Russell L. Burke

The approximately 356 species of testudines (turtles) are remarkable for their blend of phylogenetic conservatism and diversity

Reliable estimates of animal and plant population sizes are necessary to track trends in populations through time. Diamondback terrapins are an ecologically unique keystone species that are globally declining. Conservation efforts for this species rely on accurate estimates of population sizes; however, diamondback terrapin population size estimates are difficult to measure with precision or accuracy. Terrapin collection methods are often labor-, time-, and cost-intensive. The present study compares two recently developed rapid assessment methods for measuring diamondback terrapin abundances. Since mark–recapture or similar data were unavailable, we could not test the accuracy of either method directly; instead, we compared the two methods. If the methods produce similar estimates of terrapin population size, this would increase confidence in these methods. We measured the abundance of diamondback terrapins at 77 sites in Long Island, New York, using headcount surveys and surveys of parasitic trematodes that can be used as a proxy for terrapin abundance. We used random forest analyses to test whether the variation in diamondback terrapin abundance measured using headcount surveys could be explained by either the prevalence or the abundance of trematode parasites. The most variation explained by any of the models was 7.77%, indicating that trematode prevalence and abundance could not explain the variation in terrapin abundance measured using headcounts. This poor correlation between terrapin census methods indicates that one, or both, of the census measures are inaccurate, at least in the habitats found across Long Island, NY. A technique that accurately estimates the abundance of diamondback terrapin populations is critical to understanding their population fluctuations and trends. The only way to evaluate the status of the species is to have information on population numbers and trends across the species’ range, which might not be possible without a more accessible survey method.

Climate change is likely to have strong impacts on oviparous animals with minimal parental care, because nest temperature can impact egg development, sex, and survival, especially in the absence of mitigation via parental care. Nesting females may compensate for increasing temperatures by altering how, when, and where they nest. We examined the factors determining nest depth and site choice as well as the effects that nest depth and location have on nest temperature and hatching success in the diamondback terrapin (Malaclemys terrapin). We found that nest depth was not correlated with nesting female size, egg characteristics, or daily temperatures. Nest temperatures and hatching success were correlated with different environmental and nest characteristics between 2004, a cool and wet year, and 2005, a hot and dry year. Females selected nests with lower southern overstory vegetation in 2005. These results suggest that nest depth and location can play an important yet varying role in determining nest temperature and hatching success in more extreme warm and dry environmental conditions and, therefore, may mitigate the impacts of climate change on oviparous reptiles. However, we found minimal evidence that turtles choose nest locations and depths that maximize offspring survival based on short-term environmental cues.

To better understand the habitat preferences of the African spurred tortoise (Centrochelys sulcata), we tested possible associations between their distribution and land use, vegetation cover, the presence of roads, human settlements, and rainfall patterns, all of which affect the distributions of other tortoise species. African spurred tortoise distribution (based on 36 presence points compared with 250 random points) was strongly associated with 3 variables we analyzed: 1) Corine Land Cover (CLC) categories (especially sites with deciduous shrubs and high herbaceous cover relative to random bare areas), 2) distance from human settlements, and 3) distance from the nearest road.

Home range (HR) studies are a particularly common approach to investigations of animal habitat use, resource availability, and response to management manipulation such as relocations. Terrapene carolina (Eastern box turtle) and its sister taxon T. ornata (Ornate box turtle) are especially popular subjects of HR studies because they are relatively easily tracked. Terrapene HR studies have revealed a wide variation in HR sizes within and between populations, due to factors such as differences in ecoregion and analytical approach (e.g., minimum convex polygons, kernel analysis, bivariate normal, multivariate Ornstein–Uhlenbeck stochastic process, harmonic means). We performed a meta-analysis of the available literature, including unpublished work to avoid bias due to under-publication, to explore the causes for variation in HR size. We found 19 studies reporting T. carolina HR sizes and seven studies reporting T. ornata HR sizes; the resulting meta-analysis revealed patterns that are not visible in the individual studies. We found important differences between the species: female T. ornata had smaller HRs than males, whereas the opposite is true for T. carolina, and T. ornata HRs were influenced by ecoregion, while T. carolina HRs were not similarly influenced. Not surprisingly, we found that choice of analysis technique affected HR estimate; analyses using ellipses resulted in larger HR estimates than all the other techniques, while kernels were smaller than minimum convex polygons. Although not indicated by individual studies, our meta-analysis showed that the HRs of relocated T. carolina females were significantly larger than those of non-relocated females. Although the number of individual turtles in studies varied from three to 25, the sample size did not significantly affect HR size.

