Stephen Hartley

Stephen Hartley
Victoria University of Wellington · School of Biological Sciences

Doctor of Philosophy
Centre for Biodiversity and Restoration Ecology (Director)

About

69
Publications
14,603
Reads
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2,286
Citations
Citations since 2016
29 Research Items
939 Citations
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
Additional affiliations
June 2002 - present
Victoria University of Wellington
Position
  • Professor (Associate)

Publications

Publications (69)
Article
Full-text available
A barrier to successful ecological restoration of urban green spaces in many cities is invasive mammalian predators. We determined the fine- and landscape-scale habitat characteristics associated with the presence of five urban predators (black and brown rats, European hedgehogs, house mice, and brushtail possums) in three New Zealand cities, in sp...
Article
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In this paper, we focus on different roles in citizen science projects, and their respective relationships. We propose a tripartite model that recognises not only citizens and scientists, but also an important third role, which we call the ‘enabler’. In doing so, we acknowledge that additional expertise and skillsets are often present in citizen sc...
Article
Full-text available
Citizen science and participatory conservation offer benefits to urban wildlife and help foster human–nature relationships in cities. To optimize conservation and social outcomes it is important that initiatives appeal to participants of a wide range of sociodemographic backgrounds. However, this can be challenging when motivation and willingness t...
Article
In the absence of mammals, the fauna of islands is characterised by high endemism levels and a tendency towards gigantism, flightlessness and longevity. These characteristics have resulted in a high vulnerability to introduced animals, either directly via predation or indirectly through an alteration of food web interactions. Because invertebrates...
Article
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Global wetland loss has reduced biodiversity and ecosystem services. These declines have inspired many landholders to restore wetlands, but the success of these efforts remains unclear, in part, because quantifying ecosystem services requires diverse methods. Here, we blend participatory mapping and surveys, field measurements and high-resolution m...
Article
Pitfall traps are commonly used to sample surface-active invertebrates, although the efficiency of the technique varies among taxa. We investigated how baiting pitfall traps with squid influenced sampling of some ground-dwelling invertebrates in New Zealand forests. The study was conducted across a total of 21 sets of seven lethal pitfall traps est...
Article
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Over the past 1000 years New Zealand has lost 40–50% of its bird species, with over half of the extinctions attributed to predation by introduced mammals. Populations of many extant forest bird species continue to be depredated by mammals, especially rats, possums and mustelids. The management history of New Zealand's forests over the past fifty ye...
Article
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Across the globe there is an increasing number of initiatives promoting biodiversity in urban areas – both for the benefit of native wildlife and the people who live in cities. In these situations, the role that companion animals, such as cats and dogs, play as predators of wildlife becomes increasingly important. The objectives of this case study...
Article
Cities and urban processes typically have a negative impact on biodiversity via land cover change, high rates of disturbance and high densities of pest species. Increasingly, however, people are being encouraged and empowered to reduce these impacts through urban restoration and backyard conservation initiatives. Internationally, lizards are a comm...
Article
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Ecosystem services provided by contemporary landscapes are different from those of the past, and this difference is influenced by the legacies of policies that incentivized wetland drainage without considering the impact on ecosystem services. Heterogeneity in ecosystem service legacies is rarely acknowledged or documented. Even less understood is...
Article
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A widely held assumption in ecology is that specialists are more efficient than generalists. However, empirical evidence for this fundamental assumption is surprisingly scarce and often contradictory. Theoretically, the evolution of alternative life history strategies is underpinned by a trade-off between activity levels and survival. We investigat...
Article
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Study sites and wasp foraging grounds. As far as it is known, most Vespula workers forage within 300 m from their nest 1,2. We hence describe the sites surrounding the experimental colonies (see also Table S1) within this spatial range. In 2014, we studied colony A in the outskirts of a town, in the grounds of a. About 25% of the area was covered b...
Article
