Invasive predators represent the greatest extinction threat to the endangered northern bettong (Bettongia tropica)

2018 ◽  
Vol 45 (3) ◽  
pp. 208 ◽  
Author(s):  
Tegan Whitehead ◽  
Karl Vernes ◽  
Miriam Goosem ◽  
Sandra E. Abell
Keyword(s):  
Climate Change ◽  
Synergistic Effects ◽  
Management Strategies ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Active Management ◽  
Feral Cats ◽  
Juvenile Mortality ◽  
Management Actions ◽  
Eastern Australia

Context Identification of key threats to endangered species is vital for devising effective management strategies, but may be hindered when relevant data is limited. A population viability approach may overcome this problem. Aims We aimed to determine the population viability of endangered northern bettongs (Bettongia tropica) in north-eastern Australia. We also assessed the key threats to the population resilience and how the population viability responds to increases in mortality rates and changes in fire and drought frequency. Methods Using population viability analysis (PVA) we modelled survival probability of B. tropica populations under likely scenarios, including: (1) increased predation; (2) changes in drought and fire frequency predicted with anthropogenic climate change; and (3) synergistic effects of predation, fire and drought. Key results Population viability models suggest that populations are highly vulnerable to increases in predation by feral cats (Felis catus), and potentially red fox (Vulpes vulpes) should they colonise the area, as juvenile mortality is the main age class driving population viability. If B. tropica become more vulnerable to predators during post-fire vegetation recovery, more frequent fires could exacerbate effects of low-level cat predation. In contrast, it was predicted that populations would be resilient to the greater frequency of droughts expected as a result of climate change, with high probabilities of extinctions only predicted under the unprecedented and unlikely scenario of four drought years in 10. However, since drought and fire are interlinked, the impacts of predation could be more severe with climate change should predation and fire interact to increase B. tropica mortality risk. Conclusion Like other Potoroids, B. tropica appear highly vulnerable to predation by introduced mammalian predators such as feral cats. Implications Managers need information allowing them to recognise scenarios when populations are most vulnerable to potential threats, such as drought, fire and predation. PVA modelling can assess scenarios and allow pro-active management based on predicted responses rather than requiring collection of extensive field data before management actions. Our analysis suggests that assessing and controlling predator populations and thereby minimising predation, particularly of juveniles, should assist in maintaining stability of populations of the northern bettong.

scholarly journals Use of Bayesian population viability analysis to assess multiple management decisions in the recovery programme for the Endangered takahe Porphyrio hochstetteri

Oryx ◽  
2013 ◽  
Vol 47 (1) ◽  
pp. 144-152 ◽  
Author(s):  
Danilo Hegg ◽  
Darryl I. MacKenzie ◽  
Ian G. Jamieson
Keyword(s):  
Probability Distributions ◽  
Management Strategies ◽  
Population Viability Analysis ◽  
Experimental Manipulation ◽  
Population Modelling ◽  
Deterministic Models ◽  
Logistic Regression Models ◽  
Viability Analysis ◽  
Management Actions ◽  
Captive Rearing

AbstractPopulation modelling is an invaluable tool for identifying effective management strategies for threatened species whose populations are too small for experimental manipulation. Recently developed Bayesian approaches allow us to combine deterministic models with probability distributions to create stochastic models that account for uncertainty. We illustrate this approach in the case of the takahe Porphyrio hochstetteri, an Endangered flightless rail, which is supported by one of New Zealand's costliest recovery programmes. Using mark–recapture and logistic regression models implemented in a Bayesian framework we calculated demographic parameters for a fully stochastic population model based on 25 years of data collected from the last wild population of takahe in the Murchison Mountains, Fiordland. Our model results show that stoat trapping, captive rearing and cross-fostering of eggs/chicks in wild pairs all have a positive effect on takahe demography. If it were not for these management actions the Fiordland population would probably be declining (λ = 0.985; confidence interval, CI = 0.39–1.08), with a non-negligible risk of quasi-extinction (P = 16%) within 20 years. The captive rearing of eggs and chicks has been the main factor responsible for the positive growth observed during the last decade but in the future expanding stoat trapping to cover the entire Murchison Mountains would be the single most beneficial management action for the takahe population (λ = 1.038; CI = 0.86–1.10), followed by captive rearing (λ = 1.027; CI = 0.85–1.09).

