New Zealand Journal of Ecology

Gregor William Yeates, PhD, DSc (Cantuar.), FSN, FRSNZ, FNZSSS, 19 May 1944–6 August 2012

Tue, 25 Sep 2012 00:00:00 -0700

David A. Wardle and Craig Ross
NZJEcol 37(1):156–158 (2013)
Abstract. [First paragaph:]
Dr Gregor Yeates, a distinguished soil biologist, ecologist and systematist, died in his home town of Palmerston North on 6 August 2012 after a brief illness. Throughout his career he dedicated himself to understanding the ecology and systematics of soil organisms, primarily in New Zealand, and at the time of his death was an author of approximately 300 journal publications, spanning 45 years.

Economical genotyping of little blue penguin (Eudyptula minor) clades from feather-based DNA

Wed, 26 Sep 2012 00:00:00 -0700

J. Alan Clark, Jonathan C. Banks and Joseph R. Waas
NZJEcol 37(1):146–150 (2013)
Abstract. Determination of clade membership is a crucial requirement for many research questions addressing phylogeography, population structure, mating patterns, speciation, and hybridisation. The little blue penguin (Eudyptula minor) can be separated into two deeply divergent clades. However, assigning clade membership in little blue penguins requires molecular methods. Genetic sequencing can be used to identify clade membership but is expensive. Here, we present an economical alternative to the use of sequencing to determine little blue penguin clade membership. We extracted DNA from feathers using a method that produced reasonable quantities of DNA. We then amplified the D-loop section of the mitochondrial control region from total genomic DNA extracts, using the primers ‘C L-tRNAglu’ and ‘D H-Dbox’ followed by digestion with the restriction enzyme AluI. When visualised on a gel, distinctive banding patterns clearly indicated clade membership. We sequenced a subset of our samples and verified the accuracy of this method. The methods we present should facilitate little blue penguin research through a cost-effective approach to clade analysis as well as a successful technique to extract DNA from feathers when blood or tissue samples are not available.

Responses to direct versus indirect cues of predation and competition in naïve invasive mice: implications for management

Wed, 26 Sep 2012 00:00:00 -0700

Idan Shapira, Elizabeth Walker, Dianne H. Brunton and David Raubenheimer
NZJEcol 37(1):33–40 (2013)
Abstract. Many populations of invasive mice Mus musculus in New Zealand have experienced the removal of mammalian predators and competitors, with the consequence of mouse population irruptions. The effects of these removals on mouse foraging are largely unknown, yet this information is essential for developing and implementing better mouse control. We investigated the effects of direct and indirect predatory cues on foraging of free-ranging mice at a site where mammalian predators were eradicated 5 years previously. We used 17 stations, each containing four trays of millet seeds mixed thoroughly in sand, with three unfamiliar mammalian (a predator, a competitor, and a herbivore) odour treatments and a control (water), during the four phases of the moon. We measured mouse selectivity for treatment/control trays, giving-up densities (GUDs, a measure of food consumption), and tray encounter rates. Foraging by mice was not affected by odour cues from any of the unfamiliar mammals. Moonlight intensity, however, affected mouse foraging, with higher GUDs being recorded on brighter moon phases (full and waxing > new and waning) during the first night of the trials. This effect was less pronounced during the second night. Resource encounter rates were also affected, with the proportion of trays foraged lower during the brighter phases of the moon on both the first and second nights. We suggest that coordinating management efforts according to the phases of the moon has the potential to improve mouse control and reduce bait wastage.

Accurate identification of individual geckos (Naultinus gemmeus) through dorsal pattern differentiation

Fri, 27 Sep 2013 00:00:00 -0700

Carey D. Knox, Alison Cree and Philip J. Seddon
NZJEcol 37(1):60–66 (2013)
Abstract. Mark–recapture methods are frequently used to obtain the data needed to inform conservation management of vulnerable species. This typically involves animals being captured, individually marked, then released and later detected by capture or resighting. This may be stressful for individual animals and can be resource-intensive. Photo-identification has emerged as an effective, and potentially less intrusive, alternative to traditional mark–recapture methods. Photo-identification can be used when animals have stable and individually identifiable natural markings that can be photographed in the field and used for long-term identification. A database of photographs and associated capture-history data can be used for robust estimation of demographic parameters such as population size and survival if an appropriate sampling regime is used. In addition, aspects of behavioural ecology, habitat use, movement patterns and home range can be examined. We outline the creation of a photographic database for jewelled geckos (Naultinus gemmeus) from Otago Peninsula and test the accuracy and speed with which human observers can use this database to differentiate between individual jewelled geckos. Jewelled geckos found during visual searches were captured, photographed and their photographs incorporated into a database. Volunteers then had to match 15 photos of randomly selected geckos to different photographs of the same animals, which were contained within a database of 855 individuals. All users correctly matched all 15 randomly selected geckos. Experience appeared to increase the speed of correct identifications. Our results show that photo-identification can provide an effective alternative to potentially more intrusive techniques such as toe-clipping or pit-tagging for jewelled geckos on the Otago Peninsula.

Monitoring selected forest bird species through aerial application of 1080 baits, Waitutu, New Zealand

Wed, 24 Oct 2012 00:00:00 -0700

Terry C. Greene, Peter J. Dilks, Ian M. Westbrooke and Moira A. Pryde
NZJEcol 37(1):41–50 (2013)
Abstract. Robust and reliable information is required to measure impacts of aerial 1080 operations on non-target bird species. We examined the impact on seven forest bird species of an aerial pest control operation using 1080 cereal baits to poison possums (Trichosurus vulpecula) within Waitutu Forest, Fiordland National Park. The survival of South Island kaka (Nestor m. meridionalis) and ruru (Ninox novaeseelandiae) was monitored using radio telemetry, and replicated bird counts within and external to the operational area were used to monitor changes in numbers of grey warblers (Gerygone igata), kaka, kereru (Hemiphaga novaeseelandiae), riflemen (Acanthisitta chloris), robins (Petroica australis) and tomtits (P. macrocephala). All radio-tagged kaka known to be present within the operational area prior to the application of toxic baits (n = 15) were alive 6 months later. None of the 11 radio-tagged ruru present during the operation died from 1080 poisoning. One ruru found dead (cached in a hole) following the application of toxic baits was tested for the presence of 1080, and none was found. It is likely that this bird was killed or scavenged by a predator. Transect counts of tomtits and grey warblers provided the largest sample sizes and most interpretable results. There was no evidence of any negative impact of 1080 for these species. Similarly, independent measures from point counts conducted annually since 2006 at two locations within the operational area also failed to highlight any declines in distribution or relative abundance attributable to the application of 1080 baits for six of the bird species monitored. We recommend (1) further pest control operations within the Waitutu area to prevent further deterioration in diversity and size of bird populations and (2) the continuation of monitoring programmes capable of assessing direction and rates of change in key demographic parameters for the bird populations living there.

Does genetic variation among invasive house mice in New Zealand affect eradication success?

Wed, 24 Oct 2012 00:00:00 -0700

Jamie W. B. MacKay, Alana Alexander, Mark E. Hauber, Elaine C. Murphy and Mick N. Clout
NZJEcol 37(1):18–25 (2013)
Abstract. House mice (Mus musculus) were introduced to New Zealand accidentally in 1824 following the stranding of an Australian ship. Phylogeographic analyses have revealed many subsequent introductions from diverse sources. Mice have significant negative impacts on native ecosystems in New Zealand and elsewhere. This makes their eradication a desirable conservation outcome, yet a large proportion of mouse eradication attempts worldwide have failed for unknown reasons. We used a phylogeographic approach to identify mitochondrial DNA (mtDNA) D-loop haplotypes of mice obtained from 12 previously unsampled island and mainland sites to expand the previous sampling range for investigation of mouse genetics in New Zealand, and to test the hypothesis that eradication failure is linked to either mouse subspecies or source population as indicated by D-loop haplotype. We predicted that populations that had survived an eradication attempt would be of a different mouse subspecies or D-loop haplotype from those where eradication had succeeded. In addition, mouse populations at failed eradication sites may have a common D-loop haplotype, indicating a shared source population that may be more resistant to eradication attempts. Twenty-five complete mtDNA D-loop sequences were generated, describing six haplotypes including two D-loop haplotypes that had not previously been recorded in New Zealand linking New Zealand mice to populations in Portugal and Iran. A Portuguese haplotype was also recorded for the two geographic outgroup specimens sourced from Reunion Island, Indian Ocean; the first recorded mouse D-loop haplotype from that location. Mice sampled from six New Zealand populations where eradication outcome was known all possessed domesticus D-loop haplotypes. Mice in four of these six populations (three successful eradications and one failure) possessed the same D-loop haplotype (domNZ.04) making it difficult to infer a link between D-loop haplotype and mouse eradication success. Further sampling in New Zealand may uncover additional haplotypes linking New Zealand mice to other areas.

Establishment of Nothofagus solandri var. cliffortioides by seeding in Leptospermum scoparium shrublands

Wed, 24 Oct 2012 00:00:00 -0700

Murray Davis, David Henley, Clayson Howell and Graham Coker
NZJEcol 37(1):139–145 (2013)
Abstract. Large areas of mountain beech (Nothofagus solandri var. cliffortioides) forest in the South Island of New Zealand have been destroyed by fire and replaced by grassland or shrubland. Mountain beech regenerates into grassland or shrubland mainly by slow spread from forest margins, though instances of long-distance spread into manuka (Leptospermum scoparium) shrubland have been recorded. To determine if manuka shrubland may be used to facilitate establishment, seed of mountain beech was sown under moderately dense and dense manuka canopies, at manuka stand edges, and in open grassland or moss-dominated vegetation at three sites in the Waimakiriri catchment, Canterbury. Seedling establishment after 2 years was strongly influenced by both site and position in relation to the manuka canopy. Rainfall during November of the first year (after seeding in April) was low and 0.3% emergence occurred at a site with stony soils on a steep west-facing slope. Mean emergence at the other two sites was greater (10.6% and 11.5%) and at those sites was greatest at manuka-canopy-edge positions (25–30% of seed sown). Few seedlings emerged in open grassland or moss vegetation and these mostly died. Survival of emerged seedlings after 2 years was high (45–100%) under manuka and at the stand edge. Greater establishment of beech seedlings at the edge of or under manuka stands is attributed to the provision of shade and possibly mycorrhizal inoculum by manuka. Further monitoring is required to determine ultimate seedling survival.

