AimSquamate fitness is affected by body temperature, which in turn is influenced by environmental temperatures and, in many species, by exposure to solar radiation. The biophysical drivers of body temperature have been widely studied, but we lack an integrative synthesis of actual body temperatures experienced in the field, and their relationships to environmental temperatures, across phylogeny, behaviour and climate.LocationGlobal (25 countries on six continents).TaxaSquamates (210 species, representing 25 families).MethodsWe measured the body temperatures of 20,231 individuals of squamates in the field while they were active. We examined how body temperatures vary with substrate and air temperatures across taxa, climates and behaviours (basking and diel activity).ResultsHeliothermic lizards had the highest body temperatures. Their body temperatures were the most weakly correlated with substrate and air temperatures. Body temperatures of non-heliothermic diurnal lizards were similar to heliotherms in relation to air temperature, but similar to nocturnal species in relation to substrate temperatures. The correlation of body temperature with air and substrate temperatures was stronger in diurnal snakes and non-heliothermic lizards than in heliotherms. Body-substrate and body-air temperature correlations varied with mean annual temperatures in all diurnal squamates, especially in heliotherms. Thermal relations vary with behaviour (heliothermy, nocturnality) in cold climates but converge towards the same relation in warm climates. Non-heliotherms and nocturnal species body temperatures are better explained by substrate temperature than by air temperature. Body temperature distributions become left-skewed in warmer-bodied species, especially in colder climates.Main ConclusionsSquamate body temperatures, their frequency distributions and their relation to environmental temperature, are globally influenced by behavioural and climatic factors. For all temperatures and climates, heliothermic species' body temperatures are consistently higher and more stable than in other species, but in regions with warmer climate these differences become less pronounced. A comparable variation was found in non-heliotherms, but in not nocturnal species whose body temperatures were similar to air and substrate irrespective of the macroclimatic context.

Organisms whose early life stages are environmentally sensitive produce offspring within a relatively narrow range of suitable abiotic conditions. In reptiles, development rate and survival are often maximized if incubation temperatures remain under 31°C, though this upper bound may vary within and among species. We addressed this expectation by comparing responses to egg incubation at 30°C versus 33°C in congeneric turtle species pairs with broad syntopic geographic distributions. In the two softshell turtles (Apalone spp.), the greatest changes in development rate and phenotypic variance were observed in the northernmost population, which had a low survival rate (40%) at 33°C. The presumably suboptimal temperature (33°C) for northern populations otherwise yielded 76%-93% survival rates and fast swimming speeds in more southern populations. Still, in one species, northern hatchlings incubated at 33°C matched the elevated speeds of their southern counterparts, revealing a countergradient response. In northern populations of the two map turtles (Graptemys spp.), survival was also reduced (28%-60%) at 33°C and the development rate (relative to 30°C) increased by up to 75%. Our experiments on divergent taxa with similar nesting ecologies substantiate that the optimal thermal range for offspring production is variable. These findings encourage further work on how population- and species-level differences relate to local adaptation in widely distributed oviparous species.

We observed overwintering behavior of bimodally respiring hatchling Smooth Softshell Turtles, Apalone mutica, in two small outdoor ponds that differed in depth. Hatchlings buried themselves shallowly in a sand/mud substrate at the bottom of the ponds. In the deep pond, hatchlings periodically raised and lowered the posterior portion of their body into the water column in a respiratory ''pushup'' fashion. In the shallow pond, hatchlings did not perform pushups nor snorkel to breathe air. Pushups were similar in appearance and form among turtles but occurred with variable frequency within and among individual turtles. Pushup frequency of hatchling A. mutica was 43% slower than reported for larger A. mutica.

We examined the distal excurrent ductal morphology and penile anatomy of the urogenital system in the Mississippi Mud Turtle, Kinosternon subrubrum hippocrepis, from a small sample of individuals collected in Arkansas in order to provide additional information regarding turtle urogenital anatomy.Specifically, we focused on the basic anatomy and histology of distal excurrent ducts (ductus deferens and ureter), associated structures (urogenital papillae), and penile histology in this kinosternid turtle.In addition, we provide an overview of the gross urogenital anatomy in this turtle, given that little detailed information exists on this topic in the chelonian literature.

