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.

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.

Population Viability Analysis for Endangered Roanoke Logperch

2016 ◽  
Vol 7 (1) ◽  
pp. 46-64 ◽  
Author(s):  
James H. Roberts ◽  
Paul L. Angermeier ◽  
Gregory B. Anderson
Keyword(s):  
Population Growth ◽  
Carrying Capacity ◽  
Extinction Risk ◽  
Management Strategies ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Stream Fish ◽  
Fish Kills ◽  
Viability Analysis ◽  
Roanoke Logperch

Abstract A common strategy for recovering endangered species is ensuring that populations exceed the minimum viable population size (MVP), a demographic benchmark that theoretically ensures low long-term extinction risk. One method of establishing MVP is population viability analysis, a modeling technique that simulates population trajectories and forecasts extinction risk based on a series of biological, environmental, and management assumptions. Such models also help identify key uncertainties that have a large influence on extinction risk. We used stochastic count-based simulation models to explore extinction risk, MVP, and the possible benefits of alternative management strategies in populations of Roanoke logperch Percina rex, an endangered stream fish. Estimates of extinction risk were sensitive to the assumed population growth rate and model type, carrying capacity, and catastrophe regime (frequency and severity of anthropogenic fish kills), whereas demographic augmentation did little to reduce extinction risk. Under density-dependent growth, the estimated MVP for Roanoke logperch ranged from 200 to 4200 individuals, depending on the assumed severity of catastrophes. Thus, depending on the MVP threshold, anywhere from two to all five of the logperch populations we assessed were projected to be viable. Despite this uncertainty, these results help identify populations with the greatest relative extinction risk, as well as management strategies that might reduce this risk the most, such as increasing carrying capacity and reducing fish kills. Better estimates of population growth parameters and catastrophe regimes would facilitate the refinement of MVP and extinction-risk estimates, and they should be a high priority for future research on Roanoke logperch and other imperiled stream-fish species.

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.

Unsustainable harvest of dugongs in Torres Strait and Cape York (Australia) waters: two case studies using population viability analysis

2004 ◽  
Vol 7 (4) ◽  
pp. 417-425 ◽  
Author(s):  
Robert Heinsohn ◽  
Robert C. Lacy ◽  
David B. Lindenmayer ◽  
Helene Marsh ◽  
Donna Kwan ◽  
...  
Keyword(s):  
Case Studies ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Viability Analysis ◽  
Cape York ◽  
Torres Strait

Comment on sea lion population viability analysis

Polar Biology ◽  
2012 ◽  
Vol 35 (10) ◽  
pp. 1617-1618 ◽  
Author(s):  
Paul A. Breen ◽  
David J. Gilbert ◽  
Paul J. Starr
Keyword(s):  
Population Viability Analysis ◽  
Population Viability ◽  
Sea Lion ◽  
Viability Analysis
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