicuous reference to German‐language specialist literature; and (iii) his criticism of environmental damage on these offshore islands and his recommendations for their future conservation.

Grey-faced petrel (Pterodroma gouldi) productivity unaffected by kiore (Pacific rats, Rattus exulans) on a New Zealand offshore island

Burrow-nesting seabird populations are vulnerable to predation by introduced rats, because of their nesting habits and slow life histories. We investigated whether control of kiore (Pacific rats, Rattus exulans) by removal trapping, and during an unsuccessful community-led island-wide eradication attempt, had any effects on nest survival of grey-faced petrels (Pterodroma gouldi) on Ririwha (Stephenson Island), northeastern New Zealand. We compared nest survival between two plots at which rats were trapped and six un-trapped plots in 2010, as well as at all plots during and after the poisoning programme in 2011–2012. Neither mean rates of breeding burrow occupancy nor nest survival differed between trapped and un-trapped plots in 2010. We found no significant differences between years or between plots throughout the poisoning programme. Extrapolation of daily nest survival rates to the full 172-day combined egg and chick period gave an estimate of mean annual productivity for all plots combined of 0.285 (95% confidence interval 0.252–0.318), which is higher than on comparable predator-free islands. Although the absence of a detectable effect of kiore on breeding grey-faced petrels on Ririwha is reassuring, we can be less sure that smaller burrow-nesting seabirds on the island are secure.

Tsunami Forecasting and Monitoring in New Zealand

New Zealand is exposed to tsunami threats from several sources that vary significantly in their potential impact and travel time. One route for reducing the risk from these tsunami sources is to provide advance warning based on forecasting and monitoring of events in progress. In this paper the National Tsunami Warning System framework, including the responsibilities of key organisations and the procedures that they follow in the event of a tsunami threatening New Zealand, are summarised. A method for forecasting threat-levels based on tsunami models is presented, similar in many respects to that developed for Australia by Allen and Greenslade (Nat Hazards 46:35–52, 2008), and a simple system for easy access to the threat-level forecasts using a clickable pdf file is presented. Once a tsunami enters or initiates within New Zealand waters, its progress and evolution can be monitored in real-time using a newly established network of online tsunami gauge sensors placed at strategic locations around the New Zealand coasts and offshore islands. Information from these gauges can be used to validate and revise forecasts, and assist in making the all-clear decision.

Estimating regional population size and annual harvest intensity of the sooty shearwater in New Zealand

Recent comprehensive survey data from multiple New Zealand offshore islands were combined with demographic population models to produce the first formal estimate of the total population of sooty shearwaters within New Zealand territory. We estimated the total population over 1994–2005 to be 21.3 (19.0–23.6) million individual birds in the New Zealand region. This population consisted of 12.8 (12.0–13.6) million adults, 2.8 (2.5–3.1) million chicks, and 4.4 (4.2–4.7) million breeding pairs. Breeding sooty shearwaters were concentrated primarily around the southern islands of New Zealand, with 53% breeding in the Titi Islands surrounding Rakiura (Stewart Island). Rakiura Maori muttonbirders were estimated to harvest 360 000 (320 000–400 000) sooty shearwaters per year, equivalent to 18% of the chicks produced in the harvested areas and 13% of chicks in the New Zealand region. Overall, 11% of the chicks within the Titi Islands live on unharvested ground. Systematic and widespread surveys of breeding colonies in South America are needed before a reliable global sooty shearwater population estimate can be calculated.

Evolution of the south-western Pacific genus Melicytus (Violaceae): evidence from DNA sequence data, cytology and sex expression