Vast differences in available resources between habitats can have profound influences on aspects of an organism's life history, such as reproductive investment. Our study investigated how differences in nutrient availability affect sperm size in Diamond-backed Watersnakes (Nerodia rhombifer). We compared body size and sperm morphometrics between two populations with differing nutrient availability: a naturally occurring lake and a commercial fish farm. We hypothesized that prey availability affects sperm morphometrics. Our null hypothesis was that there would be no significant difference in sperm morphometrics between populations, whereas our alternative hypothesis was that the snakes from the fish farm would have significantly longer sperm. We measured total sperm length, sperm head length, sperm tail length, and snout–vent length (SVL). We then used two-tailed t-tests and AIC model selection to test our hypotheses. SVL was not correlated with sperm size. Furthermore, none of the sperm morphometrics were significantly different between the two populations. Finally, a nearly 1:1 correlation between sperm tail length and total sperm length was found. AIC model selection corroborated these results by choosing only sperm head length and sperm tail length as significant predictors of total sperm length. This is the first published study to explicitly compare sperm morphometrics between two populations of the same snake species. Additional studies of this nature are required to corroborate whether lack of significant differences in sperm morphometrics among snake populations are common.

We radiotracked eight, free-living, Red-Bellied Mudsnakes (Farancia abacura) from April to October 2019 in a bottomland hardwood forest wetland in Central Arkansas. Four snakes emerged in April from their overwintering sites in an earthen dam of a 1.2 ha pond and confined all of their movements to the pond basin. All four snakes were lost to predators during the course of the year. Four other snakes emerged from overwintering and dispersed up to 1580 m from the pond. One dispersing snake was lost to a predator when it returned to the pond. Dispersing snakes followed ephemeral streams upstream and downstream, ditches, and flooded bottomlands. The dispersal movements occurred in an extraordinarily wet period that began in August 2018 and continued through August 2019. These results contrasted sharply with the radiotracking results of eight, free-living,F. abacuraat the same locality in 2018, each of which maintained a home range in the pond and experienced no predation. Included in the eight 2018 snakes were three of the dispersing snakes radiotracked in 2019. Possible year-to-year variation in movement patterns driven by environmental variability and predator pressure should be considered in designing management plans for at-risk wetland species.

We observed the behavior of overwintering Smooth Softshell Turtles, Apalone mutica, in an outdoor simulated pond with remote cameras. Submerged overwintering turtles partially buried themselves in a sand/mud substrate where they periodically raised and lowered the posterior portion of their body into the water column in a "push-up" fashion. Push-ups occurred with variable frequency and were similar in appearance and amplitude within and among individual turtles. Push-up frequency was positively correlated with water temperature and was paused more often at lower water temperatures. We also observed push-up behavior of A. mutica under simulated winter conditions in laboratory aquaria. Turtles maintained in water with 95-100% dissolved oxygen content executed push-ups less frequently than turtles in water with lower oxygen content. Our observations of push-up behavior in A. mutica in an outdoor enclosure and laboratory are consistent with a respiratory ventilation function. Softshell turtles, known to be highly intolerant of anoxia, ostensibly sustain aerobic metabolism by creating currents that replenish the oxygen-depleted boundary layer between the turtle's thin vascularized skin and oxygenated water.

Sperrnatogenesis, the production of sperm, is a fundamental part of the reproductive cycle in vertebrates and warrants detailed study. Reptiles exhibit a hybrid pattern of spermatogenesis that has similarities with both anamniotes and amniotes. Researching this interesting transition will help us better understand vertebrate evolution. To this end, we histologically examined the spermatogenic and testicular cycle of Rough Greensnakes (Opheodrys aestivus) from Arkansas. We hypothesized that spermatogenesis in Rough Greensnakes would follow the different spermatogenic stages found in previously published studies on temperate snakes. In addition, we hypothesized that both season and seminiferous tubule diameter would have a significant effect on seminiferous tubule epithelial height. Finally, we hypothesized that Rough Greensnakes would exhibit postnuptial spermatogenesis. We constructed a cell wheel illustrating the chronological development of all germ cell stages for this species and measured seminiferous tubule diameter and seminiferous tubule epithelial height from 22 specimens. Opheodrys aestivus exhibited small seminiferous tubule diameters in spring followed by an increase in summer. By October the lumen was mostly empty of sperm because they had migrated to the vas deferens for winter storage. Seminiferous tubule epithelial height was significantly correlated with seminiferous tubule diameter. Both seminiferous tubule diameter and season significantly affected seminiferous tubule epithelial height. This species can be categorized as having postnuptial spermatogenesis where sperm are produced in the summer after spring mating. Future studies of O. aestivus need to investigate the testicular cycle in other parts of their geographic distribution to see if this monthly pattern is consistent.