Evolution of New Zealand alpine and open-habitat plant species during the late Cenozoic

Tue, 30 Oct 2012 00:00:00 -0700

Peter B. Heenan and Matt S. McGlone
NZJEcol 37(1):105–113 (2013)
Abstract. Understanding the evolutionary history and biogeography of the New Zealand alpine flora has been impeded by the lack of an integrated model of geomorphology and climate events during the Late Miocene, Pliocene and Pleistocene. A new geobiological model is presented that integrates rock uplift age, rate of uplift and the resulting summit elevations in the Southern Alps (South Island) during the last 8.0 million years with a climate template using the natural gamma radiation pattern from the eastern South Island Ocean Drilling Program Site 1119 that covers the past 3.9 million years. This model specifically defines the average treeline in relation to mountain height, allowing predictions as to the timing of the formation of the alpine zone and other open habitats. This model predicts open habitats such as rock bluffs, tussock grasslands and riverbeds would have been available from about 4.0–3.0 Ma, coinciding with the initiation of summit uplift and a cooling climate providing an opportunity for the evolution of generalist alpine and open-habitat herbs and shrubs. Alpine habitats began to form at about 1.9 Ma and were a permanent feature of the Southern Alps from about 0.95 Ma. Specialist alpine plants confined to alpine habitats can have evolved only within this period once the alpine zone was persistent and widespread. Bog habitats are likely to date from the Late Miocene (c. 6.0 Ma), and the specialist bog species would have evolved from this time. Molecular-clock dates for DNA sequences from species of specialist alpine habitats, generalist open habitats, and bog habitats are consistent with predictions made on the basis of the model.

Population density estimates of brushtail possums (Trichosurus vulpecula) in dry grassland in New Zealand

Wed, 31 Oct 2012 00:00:00 -0700

Carlos Rouco, Grant L. Norbury, James Smith, Andrea E. Byrom and Roger P. Pech
NZJEcol 37(1):12–17 (2013)
Abstract. The introduced brushtail possum (Trichosurus vulpecula) is the most important wildlife host of bovine tuberculosis in New Zealand and is considered to be a major environmental and agricultural pest. Dry grassland ecosystems in New Zealand include some of the least protected and most threatened native biota. Drylands cover 19% of the country, but there is little published information on the population density of invasive brushtail possums in these environments, and previous estimates are not based on quantitative methods. We surveyed possum density in two open dry grassland habitats on hilly slopes in the southern South Island. One site had higher shrub and rock cover than the other. We used a spatially explicit capture–mark–recapture method to estimate possum density. Possum densities were slightly higher at the more shrubby and rocky site; estimates (±SE) from capture–mark–recapture from maximum likelihood were 0.69 (±0.05) per hectare, compared with 0.44 (±0.03) per hectare in the less shrubby and rocky site. Density estimates were similar to those recorded in radiata pine (Pinus radiata) and beech (Nothofagus spp.) forests in New Zealand, but were 5- to 29-fold lower than those in podocarp–broadleaved forest. Maximum likelihood home range estimates derived from spatial trap data were larger in the less shrubby and rocky site (54.07 ha cf. 36.19 ha). These home ranges are much larger than those recorded in native forest, and probably reflect the lower abundance and more patchy distribution of food resources and shelter in dryland environments. The ecological information provided here is useful for wildlife managers planning to target possum control in dryland environments.

Patterns of past and recent conversion of indigenous grasslands in the South Island, New Zealand

Wed, 31 Oct 2012 00:00:00 -0700

Emily S. Weeks, Susan Walker, John R. Dymond, James D. Shepherd and Bruce D. Clarkson
NZJEcol 37(1):127–138 (2013)
Abstract. We used recent satellite imagery to quantify the extent, type, and rate of conversion of remaining indigenous grasslands in the inland eastern South Island of New Zealand in recent years. We describe the pattern of conversion in relation to national classifications of land use capability and land environments, and ecological and administrative districts and regions. We show that although large areas of indigenous grasslands remain, grassland loss has been ongoing. Indigenous grassland was reduced in the study area by 3% (70 200 ha) between 1990 and 2008. Almost two-thirds of post-1990 conversion occurred in threatened environments with less than 30% of indigenous cover remaining, primarily in the Waitaki, Mackenzie and Central Otago administrative districts. This conversion occurred primarily on non-arable land. In the Mackenzie and Waitaki districts the rate of conversion in 2001–2008 was approximately twice that in 1990–2001. Opportunities to protect more of the full range of indigenous grasslands lie with the continuing tenure review process in these districts.

Strategies for detection of house mice on a recently invaded island

Wed, 31 Oct 2012 00:00:00 -0700

Helen W. Nathan, Mick N. Clout, Elaine C. Murphy and Jamie W. B. MacKay
NZJEcol 37(1):26–32 (2013)
Abstract. Invasive rodents pose a grave and persistent threat to New Zealand’s native biodiversity. Rodent eradication is a successful conservation tool on islands. However, eradications may fail, and there is always potential for reinvasion. It is therefore essential that effective systems are in place for the early detection of rodents in the case of eradication failure or reincursion. We used data from a small New Zealand island experimentally colonised with house mice (Mus musculus) to investigate the effectiveness of selected mammal surveillance practices, including detection device choice, duration of deployment period, and device placement. The effect of population density on mouse detectability was assessed using population abundance estimates made regularly throughout the experimental island colonisation. We found that commonly used detection practices were highly effective for the detection of mice, even at low population density.

Impact of disturbance on above-ground water storage capacity of bryophytes in New Zealand indigenous tussock grassland ecosystems

Thu, 01 Nov 2012 00:00:00 -0700

Pascale Michel, Ian J. Payton, William G. Lee and Heinjo J. During
NZJEcol 37(1):114–126 (2013)
Abstract. Bryophytes are widespread in many plant communities and can attain cover and biomass levels that influence ecosystem processes. We investigated the impact of disturbance (fire, topsoil removal) on the composition, biomass, and water storage capacity of bryophytes in indigenous temperate tall-tussock grasslands managed to sustain an ecosystem service (regular provision of water) to nearby urban areas. We surveyed bryophyte composition, structure and water-related traits 9 years after experimental fires and topsoil removal. Total water storage capacity of non-epiphytic bryophytes in control grassland sites was estimated at 4.3 mm, a value similar to that found in temperate New Zealand forests. Total biomass, species composition, and water-related traits were the main drivers of water storage potential from bryophytes. A major shift in bryophyte species composition following disturbances reduced this potential by over 80%. Bryophyte community changed from a dense ground cover (71%) of the pleurocarpous moss Hypnum cupressiforme with high water holding capacity (c. 1400% of dry mass) in control plots, to low frequency of the colonist moss Polytrichum juniperinum in burned plots, and two Campylopus species in areas with topsoil removed for firebreaks (all three displaying a low water holding capacity of less than 800% dry mass). We concluded that despite their low species diversity (12 species in total in undisturbed sites), bryophytes form a major, previously unrecognised, component of indigenous tall-tussock grasslands in New Zealand, and contribute towards sustaining the valued water holding capacity of these systems. Like the tussock dominants, bryophytes and their associated ecological functions are highly susceptible to long-term impacts from burning and vegetation clearance. It is therefore critical to account for the recovery of bryophytes in the management of indigenous tall-tussock grasslands to maintain healthy ecosystems.

Pollen analysis of coprolites reveals dietary details of heavy-footed moa (Pachyornis elephantopus) and coastal moa (Euryapteryx curtus) from Central Otago

Wed, 14 Nov 2012 00:00:00 -0800

Jamie R. Wood and Janet M. Wilmshurst
NZJEcol 37(1):151–155 (2013)
Abstract. Palynological analysis of coprolites (preserved dung) can reveal detailed information on the diets and habitats of extinct species. Here, we present pollen assemblages from coprolites of the extinct heavy-footed moa (Pachyornis elephantopus) and coastal moa (Euryapteryx curtus) from the Central Otago region of the South Island, New Zealand. The data complement previous macrofossil (seed and leaf) analyses of the same specimens, and reinforce the interpretation that both species had generalist feeding ecologies. The pollen results reveal a broader selection of plant taxa consumed by both bird species, which has helped to discriminate between the predominantly grazing habit of the heavy-footed moa and the browsing habit of the coastal moa.