Phylogenetic analyses of nuclear DNA external transcribed spacer (ETS) and chloroplast DNA trnL–trnF markers were undertaken to reconstruct the evolutionary history of the South Pacific genus Melicytus. Bayesian analyses of the ETS sequence data produced a phylogenetic tree with several well supported groups, including clades comprising: (1) species from Australia, Tasmania and Lord Howe Island; (2) the Norfolk Island M. latifolius and New Zealand off-shore island M. novae-zelandiae subsp. novae-zelandiae; (3) the large-leaved M. ramiflorus complex; (4) M. fasciger and M. micranthus; and (5) M. obovatus and allies from the Cook Strait region. Phylogenetic analysis of trnL–trnF sequence data also retrieved some of these groups although, in general, was not as well resolved. The relationships of M. lanceolatus are equivocal, as in the ETS phylogeny it is sister to a clade comprising the large-leaved tree species M. fasciger and M. ramiflorus complex and the small-leaved M. micranthus, whereas in the trnL–trnF phylogeny it is sister to a clade of small-leaved shrub species such as M. alpinus and M. crassifolius. Several biogeographic patterns are evident, with dispersal to the west from New Zealand, to Australia, involving small-leaved shrub species. Dispersal to the north from New Zealand, to Norfolk Island and Fiji, involves large-leaved tree species. The sex expression is documented for all named species and undescribed entities, with these being either hermaphroditic or dioecious. When sex expression is mapped onto the phylogeny, the hermaphroditic system is inferred to have evolved from the dioecious system. New chromosome counts are presented for M. angustifolius (2n = 64) and M. dentatus (2n = 32), and earlier counts of 2n = 64 are confirmed for M. crassifolius and M. alpinus. An additional 17 counts are provided for two natural hybrids and several undescribed entities from Australia and New Zealand. The polyploid chromosome number of 2n = 64 occurs most frequently in small-leaved divariate plants with hermaphroditic flowers. When chromosome numbers are plotted onto the phylogeny it is inferred that high polyploids (e.g. 2n = 64) and small-leaved shrubs have evolved from large-leaved trees with functional diploid (e.g. 2n = 32) chromosome numbers.

Skull shape and feeding strategy in Sphenodon and other Rhynchocephalia (Diapsida: Lepidosauria)

The Rhynchocephalia are a group of small diapsid reptiles that were globally distributed during the early Mesozoic. By contrast, the only extant representatives, Sphenodon punctatus and S. guntheri (Tuatara), are restricted to New Zealand off-shore islands. The Rhynchocephalia are widely considered to be morphologically uniform but research over the past 30 years has revealed unexpected phenotypic and taxonomic diversity. Phylogenetically "basal taxa" generally possess relatively simple conical or columnar teeth whereas more derived taxa possessed stouter flanged teeth and sophisticated shearing mechanisms: orthal in some (e.g., Clevosaurus hudsoni) and propalinal in others (e.g., S. punctatus). This variation in feeding apparatus suggests a wide range of feeding niches were exploited by rhynchocephalians. The relationship of skull shape to skull length, phylogenetic grouping, habit, and characters relating to the feeding apparatus are explored here with geometric morphometric analysis on two-dimensional landmarks. Principle components analysis demonstrates that there are significant differences between phylogenetic groups. In particular, Sphenodon differs significantly from all well known fossil taxa including the most phylogenetically basal forms. Therefore, it is not justifiable to use Sphenodon as a solitary outgroup when studying skull shape and feeding strategy in squamates; rhynchocephalian fossil taxa also need to be considered. There are also significant differences between the skull shapes of aquatic taxa and those of terrestrial taxa. Of the observed variation in skull shape, most variation is subsumed by variation in dentary tooth base shape, the type of jaw movement employed (e.g., orthal vs. propalinal) and the number of palatal tooth rows. By comparison, the presence or absence of flanges, dentary tooth number and palatal tooth row orientation subsume much less. Skull length was also found to be a poor descriptor of overall skull shape. Compared to basal rhynchocephalians members of more derived terrestrial radiations possess an enlarged postorbital area, a high parietal, and a jaw joint positioned ventral to the tooth row. Modification of these features is closely associated with increased biting performance and thus access to novel food items. Some of these same trends are apparent during Sphenodon ontogeny where skull growth is allometric and there is evidence for ontogenetic variation in diet.

Observations of mesoscale movements in the short-tailed stingray, Dasyatis brevicaudata from New Zealand using a novel PSAT tag attachment method

Short-tailed stingrays ( Dasyatis brevicaudata) are the largest stingrays in the world. They are common in New Zealand waters and aggregate seasonally in large numbers at the Poor Knights Islands Marine Reserve (PKMR), where they are a major attraction. Pop-up satellite archival tags (PSAT) were attached to two female short-tailed stingrays at two New Zealand offshore islands (within and nearby the PKMR) to investigate patterns of movement. These are the first PSAT data published for a stingray species. The rays were tagged for 62 and 151 days using a novel method of tag attachment developed specifically for ray species. Analyses of geolocation, depth and behavioural data indicate neither ray moved large distances (≤ 25 km) from the tagging locations. However, they showed a seasonal shift to deeper waters, progressively increasing time spent at greater depths and decreasing time spent at shallow depths towards winter. In addition, one ray displayed strong diel vertical movements. The method developed for PSAT attachment to stingrays proved successful and can be applied for long-term (> 6 months) movement and behavioural studies.