This chapter reviews marking and measuring techniques for most reptiles (sea turtle and crocodilian tagging in particular are discussed in later chapters). Field and behavioural studies often require marking individuals for studies of growth and age, survivorship, movements, and other phenomena that require repeated identification of individual animals. Shell notching, toe-clipping, and scute-clipping are the most commonly used, reliable, and cost effective methods of marking reptiles. Passive integrated transponder (PIT) tags are also effective and increasingly popular for providing positive individual recognition in reptiles used in long-term studies. In addition, ethical issues relative to certain techniques may be of concern and thus, some older techniques such as radioactive tags and mutilation procedures should be discouraged.

We studied the natural somatic growth of Apalone spinifera using mark-recapture in a population inhabiting a small urban stream for 16 y. Growth was rapid and variable in hatchlings and young juveniles, but as body size increased, growth slowed, more rapidly in males than in females. Growth in the largest turtles was slow or immeasurable. Von Bertalanffy growth models indicated that males typically matured in their 4th or 5th year and females in their 12th or 13th year. The general growth pattern of A. spinifera was similar to that reported for many sexually dimorphic freshwater turtles, including A. mutica, the sister species of A. spinifera. Individual growth rate in turtles has important implications for science-based conservation efforts because of its effect on maturation, reproductive output, survivorship, and population recruitment.

—We studied the natural somatic growth of Apalone spinifera using mark-recapture in a population inhabiting a small urban stream for 16 y. Growth was rapid and variable in hatchlings and young juveniles, but as body size increased, growth slowed, more rapidly in males than in females. Growth in the largest turtles was slow or immeasurable. Von Bertalanffy growth models indicated that males typically matured in their 4 or 5 year and females in their 12 or 13 year. The general growth pattern of A. spinifera was similar to that reported for many sexually dimorphic freshwater turtles, including A. mutica, the sister species of A. spinifera. Individual growth rate in turtles has important implications for science-based conservation efforts because of its effect on maturation, reproductive output, survivorship, and population recruitment.

Abstract We present information on movement patterns and habitat selection of the endangered Euphrates softshell turtle Rafetus euphraticus (Daudin 1802) from Karkheh Regulating Dam Lake in southwestern Iran. Twelve adult turtles were trapped, fitted with radio-tracking transmitters, and relocated 21 to 51 times between May 2011 and July 2012. The mean linear range size was 2.54 ± 0.83 km, the mean river channel area was 55.35 ± 17.98 ha, the mean minimum convex polygon (MCP) size was 47.49 ± 23.36 ha, and the mean 95% kernel density estimator (KDE 95%) measured 21.75 ± 9.44 ha with a core area (KDE 50%) of 5.74 ± 2.87 ha. Range overlap was generally high; on average, individual MCPs overlapped with those of 7.5 other turtles, individual KDEs with those of 7.3 other turtles, and core areas with those of 5.5 other turtles. Selection of habitat types was not proportional to availability. Study animals preferred shallow-water edge habitats covered with Phragmites australis over all other habitat types.

—I radiotracked Desert Box Turtles (Terrapene ornata luteola) captured at a stock tank in desert grassland habitat in southeastern Arizona from 2001-2003. Individual turtles lived in well-defined 95% MCP home ranges, which included the stock tank and overlapped with home ranges of other turtles. Turtles moved 135 m daily in home ranges averaging 9.8 ha and 469 m across greatest axis. Turtles typically returned to the burrow from which they began their daily movements. There were no sexual differences in daily movement or home range size, nor were there annual differences in daily movement among individuals. Seven of 11 turtles made temporary long distance movements averaging 1,066 m away from their home ranges. Six of 11 turtles exhibited significant directionality in their movements relative to the stock tank. Terrapene o. luteola is a species of conservation concern in Arizona. The spatial information presented in this paper can assist science-based management decisions because it contributes to a better understanding of the core habitat requirements of T. o. luteola.

Twenty-one adult rough green snakes Opheodrys aestivus (Ophidia: Colubridae) were collected during 2010 and 2012 from Montgomery (n = 1) and White (n = 20) counties, Arkansas, U.S.A., and examined for helminths. A single O. aestivus (5%) harbored a massive infection of Mesocestoides sp. This represents a new host record for Mesocestoides sp., and 1 of the rare instances that O. aestivus has been reported to harbor any parasite.

