Modelling the impact of predation on reintroductions of bridled nailtail wallabies.

1995 ◽  
Vol 22 (2) ◽  
pp. 163 ◽  
Author(s):  
H McCallum ◽  
P Timmers ◽  
. Hoyle.S
Keyword(s):  
Population Viability Analysis ◽  
Population Viability ◽  
Predator Prey ◽  
Viability Analysis ◽  
Standard Population ◽  
Viable Population ◽  
Almost All ◽  
The Impact ◽  
Number Of Individuals ◽  
Simple Stochastic Model

Predation by introduced foxes and cats is generally thought to be the main reason for the poor success rate of macropod reintroductions on the Australian mainland. Predator-prey theory suggests that predation may have particularly severe impacts on very small populations, especially if a more common primary prey species is present (such as the rabbit). Thus, a sufficiently large reintroduction may overcome predation and succeed where a smaller one would fail. The minimum viable population would, however, be much larger than that predicted by standard population-viability analysis. We use a simple stochastic model based upon the bridled nailtail wallaby to explore this possibility. Even very small amounts of predation (2-4 individuals per six months) can be sufficient to cause reintroductions of up to 50 animals to fail. No clear threshold population size beyond which reintroductions will succeed is evident and, for a given mean, the probability distribution of predation has a very limited impact on the success of reintroductions. In almost all circumstances, a single reintroduction of a given size is preferable to multiple reintroductions of the same total number of individuals.

A Retrospective Analysis on the Population Viability of the Yangtze River Dolphin or Baiji (Lipotes vexillifer)

2020 ◽  
Author(s):  
Wu Bin ◽  
Wang Weiping ◽  
Wang Haihua ◽  
He Gang
Keyword(s):  
Yangtze River ◽  
Population Analysis ◽  
Relevant Literature ◽  
Population Viability Analysis ◽  
Simulation Models ◽  
Population Viability ◽  
The Yangtze River ◽  
Viability Analysis ◽  
Functional Extinction ◽  
The Impact

Background: Lipotes vexillifer, is a functionally extinct species of freshwater dolphin commonly called as Baiji dolphin of Yanzte River, China. The dolphin is thought to be the first one of it’s kind driven to extinction due to the impact of humans. Yangtze Freshwater Dolphin Expedition carried out in the year 2006 revealed the species as functionally extinct. The présent study deals with the population viability analysis of the baiji dolphin using Vortex software and also by consulting historical materials and relevant literature to explore the possible causes of the functional extinction of the baiji in the Yangtze River. The findings are to provide guidance for the effective management of another freshwater mammal, the Yangtze finless porpoise. Methods: Population viability analysis of the baiji dolphin for various parameters were assessed using Vortex software and other published information and relevant literatures. The analysis were carried out to ascertain the possible causes of the functional extinction of the baiji in the Yangtze River. Result: Simulation models were employed to identify the reasons for extinction of Yangtze River baiji population by adopting viability retrospective method. The various parameters associated with the population analysis were included to derive logical conclusion. The minimum viable population of the Yangtze River baiji was also identified by adopting various simulation models. The present study is the first attempt to apply the 10,000-time iteration method to the baiji population survivability analysis.

The impact of fire and dogs on Koalas at Port Stephens, New South Wales, using population viability analysis

2007 ◽  
Vol 13 (3) ◽  
pp. 189 ◽  
Author(s):  
Danial Lunney ◽  
Shaan Gresser ◽  
Lisa E. O'neill ◽  
Alison Matthews ◽  
Jonathan Rhodes
Keyword(s):  
New South ◽  
Local Population ◽  
New South Wales ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Phascolarctos Cinereus ◽  
Viability Analysis ◽  
South Wales ◽  
The Impact ◽  
Port Stephens

The Port Stephens Koala Phascolarctos cinereus population has been regarded as one of the strongholds for Koalas in New South Wales. This study applied population viability analysis to investigate the impact of fire and predation by dogs on the viability of the local population. The rapid decline of the modelled Koala population under basic assumptions throws the assumed security of such large populations into question. In all the modelled management scenarios, reducing mortality had more influence than any other factor. Reducing the severity and frequency of large catastrophic fires improved the probability of survival for the population, though the modelled population size still declined sharply. Any management action to improve Koala survival must be accompanied by a reduction in mortality from dog attacks. Fires and dogs will have an ever greater impact on Koala populations as coastal forests become more fragmented and isolated by urban development, and their combined control will be needed to complement land-use planning measures to address habitat loss and fragmentation.

