scholarly journals Survival, predation, and behaviour of the Mahoenui giant wētā ('Deinacrida mahoenui': Anostostomatidae: Orthoptera)

2021 ◽  
Author(s):  
◽  
Hannah Stilborn

<p>Introduced mammalian pests, such as rats (Rattus spp.), house mice (Mus musculus), brushtail possums (Trichosurus vulpecula), and European hedgehogs (Erinaceus europaeus), have been implicated in the suppression or extinction of many endemic invertebrate species in New Zealand, including the large-bodied giant wētā (Anostostomatidae: Deinacrida). The Mahoenui giant wētā (MGW; D. mahoenui) is the only lowland giant wētā species still naturally present on the mainland of New Zealand, where the last remaining individuals of the original population are currently restricted to an 187ha mainland reserve (Mahoenui Giant Wētā Scientific Reserve; MGWSR) in Mahoenui, western King Country. Having sought refuge in the introduced woody shrub, gorse (Ulex europaeus), these wētā have survived in the presence of introduced mammalian predators for almost six decades. However, due to natural succession, the reserve is gradually reverting to native bush and wētā monitoring data shows potential signs of population decline. Concerns for the species survival have been raised as it is unknown how wētā will cope in an altered habitat alongside mammalian predators.  In chapter 2, we used 14-years’ of site-occupancy monitoring data to explore changes to the reserves’ gorse mosaic and MGW population. We additionally assessed the effect of abiotic covariates on MGW occupancy and detection probabilities in 2005 and 2018. Furthermore, we assessed mammalian pest population dynamics within the reserve over the past seven years. Significant changes to the reserve’s gorse mosaic were identified, whereby unbrowsed, tall bushes, which may provide less protection to wētā, are now dominant in 2018. Population trajectory analysis revealed the MGW population has decline since 2012. This result was consistent with naïve occupancy estimates and the increase in search time (0.3hrs/year) required to find wētā, suggesting the population is in a state of decline. Plot location was identified as an important covariate for predicting MGW occupancy in 2018, whereby plots in edge habitat, potentially being preferred or safer, had a higher occupancy probability. Mammalian pests (rats, house mice, brushtail possums, and European hedgehogs) appear to be present within the reserve year-round, populations peaking in summer and autumn.  In chapter 3, we used radiotelemetry to explore MGW survival rates, movement patterns, and diurnal refuge use in gorse and native vegetation during summer (n=14), autumn (n=31), and spring (n=10). Survival rates, in relation to predation, revealed MGW inhabiting native vegetation were nine times more likely to be predated than those inhabiting gorse. This result suggests native species such as mahoe (Melicytus ramiflorus), and tree ferns (Dicksonia fibrosa and Cyathea spp.) do not provide good protection to MGW from mammalian predators. Assessment of movement behaviour revealed MGW move less in autumn (~3m/48hrs) compared to summer (~10m/48hrs) and spring (~8m/48hrs), and most commonly follow a movement pattern consistent with random-walk. Movement behaviour was also found to be temperature dependant, with both male and female MGW moving significantly further in warmer weather (>13.5°C). Radiotracked MGW were found to take refuge above 2.5m in the canopy of native vegetation, whereas in gorse habitat, wētā were most commonly found taking refuge between 0.62 – 2.38m in the denser foliage of unbrowsed gorse bushes. Furthermore, no radiotracked wētā were observed with another individual in autumn, compared to eight and 26 observations in summer and spring.  In chapter 4, we attempted to identify potential mammalian predators of the MGW by analysing the stomach contents of ship rats (R. rattus; n=10), house mice (n=10), brushtail possums (n=5), and feral cats (Felis catus; n=2). Ship rats were identified as likely predators of MGW within the MGWSR. However, due to the limited number of stomachs and species analysed, further analysis is recommended. Collectively, these results provide an overview of the MGW reserve and population status, in addition to important ecological information that can be used to inform future management, monitoring, and translocation.</p>