Toxicology and ecotoxicology of zinc phosphide as used for pest control in New Zealand

Thu, 15 Nov 2012 00:00:00 -0800

Charles Eason, James Ross, Helen Blackie and Alastair Fairweather
NZJEcol 37(1):1–11 (2013)
Abstract. Zinc phosphide (Zn₃P₂) has been used overseas as a vertebrate pest control tool for several decades. It has been favoured in the USA and Australia for the field control of rodents and other animal pest species because of its comparatively low risk of secondary poisoning and lack of environmental persistence. Zn₃P₂ paste was approved for use as a possum control agent in New Zealand by the Environmental Protection Authority in August 2011. A micro-encapsulated form of Zn₃P₂ has been developed for use in paste and in the future will be developed in solid cereal bait, initially for controlling possums and as a rodenticide. New Zealand research over the last 10–15 years has focused on several factors, including determining Zn₃P₂ effectiveness for controlling possums, animal welfare, understanding and reducing non-target risk, and environmental fate. Zn₃P₂ is fast acting when delivered at toxic doses in baits to possums, with clinical signs first appearing from 15 min, and death after a lethal dose generally occurring in 3–5 h. Its toxicity is largely mediated by phosphine, which is formed as a breakdown product when paste is digested; Zn₃P₂ interacts with stomach acid. A toxic dose for possums will be delivered in 5 g of paste containing 1.5% Zn₃P₂ w/w. When this paste is applied in bait stations in field settings following prefeeding, possum numbers will be rapidly reduced. There should be no long-term residue risks. However, considerable care must be taken when using Zn₃P₂ for the control of animal pests because, despite low secondary poisoning risks, it has the potential (like other toxins) to cause primary poisoning of non-target species, and treatment of accidental poisoning is difficult. Exposure to sublethal doses has the potential to cause adverse effects, and strict safety precautions must be enforced to protect contractors and workers in the pest control industry. Despite extensive use of Zn₃P₂ overseas there has been only limited research and practical experience with Zn₃P₂ paste in New Zealand, especially when compared with alternative tools such as baits containing sodium monofluoroacetate (1080). Additional research efforts and practical experience should enable the effective use of Zn₃P₂ in New Zealand as a tool to achieve conservation outcomes or to control vectors of bovine tuberculosis.

Habitat associations and detectability of the endemic Te Paki ground beetle Mecodema tenaki (Coleoptera: Carabidae)

Wed, 21 Nov 2012 00:00:00 -0800

Olivier J.-P. Ball, Patrick T. Whaley, Andrea M. Booth and Stephen Hartley
NZJEcol 37(1):84–94 (2013)
Abstract. 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 recently changed from ‘Nationally Critical’ to ‘Declining’. Manual searching and pitfall trapping (live-capture and lethal) were used to detect the species at 46 sites in three habitat types: native forest, pine plantation and shrubland. Between 2006 and 2010, 41 individuals were found at five locations in the east of the district, significantly increasing individual and locality records for the species. Efficacy of both forms of pitfall trapping for determining presence/absence of M. tenaki was extremely high, whereas manual searching had lower sensitivity. Beetles were only found in structurally heterogeneous native forest with a closed canopy, including edge zones. All beetles were found at sites underlain by rocks of the Parengarenga Group (mainly Kaurahoupo Conglomerate); however, neither forest community composition nor soil properties were good predictors of beetle presence. The most important factor influencing the present distribution of M. tenaki is likely to have been anthropogenic habitat disturbance. Our study shows that lethal trapping methods are not essential for studying or monitoring this threatened species. It also shows that retaining and managing even very small native forest fragments within its historical range may be important for the protection of the species, and that a site-based rather than a single-species approach is likely to be the most effective management strategy. The possibility of relocating beetles to suitable, presently unoccupied locations should not be discounted. Our results indicate that a threat ranking of ‘Nationally Vulnerable’ rather than ‘Declining’ may be more appropriate for the species.

Diet composition and prey choice of New Zealand falcons nesting in anthropogenic and natural habitats

Thu, 22 Nov 2012 00:00:00 -0800

Sara M. Kross, Jason M. Tylianakis and Ximena J. Nelson
NZJEcol 37(1):51–59 (2013)
Abstract. In a biodiversity conservation exercise a native raptor has been reintroduced to Marlborough, a wine-growing area in New Zealand’s South Island, on the assumption that the abundant passerines attracted to the grapes will provide a natural food resource for this predator. As part of a study to assess the value of vineyards as habitat for the threatened New Zealand falcon (Falco novaeseelandiae) we used remote videography and prey remains to compare the diet composition of falcons nesting in a vineyard-dominated landscape with that of falcons nesting in natural habitat in nearby hills. We also quantified the abundance and species composition of avian prey in the habitats surrounding each falcon nest. Generally there were more birds in the vineyards but the composition of available prey did not differ between vineyards and the nearby hills, nor did the composition of avian species in the breeding-season diet of falcons. Avian prey was the main food source for falcons during the breeding season, representing 97.9% of prey items by frequency and 83.3% of prey items by biomass. Mammals represented only 1.9% of prey items by frequency, but made up 16.7% of prey items by biomass. We also found that falcons preyed on introduced species more than would be expected, and on endemic species less than would be expected, based on their availability in the landscape. The absence of any significant differences in diet between native and vineyard habitats during the breeding season suggests that the latter may be a suitable alternative when natural habitats are unavailable, although further study must be conducted into the role of supplementary feeding on these effects. These findings pave the way for research in other production landscapes that could be used for conservation measures.

Enhancing nectar provision in vineyard habitats for the endemic New Zealand butterfly, Lycaena salustius

Fri, 23 Nov 2012 00:00:00 -0800

Mark Gillespie and Steve D. Wratten
NZJEcol 37(1):67–74 (2013)
Abstract. Nectar is an important factor influencing the level and persistence of butterfly populations, but particular sources of nectar may not be optimal for all species. In a farmland context, it is not always clear whether nectar sources used by butterflies are good quality species. They may be used opportunistically in the absence of true preferences, therefore possibly limiting maximal reproduction. This study investigated the use of nectar by adults of the endemic New Zealand butterfly, the common copper Lycaena salustius, in two ways: (1) a choice experiment in the field using a replicated design of different plant species, and (2) a greenhouse no-choice bioassay examining fitness enhancement by different flower species. In the field experiment, only Lycaena salustius males were observed in large numbers, and they spent a significantly longer time on flowers of Veronica ‘Youngii’ and Fagopyrum esculentum than on species already available in vineyards. In the laboratory, Veronica salicifolia and Fagopyrum esculentum flowers significantly enhanced the fitness of females over Achillea millefolium and the water control. These findings together imply that superior and preferred floral resources are not yet available to adult Lycaena salustius in vineyard landscapes. The no-choice greenhouse experiment suggests that the plant group with which the butterfly may have co-evolved is more beneficial than other exotic species, and that such plants could enhance populations in vineyards. The conservation of other butterfly populations in farmland and other ecosystems may benefit from similar investigations.

Sex- and season-dependent behaviour in a flightless insect, the Auckland tree weta (Hemideina thoracica)

Mon, 17 Dec 2012 00:00:00 -0800

Priscilla M Wehi, Murray Jorgensen and Mary Morgan-Richards
NZJEcol 37(1):75–83 (2013)
Abstract. In a polygynous mating system, males frequently compete by locating and defending sites with resources essential to female survival and reproduction. We investigated seasonal changes in site occupancy in a sexually dimorphic, harem-forming insect, the Auckland tree weta (Hemideina thoracica). First we established artificial cavities as diurnal refuge cavities and potential harem guarding sites. We then examined cavity occupancy changes, and, based on our knowledge of prior occupants, determined sex-specific patterns of arrival, departure, and aggregation at a population level throughout the year. Both season and the sex of prior occupants influenced weta occupancy patterns. Most observations were of single females. However, both males and females moved into cavities previously occupied by a weta of the opposite sex more often than expected by chance alone. Females avoided cavities where other females were present, except during summer when most harems formed. In early summer, male and female tree weta previously living apart began co-habiting. Generally there was little relationship between the number and sex of the weta inside cavities and female departure rates from cavities. Males who were sharing with other males departed cavities more frequently than single males, as might be expected in a polygynous species with male–male combat. Males were less likely to depart if they were sharing a cavity with a harem of more than two females during the summer–autumn period. Analysis of departure rates from artificial cavities indicates males are more mobile than females only in winter and spring. Based on our arrival and departure data, and high occupancy of artificial cavities, we suggest that female weta at this site are mobile and may search for mates during the summer. The data are consistent with a polygynandrous mating system as inferred for other tree weta species (Hemideina spp.).

Invertebrate communities and drivers of their composition on gravel beaches in New Zealand

Mon, 17 Dec 2012 00:00:00 -0800

Shaun A. Forgie, Mark G. St. John and Susan K. Wiser
NZJEcol 37(1):95–104 (2013)
Abstract. Gravel beaches are discrete, irregularly separated habitats along New Zealand’s coasts. They are one of a diverse range of small, disparate, naturally rare ecosystems that tend to occur in extreme environments, and provide critical habitat for threatened, rare and endemic species. New Zealand’s gravel beaches are threatened by urbanisation, weeds, adjacent agriculture, introduced animals and predicted sea-level rise. We studied 51 gravel beaches distributed along the New Zealand coastline to provide primary information on invertebrate composition, habitat patterns and threatened species, and how these relate to national (climate), landscape (surrounding habitat type and human influences), and site-level (geomorphology, vegetation) factors. Invertebrate abundance was mostly driven by beach-scale factors with little influence of the surrounding landscape. However, urbanisation and the presence of exotic plants were significant drivers of invertebrate community composition. A number of observations of interest (i.e. rare species, new localities, habitat specialists, threatened species and exotic species with incursion risk) were also recovered from gravel beaches. Our results demonstrate that vegetation surveys are not necessarily adequate indicators of other biotic components of gravel beach ecosystems and suggest that further ecological assessments of gravel beaches are warranted.