Overwintering behavior of diamond-backed terrapin (Malaclemys terrapin) hatchlings is highly unusual; a substantial percentage of hatchlings leave nests in the fall, travel overland, and rebury themselves on land farther from water. Many aspects of this behavior are poorly documented and conflicting. We tracked 81 newly emerged M. terrapin hatchlings from their nest sites in Jamaica Bay, New York, to their overwintering refugia and until spring/summer emergence. Hatchling M. terrapin used the wrack line only as short-term cover before moving upland and burying themselves in terrestrial refugia. Hatchling refugia depths were variable, up to 10 cm deep, with some vertical movement seasonally. Hatchlings selected winter refugia with relatively high levels of vegetative cover; in this way, overwintering sites differed substantially from temporary refugia. Hatchlings emerged from overwintering refugia between 17 March and 7 July following fall emergence. Our observations better characterize what may b...

The painted turtle, Chrysemys picta, is currently recognized as a continentally distributed polytypic species, ranging across North America from southern Canada to extreme northern Mexico. We analyzed variation in the rapidly evolving mitochondrial control region (CR) in 241 turtles from 117 localities across this range to examine whether the painted turtle represents a continentally distributed species based on molecular analysis. We found strong support for the novel hypothesis that C. p. dorsalis is the sister group to all remaining Chrysemys, with the remaining Chrysemys falling into a single, extremely wide-ranging and genetically undifferentiated species. Given our goal of an evolutionarily accurate taxonomy, we propose that two evolutionary lineages be recognized as species within Chrysemys: C. dorsalis (Agassiz 1857) in the southern Mississippi drainage region, and C. picta (Schneider 1783) from the rest of the range of the genus. Neither molecular nor recent morphological analyses argue for the hybrid origin of C. p. marginata as previously proposed. Within C. picta, we find evidence of at least two independent range expansions into previously glaciated regions of North America, one into New England and the other into the upper Midwest. We further find evidence of a massive extinction/recolonization event across the Great Plains/Rocky Mountain region encompassing over half the continental United States. The timing and extent of this colonization is consistent with a recently proposed regional aridification as the Laurentide ice sheets receded approximately 14,000 years ago, and we tentatively propose this paleoclimatological event as a major factor shaping genetic variation in Chrysemys.

The painted turtle, Chrysemys picta, is currently recognized as a continentally distributed polytypic species, ranging across North America from southern Canada to extreme northern Mexico. We analyzed variation in the rapidly evolving mitochondrial control region (CR) in 241 turtles from 117 localities across this range to examine whether the painted turtle represents a continentally distributed species based on molecular analysis. We found strong support for the novel hypothesis that C. p. dorsalis is the sister group to all remaining Chrysemys, with the remaining Chrysemys falling into a single, extremely wide-ranging and genetically undifferentiated species. Given our goal of an evolutionarily accurate taxonomy, we propose that two evolutionary lineages be recognized as species within Chrysemys: C. dorsalis (Agassiz 1857) in the southern Mississippi drainage region, and C. picta (Schneider 1783) from the rest of the range of the genus. Neither molecular nor recent morphological analyses argue ...

Italian wall lizards (Podarcis sicula campestris) were introduced to Long Island, New York, in 1967 and have subsequently spread through many urban and suburban communities. Their ability to spread further may be limited by their ability to tolerate the relatively cold winters of New York. We found that these lizards were able to survive cold temperatures by supercooling if they were kept dry. However, if freezing was initiated as would be expected under shallow hibernation conditions, these lizards froze and died rapidly. We speculate that Podarcis sicula must hibernate below soil freezing depth, estimated at greater than 24 cm deep, to survive.