Avoiding aliens: Behavioural plasticity in habitat use enables large, nocturnal geckos to survive Pacific rat invasions

Rodents are efficient invaders on a global scale and pose a significant threat to native biotas, particularly in systems such as oceanic islands which support a reduced suite of mammals. Pacific rats ( Rattus exulans) are implicated in extinctions, range restrictions and declines of vulnerable endemic faunas throughout the Pacific. However, research into the behavioural and ecological modifications that enable native species to persist in the presence of Pacific rats is scant. We examined the population structure, behaviour and microhabitat use of Duvaucel’s geckos ( Hoplodactylus duvaucelii; radio-telemetry), and Pacific rats (spool-and-line tracking) on three New Zealand offshore islands with different histories of rat incursions and eradication: (1) Green Island, historically rat-free, (2) Korapuki, from which rats were eradicated 20 years ago, and (3) Ōhı¯nau, before and 6 months after rat eradication. Although Pacific rats and Duvaucel’s geckos shared habitat at a broad spatial scale, little overlap in micro-habitat use existed where they were sympatric. In the presence of rats, Duvaucel’s gecko capture rates and recruitment were reduced. However, 6 months after rat eradication, and prior to any recruitment, capture rates of adult geckos increased fourfold and geckos were using a greater proportion of habitat preferred by rats. Thus, we provide strong empirical evidence that Pacific rats ecologically displace Duvaucel’s geckos. Highly plastic spatial avoidance behaviour by native prey species in response to the presence of introduced rodents may enable geckos to persist in sympatry with rodents at least in the short-term.

Successful island reintroductions of New Zealand robins and saddlebacks with small numbers of founders

Populations established with a small number of founders are thought to have a high risk of extinction due to Allee effects, demographic stochasticity, inbreeding and reduced genetic variation. We tested whether the initial number of birds released was related to persistence in reintroductions of saddlebacks (Philesturnus carunculatus) and robins (Petroica australis) to New Zealand offshore islands. Data were analysed for 31 populations that had been observed for at least 3 years since reintroductions. The numbers released ranged from 5–188. Most of the populations (26) survived and grew, including five from less than 15 founders, and four out of the five extinctions were attributable to introduced mammalian predators. The number of individuals released did not significantly affect extinction probability. The ability of these small releases to establish populations can be attributed to the closed nature of the islands (allowing birds to find mates), low mortality rates following release and high growth rates at low density. Stochastic simulation models based on data from two reintroduced populations suggested that populations with four founders (two male, two female) would have a negligible chance of extinction through demographic stochasticity and would be able to grow even if there were high rates of egg failure through inbreeding.

Erysipelas in the critically endangered kakapo (Strigops habroptilus)