Litterfall, nutrient concentrations and decomposability of litter in a New Zealand temperate montane rain forest

Wed, 01 May 2013 00:00:00 -0700

Peter J. Bellingham, Chris W. Morse, Rowan P. Buxton, Karen I. Bonner, Norman W. H. Mason and David A. Wardle
NZJEcol 37(2):162–171 (2013)
Abstract. Litterfall reflects forest productivity and is an important pathway of nutrient cycling in forests. We quantified litter quantity, nutrient concentrations, and decomposability for 22 permanently marked plots that included gradients of altitude (a range of 320–780 m), soil nutrients and past disturbance in a cool temperate evergreen montane rain forest in the western South Island of New Zealand. For each plot we quantified total fine litterfall and sorted it into components over a 2-year period, and for each of four widespread tree species in each plot (when present) we measured litter nitrogen (N) and phosphorus (P) concentrations, litter decomposability, and the release of litter N and P during decomposition. Total fine litterfall (mean 2.96 Mg ha^–1 year^–1) was low compared with other similar montane forests in New Zealand and elsewhere, and it declined with altitude and increasing successional stage of the plots. However, litterfall for none of four widespread tree species was related to successional stage and that of only one was related to altitude. Further, neither total fine litterfall nor that of these four species was related to soil N or P concentrations with one exception. For the four species we found substantial variation among plots in litter N and P concentrations (up to 16-fold for N, 57-fold for P), litter decomposability, and the release of N and P during decomposition. Despite this, these variables were only rarely correlated with altitude, successional status, or soil nutrient concentrations across plots. Our results suggest that within-species variability in litterfall, nutrient concentrations, and decomposability are likely to be substantial in systems that have a high level of spatial variability because of recurrent large disturbances, and this has potentially important implications for the cycling of carbon, N and P, at the landscape scale.

Laboratory rats as trap lures for invasive Norway rats: field trial and recommendations

Wed, 01 May 2013 00:00:00 -0700

Idan Shapira, Uri Shanas, David Raubenheimer and Dianne H. Brunton
NZJEcol 37(2):240–245 (2013)
Abstract. The Norway rat (Rattus norvegicus) is a highly destructive invasive species but while rat eradications on islands are effective, detection of survivors or reinvasions is challenging. We tested whether laboratory rats can act as lures for wild rats. We live-trapped rats first by using food baits, followed by live trapping using male and female lure rats vs controls (i.e. the same trapping device but without the lure animal). Norway rats were more frequently attracted to lure rats compared with controls. There was no sex bias in the trapped animals. Numbers of Norway rats caught with food baits compared with lure rats did not differ, but trapping rates were higher when using lure rats. Rat activity was detected only around lure rats. Ship rats (Rattus rattus) were not caught with Norway lure rats. We demonstrate the potential for detecting invasive Norway rats using conspecific rats as lures. Further research looking at conspecific attraction in other situations and in direct comparison with food-baited traps is needed to determine the efficacy of this method as a control measure.

Vertical variation in flight activity of the lesser short-tailed bat in podocarp and beech forests, Central North Island, New Zealand

Wed, 01 May 2013 00:00:00 -0700

Jessica Scrimgeour, Laura Molles and Joseph R. Waas
NZJEcol 37(2):193–198 (2013)
Abstract. Designing robust monitoring programmes for cryptic species is particularly difficult. Not detecting a species does not necessarily mean that it is absent from the sampling area. A conclusion of absence made in error can lead to misguided inferences about distribution, colonisation and local extinction estimates, which in turn affects where and how conservation actions are undertaken. It is therefore important to investigate monitoring techniques that reduce the non-detection rate of cryptic species. As habitat complexity plays an important role in the activity of bats within a forest, it was hypothesised that the amount of vegetative ‘clutter’ present at different heights within two different forest types affected the flight activity of lesser short-tailed bats (Mystacina tuberculata). This could affect detection of the species within different forest structures. To compare bat activity at three heights – top (22.0–25.0 m), middle (10.0–12.0 m) and bottom (1.5–2.0 m) – within a podocarp and a beech forest we used automatic bat monitors during January to March 2005. The number of bat passes was recorded at each height at two study areas within each forest and compared between forest types. The forest structure was described using the Recce method and vegetative cover estimated within the three height tiers sampled for bat activity. Within both forest types, the middle-level bat detectors logged the greatest amount of activity. However, differences between the forest types were most pronounced closer to the ground, where a high amount of activity was detected within the beech forest, and very little within the podocarp forest. This suggests that flight activity of lesser short-tailed bats may be affected by the level of vegetative clutter found at different heights within a forest. When designing monitoring programmes for lesser short-tailed bats, it is recommended that consideration be given to the forest structure and how this may affect detection of bat activity.

Response of a reintroduced bird population to rat reinvasion and eradication

Wed, 01 May 2013 00:00:00 -0700

Bryce M. Masuda and Ian G. Jamieson
NZJEcol 37(2):224–231 (2013)
Abstract. Many endemic species on islands are vulnerable to predation and local extinction by introduced rats (Rattus spp.). As a result, the reintroduction of species to predator-free sanctuaries is a successful conservation strategy, especially in New Zealand. Nevertheless, reintroduced populations, even those that reach high densities, are still vulnerable to predation in the event of a rat reinvasion, and may also be susceptible to non-target poisoning during a subsequent eradication operation. We quantify for the first time the changes in population size and survival rate of a well-established, reintroduced species (Stewart Island robins, Petroica australis rakiura) following the reinvasion and eradication of Norway rats (Rattus norvegicus) on Ulva Island, New Zealand, in 2011. The robin population declined by nearly one-third (31.5%; 432 to 296 adults) in the breeding season following the rat reinvasion and eradication. The survival rate of robins prior to the poison operation was only slightly lower than expected, which suggests the growing population of Norway rats may have had a relatively minor negative effect on robin survival. In contrast, the majority of the decline occurred immediately following the poison operation. This suggests the robins were susceptible to non-target poisoning from the brodifacoum poison bait, although the robin population would have likely declined even further if Norway rats had not been eradicated. Our results indicate the importance of developing permanent surveillance systems on island sanctuaries to detect and kill rats upon arrival in order to avoid the potentially high rates of non-target poisoning associated with post-invasion, large-scale eradication operations.

Assessment of protected area coverage of threatened ground beetles (Coleoptera: Carabidae): a new analysis for New Zealand

Wed, 01 May 2013 00:00:00 -0700

Lauren Fuller, Peter M. Johns and Robert M. Ewers
NZJEcol 37(2):184–192 (2013)
Abstract. Gap analysis is a tool that allows conservationists to quantify the effectiveness of protected areas at representing species diversity, but the lack of distribution maps for invertebrates has precluded its application to the world’s most diverse animal groups. Here, we overcome this limitation and conduct a gap analysis, using niche modelling, on the Pterostichini (Coleoptera: Carabidae) of New Zealand, one of the most diverse and most threatened tribes of ground beetles in the nation. Niche modelling uses data on abiotic parameters to model predicted species ranges based on records of their known distribution, and is a useful tool for conservation planning. This method is widely applicable where there is good taxonomical knowledge of the group in question and distribution records are available. We obtained sample localities from museum records for 67 species of Pterostichini, including 10 species listed as threatened, and modelled their spatial distributions based on climate, landforms and soil properties. Most species had small spatial distributions, with 48–75% of species having ranges of less than 100 000 ha. We found the areas with highest species richness fell largely outside of the protected area network, as did the distribution of most individual species, with just 20–25% of species having more than 30% of their range falling within a protected area. In terms of percent land area, New Zealand has one of the world’s largest protected area networks, but the spatial distribution of that network affords little protection to this group of invertebrates. This analysis provides support for the creation of new reserves to increase the value and efficacy of the protected areas network.

Delivery of toxic bait in clusters: a modified technique for aerial poisoning of small mammal pests

Tue, 14 May 2013 00:00:00 -0700

Graham Nugent and Grant A. Morriss
NZJEcol 37(2):246–255 (2013)
Abstract. Sowing 1080 baits for vertebrate pest control in clusters, rather than evenly, could potentially reduce toxin use. We developed a new technique for aerial delivery of 1080 baits in clusters and, in a set of four trials, compared its efficacy in controlling pests against conventional aerial broadcast baiting. In an initial trial where non-toxic prefeeding was not used (Molesworth Station, North Canterbury) we confirmed that aerial delivery of bait clusters is technically feasible and operationally practical. The reductions in possum activity indices achieved with cluster sowing (98.4%) were similar to those achieved with broadcasting sowing (97.8%), despite using 60% less 1080 bait (1 kg ha^–1). Comparable efficacy against possums was also recorded in the Landsborough Valley, Westland, where aligned prefeeding and an even lower sowing rate of toxic bait were used (0.25 kg ha^–1). In a third trial (Isolated Hill, Marlborough) the same cluster-sowing approach resulted in large reductions in possum and rat activity indices, but the possum reductions were more spatially variable than with broadcast baiting. At Maruia, Westland, near-total reductions in possum and rat activity were recorded with both broadcast and cluster sowing, even when there was a longer than usual interval (>30 days) between the aligned prefeeding and cluster baiting, and even when a wide (150 m) helicopter-flight-path spacing was used to reduce the cluster sowing rate of toxic bait to just 0.17 kg ha^–1 (92% lower than the broadcast sowing rate used). These trials suggest that cluster baiting at lower-than-usual sowing rates could lower operational costs, and substantially reduce toxin usage, while maintaining high control efficacy against rats and possums in most cases. Reduced use of toxin might go some way to allaying public concerns over 1080 usage. Further operational testing is required to refine aerial cluster baiting and to identify the optimal balance between lowering costs and toxin use yet consistently achieving high control efficacy.

Is kanuka and manuka establishment in grassland constrained by mycorrhizal abundance?