scholarly journals Stormwater Management in a Time of Climate Change: Insights from a Series of Scenario-Building Dialogues

2016 ◽  
Vol 8 (2) ◽  
pp. 163-175 ◽  
Author(s):  
Seth P. Tuler ◽  
Thomas Webler ◽  
Jason L. Rhoades
Keyword(s):  
Climate Change ◽  
Stormwater Management ◽  
Scientific Information ◽  
Management Strategies ◽  
Climate Change Impacts ◽  
Contextual Knowledge ◽  
Public And Private ◽  
Human Environment ◽  
Management Actions ◽  
Trade Offs

Abstract Numerous decision support tools have been developed to assist stormwater managers to understand future scenarios and devise management strategies. This paper presents one such tool, the Vulnerability, Consequences, and Adaptation Planning Scenarios (VCAPS) process, and reports on experiences from its deployment in 10 coastal communities on the Atlantic and Gulf coasts. VCAPS helps to elucidate local complexities, couplings, and contextual nuance through dialogue among technical experts and those with detailed contextual knowledge of a community. Participants in the process develop qualitative scenarios of climate change impacts and how different management strategies may prevent or mitigate undesirable consequences. The scenarios help stormwater managers diagnose potential problems that may emerge from climate change and variability, which can then be subject to further detailed analysis. The authors describe five challenges faced by stormwater managers and how insights that emerge from scenario-based processes like VCAPS can help address them: characterizing the implications of interacting climate stressors that originate stormwater, bringing all available expertise and local knowledge to bear on the problem of stormwater management, integrating local and scientific information about coupled human–environment systems, identifying management actions and their trade-offs, and facilitating planning for sustained coordination among multiple public and private entities.

Habitat use and movements of Australian grayling (Prototroctes maraena) in a Victorian coastal stream

2018 ◽  
Vol 69 (8) ◽  
pp. 1259 ◽  
Author(s):  
D. R. Dawson ◽  
W. M. Koster
Keyword(s):  
Habitat Use ◽  
Conservation Management ◽  
Radio Telemetry ◽  
Management Strategies ◽  
Movement Ecology ◽  
Ecological Requirements ◽  
Management Actions ◽  
Eastern Australia ◽  
The World ◽  
Australian Grayling

Riverine fishes are among the most imperilled fauna in the world; however, for many species, there is little or no understanding of their ecological requirements. The Australian grayling (Prototroctes maraena) is a small diadromous fish endemic to rivers in south-eastern Australia that has declined considerably in range and abundance and is listed as threatened nationally. To improve understanding of the species’ movement ecology and to inform the development of conservation management actions, we examined the day-to-day movements and habitat use of Australian grayling (n=7) over 8 weeks by using radio-telemetry. Tagged individuals of Australian grayling typically occupied restricted (i.e. tens to hundreds of metres) reaches of stream, and were mostly located in moderate- to fast-flowing habitats (i.e. glide or run), although, at night, use of slower-flowing habitats (i.e. pools) increased. They also undertook longer-distance downstream movements during a period of increased streamflow. Incorporation of such information into management strategies has the potential to improve our capacity to maintain or re-instate the conditions required to conserve and restore Australian grayling populations.

Using Population Viability Analysis to Predict the Effects of Climate Change on the Extinction Risk of an Endangered Limestone Endemic Shrub, Arizona Cliffrose

2006 ◽  
Vol 20 (1) ◽  
pp. 218-228 ◽  
Author(s):  
JOYCE MASCHINSKI ◽  
JOANNE E. BAGGS ◽  
PEDRO F. QUINTANA-ASCENCIO ◽  
ERIC S. MENGES
Keyword(s):  
Climate Change ◽  
Extinction Risk ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Viability Analysis

Viability analyses of an endangered donkey breed: the case of the Asinina de Miranda (Equus asinus)

2015 ◽  
Vol 55 (9) ◽  
pp. 1184 ◽  
Author(s):  
M. Quaresma ◽  
A. M. F. Martins ◽  
J. B. Rodrigues ◽  
J. Colaço ◽  
R. Payan-Carreira
Keyword(s):  
Neonatal Mortality ◽  
Management Strategies ◽  
Population Viability Analysis ◽  
Critical Factor ◽  
Mortality Rates ◽  
Population Viability ◽  
Analysis Program ◽  
Female Mortality ◽  
Viability Analysis ◽  
Equus Asinus

