Western alligator snapping turtles, Macrochelys temminckii , have experienced population declines throughout most of their distribution. The present study is the first to systematically sample aquatic habitats of western Tennessee to assess the status and distribution of this species within the state. At the 65 sites sampled, we captured 22 individual alligator snapping turtles from 4 sites, including 1 site where juveniles had been reintroduced more than a decade prior. We conclude that M. temminckii occurs at very low densities in western Tennessee, likely due to historical habitat modification (e.g., channelizing rivers or ditching).

We present a review and analysis of the conservation status and International Union for Conservation of Nature (IUCN) threat categories of all 360 currently recognized species of extant and recently extinct turtles and tortoises (Order Testudines). Our analysis is based on the 2018 IUCN Red List status of 251 listed species, augmented by provisional Red List assessments by the IUCN Tortoise and Freshwater Turtle Specialist Group (TFTSG) of 109 currently unlisted species of tortoises and freshwater turtles, as well as re-assessments of several outdated IUCN Red List assessments. Of all recognized species of turtles and tortoises, this combined analysis indicates that 20.0% are Critically Endangered (CR), 35.3% are Critically Endangered or Endangered (CR+EN), and 51.9% are Threatened (CR+EN+Vulnerable). Adjusting for the potential threat levels of Data Deficient (DD) species indicates that 56.3% of all data-sufficient species are Threatened. We calculated percentages of imperiled species and modified Average Threat Levels (ATL; ranging from Least Concern = 1 to Extinct = 8) for various taxonomic and geographic groupings. Proportionally more species in the subfamily Geoemydinae (Asian members of the family Geoemydidae) are imperiled (74.2% CR+EN, 79.0% Threatened, 3.89 ATL) compared to other taxonomic groupings, but the families Podocnemididae, Testudinidae, and Trionychidae and the superfamily Chelonioidea (marine turtles of the families Cheloniidae and Dermochelyidae) also have high percentages of imperiled species and ATLs (42.9–50.0% CR+EN, 73.8–100.0% Threatened, 3.44–4.06 ATL). The subfamily Rhinoclemmydinae (Neotropical turtles of the family Geoemydidae) and the families Kinosternidae and Pelomedusidae have the lowest percentages of imperiled species and ATLs (0%–7.4% CR+EN, 7.4%–13.3% Threatened, 1.65–1.87 ATL). Turtles from Asia have the highest percentages of imperiled species (75.0% CR+EN, 83.0% Threatened, 3.98 ATL), significantly higher than predicted based on the regional species richness, due to much higher levels of exploitation in that geographic region. The family Testudinidae has the highest ATL (4.06) of all Testudines due to the extinction of several species of giant tortoises from Indian and Pacific Ocean islands since 1500 CE. The family Testudinidae also has an ATL higher than all other larger polytypic families (≥ 5 species) of Reptilia or Amphibia. The order Testudines is, on average, more imperiled than all other larger orders (≥ 20 species) of Reptilia, Amphibia, Mammalia, or Aves, but has percentages of CR+EN and Threatened species and an ATL (2.96) similar to those of Primates and Caudata (salamanders).

Nest-site selection can influence both the survivorship of a clutch of eggs as well as the phenotype of resulting hatchlings. The purpose of this study was to determine whether nest sites of Gopherus polyphemus in southern Mississippi differed from randomly chosen prospective nest sites with respect to various habitat parameters. Data were collected that described habitat variables we thought could be biologically relevant. Univariate tests were used to both compare nest sites with non–nest sites, as well as to further narrow the list of variables into those included in an analysis with Akaike's Information Criterion (AIC). Our AIC analysis suggests that the amount of bare soil at the apron and the composition of the soil are important factors when modeling nest-site selection for this tortoise. Aprons with nests contained more bare soil (less vegetation and litter cover) and less clay content in the soil than did randomly chosen aprons that did not have nests. These results indicate that nest sites of G. polyphemus in southern Mississippi differ from random, potential nest sites, implying that females exhibit nest-site selection.

Little is known about the movement behavior of the stripe-necked musk turtle, Sternotherus minor peltifer . Using radiotelemetry, we calculated mean (± SD) home range length, which was 341.4 ± 90.3 m, with home range length not differing between the sexes (males, 335 ± 194 m; females, 346 ± 79.5 m). Sternotherus m. peltifer were active in every month of the year but decreased their movement distance and frequency between December and March; during nonwinter and winter periods, individuals used limestone bluffs most often.

Culverts are often used to increase the permeability of roaded landscapes for wildlife, including turtles. Although the benefits of culverts as safe passages for turtles are well documented, under some conditions culverts can entrap them and cause mortality. Here we report a culvert-related mortality in the federally threatened desert tortoise ( Gopherus agassizii ) at a wind energy facility in California and offer simple recommendations to mitigate the negative effects of culverts for wildlife in general.

Cryptic or undescribed species pose a major problem in conservation biology. Managing multiple unresolved taxa collectively as a single entity could precipitate the loss of unrecognized genetic variation and unique populations and, possibly, lead to extinction of undiscovered or unrecognized taxa. In contrast to other species in its clade, the Pascagoula map turtle ( Graptemys gibbonsi ), as currently recognized, is not confined to a single major river system (or a cluster formed by a major river and adjacent minor drainages) but occurs in two major river systems, the Pearl and Pascagoula Rivers. We analyzed G. gibbonsi samples from both rivers for the first time in a morphological and molecular assessment of the taxonomic status of this poorly studied species. We compared the extent of genetic differentiation (mitochondrial DNA; mtDNA) between G. gibbonsi populations with members within the pulchra clade and between Graptemys oculifera and Graptemys flavimaculata . We found significant carapace pattern variation and morphological differentiation between the Pearl and Pascagoula river samples of G. gibbonsi . Our mtDNA sequences showed greater genetic differentiation between G. gibbonsi samples from the Pearl and Pascagoula rivers than between two recognized and reciprocally sympatric species, G. oculifera (Pearl River) and G. flavimaculata (Pascagoula River), but revealed only a modest degree of differentiation when compared to other members of the pulchra clade. Based on the degree of differentiation in 1) morphology, 2) color patterns, and 3) mtDNA, in addition to their 4) allopatric distributions, we describe a new species from the Pearl River, restricting the species G. gibbonsi to the Pascagoula River.