Stochastic and spatially explicit population viability analyses for an endangered freshwater turtle, Clemmys guttata

2009 ◽  
Vol 87 (12) ◽  
pp. 1241-1254 ◽  
Author(s):  
J. J. Enneson ◽  
J. D. Litzgus
Keyword(s):  
Quantitative Methods ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Habitat Destruction ◽  
Population Persistence ◽  
Freshwater Turtle ◽  
Turtle Species ◽  
Georgian Bay ◽  
Clemmys Guttata ◽  
Risk Of Extinction

Over two thirds of the world’s turtle species are in decline as a result of habitat destruction and harvesting. Quantitative methods for predicting the risk of extinction of turtle populations are essential for status assessments and recovery planning. Spotted turtles ( Clemmys guttata (Schneider, 1792)) are considered vulnerable internationally, and endangered in Canada. We used population viability analysis to assess the risk of extirpation of a Georgian Bay, Ontario, population that has been under study since 1977 and of nine Ontario populations for which population size is known, and to examine the effects of dispersal between breeding ponds on population persistence. A simple stochastic model for the Georgian Bay population projected a 60% probability of extirpation in 100 years. A metapopulation model for the same study area projected an 18% probability of extirpation within 100 years, suggesting that dispersal between breeding ponds is important for population persistence. Spotted turtles at this relatively pristine site have a relatively high risk of extinction despite the absence of anthropogenic additive mortality. Probability of quasi-extinction as a result of stochasticity for the model simulating nine Ontario populations was low, but the probability of six or more of the nine known Ontario populations becoming extirpated within 100 years was 26%, indicating that recovery action is necessary to prevent decline of spotted turtles within the species’ Canadian range, which is restricted to Ontario.

scholarly journals Distribution range and population viability of Emys orbicularis in Slovakia: a review with conservation implications

2021 ◽  
Vol 44 ◽  
pp. 141-161
Author(s):  
Enikő Horváth ◽  
Martina Martvoňová ◽  
Stanislav Danko ◽  
Peter Havaš ◽  
Peter Kaňuch ◽  
...  
Keyword(s):  
Activity Patterns ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Freshwater Turtle ◽  
Isolated Populations ◽  
Term Survival ◽  
Emys Orbicularis ◽  
Turtle Species ◽  
Viability Analysis ◽  
Probability Of Extinction

The European pond turtle (Emys orbicularis) is the only native freshwater turtle species in Slovakia. Due to watercourse regulations in the middle of the 20th century, its range became fragmented and, currently, there are only two isolated populations. From a total of 1,236 historical records in Slovakia, most observations (782 records) came from the area of the Tajba National Nature Reserve (NNR). Three of the population viability analysis models (‘baseline’, ‘catastrophe’, ‘nest protection during a catastrophe’) indicated the extinction of the population in Tajba, with the highest probability of extinction occurring during a catastrophic event (probability of extinction 1.00). We also evaluated information about the activity patterns of seven radio-tracked individuals and about the number of destroyed nests from the area. During the period 2017–2021, we recorded only two turtles leaving the aquatic habitat of Tajba. An alarming fact is the massive number of destroyed nests found in the area during the study period (Tajba 524; Poľany 56). Our results indicate that the population in the Tajba NNR require immediate application of management steps to ensure its long-term survival.

scholarly journals How to save the rarest Darwin's finch from extinction: the mangrove finch on Isabela Island

2010 ◽  
Vol 365 (1543) ◽  
pp. 1019-1030 ◽  
Author(s):  
Birgit Fessl ◽  
Glyn H. Young ◽  
Richard P. Young ◽  
Jorge Rodríguez-Matamoros ◽  
Michael Dvorak ◽  
...  
Keyword(s):  
Population Viability Analysis ◽  
Population Viability ◽  
Habitat Destruction ◽  
Effective Management ◽  
Population Status ◽  
Breeding Sites ◽  
Island Populations ◽  
Viability Analysis ◽  
Rapid Economic Growth ◽  
Before And After

Habitat destruction and predation by invasive alien species has led to the disappearance of several island populations of Darwin's finches but to date none of the 13 recognized species have gone extinct. However, driven by rapid economic growth in the Galápagos, the effects of introduced species have accelerated and severely threatened these iconic birds. The critically endangered mangrove finch ( Camarhynchus heliobates ) is now confined to three small mangroves on Isabela Island. During 2006–2009, we assessed its population status and monitored nesting success, both before and after rat poisoning. Population size was estimated at around only 100 birds for the two main breeding sites, with possibly 5–10 birds surviving at a third mangrove. Before rat control, 54 per cent of nests during incubation phase were predated with only 18 per cent of nests producing fledglings. Post-rat control, nest predation during the incubation phase fell to 30 per cent with 37 per cent of nests producing fledglings. During the nestling phase, infestation by larvae of the introduced parasitic fly ( Philornis downsi ) caused 14 per cent additional mortality. Using population viability analysis, we simulated the probability of population persistence under various scenarios of control and showed that with effective management of these invasive species, mangrove finch populations should start to recover.

Population Viability Analysis of a Long-Lived Freshwater Turtle, Hydromedusa maximiliani (Testudines: Chelidae)

2012 ◽  
Vol 11 (2) ◽  
pp. 162-169 ◽  
Author(s):  
Shirley Famelli ◽  
Sarah Cristina Piacentini Pinheiro ◽  
Franco Leandro Souza ◽  
Rafael Morais Chiaravalloti ◽  
Jaime Bertoluci
Keyword(s):  
Population Viability Analysis ◽  
Population Viability ◽  
Freshwater Turtle ◽  
Viability Analysis

Population viability analysis of the Uruguayan Creole cattle genetic reserve

2006 ◽  
Vol 38 ◽  
pp. 19-33 ◽  
Author(s):  
E. Armstrong ◽  
A. Postiglioni ◽  
S. González
Keyword(s):  
Population Viability Analysis ◽  
Population Viability ◽  
Limiting Factor ◽  
Management Options ◽  
Viability Analysis ◽  
Risk Of Extinction ◽  
Genetic Reserve ◽  
Creole Cattle ◽  
Not At Risk ◽  
The 19Th Century

SummaryUruguayan Creole cattle are descended from animals brought by the Spanish conquerors. The population grew extensively without directional management and became semi-wild before the introduction of commercial breeds in the 19th century. Today only 575 animals remain, restricted to the San Miguel National Park. We performed a population viability analysis of this reserve using VORTEX v. 8.31 to study its demographic and genetic parameters, assess the environmental factors that affect its development, evaluate its future risk of extinction and test different management options. The probability of extinction in the next 100 years was always zero, even in the more pessimistic scenarios. The growth rate of the population was always positive and mostly affected by the mortality rate of calves. Population size increased rapidly up to carrying capacity, this being the only limiting factor for population growth. Retained heterozygosity was always above 90% and the inbreeding coefficient below 0.10. The analysis shows that the population is not at risk due to its genetic diversity and demographic structure, however all the individuals are concentrated in only one place. We suggest its subdivision into sub-populations located in different regions and connected by gene flow, decreasing the risk of extinction and accomplishing the conservation and self-sustainability goals.

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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