Sampling skinks and geckos in artificial cover objects in a dry mixed grassland-shrubland with mammalian predator control

Introduced mammalian predators threaten populations of endemic New Zealand lizards but their effects on lizard populations have not been quantified on the mainland. We trialled the use of artificial cover objects (ACOs) for sampling small terrestrial lizards (the skinks Oligosoma maccanni, O. nigriplantare polychroma and O. inconspicuum, and gecko Hoplodactylus maculatus) in three experimental mammal-management treatments: a mammal-proof fence, two sites in an intensive mammal-removal area, and an experimental control site with no mammal removal. These predator control regimes were established in 2005-2006 to protect endangered grand skinks (O. grande) and Otago skinks (O. otagense) at Macraes Flat, North Otago. We (1) counted skinks and geckos found under ACOs on a single day and compared these counts between treatments, and (2) estimated lizard population sizes (N) based on capture-mark-recapture (CMR) of lizards under ACOs in daily and weekly sampling sessions. Our results provide baseline data of the abundance of the small lizard species shortly after implementation of predator management. Single-day counts of skinks were significantly higher inside the mammal fence compared with the experimental control. No consistent differences were found between the other treatments. Significantly more skinks were counted in gully habitats than in ridge habitats. N?, counts of skinks from the first day of CMR, and the total number of individuals caught were correlated, but these relationships must be validated with independent data. Few geckos were caught unless ACOs were placed near rock outcrops. Only two skinks but 25% of geckos moved between adjacent ACOs (5-m spacing). The recapture rate of skinks was low; captures declined when ACOs were checked daily but not when they were checked weekly. Because of potential biases of these methods, we propose to compare counts in ACOs and N? based on CMR in ACOs with N? based on CMR in pitfall traps with 3-m spacing.     

Effects of habitat structure on distribution and abundance of lizards at Pukerua bay, Wellington, New Zealand

The distribution and abundance of lizards relative to habitat structure were studied at Pukerua Bay, Wellington between December 1982 and March 1988 in order to identify options for management of the habitat of the five species of lizards present. One species, Whitaker's skink (Cyclodina whitakeri), is a threatened species with only one known mainland population. Pitfall traps were set for 23 667 trap-days and yielded 2897 lizard captures. Highest capture rate was for common skinks (Oligosoma nigriplantare polychroma) and lowest rate was for C. whitakeri. Of the five lizard species at Pukerua Bay, C. whitakeri had the narrowest habitat range and was most sensitive to temperature extremes. These features, combined with predation, and habitat disturbance and degradation, have resulted in critically low numbers of C. whitakeri. Assessment of management options to lessen the threats to C. whitakeri concluded that risks from disturbance, predation and fire could best be minimised through a managed revegetation programme.     

Accuracy and precision of skink counts from artificial retreats

Index counts are commonly used to detect spatial and temporal changes in the size of wildlife populations. For indices to be valid there must be a constant (usually linear) relationship between the index and population size. In a study conducted in the Eglinton Valley (Fiordland, South Island, New Zealand), single-day index counts of common skinks (Oligosoma polychroma) from artificial retreats were compared with capture?mark?recapture (CMR) estimates of population size (N?) obtained by pitfall trapping. Generalised linear models revealed that skink counts from artificial retreats provided a reasonably accurate (P??1, which was high compared with other common skink populations. We recommend: (1) long-term monitoring of common skinks in the Eglinton Valley, using the index method described herein; (2) calibration of index counts against population size estimates collected from other habitats and species.     

Interactions between petrels, rats and rabbits on Whale Island, and effects of rat and rabbit eradication

Baited pitfall traps were used to sample Oligosoma maccanni and Oligosoma nigriplantare polychroma at Birdlings Flat, on Kaitorete Spit, Canterbury, New Zealand. The two species of skink showed distinctive patterns of habitat use with O. maccanni being almost entirely confined to dunelands while O. n. polchroma was invariably captured in the shrub-covered terraces behind the dunes. This is in direct contrast to what has been documented for these species in central Otago. Habitat partitioning appears to have also influenced the patterning and colouration of the two species which is also opposite to what has been documented for these species in Central Otago. Other factors examined did not show the same degree of deviation from what has been documented for these species elsewhere. The Birdlings Flat populations of O. maccanni and O. n. polychroma are diurnally active summer breeders, and dietary generalists.     