Tue, 14 May 2013 00:00:00 -0700

Murray Davis, Ian A. Dickie, Thomas Paul and Fiona Carswell
NZJEcol 37(2):172–177 (2013)
Abstract. Two indigenous small tree and shrub species, kanuka (Kunzea ericoides) and manuka (Leptospermum scoparium), have potential as reforestation species in New Zealand as they are forest pioneer species that can invade grassland naturally from present seed sources. The aim of this study was to determine if establishment of kanuka and manuka from seed in grassland distant from stands of these species might be constrained by lack of appropriate mycorrhizal fungi. Both species were grown in an unsterilised grassland soil from a low-productivity montane site assumed to be devoid of appropriate mycorrhizal fungi and inoculated with sterilised or unsterilised O-horizon or mineral soil from beneath three kanuka and three manuka communities expected to contain such fungi. Inoculation with unsterilised O-horizon soil improved kanuka biomass by 36–92%, depending on the source of the inoculant. Inoculation did not improve manuka biomass. No ectomycorrhizal infection was observed on either kanuka or manuka in samples examined under binocular microscope. The biomass response by kanuka to inoculation may be due to introduction of more effective arbuscular mycorrhizal fungi from kanuka communities or possibly to the introduction of soil microorganisms. Testing of inoculation under field conditions will be essential to determine whether establishment of either species in grassland soil by seeding is seriously constrained by lack of appropriate mycorrhizal fungi or soil microorganisms.

A comparison of vocalisations between mainland tui (Prosthemadera novaeseelandiae novaeseelandiae) and Chatham Island tui (P. n. chathamensis)

Mon, 03 Jun 2013 00:00:00 -0700

Samuel D. Hill, Weihong Ji, Kevin A. Parker, Christophe Amiot and Sarah J. Wells
NZJEcol 37(2):214–223 (2013)
Abstract. Vocalisations are important for territorial defence, mate attraction, and species recognition in many songbirds. Comparative studies on the songs of birds between islands and mainland populations provide insight into the evolution of vocal communication in terms of both ecological and social factors. We compared the vocalisations of tui (Prosthemadera novaeseelandiae novaeseelandiae), an endemic honeyeater from New Zealand’s mainland, with those of a subspecies from the remote Chatham Islands (P. n. chathamensis). Song spectral variables of male long-range ‘broadcasting’ songs differed between mainland and Chatham Island tui populations. Songs recorded from five mainland populations had significantly greater syllable diversity and produced a higher percentage of trills than those from the Chatham Islands. These characteristics have been revealed in past studies as being sexually selected traits positively correlated with male genetic diversity. The acoustic adaptation hypothesis could also help to elucidate the presence of a significantly higher percentage of trill components in the songs of the mainland population, as the mainland study sites in general contained more areas of open vegetation, where trills transmit more effectively than in dense forest, which dominated the sampling sites on the Chatham Islands. Future research into the variation of tui song complexity in relation to population size, geographic isolation, and habitat structure between different mainland sites would provide further insight into links between selective pressures and vocal complexity.

Fostering the next generation of reviewers in New Zealand ecology

Mon, 03 Jun 2013 00:00:00 -0700

Timothy J. Curran, Ellen Cieraad and Joanne M. Monks
NZJEcol 37(2):161 (2013)
Abstract. [First paragraph...]
Peer review is the main quality control process in science. Most would agree that the subjection of scientific discoveries to the scrutiny of expert scientists results in higher quality and more reliable scientific outcomes. Recently, several opinion pieces have drawn attention to a crisis in the peer-review system in ecology (e.g. Hochberg et al. 2009; Donaldson et al. 2010). A key problem is the trouble editors have in finding suitable reviewers to assess manuscripts. This causes delays in the time taken for a decision on manuscripts and forces editors to fall back on an often time-limited coterie of regular reviewers, which results in reviewer fatigue and further exacerbates the problem (Hochberg et al. 2009).

Little penguin (Eudyptula minor) diet at three breeding colonies in New Zealand

Fri, 07 Jun 2013 00:00:00 -0700

Scott A. Flemming, Chris Lalas and Yolanda van Heezik
NZJEcol 37(2):199–205 (2013)
Abstract. At-sea shifts in food quality and availability can affect populations of marine birds; however, it is difficult to evaluate the impacts of changes in prey composition and availability without some baseline information on diet composition. The little penguin (Eudyptula minor) is a common inshore-feeding seabird in New Zealand and Australia. To date, only two dietary studies have been undertaken on the little penguin in New Zeaalnd, at two widely separated locations. This study recorded diet of little penguins during the chick-rearing stage of breeding at three colonies in southern New Zealand. Sixty-nine stomach samples were acquired via the stomach flushing technique at Banks Peninsula, Oamaru, and Stewart Island. Prey composition differed between each site: (1) at Oamaru, Graham’s gudgeon (Grahamichthys radiata) occurred most frequently (100%) and contributed the most to meal mass (92.1%); (2) at Banks Peninsula arrow squid (Nototodarus sloanii) occurred most frequently (87.5%), but two fish species – slender sprat (Sprattus antipodum) (33.9%) and ahuru (Auchenoceros punctatus) (37.4%) – contributed most to meal mass; and (3) at Stewart Island arrow squid occurred most frequently (91.3%), and contributed most to meal mass (73.1%). Little penguins take a wide diversity of species, and may switch between species, probably in response to temporal variation in availability. In New Zealand, little penguins ate higher proportions of lower quality cephalopods than those in Australia. As top predators in the marine ecosystem, changes in little penguin diet may indicate changes occurring in the inshore marine ecosystem.

Effects of Agathis australis (New Zealand kauri) leaf litter on germination and seedling growth differs among plant species

Fri, 07 Jun 2013 00:00:00 -0700

Sarah V. Wyse and Bruce R. Burns
NZJEcol 37(2):178–183 (2013)
Abstract. Agathis australis (A. australis, New Zealand kauri, Araucariaceae) exerts a substantial influence on soil properties and nutrient cycling, and mature specimens form an acidic organic soil layer beneath them that can be up to 2 m deep. We investigated whether phytotoxic compounds occurred in A. australis leaf litter and organic soil, and whether allelopathy may explain the distinctiveness of plant communities surrounding A. australis. We extracted water-soluble compounds from fresh litter, and conducted bioassays of seed germination and seedling growth in these extracts on both A. australis-associated and non-associated species. Germination of all species except A. australis was inhibited by extracts from A. australis litter, which probably contains phytotoxic compounds. Germination of a forest species that is not associated with A. australis was inhibited by the low pH organic soils collected from beneath mature A. australis, but when these soils were neutralised using lime, its germination was not inhibited. Lactuca sativa, a species highly sensitive to phytotoxic compounds, was negatively affected by both the low pH of the organic soil and the presence of phytotoxic compounds. In contrast, there was no effect of the organic soil on the germination and growth of A. australis-associated species. These results suggest that the high acidity of A. australis organic soil plays a considerable role in structuring the composition of plant communities associated with A. australis, and also that A. australis litter probably contains unidentified phytotoxic compounds that may exert additional direct allelopathic effects on sensitive species.

Understanding the role of birds in sustaining indigenous turf communities in a lacustrine wetland in New Zealand

Fri, 07 Jun 2013 00:00:00 -0700

Annika C. Korsten, William G. Lee, Adrian Monks and J. Bastow Wilson
NZJEcol 37(2):206–213 (2013)
Abstract. Since human settlement, wetland ecosystems in New Zealand have been severely modified by fire and reduced by drainage for agricultural development. Those remaining are problematic to manage, with modified water regimes, invasive weeds and grazing by livestock. Before settlement, wetland habitats supported diverse avian herbivores, the majority of which are now extinct. However, introduced birds are increasing in wetlands. We sought to understand the role of grazing birds in the maintenance of local turf communities in a lacustrine environment in Otago, New Zealand. To determine the causes of the vegetation patterns, we investigated the influence of abiotic (water table and soil nutrients) and biotic (direct via grazing and indirect via faeces deposition) effects of the birds on the vegetation. Four plant communities were distinguished, two dominated by Leptinella and two by Carex species. The occurrence of the communities was correlated with the distance from the nearest permanent water, soil phosphorus levels, and amount of faecal deposition. The results indicate that avian grazing decreased the proportion of dominant exotic plant species by biomass removal, but not through enhanced nutrient inputs via faecal deposition. Results from this site suggest that naturalised geese facilitate the maintenance of indigenous plant species in the face of exotic invasion, and have a conservation role in highly modified wetland systems, perhaps restoring a herbivore function lost with the extinction of native avian grazers. The long-term conservation management of wetlands in New Zealand may require the utilisation of both native and introduced avian grazers to facilitate the dominance of indigenous plants.

Predator indices from artificial nests and tracking tunnels: do they tell the same story?

Wed, 19 Jun 2013 00:00:00 -0700

Christy L. Getzlaff, Karin A. Sievwright, Andrée B. Hickey-Elliott and Doug P. Armstrong
NZJEcol 37(2):232–239 (2013)
Abstract. Artificial nests and tracking tunnels are alternative predator encounter devices that can be used to predict predation risk to native species. Tracking tunnels are used ubiquitously in New Zealand, whereas artificial nests are used extensively overseas. To assess whether these devices give similar information about predation risk, we compared tracking tunnel and artificial nest data from 16 native forest fragments in the central North Island over two summers. The fragments were expected to vary in predation risk due to rat control in some fragments, and possibly due to habitat differences caused by stock grazing. We modelled the ‘survival’ of both types of devices, where ‘survival’ is defined as the probability of not being tracked or bitten by a rat over a set period (possum bites were also considered to indicate nest failure, but were rare). We used a Bayesian hierarchical framework that allowed for random effects of individual devices as well as fragments, and random time effects. Data from both devices showed clear effects of rat control, but otherwise gave different results. Tracking tunnel survival varied greatly among fragments in the absence of control, with survival generally higher in grazed than ungrazed fragments, whereas no such pattern occurred in artificial nest survival. Different habitat variables explained variation in survival at both site and fragment level; understorey density was the only useful predictor of tracking tunnel survival, whereas artificial nest survival was correlated with canopy cover, vegetation cover at 1.5 m, and supplejack presence. When both data types were modelled simultaneously, the tracking tunnel data improved capacity to explain the artificial nest data whereas the reverse was not true. Consequently, while it is unknown whether the additional inter-fragment variation detected by tracking tunnels indicates real variation in predation risk, we currently see no reason to prefer the more labour-intensive artificial nests.