2021 ◽  
Author(s):  
◽  
Hannah Stilborn

<p>Introduced mammalian pests, such as rats (Rattus spp.), house mice (Mus musculus), brushtail possums (Trichosurus vulpecula), and European hedgehogs (Erinaceus europaeus), have been implicated in the suppression or extinction of many endemic invertebrate species in New Zealand, including the large-bodied giant wētā (Anostostomatidae: Deinacrida). The Mahoenui giant wētā (MGW; D. mahoenui) is the only lowland giant wētā species still naturally present on the mainland of New Zealand, where the last remaining individuals of the original population are currently restricted to an 187ha mainland reserve (Mahoenui Giant Wētā Scientific Reserve; MGWSR) in Mahoenui, western King Country. Having sought refuge in the introduced woody shrub, gorse (Ulex europaeus), these wētā have survived in the presence of introduced mammalian predators for almost six decades. However, due to natural succession, the reserve is gradually reverting to native bush and wētā monitoring data shows potential signs of population decline. Concerns for the species survival have been raised as it is unknown how wētā will cope in an altered habitat alongside mammalian predators.  In chapter 2, we used 14-years’ of site-occupancy monitoring data to explore changes to the reserves’ gorse mosaic and MGW population. We additionally assessed the effect of abiotic covariates on MGW occupancy and detection probabilities in 2005 and 2018. Furthermore, we assessed mammalian pest population dynamics within the reserve over the past seven years. Significant changes to the reserve’s gorse mosaic were identified, whereby unbrowsed, tall bushes, which may provide less protection to wētā, are now dominant in 2018. Population trajectory analysis revealed the MGW population has decline since 2012. This result was consistent with naïve occupancy estimates and the increase in search time (0.3hrs/year) required to find wētā, suggesting the population is in a state of decline. Plot location was identified as an important covariate for predicting MGW occupancy in 2018, whereby plots in edge habitat, potentially being preferred or safer, had a higher occupancy probability. Mammalian pests (rats, house mice, brushtail possums, and European hedgehogs) appear to be present within the reserve year-round, populations peaking in summer and autumn.  In chapter 3, we used radiotelemetry to explore MGW survival rates, movement patterns, and diurnal refuge use in gorse and native vegetation during summer (n=14), autumn (n=31), and spring (n=10). Survival rates, in relation to predation, revealed MGW inhabiting native vegetation were nine times more likely to be predated than those inhabiting gorse. This result suggests native species such as mahoe (Melicytus ramiflorus), and tree ferns (Dicksonia fibrosa and Cyathea spp.) do not provide good protection to MGW from mammalian predators. Assessment of movement behaviour revealed MGW move less in autumn (~3m/48hrs) compared to summer (~10m/48hrs) and spring (~8m/48hrs), and most commonly follow a movement pattern consistent with random-walk. Movement behaviour was also found to be temperature dependant, with both male and female MGW moving significantly further in warmer weather (>13.5°C). Radiotracked MGW were found to take refuge above 2.5m in the canopy of native vegetation, whereas in gorse habitat, wētā were most commonly found taking refuge between 0.62 – 2.38m in the denser foliage of unbrowsed gorse bushes. Furthermore, no radiotracked wētā were observed with another individual in autumn, compared to eight and 26 observations in summer and spring.  In chapter 4, we attempted to identify potential mammalian predators of the MGW by analysing the stomach contents of ship rats (R. rattus; n=10), house mice (n=10), brushtail possums (n=5), and feral cats (Felis catus; n=2). Ship rats were identified as likely predators of MGW within the MGWSR. However, due to the limited number of stomachs and species analysed, further analysis is recommended. Collectively, these results provide an overview of the MGW reserve and population status, in addition to important ecological information that can be used to inform future management, monitoring, and translocation.</p>


2003 ◽  
Vol 30 (4) ◽  
pp. 377 ◽  
Author(s):  
Chris Jones ◽  
Susan Bettany ◽  
Henrik Moller ◽  
David Fletcher ◽  
Justine de Cruz

Breeding colonies of sooty shearwaters ('muttonbird', tïtï, Puffinus griseus) on mainland New Zealand have declined in recent years. New data on burrow occupancy and colony productivity for seven sooty shearwater breeding colonies on the coast of Otago, New Zealand for the 1996–97 and 1997–98 breeding seasons are presented and analysed as part of a five-year data set. Detection of a burrow's occupants using a fibre-optic burrowscope may underestimate absolute occupancy rates, but is still of value in the analysis of trends. Detection probabilities estimated by the novel use of mark–recapture models corresponded with those of previous studies of the technique's accuracy. Mainland declines are associated with a lack of control of introduced mammalian predators at most mainland colonies superimposed on a global pattern of decline in the species' abundance. Large numbers of recovered carcasses and an absence of burrow activity at two small mainland colonies show the decline to extinction of these colonies over the five years of collecting data. At one mainland colony with intensive predator control, survival rates and parameter variances are comparable with those found on a predator-free offshore island. All other mainland colonies showed negligible breeding success. There was a significant positive relationship between egg survival and an index of relative adult survival, with an apparent threshold below which few eggs hatch. Adult survival during the breeding season is likely to be the most important parameter in maintaining a colony's viability.