Skink predation by hedgehogs at Macraes Flat, Otago, New?Zealand

The stomach contents of 158 hedgehogs captured at Macraes Flat, Otago, New Zealand, over two summers in 2000 and 2001 were examined for the occurrence of lizards. The remains of at least 43 skinks (both Oligosoma nigriplantare polychroma and O.?maccanni) and one gecko (Hoplodactylus sp.) were found. Twenty-one percent (n?=?33; 8 males and 25 females) of the examined hedgehogs had fed on skinks. Female hedgehogs ate significantly more skinks than did males. Our results suggest that the presence of large numbers of hedgehogs can have a high impact on native reptile populations in New Zealand and therefore they should be targeted in future trapping programmes.     

Lizards in the suburbs: a single-garden study of a small endemic New Zealand skink (Oligosoma aeneum)

Detailed investigations of ecology and life history of lizards in New Zealand/Aotearoa are needed to inform their conservation and management. An early demographic study of copper skinks (Oligosoma aeneum) in a suburban garden was undertaken in Lower Hutt using mark–recapture methods, sampling weekly from March 1971 to December 1973. Oligosoma aeneum were seen on 1372 occasions, with 972 captures of 169 individuals. The maximum snout–vent length was 66 mm, 33% of skinks had complete tails, and colour differences suggested sexual signalling and warrant further study. Most captures occurred over November–March, with fewest over June–August. The estimated spring/summer population size in the garden (± SEM) was 83.6 (± 9.4) skinks, and the annual survival rate (± SEM) was 38.0% (± 16.0%). This is one of the few New Zealand lizard studies that have extended through all months of the year and it adds to limited information on lizard populations in suburban areas.     

Origin and post-colonization evolution of the Chatham Islands skink (Oligosoma nigriplantare nigriplantare)

Island ecosystems provide an opportunity to examine a range of evolutionary and ecological processes. The Chatham Islands are an isolated archipelago situated approximately 800 km east of New Zealand. Geological evidence indicates that the Chatham Islands re-emerged within the last 1-4 million years, following a prolonged period of marine inundation, and therefore the resident flora and fauna is the result of long-distance overwater dispersal. We examine the origin and post-colonization evolution of the Chatham Islands skink, Oligosoma nigriplantare nigriplantare, the sole reptile species occurring on the archipelago. We sampled O. n. nigriplantare from across nine islands within the Chatham Islands group, and representative samples from across the range of its closest relative, the New Zealand mainland common skink (Oligosoma nigriplantare polychroma). Our mitochondrial sequence data indicate that O. n. nigriplantare diverged from O. n. polychroma 5.86-7.29 million years ago. This pre-dates the emergence date for the Chatham Islands, but indicates that O. n. nigriplantare colonized the Chatham Islands via overwater dispersal on a single occasion. Despite the substantial morphological variability evident in O. n. nigriplantare, only relatively shallow genetic divergences (maximum divergence approximately 2%) were found across the Chatham Islands. Our analyses (haplotypic diversity, Phi(ST), analysis of molecular variance, and nested clade phylogeographical analysis) indicated restricted gene flow in O. n. nigriplantare resulting in strong differentiation between islands. However, the restrictions to gene flow might have only arisen recently as there was also a significant pattern of isolation by distance, possibly from when the Chatham Islands were a single landmass during Pleistocene glacial maxima when sea levels were lower. The level of genetic and morphological divergence between O. n. nigriplantare and O. n. polychroma might warrant their recognition as distinct species.     

Phylogeny recapitulates geography, or why New Zealand has so many species of skinks

The evolutionary history of 25 New Zealand scincid lizards in the endemic genera Oligosoma and Cyclodina was examined using 12S rRNA sequence data. Phylogenetic resolution was poor, despite there being up to 9% sequence divergence between taxa. Lack of resolution was not attributable to biases in the data, such as site saturation or differences in sites free to vary, so we infer that New Zealand skinks underwent two relatively rapid phases of divergence. The rate of substitution for the skink sequences appears to be similar to some bird and mammal groups for which times of divergence have been estimated. Using fhese calibrations diversification of Oligosoma skinks probably began at least 23 million years ago (Mya). The pattern of relationships and the timing of this diversification are interpreted as resulting from rapid allopatric speciation during the Oligocene (25–35 Mya) when New Zealand was fragmented into many low lying islands. A second major phase of speciation involving the Cyclodina seems to have occurred during the Miocene (15–24 Mya), probably as a consequence of increasing land area and habitat diversity. This pattern of skink evolution contrasts with the Oligocene 'environmental crisis' hypodiesis of Cooper & Cooper (Proc. R. Soc. Land. B. 261, 293–302), but can be attributed to differences in the ecology of different taxa. This can be tested by examination of other groups, such as land snails and geckos. The large number of lizard species in New Zealand can be considered a legacy both of past geography as well as the absence of small mammals which would have been both competitors and predators.     

