Life History and Demographic Characteristics of the Magdalena River Turtle (<i>Podocnemis lewyana</i>): Implications for Management

Páez, Vivian P.; Bock, Brian C.; Espinal-García, Paula A.; Rendón-Valencia, Beatriz; Alzate-Estrada, Diego A.; Cartagena-Otálvaro, Viviana M.; Heppell, Selina S.

doi:10.1643/ce-14-191

Cited by 23 publications

(26 citation statements)

References 49 publications

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“…data-driven estimates of survival for gopher tortoises, a parameter important to population growth of other large, long-lived turtles (Crouse et al 1987, Cunnington and Brooks 1996, Mogollones et al 2010, Páez et al 2015, Folt et al 2016. To be most accurate during site-specific projections, PVAs should incorporate demographic estimates from relevant populations of interest whenever possible (Ralls et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Contrasting Patterns of Demography and Population Viability Among Gopher Tortoise Populations in Alabama

et al. 2021

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Population viability analyses are useful tools to predict abundance and extinction risk for imperiled species. In southeastern North America, the federally threatened gopher tortoise (Gopherus polyphemus) is a keystone species in the diverse and imperiled longleaf pine (Pinus palustris) ecosystem, and researchers have suggested that tortoise populations are declining and characterized by high extinction risk. We report results from a 30-year demographic study of gopher tortoises in southern Alabama , where 3 populations have been stable and 3 others have declined. To better understand the demographic vital rates associated with stable and declining tortoise populations, we used a multi-state hierarchical markrecapture model to estimate sex-and stage-specific patterns of demographic vital rates at each population. We then built a predictive population model to project population dynamics and evaluate extinction risk in a population viability context. Population structure did not change significantly in stable populations, but juveniles became less abundant in declining populations over 30 years. Apparent survival varied by age, sex, and site; adults had higher survival than juveniles, but female survival was substantially lower in declining populations than in stable ones. Using simulations, we predicted that stable populations with high female survival would persist over the next 100 years but sites with lower female survival would decline, become male-biased, and be at high risk of extirpation. Stable populations were most sensitive to changes in apparent survival of adult females. Because local populations varied greatly in vital rates, our analysis improves upon previous demographic models for northern populations of gopher tortoises by accounting for population-level variation in demographic patterns and, counter to previous model predictions, suggests that small tortoise populations can persist when habitat is managed effectively.

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Section: Discussionmentioning

confidence: 99%

Contrasting Patterns of Demography and Population Viability Among Gopher Tortoise Populations in Alabama

et al. 2021

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“…Additionally, head-starting may interrupt a vital part of the turtles’ life cycle, as post-hatching parental care has been reported for this species (Ferrara et al, 2013). Studies using population models and elasticity analyses show that the survival of river turtle populations is affected more by the survival rates of adults and subadults than that of hatchlings and yearlings (Mogollones et al, 2010; Páez et al, 2015). Therefore, and considering the potential negative effects of head-starting, we recommend that turtle conservation programmes focus on in situ conservation strategies such as protecting nesting beaches and reducing the hunting of adult female turtles.…”

Section: Discussionmentioning

confidence: 99%

On the future of the giant South American river turtle Podocnemis expansa

Forero–Medina¹,

Ferrara²,

Vogt

et al. 2019

Oryx

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There is a long history of exploitation of the South American river turtle Podocnemis expansa. Conservation efforts for this species started in the 1960s but best practices were not established, and population trends and the number of nesting females protected remained unknown. In 2014 we formed a working group to discuss conservation strategies and to compile population data across the species’ range. We analysed the spatial pattern of its abundance in relation to human and natural factors using multiple regression analyses. We found that > 85 conservation programmes are protecting 147,000 nesting females, primarily in Brazil. The top six sites harbour > 100,000 females and should be prioritized for conservation action. Abundance declines with latitude and we found no evidence of human pressure on current turtle abundance patterns. It is presently not possible to estimate the global population trend because the species is not monitored continuously across the Amazon basin. The number of females is increasing at some localities and decreasing at others. However, the current size of the protected population is well below the historical population size estimated from past levels of human consumption, which demonstrates the need for concerted global conservation action. The data and management recommendations compiled here provide the basis for a regional monitoring programme among South American countries.

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“…Thus, long-term monitoring studies are needed for more species, given that generation time is known for only one species, the longevity of no species is known, and only for R. nasuta and P. lewyana are there published data on survival rates. For P. lewyana , there are also data on fertility rates (Garcés-Restrepo, Giraldo, & Carr, 2014; Giraldo, Garcés-Restrepo, Carr, & Loaiza, 2012b; Páez et al., 2015).…”

Section: Discussionmentioning

confidence: 99%

Research and Conservation Priorities for Tortoises and Freshwater Turtles of Colombia

Forero–Medina¹,

Páez

Garcés-Restrepo

et al. 2016

Tropical Conservation Science

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The objective of our study was to review and quantify the level of knowledge of the biology of tortoise and freshwater turtle species of Colombia based on studies conducted in the country. We used the resulting rankings in knowledge, in combination with IUCN threat category, presence in protected areas, and endemism, to propose conservation priorities. This process also allowed us to evaluate which aspects of turtle biology have been least studied. Four species obtained total values of zero or one over the 21 knowledge criteria employed, so they were ranked as the highest priority for research based on the lack of knowledge of their biology: Black-lined Toad-headed Turtle (Mesoclemmys raniceps), Amazon Toad-headed Turtle (Mesoclemmys heliostemma), Gibba Toad-headed Turtle (Mesoclemmys gibba), and Dunn's Mud Turtle (Kinosternon dunni). Moreover, species in the family Chelidae in general were found to have limited levels of knowledge, which makes this group a priority for investigation. Evaluation of the distinct criteria used in the knowledge assessment revealed that the best-known criteria were geographic distribution (modeled), presence or absence in protected areas, and clutch size. The most poorly known biological characteristics, which constitute research priorities, are the frequency of nesting, longevity and generation time, and population parameters. According to the criteria used, the priority species for conservation were the Magdalena River Turtle (Podocnemis lewyana), Dahl's Toad-headed Turtle (Mesoclemmys dahli), K. dunni, and Maracaibo Wood Turtle (Rhinoclemmys diademata), three of which are endemic or semiendemic (R. diademata only occurs in Colombia and Venezuela), followed by two species of Mesoclemmys.

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Life History and Demographic Characteristics of the Magdalena River Turtle (Podocnemis lewyana): Implications for Management

Cited by 23 publications

References 49 publications

Contrasting Patterns of Demography and Population Viability Among Gopher Tortoise Populations in Alabama

Contrasting Patterns of Demography and Population Viability Among Gopher Tortoise Populations in Alabama

On the future of the giant South American river turtle Podocnemis expansa

Research and Conservation Priorities for Tortoises and Freshwater Turtles of Colombia

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