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Predation of indigenous birds by ship rats (Rattus rattus, [Muridae]) is an international conservation crisis and has been implicated in the decline of many endemic species. Effective management of threatened ecosystems relies on accurate assessments of invasive species impacts on native wildlife. To quantify the link between ship rat abundance and...
Presentation
Full-text available
Invasive mammals are a major contributor to the decline and extinction of many native species throughout the world. The impacts of invasive mammals in urban ecosystems, however, are still poorly understood. To better understand the ecology of these species in urban areas we deployed remote cameras in 48 forested sites in Wellington, New Zealand, be...
Article
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Aim Predicting the distribution of species relies increasingly on understanding the spatially explicit constraints of environmental conditions on an organism's physiological traits. We combined an empirical model of temperature‐dependent embryonic development with a mechanistic model of soil temperatures to examine potential thermal limitations on...
Article
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Numerous conservation projects in New Zealand aim to reduce populations of invasive mammalian predators to facilitate the recovery of native species. However, results of control efforts are often uncertain due to insufficient monitoring. Remote cameras have the potential to monitor multiple species of invasive mammals. To determine the efficiency o...
Article
Full-text available
Remotely activated cameras are increasingly used worldwide to investigate the distribution, abundance and behaviour of animals. The number of studies using remote cameras in urban ecosystems, however, is low compared to use in other ecosystems. Currently, the time and effort required to classify images is the main constraint of this monitoring tech...
Article
Automated sound recording devices have become an important monitoring tool used to estimate species richness and abundance of birds in a variety of ecological and conservation studies. The prevalence of calls detected in a specific time period can be used as an index of relative abundance, to compare between populations. However, the statistical po...
Article
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Recognition that statistical models do not always reliably predict habitat suitability under future climate scenarios is leading increasingly to explicit incorporation of the physiological constraints that underlie species’ distributions into spatially explicit predictions. However, computational intensity constrains the use of high-resolution, pro...
Article
Mosquito communities across the globe frequently comprise a mix of native and cosmopolitan species. New Zealand's mosquito communities are no exception. Here we describe the abundance, distribution and phenological patterns for a community of six mosquito taxa resident across the Kaipara Harbour region of northern New Zealand. Adult mosquitoes were...
Article
There is growing concern about mitigation-driven translocations that move animals from anthropogenic threats at donor sites because of their failure rate and lack of application of scientific principles and best practice. We reviewed all known lizard translocations in New Zealand between 1988 and 2013 and identified 85 translocations of 30 lizard t...
Article
Studies of realized niche shifts in alien species typically ignore the potential effects of intraspecific niche variation and different invaded-range environments on niche lability. We incorporate our detailed knowledge of the native-range source populations and global introduction history of the delicate skink (Lampropholis delicata) to examine in...
Article
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The urgency of predicting future impacts of environmental change on vulnerable populations is advancing the development of spatially explicit habitat models. Continental-scale climate and microclimate layers are now widely available. However, most terrestrial organisms exist within microclimate spaces that are very small, relative to the spatial re...
Article
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We studied the variability and plasticity of individual aggressiveness in a social insect, describing and quantifying the sting extension response (SER) of the common wasp Vespula vulgaris. As a proxy for individual aggressiveness we measured the SER of individual wasps, scoring the extent by which the sting was extruded in response to a mild elect...
Article
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Food-based baits and lures remain the mainstay of eradication and monitoring methodologies for invasive mammalian species. To date, however, best-practise baits and lures for rats and possums have not been systematically compared to alternative food-based products in ways that quantify their effectiveness on free-ranging, wild animals. We designed...
Article
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The apparent absence of intra-nest signals and communication about food resources (recruitment) among social wasps does not rule out the possibility of information transfer and coordinated foraging among nestmates. In the present study, we tested the hypothesis that the common wasp (Vespula vulgaris) shows nest-based information transfer and foragi...
Article