Preliminary predictions of the impacts of habitat area and catastrophes on the viability of Mahogany Glider Petaurus gracilis populations

1999 ◽  
Vol 5 (1) ◽  
pp. 56 ◽  
Author(s):  
Stephen M. Jackson
Keyword(s):  
Population Size ◽  
Population Viability Analysis ◽  
Adult Mortality ◽  
Population Viability ◽  
Key Populations ◽  
Management Options ◽  
Viability Analysis ◽  
Reserve Size ◽  
The Impact ◽  
Negative Population

The population viability analysis (PVA) program VORTEX was used to examine the viability of different sized populations of the Mahogany Glider Petaurus gracilis, and to examine the impact of a one in a hundred year catastrophe (each requiring a different reserve size) of different severities on different sized populations. The PVA showed that populations up to 300 individuals (1 500 ha) have a negative population growth rate, high losses of genetic diversity and a greater than 5% chance of extinction within 100 years. Populations of 400?700 individuals (2 000?3 500 ha) showed a decreasing trend in population size suggesting they are likely to become extinct after 100 years. A population of 800 individuals (4 000 ha) was needed for the population size to stabilize. Sensitivity analysis showed adult mortality of greater than 25% to be important in decreasing the viability of populations. Populations of 400 were resistant to a one in 100 year catastrophe which had a 20% mortality and 20% decrease in reproduction. When the mortality was 70%, with 70% decrease in reproduction, a population of 1 000 still had a 12% chance of extinction. As only approximately 50% of the available habitat appears to be occupied, an area up to 8 000 ha (800 individuals) is suggested to be required to maintain viable populations of Mahogany Gliders. A number of management options are recommended including the retention of habitat, establishing corridors between key populations, and using fire to minimize rainforest expansion.

scholarly journals MetaConnect, a new platform for population viability modelling to assist decision makers in conservation and urban planning

2020 ◽  
Author(s):  
Sylvain Moulherat ◽  
Elvire Bestion ◽  
Michel Baguette ◽  
Matthieu Moulherat ◽  
Stephen C.F. Palmer ◽  
...  
Keyword(s):  
Landscape Connectivity ◽  
Population Viability Analysis ◽  
Main Tool ◽  
Biodiversity Loss ◽  
Population Viability ◽  
Decision Makers ◽  
Policy Makers ◽  
Viability Analysis ◽  
The Impact

AbstractIn a context of global change, scientists and policy-makers require tools to address the issue of biodiversity loss. Population viability analysis (PVA) has been the main tool to deal with this problem. However, the tools developed during the 90s poorly integrate recent scientific advances in landscape genetics and dispersal. We developed a flexible and modular modelling platform for PVA that addresses many of the limitations of existing software. MetaConnect is an individual-based, process-based and PVA-oriented modelling platform which could be used as a research or a decision-making tool. Here, we present the core base modelling of MetaConnect. We demonstrate its potential use through a case study illustrating the platform’s capability for performing integrated PVA including extinction probability estimation, genetic differentiation and landscape connectivity analysis. We used MetaConnect to assess the impact of infrastructure works on the natterjack toad metapopulation functioning.

scholarly journals A Population Viability Analysis for Sharp-Tailed Grouse to Inform Reintroductions

2018 ◽  
Vol 9 (2) ◽  
pp. 565-581 ◽  
Author(s):  
Megan C. Milligan ◽  
Smith L. Wells ◽  
Lance B. McNew
Keyword(s):  
Habitat Management ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Average Density ◽  
Western Montana ◽  
Management Scenarios ◽  
Winter Habitat ◽  
Viability Analysis ◽  
Continental Divide ◽  
Viable Population

Abstract Sharp-tailed grouse Tympanuchus phasianellus were effectively extirpated from western Montana during the last century as a result of settlement by Euro-Americans. Recent interest in reestablishing the species west of the Continental Divide has identified information gaps related to the potential success of a restoration effort. Elsewhere, sharp-tailed grouse are widespread and exhibit plasticity in habitat use, suggesting a high potential for successful reintroduction. Using life history information from the published literature, we conducted a population viability analysis to assess the potential viability of a reintroduced population of sharp-tailed grouse in western Montana and to evaluate what management scenarios, with regard to both translocation protocols and habitat management, would be necessary to produce a viable population. Results of the population viability analysis indicated that a population parameterized with mean reported demographic rates and related environmental variation would not be viable and suggest a potential downward bias in demographic estimates in the published literature. Based on our simulation results, improvements in both fecundity and annual survival resulting from improvements in nesting and winter habitat would be necessary to produce a viable population of sharp-tailed grouse in western Montana. The minimum amount of habitat required to support a viable population of 280 individuals was 1,867–5,600 ha, assuming habitat is sufficient to support an average density of 5–15 grouse per km2. We provide a review of demographic and reintroduction information for sharp-tailed grouse and recommendations regarding reintroduction approaches based on our population viability analysis results that should increase the relative success of restoration efforts in western Montana and elsewhere. We recommend that nesting and winter habitat improvements be the focus of pre- and postrelease management and that post-translocation population studies be conducted to monitor reintroduced populations and provide site-specific demographic information to update population viability analyses.