2019 ◽  
Vol 15 (9) ◽  
pp. 20190491 ◽  
Author(s):  
Nicolas Dussex ◽  
Johanna von Seth ◽  
Michael Knapp ◽  
Olga Kardailsky ◽  
Bruce C. Robertson ◽  
...  

Human intervention, pre-human climate change (or a combination of both), as well as genetic effects, contribute to species extinctions. While many species from oceanic islands have gone extinct due to direct human impacts, the effects of pre-human climate change and human settlement on the genomic diversity of insular species and the role that loss of genomic diversity played in their extinctions remains largely unexplored. To address this question, we sequenced whole genomes of two extinct New Zealand passerines, the huia ( Heteralocha acutirostris ) and South Island kōkako ( Callaeas cinereus ). Both species showed similar demographic trajectories throughout the Pleistocene. However, the South Island kōkako continued to decline after the last glaciation, while the huia experienced some recovery. Moreover, there was no indication of inbreeding resulting from recent mating among closely related individuals in either species. This latter result indicates that population fragmentation associated with forest clearing by Maōri may not have been strong enough to lead to an increase in inbreeding and exposure to genomic erosion. While genomic erosion may not have directly contributed to their extinctions, further habitat fragmentation and the introduction of mammalian predators by Europeans may have been an important driver of extinction in huia and South Island kōkako.


2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Angela Brenton-Rule ◽  
Daniel Harvey ◽  
Kevin Moran ◽  
Daniel O’Brien ◽  
Jonathon Webber

Abstract Background Podiatrists in New Zealand have a duty of care to assist patients in an emergency, and current cardiopulmonary resuscitation (CPR) certification is a requirement for registration. However, it is unknown how competent and confident podiatrists are in administering CPR and how they would respond in an emergency. Having a health professional who has a competent knowledge of CPR and skills in basic life support, can improve survival rates from sudden cardiac arrest. Therefore, the aim of this study was to survey New Zealand podiatrists to determine their CPR knowledge and qualifications; beliefs about the application of CPR; and perceptions of their competency in CPR. Methods This cross-sectional study used a web-based survey. Participants were New Zealand registered podiatrists with a current annual practising certificate. The 31-item survey included questions to elicit demographic information, CPR practice and attitudes, and CPR knowledge. Responses were collected between March and August 2020. Results 171 podiatrists responded to the survey. 16 % of the podiatrists (n = 28) had performed CPR in an emergency, with a 50 % success rate. Participants were predominantly female (n = 127, 74 %) and working in private practice (n = 140,82 %). Nearly half of respondents were younger than 40 years (n = 75,44 %) and had less than 10 years of clinical experience (n = 73, 43 %). Nearly all (n = 169,97 %) participants had received formal CPR training in the past two years, with 60 % (n = 105) receiving training in the past 12 months. Most respondents (n = 167,98 %) self-estimated their CPR ability as being effective, very effective, or extremely effective. Participants’ knowledge of CPR was variable, with the percentage of correct answers for CPR protocol statements ranging between 20 and 90 %. Conclusions This study provides the first insight into New Zealand podiatrists’ CPR knowledge and perceptions. Podiatrists were found to have high levels of CPR confidence but demonstrated gaps in CPR knowledge. Currently, New Zealand registered podiatrists require biennial CPR re-certification. However, resuscitation authorities in New Zealand and overseas recommend an annual update of CPR skills. Based on this study’s findings, and in line with Australia and the United Kingdom, the authors recommend a change from biennial to annual CPR re-certification for podiatrists in New Zealand. Trial registration The study was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12620001144909).


2021 ◽  
Author(s):  
Natalia F Versiani ◽  
Larissa L Bailey ◽  
Nielson Pasqualotto ◽  
Thiago F Rodrigues ◽  
Roberta M Paolino ◽  
...  