Fungal infections of the phytoplankton: seasonality, minimal host density, and specificity in a mesotrophic lake

Phytoplankton infections by fungal parasites in the upper, mixed layer of a mesotrophic northern temperate lake were analysed according to the following parameters: host and parasite species, host population density and prevalence of infection, resting spore formation by the parasite, and the lowest host density at which parasites appeared. The phytoplankton taxa recorded included the Cyanobacteria, Dinomastigota, Chrysophyceae, Bacillariophyceae, Chlorophyceae, Cryptophyceae and Haptophyceae, but infection was never found in the last two classes. The parasites belonged almost exclusively to the monocentric Chytridiomycetes. Fungal epidemics occurred at all times of the year. Parasites appeared at population densities as low as about 1 cell ml⁻¹ in some host species, with infection prevalence sometimes exceeding 80%. The proportion of the total phytoplankton biovolume infected by fungi was usually much <1%, but occasionally reached 10%. Parasitism proved to be highly species-specific, with one parasite species usually infecting only one host species. In the case of Zygorhizidium planktonicum , which infected both Asterionella formosa and Synedra acus , there is evidence that two species-specific formae speciales , each infecting only one of these two host species, are present in the lake.     

Improving search strategies for the cryptic New Zealand striped skink (

The striped skink (Oligosoma striatum) is a poorly known New Zealand endemic species rarely seen in the wild despite ongoing efforts to locate specimens. It is uncertain whether its threatened status is due to low numbers, or to unusual habitat use and activity patterns that make it difficult to detect. Anecdotal reports indicate the species may be partly arboreal. We carried out captive-based behavioural comparisons between striped skinks and the common terrestrial brown skink (Oligosoma zelandicum). Brown skinks are of similar mass to striped skinks and overlap in geographic range and habitat, but are easily captured by hand and pitfall trapping in the wild. They were therefore a suitable comparison from which to assess activity levels and arboreal tendencies in striped skinks, with the aim of improving survey methods. Point samples and total frequencies of behaviours were collected using time-lapse video recordings taken concurrently of individuals of each species occupying identical enclosures. Striped skinks had significantly higher levels of diurnal activity than brown skinks. They also showed periods of nocturnal activity associated with high moisture levels. When active, the types of behaviours carried out by each species were very similar, as were the proportions of active time spent carrying out each behaviour. Striped skinks spent significantly longer periods at greater heights within the enclosure than brown skinks, indicating stronger arboreal tendencies. High levels of arboreal activity and in particular nocturnal activity may make striped skinks more vulnerable to introduced predators such as rodents and possums. In order to accurately assess the status and carry out long-term monitoring of the striped skink, new survey and capture techniques will be required. Arboreal traps, visual canopy surveys and surveying felled trees are recommended.     

A significant range extension and sanctuary for the rare Open Bay Island skink (Oligosoma taumakae)

Abstract

The Open Bay Island skink (Oligosoma taumakae) is one of New Zealand's rarest lizard species. Until 2010, it was known only from two small islands in the Open Bay Island Group, a Māori-owned wildlife sanctuary in South Westland, New Zealand. Skinks on these islands are threatened by predation from weka (Gallirallus australis), a flightless native rail thought to have been introduced to the Open Bay Islands c. 100 years ago. Here, we describe the discovery of Open Bay Island skinks on two vegetated rock stacks located off the coast of Barn Bay, 52 km southwest of the Open Bay Islands. Although small (c. 0.10 and 0.36 ha), the Barn Islands appear to be predator-free, providing an important sanctuary for the skinks. We recommend: (1) a survey of mainland sites with suitable habitat; and (2) an evaluation of the need for island biosecurity measures for detecting and responding to incursions of small mammals.     

Inbreeding and promiscuity in the endangered grand skink

The inbreeding avoidance hypothesis predicts that organisms that often encounter relatives as potential mates should evolve behaviours to avoid incestuous matings. Avoidance behaviours have practical importance for small populations because deleterious genetic processes may be less imminent than otherwise expected from genetic models that assume random mating. I used genetic techniques to investigate the extent of inbreeding and inbreeding avoidance behaviours in rare lizards from southern New Zealand. Grand skinks, Oligosoma grande, live in small patchily distributed groups, and have low rates of inter-group dispersal (ca. 3–20% disperse). I used data from 15 microsatellite loci to test the hypothesis that adults are likely to encounter kin as potential mates and will inbreed. These data showed that adult skinks usually inhabited rock outcrops with adult relatives of the opposite sex – up to 35% of potential mates were of equivalent relatedness as half-sibs and 17% were equivalent to full sibs. However, skinks did not preferentially breed with less related mates, and 18.2% of matings were between individuals of equivalent relatedness as full-sibs. Instead, skinks mated with partners of all levels of relatedness, and were promiscuous – almost half of adult females and nearly three quarters of adult males reproduced with multiple partners. In addition, inbreeding had no effect on survival of offspring in their first year. Two other putative mechanisms of inbreeding avoidance, sex-biased and natal dispersal, were not pronounced in this species. This study adds to a growing list of species that inbreed despite the risks.     

