Cold-hardiness and evaporative water loss in hatchling turtles.

North American turtles hatch in late summer and spend their first winter either on land or underwater. Adaptations for terrestrial overwintering of hatchlings in northern regions, where winter thermal and hydric regimes are harsh, have not been systematically investigated in many species. We measured intrinsic supercooling capacity, resistance to inoculative freezing, and desiccation resistance in hatchlings of terrestrial and aquatic turtles collected from northern (Terrapene ornata, Chrysemys picta bellii, Kinosternon flavescens, Chelydra serpentina) and southern (Chrysemys picta dorsalis, Trachemys scripta, Sternotherus odoratus, Sternotherus carinatus) locales. Supercooling capacity was estimated from the crystallization temperature of turtles cooled in the absence of external ice nuclei. Mean values ranged from −8.1° to −15.5°C and tended to be lower in terrestrial hibernators. Inoculation resistance was estimated from the crystallization temperature of turtles cooled in a matrix of frozen soil. These values (range of means: −0.8° to −13.6°C) also tended to be lower in the terrestrial hibernators, especially C. picta bellii. Mean rates of evaporative water loss varied markedly among the species (0.9–11.4 mg g−1 d−1) and were lowest in the terrestrial hibernators. Most species tolerated the loss of a modest amount of body water, although half of the sample of S. carinatus died from desiccation. In general, turtles did not regain lost body water from wet soil, and immersion in free water was required for rehydration. Therefore, desiccation resistance may be an important adaptation to terrestrial hibernation. Resistances to inoculative freezing and desiccation were directly correlated, perhaps because they are governed by the same morphological characteristics

Lack of support for Rensch's rule in an intraspecific test using red flour beetle (Tribolium castaneum) populations

Rensch's rule proposes a universal allometric scaling phenomenon across species where sexual size dimorphism (SSD) has evolved: in taxa with male‐biased dimorphism, degree of SSD should increase with overall body size, and in taxa with female‐biased dimorphism, degree of SSD should decrease with increasing average body size. Rensch's rule appears to hold widely across taxa where SSD is male‐biased, but not consistently when SSD is female‐biased. Furthermore, studies addressing this question within species are rare, so it remains unclear whether this rule applies at the intraspecific level. We assess body size and SSD within Tribolium castaneum (Herbst), a species where females are larger than males, using 21 populations derived from separate locations across the world, and maintained in isolated laboratory culture for at least 20 years. Body size, and hence SSD patterns, are highly susceptible to variations in temperature, diet quality and other environmental factors. Crucially, here we nullify interference of such confounds as all populations were maintained under identical conditions (similar densities, standard diet and exposed to identical temperature, relative humidity and photoperiod). We measured thirty beetles of each sex for all populations, and found body size variation across populations, and (as expected) female‐biased SSD in all populations. We test whether Rensch's rule holds for our populations, but find isometry, i.e. no allometry for SSD. Our results thus show that Rensch's rule does not hold across populations within this species. Our intraspecific test matches previous interspecific studies showing that Rensch's rule fails in species with female‐biased SSD.The authors further thank NERC (Standard research grant to MJGG, BCE and OYM), Swiss National Science Foundation (postdoctoral fellowships and Ambizione grants to OYM), the University of East Anglia and ETH Zürich for support.Peer Reviewe

A systematic review of snake translocations to identify potential tactics for reducing postrelease effects

Advancements in the field of reintroduction biology are needed, but understanding of how to effectively conduct translocations, particularly with snakes, is lacking. We conducted a systematic review of snake translocation studies to identify potential tactics for reducing postrelease effects. We included studies on intentional, human-mediated, wild–wild, or captive–wild translocations to any location, regardless of motive or number of snakes translocated. Only studies that presented results for at least 1 of 4 outcomes (movement behavior, site fidelity, survival, or population establishment) were included. We systematically searched 4 databases for published studies and used 5 methods to search the gray literature. Our search and screening criteria yielded 121 data sources, representing 130 translocation cases. We quantified the association between 15 translocation tactics and short-term translocation outcomes by calculating odds ratios and used forest plots to display results. Snake translocations involved 47 species (from mainly 2 families), and most were motivated by research, were monitored for at least 6 months, occurred in North America, and took place from the 1990s onward. The odds of a positive snake translocation outcome were highest with release of captive reared or juvenile snakes, release of social groups together, delayed release, provision of environmental enrichment or social housing before release, or minimization of distance translocated. The odds of a positive outcome were lowest when snakes were released early in their active season. Our results do not demonstrate causation, but outcomes of snake translocation were associated with 8 tactics (4 of which were strongly correlated). In addition to targeted comparative studies, we recommend practitioners consider the possible influence of these tactics when planning snake translocations

Ice nuclei in soil compromise cold hardiness of hatchling painted turtles, Chrysemys picta.

