No abstract

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.

Habitat loss and fragmentation caused by the conversion of tropical forests are among the most important threats to biodiversity globally. Habitat specialists and species with low dispersal capacity are expected to be the most sensitive to such changes. Relatively little is known, however, about how habitat change and life history interact to impact natal dispersal and population viability in tropical species. Here, we characterized natal dispersal patterns, habitat selection and survival rates in two‐toed (Choloepus hoffmanni) and three‐toed (Bradypus variegatus) sloths within a human‐dominated tropical landscape in Costa Rica consisting of a shade‐grown cacao plantation surrounded by riparian forests and cattle pastures. Radio‐marked individuals of both species preferentially selected tropical forests during natal dispersal and were commonly observed using riparian forest buffers for dispersal. The more specialized and sedentary three‐toed sloth, however, avoided both pastures and shade‐grown cacao for dispersal, whereas two‐toed sloths only avoided pastures. Juvenile survival was lower for three‐toed than two‐toed sloths, and was lowest immediately following maternal independence for both species. However, despite interspecific differences, juvenile survival was high and sufficient to maintain stable populations of both species. Synthesis and applications. Our results indicate that tropical forest conversion is more likely to impact the natal dispersal success of specialized and dispersal‐limited species. Moreover, riparian forest buffers appear to provide critical corridors for maintaining such species, and biodiversity more broadly, in modified tropical landscapes.

No abstract

Few long-term demographic studies have been conducted on freshwater turtles of South America, despite the need for this type of inquiry to investigate natural variation and strengthen conservation efforts for these species. In this study, we examined the variation in demography of the Chocoan River Turtle (Rhinoclemmys nasuta) based on a population from an island locality in the Colombian Pacific region between 2005 and 2017. We calculated survival, recapture, and transition probabilities, and the effects of stream substrate and El Niño-Southern Oscillation (ENSO) phases (El Niño, Neutral, La Niña) on these variables using a multi-state model. We found differences in survival probabilities between ENSO phases, likely as a consequence of an increase in flood events. In addition, we found support for survival being greater in muddy streams than rocky streams, possibly because it is easier to escape or hide in mud substrates. Recapture probabilities varied by life stages; differences in the probability of recapture between size classes were associated with the high fidelity to territories by adults. The present increases in frequency and severity of El Niño and La Niña may exacerbate the consequences of climatic regimes on natural populations of turtles by increasing the mortality caused by drastic phenomena such as floods.Diversity 2019, 11, 97 2 of 12 scenarios [18][19][20]. The slow life history of turtles makes it necessary for long-term demographic research to generate information relevant to their conservation [21][22][23]. Long-term studies have been relatively common in the north temperate zone, including data of up to three decades' duration on threatened species [24][25][26]. For South America, this kind of long-term research is rare; only the research of Martins and Souza on Hydromedusa maximiliani has included data collected for longer than a decade [27].With 27 species of terrestrial and freshwater turtles, Colombia is considered the seventh most species-rich country in the world, and third at the level of South America behind Brazil and Ecuador [28]. Despite this great diversity, turtles are far from being one of the best-studied animal groups in Colombia; many aspects of their basic biology remain unknown, and long-term research is almost nonexistent or just beginning to be published [29,30]. Among the freshwater turtles recorded in Colombia, the Chocoan River Turtle, Rhinoclemmys nasuta (Geoemydidae), is found only in Colombia and Ecuador [31], and its conservation status is categorized as near-threatened (NT) globally [3], NT in Colombia [32], and endangered (E) in Ecuador [33]. As a consequence of the threatened status of this species, we began studying an island population of R. nasuta in 2005 on Isla Palma, Bahía Málaga, in the central Pacific coastal region of the Department of Valle del Cauca in Colombia [31,34].Using information recorded on R. nasuta during the sampling efforts conducted between 2005 and 2017 on Isla Palma, this research has the goal of evaluating the long-term variation in su...