Decline in lizard species diversity,abundance and ectoparasite load across an elevational gradient in the Australian alps

The rapid changes in altitude, and associated habitat, of mountain ecosystems make them ideal natural laboratories for testing the effect of environmental heterogeneity on species assemblage. Our understanding of the sensitivity of Australian reptiles to elevational clines is limited. We examined lizard distribution across three elevation zones (montane, subalpine and alpine), spanning from 900 to 1840 m above sea level, in the Australian alps. We aimed to examine how elevation influences species diversity and abundance, and ectoparasite load, and whether species alter their habitat use amongst different elevational zones. Active searches were conducted across the elevation zones to identify lizard community structure (at least 16 species) across elevational zones, along with skink habitat preferences and the ectoparasite load. Skink diversity and abundance were negatively correlated with increased elevation. The alpine zone had significantly lower diversity and abundance of skinks. Habitat use differed amongst both elevations and species. Ectoparasite prevalence was also significantly diminished in the alpine zone. Ectoparasites only infected a subset of the skink community, with ectoparasite load increasing as the active season progressed. This study provides evidence of the complex interplay between elevation and species diversity, as well as the differences in ectoparasite pressure along elevational gradients in the Australian alps.     

Detection of a malaria parasite (Plasmodium mexicanum) in ectoparasites (mites and ticks), and possible significance for transmission

Two species of sandflies (Lutzomyia) are competent vectors of Plasmodium mexicanum, a malaria parasite of lizards. The very patchy distribution of sites with high P. mexicanum prevalence in the lizards, and often low or even nil sandfly density at such sites, provoked an evaluation of 2 common lizard ectoparasites, the tick Ixodes pacificus and the mite Geckobiella occidentalis, as potential passive vectors. Plasmodium sp.-specific polymerase chain primers were used to amplify a long segment of the mitochondrial cytochrome b gene that is unlikely to survive intact if the parasite cells are killed within a blood-feeding arthropod. The segment was strongly amplified from sandflies (the positive control for the method) from 1 to 96 hr postfeeding on an infected lizard. For ticks, the gene fragment was poorly amplified at 0 hr postfeed, and not amplified after 2 hr. In contrast, strong amplification of the parasite DNA was observed from mites from 0 to 20 hr postfeed, and weak amplification even at 96 hr.     

Size-dependent predation by snakes: selective foraging or differential prey vulnerability?

I staged replicate encounters between unrestrained lizards andsnakes in outdoor enclosures to examine size-dependent predationwithin the common garden skink (Lampropholis guichenoti). Yellow-facedwhip snakes (Demansia psammophis) forage widely for activeprey and most often consumed large skinks, whereas death adders(Acanthophis antarcticus) ambush active prey and most oftenconsumed small skinks. Small-eyed snakes (Rhinoplocephalusnigrescens) forage widely for inactive prey and consumed bothsmall and large skinks equally often. Differential predationmay reflect active choice by the predator, differential preyvulnerability, or both. To test for active choice, I presentedforaging snakes with an inert small lizard versus an inertlarge lizard. They did not actively select lizards of a particularbody size. To test for differential prey vulnerability, I quantifiedvariation between small and large lizards in behavior thatis important for determining the outcome of predator—prey interactions. Snakes did not differentiate between integumentarychemicals from small and large lizards. Large lizards tendto flee from approaching predators, thereby eliciting attackby the visually oriented whip snakes. Small lizards were moremobile than large lizards and therefore more likely to passby sedentary death adders. Additionally, small skinks were more effectively lured by this sit-and-wait species and less likelyto avoid its first capture attempt. In contrast, overnightretreat site selection (not body size) determined a lizard'schances of being detected by small-eyed snakes. Patterns ofsize-dependent predation by elapid snakes may arise not becauseof active choice but as a function of species-specific predatortactics and prey behavior.     