Abstract The drastic reduction of the Brazilian Cerrado has transformed this savanna hotspot into vast swaths of commodity-based agriculture fields, mainly soybean, sugarcane, and beef-production pasturelands. The resulting habitat loss and fragmentation are the principal factors underlying population decline of native species inhabiting the Cerrado, particularly those with a high demand for space, low population density, and specialized diet, such as the endangered giant anteater (Myrmecophaga tridactyla). Although the species has been studied in protected areas, we know much less about its ability to endure in disturbed landscapes. Here, we analyzed camera-trapping data to estimate a proxy of habitat use (ψ^; occupancy) and detection probabilities of the giant anteater, identifying environmental covariates influencing these parameters in landscapes with intensive agriculture and commercial forestry. We found this species using about half of the study area (model average ψ^ = 0.51, CI = 0.40–0.62), with two predictors strongly influencing habitat use: protected areas and unpaved roads. In turn, detection probability correlates positively with area of open Cerrado and negatively with area of settlements. The species is more likely to use unpaved roads inside protected areas (ψ^ = 0.90, CI = 0.47–0.75), compared to off road sites in the surrounding areas (ψ^ = 0.19, CI = 0.10–0.34). Our findings indicate that giant anteaters are dependent on nature reserves and native vegetation areas existing on private properties, whose protection is regulated by the Brazilian Native Vegetation Protection Law. Given the relative paucity of state-owned protected areas in the Brazilian Cerrado, increasing the adherence of rural owners to this law is, therefore, key for the conservation of the giant anteater. The intense use of unpaved roads might reflect travelling and/or foraging optimization, a behavioral response that, nevertheless, may compound this species’ susceptibility to suffer mortality from roadkill.


2007 ◽  
Vol 121 (2) ◽  
pp. 150
Author(s):  
Vanessa B. Harriman ◽  
Justin A. Pitt ◽  
Serge Larivière

Ground-nesting birds typically experience high predation rates on their nests, often by mammalian predators. As such, researchers and wildlife managers have employed numerous techniques to mitigate nest predation. We investigated the use of scents as repellents to deter predators from both artificial and natural ground nests. Survival rates of artificial nests did not differ among six groups of substances (Wald ?2 df = 5 = 4.53, P < 0.48); however the chronology of predation among groups differed. A commercial Coyote urine based deterrent (DEER-D-TERTM), human hair, and Worcestershire sauce were depredated faster than the control (F4,5 = 40.3, P < 0.001). Nest survival of natural nests differed among those groups tested (Wald ?2 df = 2 = 11.8, P < 0.005); the eight mothball treatment decreased survival (Wald ?2 df = 1 = 11.5, P < 0.005), which indicated that novel smells may attract predators or result in duck nest abandonment when coupled with natural duck scent. Chronologies of predation events among treatment groups were not different for natural nests (F2,3 = 1.9, P = 0.22). These findings indicate an interaction between novel scents and predator olfactory cues.


2021 ◽  
Author(s):  
◽  
Roald Egbert Harro Bomans

<p>Introduced mammalian predators, namely possums, stoats and rats, are the leading cause of decline in native avifauna in New Zealand. The control of these species is essential to the persistence of native birds. A major component of mammal control in New Zealand is carried out through the aerial distribution of the toxin sodium monofluoroacetate (otherwise known as 1080). The use of this toxin, however, is subject to significant public debate. Many opponents of its use claim that forests will ‘fall silent’ following aerial operations, and that this is evidence of negative impacts on native bird communities. With the continued and likely increased use of this poison, monitoring the outcomes of such pest control operations is necessary to both address these concerns and inform conservation practice. The recent growth in autonomous recording units (ARUs) provides novel opportunities to conduct monitoring using bioacoustics. This thesis used bioacoustic techniques to monitor native bird species over three independent aerial 1080 operations in the Aorangi and Rimutaka Ranges of New Zealand.  In Chapter 2, diurnal bird species were monitored for 10-12 weeks over two independent operations in treatment and non-treatment areas. At the community level, relative to non-treatment areas, the amount of birdsong recorded did not decrease significantly in treatment areas across either of the operations monitored. At the species level, one species, the introduced chaffinch (Fringilla coelebs), showed a significant decline in the prevalence of its calls in the treatment areas relative to non-treatment areas. This was observed over one of the two operations monitored. Collectively, these results suggest that diurnal native avifaunal communities do not ‘fall silent’ following aerial 1080 operations.  The quantity of data produced by ARUs can demand labour-intensive manual analysis. Extracting data from recordings using automated detectors is a potential solution to this issue. The creation of such detectors, however, can be subjective, iterative, and time-consuming. In Chapter 3, a process for developing a parsimonious, template-based detector in an efficient, objective manner was developed. Applied to the creation of a detector for morepork (Ninox novaeseelandiae) calls, the method was highly successful as a directed means to achieve parsimony. An initial pool of 187 potential templates was reduced to 42 candidate templates. These were further refined to a 10-template detector capable of making 98.89% of the detections possible with all 42 templates in approximately a quarter of the processing time for the dataset tested. The detector developed had a high precision (0.939) and moderate sensitivity (0.399) with novel recordings, developed for the minimisation of false-positive errors in unsupervised monitoring of broad-scale population trends.  In Chapter 4, this detector was applied to the short-term 10-12 week monitoring of morepork in treatment and non-treatment areas around three independent aerial 1080 operations; and to longer-term four year monitoring in two study areas, one receiving no 1080 treatment, and one receiving two 1080 treatments throughout monitoring. Morepork showed no significant difference in trends of calling prevalence across the three independent operations monitored. Longer-term, a significant quadratic effect of time since 1080 treatment was found, with calling prevalences predicted to increase for 3.5 years following treatment. Collectively, these results suggest a positive effect of aerial 1080 treatment on morepork populations in the lower North Island, and build on the small amount of existing literature regarding the short- and long-term response of this species to aerial 1080 operations.</p>