The donkey breed Asinina de Miranda, with fewer than 1000 breeding females, is in danger of extinction. The objectives of this study were to predict the progression of the breed under present management and identify determinants for survival, by means of a population viability analysis program, in order to suggest suitable management strategies. The simulation showed a high risk of extinction. The most critical factor for breed survival was the percentage of females breeding per year, but the actual percentage needed depended on the carrying capacity of the breed. Reducing female mortality and age at production of first offspring, assuring registration in the Studbook, and tracking the foals will significantly foster this donkey breed’s recovery and maintenance. The breed comprised a potentially reproductive population of 589 individuals; however, just 54.1% of the adult females registered in the Studbook ever foaled, and of these 62.7% foaled just once. The overall neonatal mortality for the first month of life was 8.92% and was lower in females (6.51%) than in males (12.0%) (P = 0.028). Neonatal mortality was unevenly distributed throughout the year, with lower mortality rates recorded in February–May and October–November, and higher mortality rates in June–September and again in December–January. The neonatal foal mortality rate was lower with females aged 5–15 years (8.06%) than those younger than 4 years (10.3%) or older than 16 years (14.1%) at foaling.

Modelling the determinants of ignition in the Sydney Basin, Australia: implications for future management

2013 ◽  
Vol 22 (4) ◽  
pp. 469 ◽  
Author(s):  
T. D. Penman ◽  
R. A. Bradstock ◽  
O. Price
Keyword(s):  
Climate Change ◽  
Urban Expansion ◽  
Management Strategies ◽  
Fire Weather ◽  
Biomass Growth ◽  
Effective Management ◽  
Variable Effect ◽  
Eastern Australia ◽  
Insight Into ◽  
Future Management

Variations in area burnt by fire are governed by four processes: biomass growth, availability to burn, fire weather and ignitions. Insight into these how these processes are shaped by biophysical and human influences is required to underpin the development of effective management strategies. Patterns of natural and arson ignitions were examined within the densely populated Sydney region of south-eastern Australia to determine the extent to which management can alter the risk of ignition. Arson ignitions were more likely on ridges in association with human infrastructure, i.e. roads and houses. Lightning ignitions also occurred more frequently on ridges, but at greater distances from human infrastructure. These patterns are consistent with those reported in studies from forested regions in the northern hemisphere. Fuel age had a variable effect with lightning more likely in older fuels (>25 years) and arson more likely in younger fuels (<10 years). Probability of both ignition types increased under more severe fire weather. Climate change is predicted to increase the severity of fire weather and is therefore likely to result in an increase in ignition frequency in the Sydney Basin. Urban expansion is also likely to have significant effects on ignitions and resultant risks to people and property via an increase in the probability of arson ignitions.

scholarly journals Predators and genetic fitness: key threatening factors for the conservation of a bettong species

2017 ◽  
Vol 23 (2) ◽  
pp. 200 ◽  
Author(s):  
Carlo Pacioni ◽  
Matthew R. Williams ◽  
Robert C. Lacy ◽  
Peter B. S. Spencer ◽  
Adrian F. Wayne
Keyword(s):  
Management Strategies ◽  
Population Viability Analysis ◽  
Active Management ◽  
Viability Analysis ◽  
Similar Work ◽  
Bettongia Penicillata ◽  
Viable Population ◽  
Threatening Processes ◽  
Minimum Viable Population Size ◽  
Future Work

Globally, many wildlife species are declining and an increasing number are threatened by extinction or are extinct. Active management is generally required to mitigate these trends and population viability analysis (PVA) enables different scenarios to be evaluated and informs management decisions. Based on population parameters obtained from a threatened bettong, the woylie (Bettongia penicillata ogilbyi), we developed and validated a PVA model. We identified the demographic and genetic responses to different threatening factors and developed a general framework that would facilitate similar work in other bettong species. The two main threatening processes are predation by introduced animals and its interaction with reduced fitness (e.g. due to inbreeding depression or a disease). Although predation alone can drive a decline in certain circumstances (e.g. when predation success is independent from prey population density), synergistically, predation and reduced fitness can be particularly relevant, especially for small populations. The minimum viable population size was estimated at 1000–2000 individuals. In addition, the models identified that research into age-specific mortality rates and predation rates by introduced animals should be the focus of future work. The PVA model created here provides a basis to investigate threatening processes and management strategies in woylie populations and other extant bettong species, given the ecological and physiological similarities among these threatened species.