Hatchling painted turtles (Chrysemys picta) commonly overwinter within their natal nests and survive exposure to temperatures as low as -12 degrees C by supercooling. We report that the supercooling capacity of hatchling C. picta is reduced by direct contact with nest soil which, in samples from northwestern and north-central Nebraska, Indiana, and Ontario, contained potent ice nuclei active in the range of -3.5 degrees to -5 degrees C. These nuclei were sensitive to autoclaving and extractable in water. The supercooling capacity of C. picta hatched in native nest soil, or hatched in sterilized vermiculite (which lacks water-extractable nuclei), and subsequently exposed to nest soil, was reduced by ∼10 degrees C relative to control turtles that were hatched and reared in sterilized vermiculite. The effect of these nuclei was potentiated by the presence of environmental moisture, although even transient exposure to dry nest soil markedly reduced supercooling capacity in ∼ 50% of the turtles. Unlike turtle species that hibernate underwater (Sternotherus odoratus, Chelydra serpentina, Apalone spinifera), hatchlings of C. picta exhibited an extraordinary capacity for supercooling (temperature of crystallization, -16 degrees to -20 degrees C) when cooled in isolation from external ice nuclei. However, hatchlings of these four species were equally susceptible to inoculation by suspensions of the ice-nucleating bacterium, Pseudomonas syringae. Indirect evidence suggests that the soil nuclei are associated with such microbes. Nucleating activity was higher in soil collected within nests than in soil collected at the same depth, adjacent to these nests. Differences in the activities of ice nuclei in nesting soils may account for geographic and local variation in winter survival of hatchling C. picta. Our finding that similar agents occur in various other terrestrial habitats in central North America suggests that such nuclei may pose a formidable challenge to the overwintering survival of ectothermic animals that rely on supercooling to withstand frost exposure

Ice nuclei in soil compromise cold hardiness of hatchling painted turtles, Chrysemys picta.

Hatchling painted turtles (Chrysemys picta) commonly overwinter within their natal nests and survive exposure to temperatures as low as -12 degrees C by supercooling. We report that the supercooling capacity of hatchling C. picta is reduced by direct contact with nest soil which, in samples from northwestern and north-central Nebraska, Indiana, and Ontario, contained potent ice nuclei active in the range of -3.5 degrees to -5 degrees C. These nuclei were sensitive to autoclaving and extractable in water. The supercooling capacity of C. picta hatched in native nest soil, or hatched in sterilized vermiculite (which lacks water-extractable nuclei), and subsequently exposed to nest soil, was reduced by ∼10 degrees C relative to control turtles that were hatched and reared in sterilized vermiculite. The effect of these nuclei was potentiated by the presence of environmental moisture, although even transient exposure to dry nest soil markedly reduced supercooling capacity in ∼ 50% of the turtles. Unlike turtle species that hibernate underwater (Sternotherus odoratus, Chelydra serpentina, Apalone spinifera), hatchlings of C. picta exhibited an extraordinary capacity for supercooling (temperature of crystallization, -16 degrees to -20 degrees C) when cooled in isolation from external ice nuclei. However, hatchlings of these four species were equally susceptible to inoculation by suspensions of the ice-nucleating bacterium, Pseudomonas syringae. Indirect evidence suggests that the soil nuclei are associated with such microbes. Nucleating activity was higher in soil collected within nests than in soil collected at the same depth, adjacent to these nests. Differences in the activities of ice nuclei in nesting soils may account for geographic and local variation in winter survival of hatchling C. picta. Our finding that similar agents occur in various other terrestrial habitats in central North America suggests that such nuclei may pose a formidable challenge to the overwintering survival of ectothermic animals that rely on supercooling to withstand frost exposure

Cold-hardiness and evaporative water loss in hatchling turtles.