Demography of takahe (Porphyrio hochstetteri) in Fiordland: environmental factors and management affect survival and breeding success

Tue, 30 Aug 2011 00:00:00 -0700

Danilo Hegg, Glen Greaves, Jane M. Maxwell, Darryl I. MacKenzie and Ian G. Jamieson
NZJEcol 36(1):75–89 (2012)
Abstract. The last remaining natural population of the critically endangered takahe (Porphyrio hochstetteri) is confined to the Murchison Mountains in Fiordland, New Zealand. This mainland population contains about half of the c. 300 remaining takahe and benefits from one of the costliest recovery programmes in the country. Management activities include deer culling, stoat trapping, nest manipulation (e.g. removal of infertile eggs) and captive rearing of chicks. To determine what effect this intensive management has had on the recovery of the Fiordland takahe population, we modelled 25 years of survival and breeding success data as a function of environmental factors (e.g. precipitation, temperature, beech seedfall, tussock flowering) and specific management activities (egg manipulation, captive rearing, stoat control). Annual adult survival, estimated at 78% (credibility interval (CI) = 75–81%), is significantly increased to 85% (76–92% CI) in presence of stoat trapping, but is still low relative to introduced takahe populations on offshore islands and other large New Zealand bird species in predator-free environments. This suggests that the harsh environment of Fiordland may be suboptimal habitat in terms of survival for takahe. On the other hand, reproductive output in Fiordland is similar to that for introduced island populations, and is improved even further by management. Number of chicks per pair fledged with nest manipulation and captive rearing is estimated at 0.66 compared with 0.43 in the absence of nest management. The difference is explained mainly by low fledging success in the wild, especially for double clutches, which justifies the practice of removing one of two viable eggs and transferring it to a captive-rearing facility. The results of this study indicate that current management activities such as stoat trapping and captive rearing have a strong positive effect on population growth of the Murchison Mountains takahe population.

Ecology of brushtail possums in a New Zealand dryland ecosystem

Wed, 07 Sep 2011 00:00:00 -0700

Alistair S. Glen, Andrea E. Byrom, Roger P. Pech, Jennyffer Cruz, Astrid Schwab, Peter J. Sweetapple, Ivor Yockney, Graham Nugent, Morgan Coleman and Jackie Whitford
NZJEcol 36(1):29–37 (2012)
Abstract. The introduced brushtail possum (Trichosurus vulpecula) is a major environmental and agricultural pest in New Zealand but little information is available on the ecology of possums in drylands, which cover c. 19% of the country. Here, we describe a temporal snapshot of the diet and feeding preferences of possums in a dryland habitat in New Zealand's South Island, as well as movement patterns and survival rates. We also briefly explore spatial patterns in capture rates. We trapped 279 possums at an average capture rate of 9 possums per 100 trap nights. Capture rates on individual trap lines varied from 0 to 38%, decreased with altitude, and were highest in the eastern (drier) parts of the study area. Stomach contents were dominated by forbs and sweet briar (Rosa rubiginosa); both items were consumed preferentially relative to availability. Possums also strongly preferred crack willow (Salix fragilis), which was uncommon in the study area and consumed only occasionally, but in large amounts. Estimated activity areas of 29 possums radio-tracked for up to 12 months varied from 0.2 to 19.5 ha (mean 5.1 ha). Nine possums (4 male, 5 female) undertook dispersal movements (≥ 1000 m), the longest of which was 4940 m. The most common dens of radio-collared possums were sweet briar shrubs, followed by rock outcrops. Estimated annual survival was 85% for adults and 54% for subadults. Differences between the diets, activity areas and den use of possums in this study and those in forest or farmland most likely reflect differences in availability and distribution of resources. Our results suggest that invasive willow and sweet briar may facilitate the existence of possums by providing abundant food and shelter. In turn, possums may facilitate the spread of weeds by acting as a seed vector. This basic ecological information will be useful in modelling and managing the impacts of possum populations in drylands.

Breeding variation in female kakapo (Strigops habroptilus) on Codfish Island in a year of low food supply

Tue, 30 Aug 2011 00:00:00 -0700

Joanna Whitehead, Brad Case, Kerry-Jayne Wilson and Laura Molles
NZJEcol 36(1):64–74 (2012)
Abstract. We investigated why some mature females of New Zealand’s critically endangered parrot, the kakapo (Strigops habroptilus), did not attempt to breed during the 2005 breeding season on Codfish Island. At a population level, the initiation of kakapo breeding appears to correspond with years of mast fruiting of rimu (Dacrydium cupressinum) trees, with the proportion of females that breed each season dependent on the quantity of rimu fruit available. This research investigates possible links between habitat quality within individual home ranges and the breeding status of adult females during 2005, when the abundance of available rimu fruit was low. We assessed the importance of both home range size and habitat characteristics in determining breeding attempts. Foraging home ranges were characterised using radio-tracking and triangulation techniques. The relative importance of habitat variables in optimal breeding habitat was assessed using ecological niche factor analysis. Our results show that female kakapo breeding in 2005 had, on average, home ranges twice the size of those females that did not breed that season and the ranges contained a significantly greater quantity of mature rimu forest. Multivariate analysis illustrates female kakapo were effectively partitioning available habitat, as breeders’ foraging locations were positively correlated with high-abundance rimu forest with a tall canopy, described as optimal breeding habitat. In contrast non-breeders’ locations were weakly correlated with short forest containing little or no mature rimu forest. To maximise reproductive output each breeding season, conservation managers need to ensure that all breeding-aged females occupy optimal breeding habitat on Codfish Island. Removal to other islands of kakapo not required in the breeding population may enable females to increase their home range size and occupy better breeding habitat.

Is cool egg incubation temperature a limiting factor for the translocation of tuatara to southern New Zealand?

Tue, 08 Nov 2011 00:00:00 -0800

Anne A. Besson, Nicola J. Nelson, Cathy M. Nottingham and Alison Cree
NZJEcol 36(1):90–99 (2012)
Abstract. Conservation strategy for maintaining and protecting tuatara (Sphenodon punctatus), a rare endemic reptile from New Zealand, includes the reinstatement of populations through the past historical range. A proposal exists to translocate tuatara from Stephens Island in Cook Strait to the Orokonui Ecosanctuary (Te Korowai o Mihiwaka), a coastal site in southern New Zealand. The proposed site is within the former latitudinal range of the genus, but lies outside the current distribution of tuatara, where the climate is warmer. In this study, we examined whether cool incubation temperature is a limiting factor for the proposed reintroduction of tuatara to Orokonui. The tuatara is a species with temperature-dependent sex determination, with only females being produced at low incubation temperatures. Thus, cool southern temperatures may produce only females, even if incubation temperatures are high enough to support successful development. We experimentally translocated tuatara eggs to the ecosanctuary and found that nest temperatures were consistently below those of nests in their current natural distribution and would produce only female hatchlings if successful incubation occurred. An addition of sand to soil did not raise temperatures sufficiently to produce both sexes. However, additional assessments of soil temperatures in a third year indicated that some new sites were warm enough for males to be produced. Given that other aspects of site suitability appear favourable, and that global temperatures are predicted to rise in the near future, which should produce a more viable incubation environment, translocation of this long-lived reptile to the southern ecosanctuary is worth further exploration. However, monitoring of female nesting behaviour, including nest locations, depths and resulting temperatures, will be essential. Our study demonstrates an experimental approach for assessing site suitability for translocation that may be relevant to other egg-laying reptiles.

Nitrogen cycling in gorse-dominated ecosystems in New Zealand

Tue, 08 Nov 2011 00:00:00 -0800

Guna N. Magesan, Hailong Wang and Peter W. Clinton
NZJEcol 36(1):21–28 (2012)
Abstract. The legume gorse (Ulex europaeus) is one of the most widespread nitrogen (N) fixing species and is also one of the most invasive weeds of New Zealand. Despite its widespread occurrence, little research has been undertaken on N cycling in gorse ecosystems. This lack of knowledge is important since gorse covers up to 900 000 ha in New Zealand and there is a potential for a large environmental impact from the cycling of large amounts of N fixed by gorse entering waterways and water bodies. We undertook this overview to summarise the current understanding of N cycling in gorse-dominated ecosystems and identify knowledge gaps and provide recommendations for future research in New Zealand. Specifically, we describe some key biological processes associated with N cycling under gorse-dominated ecosystems. Gorse is capable of fixing up to 200 kg ha^–1 N annually during the period of rapid dry-matter accumulation. External factors such as temperature, fertiliser application, moisture, pH and atmospheric CO₂ can affect biological N fixation in legumes, but such information is scarce for gorse. Gorse produces large quantities of litter, and N concentrations are generally higher in gorse litter than in the litters collected under other shrubs and trees. During and after litter decomposition, N is released into the surrounding soil, resulting in higher N concentration in the soils under gorse sites compared with under other species. This is due to the ability of gorse to fix N and produce large quantities of litter. The contribution of gorse-infested land to surface water eutrophication is also discussed because gorse has invaded large areas within the catchment of some significant lakes in New Zealand. From this review a good understanding of N cycling under gorse ecosystems has emerged. To better understand the wider environmental impact of gorse-dominated ecosystems in New Zealand, further research is needed including monitoring and modelling the impact of climate change on N fixation, leaching and C sequestration in gorse-dominated ecosystems.