Uncertainty in assessing the viability of the Powerful Owl Ninox strenua in Victoria, Australia

1999 ◽  
Vol 5 (2) ◽  
pp. 144 ◽  
Author(s):  
Michael A. McCarthy ◽  
Alan Webster ◽  
Richard H. Loyn ◽  
Kim W. Lowe
Keyword(s):  
Management Strategies ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Large Field ◽  
Adult Survival ◽  
Metapopulation Dynamics ◽  
Viability Analysis ◽  
Term Monitoring ◽  
Predicted Risk

A model of the metapopulation dynamics of Powerful Owls Ninox strenua in Victoria, Australia is described, and its parameters were derived from available data. Sensitivity analysis indicates that the survival rate of adult owls is the most important parameter in the model. Because estimates of this parameter are uncertain, the predictions of the model are uncertain and unreliable. Using the best estimates of the parameters, the predicted risk of decline across Victoria is low, and local populations larger than 100 pairs have a low risk of extinction. If the lower estimates of adult and sub-adult survival are used, the abundance of Powerful Owls across Victoria is predicted to decline exponentially and faces extinction from deterministic forces. A prohibitively large field programme involving monitoring of individuallyrecognizable owls would be required to obtain an improved estimate of adult survival, and so further use of population viability analysis to assess the adequacy of particular management strategies is unlikely to be useful for this species. An alternative is to establish a long-term monitoring programme to document changes in abundance of the species in logged and unlogged landscapes.

The dynamics of feral pig (Sus scrofa) populations in response to food supply

2019 ◽  
Vol 46 (3) ◽  
pp. 191 ◽  
Author(s):  
Matthew Gentle ◽  
Anthony Pople ◽  
Joseph C. Scanlan ◽  
John Carter
Keyword(s):  
Food Supply ◽  
Sus Scrofa ◽  
Predictor Variable ◽  
Numerical Response ◽  
Initial Population ◽  
Population Densities ◽  
Juvenile Mortality ◽  
Management Actions ◽  
Eastern Australia ◽  
Feral Pig

Context Feral pigs (Sus scrofa) are highly fecund, and populations can increase rapidly under favourable conditions. Population size can also fluctuate widely, driven largely by changes in juvenile mortality in response to food availability, but these relationships have only been explored on a limited number of sites and over short periods. Aims The present study aimed to investigate and quantify the numerical response of feral pig populations to changes in their food supply in north-eastern Australia. Methods Pig population densities were determined from aerial surveys conducted over a 21-year period on 10 regional blocks (~2000–6000 km2) throughout the Queensland rangelands. Densities were used to calculate annual exponential rates of increase (r), which were then corrected for anthropogenic mortality (baiting and commercial harvesting). Six proxy measures of annual food supply, including rainfall, pasture biomass and pasture growth (using the AussieGRASS model), were calculated for each survey block, and assessed as predictors of corrected r. The rates of increase predicted from the first half of the data series were then applied to initial population densities to estimate successive pig densities during the second period in each bioregion. Key results The most parsimonious model of the numerical response had parameters common to three bioregions, with rainfall in the 12 months between surveys being the best predictor variable. Modelled densities for each bioregion were a good fit to actual, observed densities. Relationships between r and each measure of food supply at the individual block level were inconsistent. Conclusions Using rainfall as a measure of food supply, the numerical response relationship provides a method for predicting the dynamics of feral pig populations at the bioregional scale. Predicting population dynamics at any one site using this relationship is less precise, suggesting that differences in landscape composition affect utilisation of resources supporting population growth. Implications The results from the present study could be used to predict feral pig population changes at the bioregional level, supplementing or reducing the need for more frequent, expensive population surveys. This improved ability to predict fluctuations in regional feral pig populations can help guide future management actions.

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