North American turtles hatch in late summer and spend their first winter either on land or underwater. Adaptations for terrestrial overwintering of hatchlings in northern regions, where winter thermal and hydric regimes are harsh, have not been systematically investigated in many species. We measured intrinsic supercooling capacity, resistance to inoculative freezing, and desiccation resistance in hatchlings of terrestrial and aquatic turtles collected from northern (Terrapene ornata, Chrysemys picta bellii, Kinosternon flavescens, Chelydra serpentina) and southern (Chrysemys picta dorsalis, Trachemys scripta, Sternotherus odoratus, Sternotherus carinatus) locales. Supercooling capacity was estimated from the crystallization temperature of turtles cooled in the absence of external ice nuclei. Mean values ranged from −8.1° to −15.5°C and tended to be lower in terrestrial hibernators. Inoculation resistance was estimated from the crystallization temperature of turtles cooled in a matrix of frozen soil. These values (range of means: −0.8° to −13.6°C) also tended to be lower in the terrestrial hibernators, especially C. picta bellii. Mean rates of evaporative water loss varied markedly among the species (0.9–11.4 mg g−1 d−1) and were lowest in the terrestrial hibernators. Most species tolerated the loss of a modest amount of body water, although half of the sample of S. carinatus died from desiccation. In general, turtles did not regain lost body water from wet soil, and immersion in free water was required for rehydration. Therefore, desiccation resistance may be an important adaptation to terrestrial hibernation. Resistances to inoculative freezing and desiccation were directly correlated, perhaps because they are governed by the same morphological characteristics

Altered spring phenology of North American freshwater turtles and the importance of representative populations

Globally, populations of diverse taxa have altered phenology in response to climate change. However, most research has focused on a single population of a given taxon, which may be unrepresentative for comparative analyses, and few long‐term studies of phenology in ectothermic amniotes have been published. We test for climate‐altered phenology using long‐term studies (10–36 years) of nesting behavior in 14 populations representing six genera of freshwater turtles (Chelydra, Chrysemys, Kinosternon,Malaclemys, Sternotherus, and Trachemys). Nesting season initiation occurs earlier in more recent years, with 11 of the populations advancing phenology. The onset of nesting for nearly all populations correlated well with temperatures during the month preceding nesting. Still, certain populations of some species have not advanced phenology as might be expected from global patterns of climate change. This collection of findings suggests a proximate link between local climate and reproduction that is potentially caused by variation in spring emergence from hibernation, ability to process food, and thermoregulatory opportunities prior to nesting. However, even though all species had populations with at least some evidence of phenological advancement, geographic variation in phenology within and among turtle species underscores the critical importance of representative data for accurate comprehensive assessments of the biotic impacts of climate change

Road avoidance and its energetic consequences for reptiles

Roads are one of the most widespread human-caused habitat modifications that can increase wildlife mortality rates and alter behavior. Roads can act as barriers with variable permeability to movement and can increase distances wildlife travel to access habitats. Movement is energetically costly, and avoidance of roads could therefore impact an animal's energy budget. We tested whether reptiles avoid roads or road crossings and explored whether the energetic consequences of road avoidance decreased individual fitness. Using telemetry data from Blanding's turtles (Emydoidea blandingii; 11,658 locations of 286 turtles from 15 sites) and eastern massasaugas (Sistrurus catenatus; 1,868 locations of 49 snakes from 3 sites), we compared frequency of observed road crossings and use of road-adjacent habitat by reptiles to expected frequencies based on simulated correlated random walks. Turtles and snakes did not avoid habitats near roads, but both species avoided road crossings. Compared with simulations, turtles made fewer crossings of paved roads with low speed limits and more crossings of paved roads with high speed limits. Snakes made fewer crossings of all road types than expected based on simulated paths. Turtles traveled longer daily distances when their home range contained roads, but the predicted energetic cost was negligible: substantially less than the cost of producing one egg. Snakes with roads in their home range did not travel further per day than snakes without roads in their home range. We found that turtles and snakes avoided crossing roads, but road avoidance is unlikely to impact fitness through energetic expenditures. Therefore, mortality from vehicle strikes remains the most significant impact of roads on reptile populations

Altered spring phenology of North American freshwater turtles and the importance of representative populations

Globally, populations of diverse taxa have altered phenology in response to climate change. However, most research has focused on a single population of a given taxon, which may be unrepresentative for comparative analyses, and few long-term studies of phenology in ectothermic amniotes have been published. We test for climate- altered phenology using long-term studies (10–36 years) of nesting behavior in 14 populations representing six genera of freshwater turtles (Chelydra, Chrysemys, Kinosternon, Malaclemys, Sternotherus, and Trachemys). Nesting season initiation oc- curs earlier in more recent years, with 11 of the populations advancing phenology. The onset of nesting for nearly all populations correlated well with temperatures during the month preceding nesting. Still, certain populations of some species have not advanced phenology as might be expected from global patterns of climate change. This collection of findings suggests a proximate link between local climate and reproduction that is potentially caused by variation in spring emergence from hibernation, ability to process food, and thermoregulatory opportunities prior to nesting. However, even though all species had populations with at least some evi- dence of phenological advancement, geographic variation in phenology within and among turtle species underscores the critical importance of representative data for accurate comprehensive assessments of the biotic impacts of climate change