Predation of a Yellow-headed Gecko, Gonatodes albogularis, by a Dry Forest Hognosed Pitviper, Porthidium ophryomegas

Diversity is a property of community that can described, characterized, and understood according to the functioning of ecosystems. To study the richness and local abundance and species replacement between habitats around the Zapatosa's wetland complex (El Cesar Department), I carried out four field trips between November of 2006 and October of 2007. A total of 640 sampling hours/man analyzed five habitat types chasmophyte forest, dry forest, riparian forest, palm-grove and tree-lined savanna; with the exception of the palm-grove sampled at its 75%, the others were sampled up to their 80%. I found 847 reptiles that were distributed in 48 species. The group with the highest number of species was Colubridae with 14, followed by Gekkonidae with five. Five endemic species and eight with some conservation threat grade at a national level are reported. The riparian forest was the richest and most abundant habitat with 34 species and 196 individuals. For each habitat, Colubridae had the highest number of species, followed by the families Polychrotidae, Gekkonidae and Teiidae, in that order. The reptile species composition was not different between the tree-lined savanna and the chasmophyte forest, but differed among the tree-lined savanna and the riparian forest, palm-grove and dry forest habitats. The most important differences in the species composition among almost all the habitats were influenced by the species Anolis tropidogaster and Gonatodes albogularis, and the higher occurrence of Stenocercus erythrogaster in the chasmophyte forest. The species replacement had an average value of 50%; the biggest amounts of shared species were the lizards, while the snake Leptodeira septentrionalis was the only one present in all habitat types. The forest grows-among-rocks showed the biggest complementarity and number of unique species compared to the other habitats. The wetland complex provides two thirds of the reptile's species reported until now for the Caribbean region, and more than 80% of those reported for the El Cesar department. This wetland complex seems to behave as a center for low land species concentration as it hosts a high proportion of species from those places.

Flight initiation distance is defined as the distance between a prey and an approaching predator when the prey starts to flee. Escape theory predicts that the optimal flight initiation distance is the distance where predation risk rises to the point at which it equals the cost of fleeing. Therefore, staying close to refuge and occupying microhabitats with more abundant shelters (i.e., crevices or shrubs) may allow lizards to have shorter flight initiation distance. By simulating an approaching predator, we studied the effect of microhabitat structural complexity on escape behaviour, in particular, the distance fled before stopping and final distance (predator-prey distance when the prey stops fleeing), of a small diurnal tropical gecko, the yellow-headed gecko Gonatodes albogularis inhabiting a tropical dry forest. The findings indicate that refuge abundance and distance to the nearest potential refuge influence escape behaviour of G. albogularis. In addition, we found sex differences in escape behaviour which are not explained by microhabitat use. Females had longer flight initiation distance but shorter distance fled, and longer final distances than males.

We studied the reproductive characteristics of a population of Gonatodes albogularis in an Andean tropical dry forest with a bimodal rainfall regime. Females were smaller than males in snout-vent length (SVL). Males and females reached sexual maturity at similar body sizes (close to 31 mm SVL) and had continuous reproductive activity during the sampling year. All adult females were reproductive (vitellogenic and gravid females); they were found throughout the year and we did not observe differences among months in reproductive stages, nor in the follicular and ovarian sizes. Gravid females produced only one egg and had simultaneously one large vitellogenic follicle, suggesting a continuous reproductive activity. Adult males had spermatozoa in testes and ducts during all months and there were no significant changes among months in the volume and mass of testes adjusted to body size. These data, plus the observation of neonates and communal nests in every month of the year, confirm a pattern of con...