ABSTRACT Trionyx muticus is abundant in the Kansas River, especially in sandy habitats. Egg-laying occurs chiefly in June and July and a female may produce two or more clutches per season. Clutches found in nests averaged 12.6 eggs. Nests averaged 38.2 m from the water and 1.34 m above the water level, and the average depth to the eggs was 16.2 cm. Eggs are approximately spherical, with a mean maximum diameter of 22.9 mm and a mean weight of 6.72 g. Hatchlings, emerging in late August and September, have an average carapace length of 34.84 mm and average weight of 4.91 g. By mid-June of the following year the hatchling cohort has gained 36% in length and 95% in weight. A crude estimate of population structure is made from the analysis of tracks left by basking turtles.

We examined the histology, histochemistry, and ultrastructure of Rathke's glands in hatchlings of the three-toed box turtle, Terrapene carolina triunguis, and the desert box turtle, Terrapene ornata luteola. Both species possess one pair (axillary) of Rathke's glands, which are similar, anatomically and histochemically to one another. Each gland is composed of a single, highly vascularized secretory lobule, which is surrounded by a thick sheath of striated muscle. Two types of large secretory vacuoles characterize most of the holocrine cells produced by a relatively thin glandular secretory epithelium. Analysis of our results suggests that the chief secretory material of the smaller dark-staining type 1 secretory vacuole appears to be a glycoprotein complex. The larger, mostly translucent type 2 secretory vacuole contains multilayered and variously sized lamellar bodies, whose structural design is reminiscent of an epidermal lipid delivery system in vertebrates. The functional role of Rathke's glands in Terrapene and in other turtles remains unclear at the present time.

We report on a Euphrates softshell turtle (Rafetus euphraticus) nest and hatchlings that emerged from the nest that was constructed in a sand patch of the Dez River in southwestern Iran and discovered on 8 July 2012. Information on nest location and structure and hatchling morphology is presented.

Because particular life history traits affect species vulnerability to development pressures, cross-species summaries of life history traits are useful for generating management guidelines. Conservation of aquatic turtles, many members of which are regionally or globally imperiled, requires knowing the extent of upland habitat used for nesting. Therefore, we compiled distances that nests and gravid females had been observed from wetlands. Based on records of > 8000 nests and gravid female records compiled for 31 species in the United States and Canada, the distances that encompass 95% of nests vary dramatically among genera and populations, from just 8 m for Malaclemys to nearly 1400 m for Trachemys. Widths of core areas to encompass varying fractions of nesting populations (based on mean maxima across all genera) were estimated as: 50% coverage = 93 m, 75% = 154 m, 90% = 198 m, 95% = 232 m, 100% = 942 m. Approximately 6-98 m is required to encompass each consecutive 10% segment of a nesting population up to 90% coverage; thereafter, ca. 424 m is required to encompass the remaining 10%. Many genera require modest terrestrial areas (<200 m zones) for 95% nest coverage (Actinemys, Apalone, Chelydra, Chrysemys, Clemmys, Glyptemys, Graptemys, Macrochelys, Malaclemys, Pseudemys, Sternotherus), whereas other genera require larger zones (Deirochelys, Emydoidea, Kinosternon, Trachemys). Our results represent planning targets for conserving sufficient areas of uplands around wetlands to ensure protection of turtle nesting sites, migrating adult female turtles, and dispersing turtle hatchlings. (C) 2012 Elsevier Ltd. All rights reserved.

—We used radiotelemetry to assess the diet of Sternotherus odoratus in Gin Creek, Arkansas, USA. Gin Creek is a small, frequently disturbed, urban stream in which the invasive Asiatic Clam, Corbicula fluminea, has attained high densities. Turtles foraged in small, well-defined home ranges within which we sampled the substrate for potential food items. The diet of S. odoratus, as determined by analysis of fecal samples, compared favorably to prey availability in the creek. The diet was similar to that found in previous dietary studies of typically omnivorous S. odoratus except that clams were eaten much more frequently. An Index of Relative Importance (IRI) revealed the most important prey in both the fecal samples and substrate was C. fluminea. We suggest the diet of S. odoratus in Gin Creek has shifted toward molluscivory as the result of a probable 40-year presence of C. fluminea.