Ecological areas – premier protected natural areas

Wed, 14 Dec 2011 00:00:00 -0800

David A. Norton and Fred B. Overmars
NZJEcol 36(1):108–120 (2012)
Abstract. The establishment of ecological areas, a network of predominantly forest reserves, was initiated by the former New Zealand Forest Service (NZFS) in the 1970s within the context of large-scale utilisation and exotic conversion proposals for indigenous State forest lands on the West Coast and in Southland. Unlike other types of protected natural area, ecological areas were primarily selected to be representative of the natural features within ecological districts. Although 112 ecological areas covering 344 753 ha (1.29% of New Zealand’s land area) have now been established, their geographic distribution is uneven with disproportionately large numbers in the West Coast, Waikato and East Coast Bay of Plenty Department of Conservation conservancies. While the intent of the NZFS in gazetting ecological areas was that they would receive the highest level of protection possible, they have not been afforded this level of protection under the Conservation Act 1987 and the Crown Minerals Act 1991, or under conservation management strategies. The identification and protection of ecological areas has not extended beyond former State forest land. With two exceptions, all ecological areas are open to mining despite their high values. Ecological areas are on a par with national parks in terms of their ecological values and they warrant the highest level of protection and management. Specific actions to recognise the special value of ecological areas in legislation, policy and management are recommended.

Identification of predators at black-fronted tern Chlidonias albostriatus nests, using mtDNA analysis and digital video recorders

Thu, 17 Nov 2011 00:00:00 -0800

Kate E. Steffens, Mark D. Sanders, Dianne M. Gleeson, Kiri M. Pullen and Christopher J. Stowe
NZJEcol 36(1):48–55 (2012)
Abstract. Predators at black-fronted tern (Chlidonias albostriatus) nests on the Wairau braided riverbed in Marlborough, New Zealand, were identified using (1) mtDNA analysis of 438 swabs from shell remains, nest contents, and carcass remains, and (2) digital video surveillance of 85 nests. DNA analysis suggested harriers (Circus approximans) were the main predator of tern eggs (171 of 192 shell samples containing predator DNA). Cats (Felis catus) and stoats (Mustela erminea) were the probable predators of the majority of adult terns killed (9 and 8 respectively, of swabs from 19 carcasses). Video results were broadly, though not entirely, consistent with the DNA results, and showed that harriers were the main predator of eggs (9 of 19 videoed predation events), followed by Southern black-backed gulls (Larus dominicanus dominicanus; 3/19); hedgehogs (Erinaceus europaeus occidentalis; 2/19), ship rats (Rattus rattus; 2/19), pied oystercatchers (Haematopus finschi; 2/19) and stoats (1/19). DNA was analysed from nine of the 19 videoed nests but the only predator DNA obtained was from harriers (four nests). Sixty-four percent of depredated nests (683/1063) contained no eggshell remains at the next monitoring visit after predation. DNA analysis of nest material from 71 of these empty nests yielded only one predator result; video footage was therefore essential to identify the cause of 12 empty nests at 19 videoed nest predations. Terns removed the depredated egg remains from eight nests; black-backed gulls consumed eggs at three nests; and a stoat carried the eggs away from one nest. Hedgehog DNA was not found on shell remains from nests with videoed hedgehog predations. Analysing DNA from eggshell and carcass remains is a valuable new tool in wildlife research and management because it can identify predator species and indicate their relative importance. However, our results show that predator species are not equally detectable using this technique, leading to biases in the DNA results. This ‘detectability bias’ needs to be further quantified, and recognised when interpreting DNA results.

Anthropogenic lead (Pb) exposure in populations of a wild parrot (kea Nestor notabilis)

Fri, 09 Dec 2011 00:00:00 -0800

Clio Reid, Kate McInnes, Jennifer M. McLelland and Brett D. Gartrell
NZJEcol 36(1):56–63 (2012)
Abstract. Kea (Nestor notabilis), large parrots endemic to hill country areas of the South Island, New Zealand, are subject to anthropogenic lead (Pb) exposure in their environment. Between April 2006 and June 2009 kea were captured in various parts of their range and samples of their blood were taken for blood lead analysis. All kea (n = 88) had been exposed to lead, with a range in blood lead concentrations of 0.014 – 16.55 ìmol L^–1 (mean ± SE, 1.11 – 0.220 ìmol L^–1). A retrospective analysis of necropsy reports from 30 kea was also carried out. Of these, tissue lead levels were available for 20 birds, and 11 of those had liver and/or kidney lead levels reported to cause lead poisoning in other avian species. Blood lead levels for kea sampled in populated areas (with permanent human settlements) were significantly higher (P < 0.001) than those in remote areas. Sixty-four percent of kea sampled in populated areas had elevated blood lead levels (> 0.97 ìmol L^–1, the level suggestive of lead poisoning in parrots), and 22% had levels > 1.93 ìmol L^–1 – the level diagnostic of lead poisoning in parrots. No kea from remote areas had levels > 0.97 ìmol L^–1. The kea is a long-lived, slow-reproducing species at a high risk of decline from even a small reduction in its survival rate. Based on our findings, we conclude there is an urgent need to implement lead abatement strategies in areas of the kea range that overlap with permanent human settlement.

Invasional meltdown: pollination of the invasive liana Passiflora tripartita var. mollissima (Passifloraceae) in New Zealand

Fri, 09 Dec 2011 00:00:00 -0800

Merodie A. Beavon and Dave Kelly
NZJEcol 36(1):100–107 (2012)
Abstract. Banana passionfruit (Passiflora tripartita var. mollissima) is an invasive vine in New Zealand where it lacks its natural hummingbird pollinator. We investigated the mating system and reproductive traits that facilitate its spread in the Marlborough Sounds. Flower observations revealed that visitors were almost exclusively introduced honeybees and bumblebees, indicating an invasive mutualism. We investigated the pollination system of banana passionfruit by comparing fruit set, fruit size, seed set, and germination success between hand-selfed, hand-crossed, bagged and open flowers, and inbreeding depression in seedlings grown in competition. Fruit set was reduced by 83% when pollinators were excluded (3.0% fruit set, compared with 18.0% for unmanipulated flowers) indicating reliance on pollinators for reproduction. While banana passionfruit is partially self-compatible, fruit set was significantly reduced in hand-selfed flowers (17.5%) compared with crossed flowers (29.5%), and we found significant pollen limitation (hand-crossed vs unmanipulated, Pollen Limitation Index = 0.39). There was no significant inbreeding depression found in fruit size, seeds per fruit, germination success, seedling growth or seedling survival. Combining these data showed that natural unmanipulated flowers produce more seedlings per flower (1.7) than bagged flowers (0.9), but fewer than hand-selfed (3.0) and hand-crossed (5.3) flowers. Thus, reproduction in Passiflora tripartita var. mollissima is facilitated by an (imperfect) new association with exotic bees.

A research strategy for biodiversity conservation on New Zealand’s offshore islands

Wed, 14 Dec 2011 00:00:00 -0800

David R. Towns, Peter J. Bellingham, Christa P. H. Mulder and Phil O’B. Lyver
NZJEcol 36(1):1–20 (2012)
Abstract. New Zealand’s offshore islands are refuges for many threatened species, a high proportion of vertebrate diversity, and the world’s most diverse fauna of seabirds. We present key issues and questions that can be used to guide research on the conservation of biodiversity on these islands. Four global reviews formed a basis from which we identified research questions of potential relevance to the management of these islands. The research questions were assigned in the context of nine objectives proposed as a means of achieving ecological integrity. For each of the nine objectives, we then asked what has been achieved in terms of island research and management, and what needs to be achieved in order to meet long-term goals. We used local examples to identify issues and questions specific to the islands of New Zealand. Our analyses revealed two research areas in which current understanding is poor. One is the need to understand ecosystem processes and their resilience to long-term environmental change. The second is the need to define and better understand the consequences of direct involvement by the public in the management of islands, including partnerships between government agencies, tangata whenua (original people of the land – Maori) and non-government organisations such as community groups.

Modelling the distribution of stoats on New Zealand offshore islands

Wed, 14 Dec 2011 00:00:00 -0800

Andrew J. Veale, Oliver D. Hannaford, James C. Russell and Mick N. Clout
NZJEcol 36(1):38–47 (2012)
Abstract. Establishing the factors that correlate with the distribution of invasive species on islands provides a means of evaluating invasion potential and pathways, and enables the invasion risk for specific areas to be predicted. These island risk profiles then provide a basis for conservation managers to prioritise conservation areas, and to create appropriate monitoring regimes. In New Zealand, stoats (Mustela erminea) are invasive predators responsible for numerous local extinctions of birds, and they present a significant invasion risk for offshore islands. Here we examine the distribution of stoats on New Zealand's offshore islands in order to establish what factors are correlated with their distribution, and predict which islands display a high invasion risk. Data on the distribution of stoats were compiled, along with the characteristics of New Zealand's islands and their settlement history. The distribution of stoats on these islands was regressed on island characteristics using a logistic generalised linear model. Species interactions were examined by including the distribution of a range of other introduced mammalian species. The distribution of stoats was found to be strongly affected by the distance offshore and by the area of the island. No significant correlations with the extent of human settlement or the presence of other animals were detected. The model indicates that the invasibility of islands by stoats has been underestimated. Islands within 1 km of the mainland have a very high stoat invasion risk, which is consistent with known invasions, and for large islands (≥ 500 ha) there remains a significant risk to at least 3 km offshore. This model provides a framework for assessing risks of stoat incursion and makes specific predictions of islands with a significant invasion risk that have not had stoats detected before.

