We report the results of a field study on Mexican Spotted Wood Turtles (Rhinoclemmys rubida perixantha) in a seasonally dry tropical forest of coastal Jalisco, Mexico. We used field surveys, trail spools, and radio telemetry to investigate activity patterns, estimate home range size with three different techniques, and develop a generalized linear model to identify features associated with habitats used by R. r. perixantha. We found that turtles were most frequently active at midday, with peak activity occurring from 0900 to 1500 h. During the dry season (January-mid-June), R. r. perixantha showed reduced activity (fewer movements and shorter travel distances) compared to the wet season (late June-September). Home range size did not differ among the three methods we compared, and all estimates revealed that R. r. perixantha have small home ranges, with males having larger home ranges than females. Sites used by turtles were positively associated with leaf litter and woody debris, herbaceous plants, vegetation, vine-like shrubs, and sloped terrain, and negatively associated with bare ground. Our findings can be used to strengthen future conservation efforts for R. r. perixantha, as well as other terrestrial geoemydids.

Given that morphology directly influences the ability of an organism to utilize its habitat and dietary resources, it also influences fitness. Comparing the relationship between morphology, performance and ecology is fundamental to understand how organisms evolve to occupy a wide range of habitats and diets. In turtles, studies have documented important relationships between morphology, performance and ecology, but none was field based or considered limb, shell and head morphology simultaneously. We compared the morphology, performance and ecology of 14 turtle taxa (12 species) in Mexico that range in their affinity to water and in their diet. We took linear measurements of limb, shell and head variables. We measured maximum swimming speed, maximum bite force and how often turtles were encountered on land, and we used stable isotopes to assess trophic position. We used these data to test the following three hypotheses: (1) morphology, performance and ecology covary; (2) limb and shell variables, like hand length, are correlated with swimming speed and the percentage of time spent on land; and (3) head variables, such as head width, are correlated with bite force and stable isotopes. We find support for these hypotheses and provide the first evidence that morphology influences performance and ecology in turtles in the field.

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Apart from hibernation, dormancy strategies in animals have been understudied. Aestivation is a functional and behavioral trait that responds to the effects of water reduction during dry and hot seasons. It has been detected in many species of terrestrial and aquatic turtles, however, several ecological and evolutionary aspects of chelonian aestivation remain to be evaluated and understood. We conducted a comparative exploration of macroevolutionary trends in turtle aestivation and tested the potential effect of shell morphology on the aestivation times. We compiled a dataset of aestivation status, aestivation times, and measurements of shell morphology of 225 turtle species. We reconstructed ancestral states along a time-calibrated phylogeny and tested different models with compared evolutionary rate changes on traits associated with aestivation. We also performed phylogenetic comparative analysis to explore shell morphological variables likely associated with maximum and mean aestivation times. We found evidence of aestivation in 44 percent of the evaluated turtle species. The longest aestivation times were found in the Chelidae, Pelomedusidae, Geoemydidae, and Kinosternidae, and shortest times were detected for Emydidae and Testudinidae. Inference of ancestral states revealed that turtle aestivation is a derived trait with multiple evolutions in the two major turtle clades. We found clade-specific evolutionary trends, with some clades showing increased aestivation (e.g., Pelomedusidae and Kinosternidae), clades exhibiting aestivation losses (e.g., Podocnemididae and Trionychidae) and contrasting patterns (loss vs. maintenance) in most clades of Testudinidae and Geoemydidae families. Otherwise, additive effects of different shell morphological variables correlated both positively and negatively with maximum aestivation times across most chelonian families. This is the first study exploring the evolution of aestivation in turtles and provides evidence that shell morphology in different chelonian families can influence aestivation time. We conclude that aestivation in turtles is a complex ecological and evolutionary process which needs to be studied in more detail.