Phylogeography of the endangered Otago skink, Oligosoma otagense: population structure, hybridisation and genetic diversity in captive populations

Climatic cooling and substantial tectonic activity since the late Miocene have had a pronounced influence on the evolutionary history of the fauna of New Zealand's South Island. However, many species have recently experienced dramatic range reductions due to habitat fragmentation and the introduction of mammalian predators and competitors. These anthropogenic impacts have been particularly severe in the tussock grasslands of the Otago region. The Otago skink (Oligosoma otagense), endemic to the region, is one of the most critically endangered vertebrates in New Zealand. We use mitochondrial DNA sequence data to investigate the evolutionary history of the Otago skink, examine its population genetic structure, and assess the level of genetic diversity in the individuals in the captive breeding program. Our data indicate that the Otago skink diverged from its closest relatives in the Miocene, consistent with the commencement of tectonic uplift of the Southern Alps. However, there is evidence for past introgression with the scree skink (O. waimatense) in the northern Otago-southern Canterbury region. The remnant populations in eastern Otago and western Otago are estimated to have diverged in the mid-Pliocene, with no haplotypes shared between these two regions. This divergence accounts for 95% of the genetic diversity in the species. Within both regions there is strong genetic structure among populations, although shared haplotypes are generally evident between adjacent localities. Although substantial genetic diversity is present in the captive population, all individuals originate from the eastern region and the majority had haplotypes that were not evident in the intensively managed populations at Macraes Flat. Our data indicate that eastern and western populations should continue to be regarded as separate management units. Knowledge of the genetic diversity of the breeding stock will act to inform the captive management of the Otago skink and contribute to a key recovery action for the species.     

A SINE of restricted gene flow across the Alpine Fault: phylogeography of the New Zealand common skink (Oligosoma nigriplantare polychroma)

New Zealand has experienced a complex climatic and geological history since the Pliocene. Thus, identifying the processes most important in having driven the evolution of New Zealand's biota has proven difficult. Here we examine the phylogeography of the New Zealand common skink ( Oligosoma nigriplantare polychroma ) which is distributed throughout much of New Zealand and crosses many putative biogeographical boundaries. Using mitochondrial DNA sequence data, we revealed five geographically distinct lineages that are highly differentiated (pairwise Φ_ST 0.54–0.80). The phylogeographical pattern and inferred age of the lineages suggests Pliocene mountain building along active fault lines promoted their divergence 3.98–5.45 million years ago. A short interspersed nuclear element (SINE) polymorphism in the myosin gene intron ( MYH-2 ) confirmed a pattern of restricted gene flow between lineages on either side of the mountain ranges associated with the Alpine Fault that runs southwest to northeast across the South Island of New Zealand. An analysis of molecular variance confirmed that ~40% of the genetic differentiation in O. n. polychroma is distributed across this major fault line. The straits between the main islands of New Zealand accounted for much less of the variation found within O. n. polychroma , most likely due to the repeated existence of landbridges between islands during periods of the Pleistocene that allowed migration. Overall, our findings reveal the relative roles of different climatic and geological processes, and in particular, demonstrate the importance of the Alpine Fault in the evolution of New Zealand's biota.     

Schellackia occidentalis n.sp., a Blood-inhabiting Coccidian Found in Lizards in Southern California

SUMMARY. Schellackia occidentalis n. sp., is described from the following lizards from southern California: Sceloporus occidentalis becki, S. o. biseriatus , and Uta stansburiana hesperis. Evidence is presented to show that lizards become infected by ingestion of the lizard mite Geckobiella texana. The mite acts as a passive vector by swallowing infected erythrocytes. After ingestion of the mites carrying parasitized red cells, the lizard is infected by migration of the sporozoites into the lizard's intestinal epithelial cells. Schizogony and sporogony occur in the intestinal wall of the lizard. Sporozoites appear in the peripheral blood from 30 to 45 days after ingestion of infected mites. This is the first species of the genus Schellackia to be described in the Western Hemisphere.     

Parasite in peril? A new species of mite in the genus Ophiomegistus Banks (Parasitiformes: Paramegistidae) on an endangered host,the pygmy bluetongue lizard Tiliqua adelaidensis (Peters) (Squamata: Scincidae)

Host‐parasite relationships are generally understudied in wild populations but have a potential to influence host population dynamics and the broader ecosystem, which becomes particularly important when the host is endangered. Herein we describe a new species of parasitic mite from the genus Ophiomegistus (Parasitiformes: Mesostigmata: Paramegistidae) of an endangered South Australian skink; the pygmy bluetongue lizard (Tiliqua adelaidensis). Adult mites were observed on lizard hosts in three different host populations, among which prevalence varied. No temporal trend in prevalence was evident over two spring‐summer seasons of monitoring. We hypothesise that the reliance on burrows as refuges by T. adelaidensis may be essential for the completion of the mite life cycle and also for horizontal transmission. The conservation implications of not only its effect on the host, but also its potential status as an endangered species itself, are considered.