2021 ◽  
Author(s):  
◽  
Cherie Balls

<p>Introduced mammalian predators are one of the largest conservation threats to New Zealand native flora and fauna, and there is an increasing concern about their presence in urban environments, coupled with a recognition that cities present a unique opportunity for ecological restoration, due to the availability of a large number of volunteers and options for intensive management of green spaces and gardens. Predator control is an essential step towards the ecological restoration of urban environments, however, it requires an understanding of the factors influencing the distribution of these mammalian predators before successful control operations can be implemented. Few studies have investigated mammalian predators in urban environments, and there is little certainty about what drives their distribution in these environments. This thesis used simple mammal monitoring techniques and trapping data to investigate the distribution of mammalian predators within broad scale urban environments, with the aim of identifying drivers of their distribution.  Chew cards and tracking tunnels collected across three New Zealand cities were assessed for their efficacy as accurate monitoring devices in urban environments. In Chapter 2, monitoring devices were cross-checked between observers to assess the level of consistency in interpretation of chew and tracking marks. The consistency of chew card and tracking tunnel identifications was relatively high overall and were not substantially influenced by the city of identification, or the duration of card exposures. Monitoring devices were also assessed for their change in sensitivity between one and six-night exposures. Both devices were effective at detecting rats, however, tracking tunnels showed greater sensitivity and consistency in detecting mice and hedgehogs, whereas chew cards were better suited to the monitoring of possums. Neither device was particularly effective at detecting mustelids or cats.  In Chapter 3, mammalian predators were monitored across 24 monitoring lines in autumn, 2018, and results were compiled with spring 2017 and autumn 2018 data, pre-collected in two other cities, following the same procedures. There were distinct differences in the broad-scale habitat utilisation of rats, mice, hedgehogs, with possums being the only species to show a strong preference for urban forests. Only two of the tested microhabitat variables had an influence on species distributions. Detection of rats declined with increasing distance to the coast, and the increase in human population size was related to a significant increase in hedgehogs. There was a strong seasonal difference on the influence of local trap density and the detection of mammals. The increase in trap density within 25-50m radii was significantly related to a decrease in rat and hedgehog detections. Overall, there are substantial differences between the distributions of species in an urban environment.  Trapping is one of the main methods of predator control in New Zealand, and is already widespread within urban and suburban Wellington. In Chapter 4, I compiled trap data from 22 community trapping groups operating in residential and reserve areas in Wellington City. Residential groups (“backyard trappers”) used a high proportion of Victor and various rat and mouse traps, which was strongly linked to their high number of rat and mouse catches. Groups trapping in reserves used a high proportion of DOC 200, Victor and A24 traps, however, fewer hedgehogs were caught compared to residential areas. Catches were significantly influenced by various landscape variables. An increased distance of traps to streams led to significantly higher catches of rats, conversely, proximity to streams resulted in significantly higher catches of mice and hedgehogs. Although few catches of weasels were reported, traps closer to the coast and to forest fragments caught significantly more individuals.  The research in this thesis contributes to the small body of research conducted on mammalian predators within urban environments. The findings in this thesis can assist with the current and future predator management programmes, by highlighting areas of potential significance, particularly in Wellington.</p>


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