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Planting container-grown native seedlings is a restoration technique widely used to enhance biodiversity, including in urban areas in New Zealand. We measured survival and growth of seedlings of three native tree species (Aristotelia serrata, wineberry (n = 743); Cordyline australis, cabbage tree (n = 666); and Pittosporum eugenioides, lemonwood (n...
Article
Parasitoid insects are important natural biocontrols of insect herbivores. How parasitoids choose particular hosts among many larvae on different plants is not fully understood. Our study system was the coastal plant Senecio lautus and its tephritid herbivore Sphenella fascigera parasitised by an undescribed parasitoid wasp Pteromalus sp. We locate...
Article
Mobile organisms frequently forage for patchy resources; e.g. herbivorous insects searching for host plants. The resource diffusion hypothesis predicts that insect herbivores, such as Pieris rapae butterflies, are disproportionally attracted to more isolated, or 'diffused', host plants. Surprisingly little is known about how this response to variat...
Article
An ability to tolerate salinity can be critical for plants growing in coastal environments. We hypothesised that differences in salinity tolerance might explain variations in vigour and distribution patterns among four iceplant taxa on the Wellington coast. Growth rates, biomass allocation and quantum efficiencies of photosystem II were compared un...
Conference Paper
Full-text available
Pitfall traps are commonly used to sample active and surface-living invertebrates, though this technique could be not effective to study some target invertebrate species. The goal of this approach is to evaluate the efficacy of squid baits on sampling weta species as part of the PhD research: Top-down and bottom-up forces in forest invertebrate com...
Article
Te Paki Ecological District in Northland is regarded as a New Zealand biodiversity hotspot, but habitat loss and forest fragmentation have adversely affected many of its endemic species. We investigated the distribution and habitat associations of Mecodema tenaki (Coleoptera: Carabidae), a Te Paki endemic ground beetle whose threat status was recen...
Article
The increasing amount of internet trade in live animals has facilitated the sale and circulation of exotic species all over the world. This is an area of concern, as the deliberate or accidental release of pets is an important pathway by which exotic species are often introduced into new environments, often with negative effects on the local specie...
Article
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The Argentine ant, Linepithema humile (Mayr), is a highly invasive global pest. It has been just over twenty years since Argentine ants were fi rst discovered in New Zealand. Through the result of human-mediated dispersal, they are now relatively widespread, but patchily distributed, in many North Island towns and cities, and also in several locati...
Article
Full-text available
Because invasive species threaten the integrity of natural ecosystems, a major goal in ecology is to develop predictive models to determine which species may become widespread and where they may invade. Indeed, considerable progress has been made in understanding the factors that influence the local pattern of spread for specific invaders and the f...
Article
Full-text available
Synergies between invasive species and climate change are widely considered to be a major biodiversity threat. However, invasive species are also hypothesized to be susceptible to population collapse, as we demonstrate for a globally important invasive species in New Zealand. We observed Argentine ant populations to have collapsed in 40 per cent of...
Article
1. Using a hierarchical generalised linear model we examined effects of landscape fragmentation (fragment area, isolation, and urbanisation of the surrounding matrix), within-fragment habitat quality (host plant abundance and plant species richness), and properties of the individual trees, on plant herbivore and parasitoid abundance. 2. The present...
Article
1. While previous studies have demonstrated rapid evolution in introduced plants and animals, most focus on single species. They are therefore unable to show whether these are special cases, or if rapid evolution is a common phenomenon in introduced species. 2. We used over 1900 herbarium specimens to determine whether morphological traits [plant h...
Article
Once widespread, Cook's scurvy grass (or nau, Lepidium oleraceum) is now confined to a few offshore populations. Classed as nationally endangered by the New Zealand Department of Conservation, populations of Cook's scurvy grass are threatened by a number of factors, including introduced herbivorous insect species such as the white butterfly (Pieris...
Article
Invasive species threaten biodiversity; hence, predicting where they may establish is vital for conservation. Our aim is to provide a robust predictive model for an invasive species suitable for managers acting at both global and regional scales. Specifically, we investigate one of the world's worst invasive species [the red-eared slider turtle (RE...
Article
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Mechanistic models for predicting species’ distribution patterns present particular advantages and challenges relative to models developed from statistical correlations between distribution and climate. They can be especially useful for predicting the range of invasive species whose distribution has not yet reached equilibrium. Here, we illustrate...