scholarly journals Modeling The Fate of Sumatran Elephants in Bukit Tigapuluh Indonesia: Research Needs & Implications for Population Management

2016 ◽  
Vol 10 (1) ◽  
pp. 5 ◽  
Author(s):  
Alexander Markus Moßbrucker ◽  
Muhammad Ali Imron ◽  
Satyawan Pudyatmoko ◽  
Peter-Hinrich Pratje ◽  
Sumardi
Keyword(s):  
Inbreeding Depression ◽  
Local Population ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Habitat Destruction ◽  
Parameter Uncertainties ◽  
Sensitivity Testing ◽  
Viability Analysis ◽  
Conservation Measures ◽  
The Impact

The critically endangered Sumatran elephant persists in mainly small and isolated populations that may require intensive management to be viable in the long term. Population Viability Analysis (PVA) provides the opportunity to evaluate conservation strategies and objectives prior to implementation, which can be very valuable for site managers by supporting their decision making process. This study applies PVA to a local population of Sumatran elephants roaming the Bukit Tigapuluh landscape, Sumatra, with the main goal to explore the impact of pre-selected conservation measures and population scenarios on both population growth rate and extinction probability. Sensitivity testing revealed considerable parameter uncertainties that should be addressed by targeted research projects in order to improve the predictive power of the baseline population model. Given that further habitat destruction can be prevented, containing illegal killings appears to be of highest priority among the tested conservation measures and represents a mandatory pre-condition for activities addressing inbreeding depression such as elephant translocation or the establishment of a conservation corridor.Keywords: Elephas maximus sumatranus; population viability analysis (PVA); Asian elephant; elephant conservation; Vortex AbstractGajah Sumatera yang berstatus kritis sebagian besar bertahan dalam populasi kecil dan terisolasi membutuhkan pengelolaan intensif agar dapat tetap lestari dalam jangka panjang. Analisis Viabilitas Populasi (Population Viability Analysis, PVA) berpeluang untuk digunakan sebagai sarana evaluasi atas tujuan dan strategi konservasi yang disusun sebelum implementasi, yang akan sangat bermanfaat bagi pengelola kawasan guna mendukung pengambilan keputusan. Studi ini menggunakan PVA pada populasi lokal gajah Sumatera yang menjelajahi lanskap Bukit Tigapuluh, Sumatera, dengan tujuan utama mengeksplorasi dampak atas skenario upaya konservasi dan populasi terpilih terhadap laju pertumbuhan populasi dan probabilitas kepunahan. Uji sensitivitas menunjukkan adanya ketidakpastian atas sejumlah parameter pokok yang seharusnya diteliti untuk meningkatkan kekuatan prediksi atas baseline model populasi. Mengingat kerusakan habitat yang lebih parah dapat dicegah, untuk itu upaya penangkalan pembunuhan ilegal merupakan prioritas tertinggi di antara upaya-upaya konservasi yang sudah diuji dan menjadi prasyarat wajib untuk menjawab masalah kemungkinan dampak perkawinan sedarah (inbreeding depression) seperti translokasi gajah atau membangun koridor konservasi. 

scholarly journals Can we reestablish a self-sustaining population? A case study on reintroduced Crested Ibis with population viability analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yashuai Zhang ◽  
Fang Wang ◽  
Zhenxia Cui ◽  
Min Li ◽  
Xia Li ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Carrying Capacity ◽  
Wild Population ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Viability Analysis ◽  
Crested Ibis ◽  
Reintroduced Population

Abstract Background One of the most challenging tasks in wildlife conservation and management is clarifying which and how external and intrinsic factors influence wildlife demography and long-term viability. The wild population of the Crested Ibis (Nipponia nippon) has recovered to approximately 4400, and several reintroduction programs have been carried out in China, Japan and Korea. Population viability analysis on this endangered species has been limited to the wild population, showing that the long-term population growth is restricted by the carrying capacity and inbreeding. However, gaps in knowledge of the viability of the reintroduced population and its drivers in the release environment impede the identification of the most effective population-level priorities for aiding in species recovery. Methods The field monitoring data were collected from a reintroduced Crested Ibis population in Ningshan, China from 2007 to 2018. An individual-based VORTEX model (Version 10.3.5.0) was used to predict the future viability of the reintroduced population by incorporating adaptive patterns of ibis movement in relation to catastrophe frequency, mortality and sex ratio. Results The reintroduced population in Ningshan County is unlikely to go extinct in the next 50 years. The population size was estimated to be 367, and the population genetic diversity was estimated to be 0.97. Sensitivity analysis showed that population size and extinction probability were dependent on the carrying capacity and sex ratio. The carrying capacity is the main factor accounting for the population size and genetic diversity, while the sex ratio is the primary factor responsible for the population growth trend. Conclusions A viable population of the Crested Ibis can be established according to population viability analysis. Based on our results, conservation management should prioritize a balanced sex ratio, high-quality habitat and low mortality.

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