Olga Victoria Castaño-Mora

Ecology and Status of the Magdalena River Turtle, Podocnemis lewyana, a Colombian Endemic

ABSTRACT We studied distribution, habitat selection, and reproductive ecology of the Magdalena river turtle, Podocnemis lewyana, from January to June 2003 and from January to March 2005 in the mid and low Sinú River, Córdoba, Colombia. The southern limit of its distribution occurs in the town of Carrizola, and the northern limit is near La Doctrina. We found more turtles of bigger size classes in the mid basin than in the low basin. Ninety-two individuals were observed basking in the river. Larger turtles were mostly observed in deep pools (> 3 m) with loamy or sandy bottoms, with easy access to basking sites, such as riverbanks, fallen trees, or beaches, and in areas with all types of shoreline vegetation but especially with riparian forest. Smaller turtles were found in colder, shallower, and more turbid waters than were adults, mainly in areas without riparian forest or in pastures with few trees, usually hidden in pastures flooded by the river. Adults ventured farther from shore than did juveniles. Along the study area, 5 nesting beaches were located: 3 in the mid basin and 2 in the low basin. Main nesting sites were sand and gravel beaches, but riverbanks were also used. Nesting occurred in small groups or individually in 2 reproductive seasons: one from December to March and the second from June to August. The main threats identified for P. lewyana in the Sinú River were floods caused by water release by Urrá Dam, human consumption and exploitation, nest damage caused by beach mining, and riparian forest destruction for pasture establishment.

Weak genetic divergence between the two South American toad-headed turtles Mesoclemmys dahli and M. zuliae (Testudines: Pleurodira: Chelidae)

Mesoclemmys dahli and M. zuliae are two endangered, little-known toad-headed turtles with small distribution ranges in Colombia and Venezuela, respectively. Using the mitochondrial cytochrome b gene as a marker, we investigate their phylogeographic differentiation. Furthermore, based on 2341 bp of mtDNA and 2109 bp of nDNA of M. dahli, M. zuliae and allied chelid turtles, we infer their divergence time using a fossil-calibrated relaxed molecular clock approach. Mesoclemmys dahli and M. zuliae are closely related species, with an estimated mean divergence time of 10.6 million years. This estimate correlates with the uplift of the Serrania de Perija, an Andean mountain chain separating their distribution ranges, suggesting that this event could have caused the evolution of the two species. Haplotype and nucleotide diversities of M. dahli are markedly higher than in Podocnemis lewyana, another endemic turtle species of Colombia. This pronounced dissimilarity may reflect differences in the phylogeographies and demographic histories of the two species, but also different habitat preferences.

Abundance, Population Structure, and Conservation of Kinosternon scorpioides albogulare on the Caribbean Island of San Andrés, Colombia

ABSTRACT We estimated population sizes, densities, structure, and the sex ratio of a locally endangered species of mud turtle, Kinosternon scorpioides albogulare, on the Caribbean island of San Andrés, Colombia. We estimated the population size at 4343 turtles on the island in 2002, inhabiting both freshwater ponds and mangroves. Densities for the main populations varied from 77 to 254 turtles/ha. The population structure showed that most of the individuals belong to intermediate size classes (110- to 140-mm carapace length) and a few belong to the smaller or larger size classes (< 110- or > 140-mm carapace length). The sex ratio was significantly different from 1:1 and was skewed toward females, 1 male per 1.97 females. No common use was found for the species among native islanders, although people from the continent living on the island use it for diverse purposes. Some threats were identified, such as mangrove pollution and the presence of the introduced species Tupinambis teguixin.

Abundance, Home Range, and Movement Patterns of the Endemic Species Dahl's Toad-Headed Turtle (Mesoclemmys dahli) in Cesar, Colombia

Abstract Population monitoring and evaluation of spatial requirements of species are key actions for the conservation of wild populations, especially for endemic and threatened species. We estimated the abundance of the endemic species Mesoclemmys dahli in 2 streams in Cesar, Colombia, from February 2008 to February 2009, by using aquatic sampling. We monitored fluctuations in abundance through the year and used mark–recapture sampling and the Jolly–Seber model to estimate population size and density. Home ranges and movement patterns were studied by using very high frequency (VHF) radio telemetry. We calculated home ranges for the year and for the wet and dry season independently. Estimated population size for the 2 streams varied during the year from 16 (95% CI, 7–30) to 175 (95% CI, 32–298) turtles. Densities ranged from 16 turtles/ha in April to approximately 170 turtles/ha in June, which is lower than other populations of M. dahli in Colombia as well as other South American chelids. Individuals captured during the wet season had a significantly higher mean body mass than those captured during the dry season, which suggests that larger animals may leave the streams during the dry months or that animals may lose weight during this period. Home ranges for 1 year varied from 1.6 to 30.8 ha when using the minimum convex polygon method and from 9.2 to 22.5 ha when using the fixed kernel density estimator. There were no significant differences in the mean movements during the dry and wet seasons. However, the greatest movements were documented either during the transition from wet to dry months or during the dry months. Conservation of M. dahli will require protection of the few streams where it occurs, as well as the associated riparian vegetation and surrounding areas used by the species.