Article
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Aim To identify geographical and climatic correlates of the timing of fruit production in fleshy fruited plant communities. Location Global. Methods We searched the literature for studies documenting monthly variation in the number of fleshy fruited species bearing ripe fruits in plant communities (i.e. fruit phenologies). From these data, we used...
Chapter
We know that there are tens of millions of plant and animal species, but we do not know enough to be able to describe the patterns and processes that characterise the distribution of species in space, time and taxonomic groups. Given that in practical terms it is impossible to expect to be able to document biodiversity with any degree of completene...
Article
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Maps of a species' potential range make an important contribution to conservation and invasive species risk analysis. Spatial predictions, however, should be accompanied by an assessment of their uncertainty. Here, we use multimodel inference to generate confidence intervals that incorporate both the uncertainty involved in model selection as well...
Article
Summary1 The distribution patterns of 391 rare and scarce British plants (species recorded in 100 or fewer 10 × 10 km squares) were characterized by their distributional area (area of occupancy at 1‐km scale: AOO1) and levels of aggregation (as reflected in fractal dimensions measured across two scales: D 1−10 and D 10−100). 2 Eighteen plant traits...
Article
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This Masters project intends to explore by computer simulation the effects of individual foraging behaviour and resource aggregation on foraging patterns at multiple scales. An object-oriented approach will be taken to provide a flexible framework within which different simulation methods may be applied and compared. Examples of previously publishe...
Article
Fractals have found widespread application in a range of scientific fields, including ecology. This rapid growth has produced substantial new insights, but has also spawned confusion and a host of methodological problems. In this paper, we review the value of fractal methods, in particular for applications to spatial ecology, and outline potential...
Article
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The spatial distribution of a species can be characterized at many different spatial scales, from fine-scale measures of local population density to coarse-scale geographical-range structure. Previous studies have shown a degree of correlation in species' distribution patterns across narrow ranges of scales, making it possible to predict fine-scale...
Article
In developing red data books of threatened species, the World Conservation Union uses measures of rarity, rates of decline, and population fragmentation to categorize species according to their risk of extinction. However, most quantitative measures of these three concepts are sensitive to the scale at which they are made. In particular, definition...
Article
Full-text available
Approximately 30 exotic ant species have been introduced into New Zealand, including the Argentine ant Linepithema humile (Mayr). Many of these ant species are known to affect horticulture worldwide by tending hemipteran insects. These ants may protect these hemiptera from their natural enemies, resulting in higher pest densities and potential econ...
Article
Full-text available
The Argentine ant, Linepithema humile, is an invasive species with the potential to cause significant economic and ecological damage in New Zealand. Using published information on rates of development, we induced parameters for a cumulative degree-day model for each life-stage of the Argentine ant.A summary model suggested that complete development...
Article
Summary 1. The aggregation model of coexistence has been used widely to explain the coexist- ence of competing species that utilize patchy and ephemeral resources. Over the years, it has been reformulated in many different ways, using different assumptions, indices and analyses, leading sometimes to contradictory conclusions. We present a general f...
Article
We derive the species-area relationship (SAR) expected from an assemblage of fractally distributed species. If species have truly fractal spatial distributions with different fractal dimensions, we show that the expected SAR is not the classical power-law function, as suggested recently in the literature. This analytically derived SAR has a distinc...
Article
In the largely organic soils in which ectomycorrhizas are commonly found, a preference for absorbing organic nitrogen over mineral forms is likely to be an advantage, especially where mineralisation rates are low. To determine rates of both independent and preferential growth of ectomycorrhizal basidiomycetes on organic and inorganic nitrogen, stra...
Article
Recent attempts to examine the role of different mechanisms in generating a positive abundance-occupancy relationship failed to properly distinguish between Brown's (1984) sampling artefact, and the form of relationship to be expected from a random distribution of individuals.Because random distributions generate a positive relationship, one can ne...

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