Potential for invasive mammalian herbivore control to result in measurable carbon gains

Mon, 16 Apr 2012 00:00:00 -0700

Robert J. Holdaway, Larry E. Burrows, Fiona E. Carswell and Anna E. Marburg
NZJEcol 36(2):252–264 (2012)
Abstract. Invasive mammalian herbivores (e.g. deer, feral goats and brushtail possums; hereafter ‘herbivores’) are widespread throughout New Zealand and their control is important for conservation. In addition to known biodiversity benefits, it has recently been suggested that herbivore control could lead to measureable carbon gains when aggregated across a large area of conservation land. However, a significant amount of uncertainty exists regarding the potential effects of herbivore control on carbon, and the practicalities of successfully implementing such projects. This paper provides a general basis for managers and ecologists to design scientifically robust herbivore control projects for carbon gain in New Zealand. Although there are few direct data on changes in carbon sequestration rates following herbivore control, the data that are available suggest that effect sizes are likely to be small in magnitude, variable in direction, and to occur primarily though complex indirect mechanisms. The largest positive effects of herbivore control (carbon sequestration rate of 1–2 Mg C ha^–1 year^–1) are likely to occur in localised areas of highly palatable early-successional vegetation and high herbivore densities where control initiates rapid development of woody vegetation. Project location is therefore critical in determining the potential for carbon gain in herbivore control projects. A power analysis reveals that the ability to monitor changes in carbon stock using plot-based methods is limited to effect sizes of > 0.5 Mg C ha^–1 year^–1, as smaller effect sizes would require an impractically large number of plots (i.e. >100), and the financial and carbon costs of implementing the control and quantifying the effects are likely to outweigh any potential carbon gains. Although more research is urgently required to quantify potential gains, and the mechanisms that underlie them, our findings suggest that with careful site selection, implementation, and monitoring, control of invasive mammalian herbivores could sometimes provide carbon gains in certain areas of New Zealand’s indigenous vegetation.

Sensitivity of GIS patterns to data resolution: a case study of forest fragmentation in New Zealand

Mon, 16 Apr 2012 00:00:00 -0700

Charlotte Staples, Sadia Ahmed and Robert M. Ewers
NZJEcol 36():0 (2012)
Abstract. Spatial pattern plays an influential role in the ecological processes of ecosystems, and landscape pattern metrics computed from remotely sensed data offer a way to quantify the correlation between pattern and process. However, the resolution of geographic data affects the landscape metrics obtained from a GIS, with consequent implications for the interpretation of biological effects studied at landscape scales. Here, we studied the effect of data resolution on estimates of three metrics of forest cover commonly used in the landscape ecology literature: percent forest cover, forest edge density, and mean fractal dimension of forest patches. Estimates of each metric were computed for six landscapes (30 × 30 km) in the North Island of New Zealand at 10 different data resolutions with pixels ranging from 30 to 1000 m. All three metrics exhibited significant changes in value as a result of changing resolution, and the sensitivity of the fragmentation metrics to data resolution was impacted in a non-linear manner by the amount of forest cover in a landscape. In landscapes with low forest cover, changing pixel size altered estimates of percent forest cover by as much as 75%. Extrapolation to correct for effects of changing resolution and different landscapes seems a likely solution in the case of some, but not all, metrics. The scaling problem hinders efforts to correlate spatial pattern with ecosystem process and the subsequent conclusions concerning biodiversity and conservation policy.

Quantifying the benefits of long-term integrated pest control for forest bird populations in a New Zealand temperate rainforest

Mon, 16 Apr 2012 00:00:00 -0700

Colin F. J. O’Donnell and Joanne M. Hoare
NZJEcol 36(2):131–140 (2012)
Abstract. The control of introduced mammalian predators has become a standard response to protecting the viability of threatened wildlife species on oceanic islands. However, examples of successful outcomes of integrated pest control in forests are few. We investigated the efficacy of a pest control programme in the Landsborough Valley, New Zealand, during 1998–2009, which used continuous trapping to control mustelids and pulsed aerial application of the toxin 1080 to control rats (Rattus spp.) and brushtail possums (Trichosurus vulpecula). We predicted recovery in the populations of mohua (Mohoua ochrocephala) and other predator-sensitive hole-nesting birds and maintenance of numbers of South Island kaka (Nestor meridionalis meridionalis). In addition, we examined whether annual mean counts of mohua and kaka, as potential ‘population indicator species’, could predict those of other forest bird species. Annual counts of nine species (eight indigenous: bellbird Anthornis melanura, brown creeper Mohoua novaeseelandiae, fantail Rhipidura fuliginosa, grey warbler Gerygone igata, mohua, rifleman Acanthisitta chloris, tui Prosthemadera novaeseelandiae and yellow-crowned parakeet Cyanoramphus auriceps; one introduced: song thrush Turdus philomelos) showed significant increases during the 12-year study period. South Island kaka and redpoll (Carduelis flammea) showed no change with time. In general, trends in the two focal threatened taxa (mohua and kaka) were poor predictors of trends in other bird species. Lack of correlation in annual counts between bird species that share a recovery trajectory are likely due to differences in breeding biology and resource use. Our results suggest that an integrated strategy for predator management is effective at mitigating the impacts of predation by introduced mammals on forest birds, including the most vulnerable species, at a landscape scale.

Sensitivity of GIS patterns to data resolution: a case study of forest fragmentation in New Zealand

Mon, 16 Apr 2012 00:00:00 -0700

Charlotte Staples, Sadia Ahmed and Robert M. Ewers
NZJEcol 36(2):203–209 (2012)
Abstract. Spatial pattern plays an influential role in the ecological processes of ecosystems, and landscape pattern metrics computed from remotely sensed data offer a way to quantify the correlation between pattern and process. However, the resolution of geographic data affects the landscape metrics obtained from a GIS, with consequent implications for the interpretation of biological effects studied at landscape scales. Here, we studied the effect of data resolution on estimates of three metrics of forest cover commonly used in the landscape ecology literature: percent forest cover, forest edge density, and mean fractal dimension of forest patches. Estimates of each metric were computed for six landscapes (30 × 30 km) in the North Island of New Zealand at 10 different data resolutions with pixels ranging from 30 to 1000 m. All three metrics exhibited significant changes in value as a result of changing resolution, and the sensitivity of the fragmentation metrics to data resolution was impacted in a non-linear manner by the amount of forest cover in a landscape. In landscapes with low forest cover, changing pixel size altered estimates of percent forest cover by as much as 75%. Extrapolation to correct for effects of changing resolution and different landscapes seems a likely solution in the case of some, but not all, metrics. The scaling problem hinders efforts to correlate spatial pattern with ecosystem process and the subsequent conclusions concerning biodiversity and conservation policy.

First coprolite evidence for the diet of Anomalopteryx didiformis, an extinct forest ratite from New Zealand

Tue, 01 May 2012 00:00:00 -0700

Jamie R. Wood, Janet M. Wilmshurst, Trevor H. Worthy and Alan Cooper
NZJEcol 36(2):164–170 (2012)
Abstract. Evidence of diet has been reported for all genera of extinct New Zealand moa (Aves: Dinornithiformes), using preserved gizzard content and coprolites, except the forest-dwelling Anomalopteryx. Skeletal features of the little bush moa (Anomalopteryx didiformis) have led to competing suggestions that it may have either browsed trees and shrubs or grubbed for fern rhizomes. Here, we analyse pollen assemblages from two coprolites, identified by ancient DNA analysis as having been deposited by Anomalopteryx didiformis. The pollen results, together with identified fragments of leaf cuticles from the coprolites, support the hypothesis that Anomalopteryx didiformis browsed trees and shrubs in the forest understorey.

Seed dispersal of matai (Prumnopitys taxifolia) by feral pigs (Sus scrofa)

Tue, 01 May 2012 00:00:00 -0700

Sarah-Jane O’Connor and Dave Kelly
NZJEcol 36(2):228–231 (2012)
Abstract. Introduced feral pigs (Sus scrofa) include native fruit and seed in their diet, and thus may act as seed dispersers if seeds are passed intact. The aim of this study was to determine whether pigs consume, and subsequently disperse, intact seeds of the New Zealand native tree matai (Prumnopitys taxifolia). Two captive pigs were fed 100 ripe fruit of matai and their faeces were checked for seeds for 4 days. Fourteen intact seeds (14%) were recovered and 57% of these germinated under glasshouse conditions, comparable with germination from hand-cleaned seeds. We collected 3.5 kg of feral pig faeces from matai-dominated forest in Isolated Hill Reserve, southern Marlborough. This sample contained over 450 intact matai seeds; these seeds readily germinated in the glasshouse, reaching 68% germination after 22 months. These results indicate that pigs are consuming native fruit and passing some viable seeds out – thus potentially acting as occasional seed dispersers.

Assessment of microbranding as an alternative marking technique for long-term identification of New Zealand lizards

Tue, 01 May 2012 00:00:00 -0700

Rod Hitchmough, Keri Neilson, Kara Goddard, Mike Goold, Brett Gartrell, Stu Cockburn and Nicholas Ling
NZJEcol 36(2):151–156 (2012)
Abstract. ‘Microbranding’, a system for individually identifying reptiles and amphibians based on a numbered code of spot brands applied to the body and limbs, was tested on New Zealand skinks and geckos. Common geckos (Woodworthia maculata) and copper skinks (Oligosoma aeneum) were used as test animals. Brands applied in autumn took 3 months or more to heal. There was no evidence of brand-related mortality or increased parasite loads in branded animals. However, after healing the brands faded very rapidly in the skinks to become totally unreadable in all surviving branded skinks after 2.5 years and not accurately readable in most geckos after 3 years. We therefore consider the technique unsuitable as a standard marking procedure for New Zealand lizards.