This paper describes the effect of a disease outbreak on the success of a translocation for conservation management in a critically endangered species. Three juvenile kakapo from a group of 19 translocated birds died within 72 h of transport between New Zealand offshore islands. Clinical findings, gross necropsy changes, cytology, histopathology and bacterial culture confirmed systemic disease caused by Erysipelothrix rhusiopathiae. On the island from which the kakapo were sourced, positive cultures of E. rhusiopathiae were obtained from the medulla of the ulna from 10 out of 15 seabird carcasses examined, suggesting that this could be the source of infection for the kakapo. Immediately after the diagnosis, all of the translocated birds were re-captured and treated with antibiotics. A vaccination programme has commenced using a commercial killed bacterin developed for turkeys. The disease outbreak has had costly implications for the population and conservation management of the species. This is the first report of erysipelas in wild parrots, and the first report of the management of erysipelas in a critically endangered wild population of birds. L'érysipèle chez des strigops kakapo (Strigops habroptilus) en voie d'extinction Dans cet article il est décrit l'effet d'un cas pathologique sur le succès du transfert d'une espèce en voie d'extinction pour parvenir à sa conservation. Trois jeunes strigops kakapo, appartenant à un groupe de 19 oiseaux qui ont été transférés, sont morts au cours des 72 heures de transport entre les îles proches du littoral de Nouvelle Zélande. Les observations cliniques, les lésions macroscopiques, la cytologie, l'histopathologie et la culture bactérienne ont confirmé la présence d'une maladie systémique causée par Erysipelothrix rhusiopathiae. Sur l'île d'où provenaient les strigops kakapo, E. rhusiopathiae a été isolé par culture à partir de la moelle du cubitus de 10/15 carcasses d'oiseaux marins examinés suggérant qu'ils pouvaient être la source de l'infection des strigops kakapo. Immédiatement après le diagnostic, tous les animaux transférés ont été de nouveau capturés et traités aux antibiotiques. Un programme de vaccination a commencé en utilisant le vaccin inactivé commercial développé pour les dindes. Ce cas pathologique, a eu des répercussions coûteuses pour la population et la réussite de la conservation de l'espèce. C'est le premier rapport d'un cas d'érysipèle chez des perroquets sauvages et le premier rapport de la gestion de l'érysipèle chez une population sauvage d'oiseaux en voie d'extinction Rotlauf bei stark vom Aussterben bedrohten Eulenpapgeien (Strigops habroptilus) Diese Veröffentlichung beschreibt die Auswirkung eines Krankheitsausbruchs auf den Erfolg eines Umsiedlungsprogramms als Erhaltungsmaßnahme bei einer bedrohten Tierspezies. Drei juvenile Eulenpapageien aus einer Gruppe von 19 umgesiedelten Tieren starben innerhalb von 72 Stunden Transportzeit zwischen den vor der Küste gelegenen Inseln Neuseelands. Klinik, Pathologie, Zytologie, Histopathologie und bakteriologische Kultivierung bestätigten Erysipelothrix rhusiopathiae als Ätiologie der systemischen Erkrankung. Auf der Insel, von der die Eulenpapageien stammten, wurde E. rhusiopathiae aus der Medulla der Ellenbogenknochen bei 10 von 15 Seevogelkarkassen isoliert, die in der Annahme untersucht wurden, dass sie die Infektionsquelle für die Eulenpapageien gewesen sein könnten. Unmittelbar nach der Diagnose wurden alle umgesiedelten Vögel wieder eingefangen und antibiotisch behandelt. Ein Vakzinationsprogramm unter Verwendung eines kommerziellen für Puten entwickelten Totimpfstoffs wurde begonnen. Dieser Krankheitsausbruch hatte kostspielige Auswirkungen auf die Population und das Erhaltungsprogramm für diese Spezies. Dies ist die Erstbeschreibung von Rotlauf bei wildlebenden Papageien und der erste Bericht über eine Rotlaufbekämpfung in einer vom Aussterben bedrohten Wildvogelpopulation. Erisipelas en el kakapo (Strigops habroptilus) en peligro de extinción Este artículo describe el efecto de un brote de enfermedad que ocurrió durante el traslado por motivos de conservación de una especie en peligro de extinción. Tres kakapos juveniles de un grupo de 19 aves que fueron trasladadas murieron durante las 72 horas de transporte entre islas (off shore islands) en Nueva Zelanda. Los hallazgos clínicos, las lesiones macroscópicas a la necropsia, las citologías, histologías y el cultivo bacterológico confirmaron que la enfermedad sistémica fue causada por Erysipelothrix rhusiopathiae. En la isla de la que provenían los kakapos, se obtuvieron cultivos positivos de E. rhusiopathiae de la médula de la ulna de 10 de 15 cadáveres de aves marítimas examinadas, lo que sugirió que ésta podría ser la fuente de infección de los kakapos. Inmediatamente tras el diagnóstico, todas las aves trasladadas fueron capturadas y tratadas con antibióticos. Se ha iniciado un programa de vacunación con una bacterina comercial desarrollada para pavos. El brote de enfermedad tuvo implicaciones costosas para la población y para el manejo y conservación de la especie. Esta es la primera descripción de brote de erisipelas en loros salvajes, y también es la primera descripción el manejo de esta enfermedad en una población de aves salvajes en peligro de extinción.

Photoreceptor cell types in the retina of the tuatara ( Sphenodon punctatus) have cone characteristics

The tuatara Sphenodon punctatus, restricted to a few New Zealand offshore islands and now strictly protected, belongs to the Rhynchocephalia, the smallest order of extant reptiles. Earlier light microscopical studies on the retina of this species described photoreceptors with both rod- and cone-like features and the presence of a fovea. A limited amount of retinal material from S. punctatus has now allowed us to prepare the first-ever electron microscopic observations on the eye of this reptile. We were able to distinguish three types of photoreceptor, all with fine structural features characteristic of cone cells. Large single cones as well as double cones had open discs in their outer segments and straight axons with pedicle-type terminals. An additional cone type, characterized by somewhat more slender inner and outer segments, vitreally-displaced cell bodies and oblique axons, resembled short-wavelength cones known from other sauropsids. No cells with rod characteristics could be confirmed in the samples, although they might occur in retinal regions not available for this study. We conclude that the tuatara has cone-like photoreceptors, which—as in other crepuscular or nocturnal reptiles—have acquired rod-like features. The phenotypic adaptations notwithstanding, the set of photoreceptor types is quite typical of the reptilian eye and in some respects reminiscent of those seen in lizards and turtles.

Modelling the distribution and interaction of introduced rodents on New Zealand offshore islands

ABSTRACTAim To establish the factors that correlate with the distribution of the four most commonly introduced rodent species on New Zealand offshore islands — ship rat (Rattus rattus), Norway rat (R. norvegicus), Pacific rat or kiore (R. exulans) and house mouse (Mus musculus) — and examine if these distributions are interactive at the archipelago scale.Location The 297 offshore islands of the New Zealand archipelago (latitude: 34° S to 47° S; longitude: 166° E to 179° E).Methods Data on the distribution of all four introduced rodent species and the characteristics of New Zealand offshore islands were collated from published surveys and maps. The distribution of individual rodent species was regressed on island characteristics using a logistic generalized linear model. Interactions were examined by including the distributions of other rodent species as predictors in models.Results All four rodent species appear to be limited by a variety of factors, which differ between species in both number and type. The distribution of ship rats is limited by the most factors, reflecting the extent of its distribution across the archipelago. The distribution of mice is the least explicative. Only the three rat species interacted in their distribution. The distribution of kiore on offshore islands is significantly negatively related to that of ship rats and to a lesser extent Norway rats. The distribution of mice did not appear affected in any way by the number of other rodent species on an island.Main conclusions Differences in competitive ability and dispersal allow all four species to inhabit the New Zealand archipelago. Kiore distribution appears to be most limited by ship rat (and to a lesser extent Norway rat) distribution. The distribution of kiore was not found to interact with the distribution of mice on offshore islands, as has been suggested by others. The distribution of mice on offshore islands was difficult to model, which highlights the difficulties in managing this species. Overall the results offer valuable insights for management methods to assist preventing the invasion of offshore islands.

Island biogeography and the species richness of introduced mammals on New Zealand offshore islands

AbstractAim To investigate and establish the significance of various island biogeographic relationships (geographical, ecological and anthropological) with the species richness of introduced mammals on offshore islands.Location The 297 offshore islands of the New Zealand archipelago (latitude: 34–47°S; longitude: 166–179°E).Methods Data on New Zealand offshore islands and the introduced mammals on them were collated from published surveys and maps. The species richness of small and large introduced mammals were calculated for islands with complete censuses and regressed on island characteristics using a Poisson distributed error generalized linear model. To estimate the ‘z‐value’ for introduced mammals on New Zealand islands, least‐squares regression was used [log10 S vs. log10 A].Results High collinearity was found between the area, habitat diversity and elevation of islands. The island characteristics related to the species richness of introduced mammals differed predictably between large and small mammals. The species richness of introduced large mammals was mostly related to human activities on islands, whereas species richness of introduced small mammals was mostly related to island biogeographical parameters. The ‘z‐value’ for total species richness is found to be expectedly low for introduced mammals.Main conclusions Distance appears to have become ecologically trivial as a filter for introduced mammal presence on New Zealand offshore islands. There is strong evidence of a ‘small island’ effect on New Zealand offshore islands. The species richness of both small and large introduced mammals on these islands appears to be most predominantly related to human use, although there is some evidence of natural dispersal for smaller species. The ecological complexity of some islands appears to make them less invasible to introduced mammals. Some human activities have an interactive effect on species richness. A small number of islands have outlying species richness values above what the models predict, suggesting that the presence of some species may be related to events not accounted for in the models.