Evin T. Carter

Roads are associated with a blunted stress response in a North American pit viper

Whereas numerous studies have examined roads as anthropogenic stressors in birds and mammals, comparatively few studies have been undertaken on reptiles. We investigated plasma corticosterone (CORT) levels at baseline and following 30min of restraint stress in free-ranging copperhead snakes (Agkistrodon contortrix) captured within the forest interior or while in contact with public roads. There was no difference in baseline CORT levels between snakes in the forest and on roads. Copperheads responded to restraint stress by increasing plasma levels of CORT; however snakes on roads exhibited a lower CORT stress response compared to forest snakes. Additionally, among snakes captured on roads there was a negative association between road traffic and baseline CORT, stressed CORT, and the magnitude of the CORT response. Our results suggest that roads are associated with a blunted stress response in copperheads. Reduced stress responses may be indicative of acclimation, the inhibited ability to mount a stress response in the face of prolonged chronic stress, or that road environments select for individuals with lower CORT responsiveness. Either scenario could result in increased road mortality if snakes do not perceive roads as a potential threat.

An Independent Observation of Facultative Parthenogenesis in the Copperhead (Agkistrodon contortrix)

Abstract Among reptiles, reproduction in the absence of males is often assumed to result from long-term sperm storage. Through the application of molecular genetic tools, biologists are beginning to recognize that facultative parthenogenesis can also explain such reproductive events in snakes. We observed a Copperhead (Agkistrodon contortrix) give birth to a stillborn neonate and four infertile ova after 9 yr in isolation from male snakes. To test the hypothesis that the neonate was produced asexually, we screened a panel of 10 microsatellite loci to genotype the mother and her offspring, as well as wild-caught individuals in the mothers population of origin, to assess the probability of paternity. Confirming prior research on Copperheads that suggests parthenogenesis by terminal fusion automixis, we found that four heterozygous maternal loci were homozygous in the neonate. We calculated the probability of a random male from the population as a sire to the neonate to be 2.32 × 10−13 by using the population allele frequencies and the genotype of the neonate. These results further confirm that Copperheads are facultatively parthenogenetic and suggest that this reproductive mode may be general within the species.

Rediscovery and conservation status of six short‐range endemic Pseudanophthalmus cave beetles (Carabidae: Trechini)

The North American endemic cave beetle genus Pseudanophthalmus is exceptionally diverse, with >150 described taxa in karst regions of the eastern United States. Eighty‐seven per cent of taxa, however, are at risk of extinction due to small, restricted distributions, low abundance, and several potential anthropogenic threats to their habitats. Six species in Tennessee are exceedingly rare and are candidates for listing under the U.S. Endangered Species Act: Coleman Cave Beetle (P. colemanensis), Fowlers Cave Beetle (P. fowlerae), Inquirer Cave Beetle (P. inquisitor), Bakers Station Cave Beetle (P. insularis), Nobletts Cave Beetle (P. paulus), and Soothsayer Cave Beetle (P. tiresias). Each species is an extreme short‐range endemic. Four species have not been observed in several decades, and two species (P. insularis and P. paulus) are considered possibly extinct. We searched 57 caves in 15 counties in Tennessee, including eight of the nine historical localities of the six Pseudanophthalmus species between July 2013 and March 2016 to determine if populations were still extant, to search for new populations, and to estimate relative abundance. We confirmed the continued existence of all six species, including P. fowlerae, P. insularis, P. paulus, and P. tiresias, which had not been observed in 52, 60, 50, and 42 years, respectively. We also discovered five new populations in total, one for each species except for P. paulus. Although U.S. Fish and Wildlife Service ruled that all six species do not warrant federal listing, all species continue to have restricted ranges and remain at an elevated risk of extinction.

Population Viability of Nonnative Mediterranean House Geckos (Hemidactylus turcicus) at an Urban Site Near the Northern Invasion Front

Abstract Biological invasions are one of the most serious threats to biodiversity conservation. Although success and impacts of many invaders, particularly ectotherms, are likely to be limited by a combination of climatic and demographic factors, human modifications to the environment can facilitate distributional expansion into otherwise low-quality landscapes. We assessed factors that might promote or preclude population viability of a nonnative ectotherm, Hemidactylus turcicus (Mediterranean House Gecko), within an urban center at the northern periphery of its known North American range. Mediterranean House Geckos are increasingly apparent in the southeastern United States, but their potential for establishment and spread in more temperate regions is less well known. We gathered data using capture–recapture methods and the unique dorsal patterns of individual geckos. Despite a more temperate climate compared to other areas in their introduced range, and refuge temperatures falling below the critical thermal minimum previously documented for other introduced Mediterranean House Gecko populations, geckos survived the winter and reproduced successfully. Cormack–Jolly–Seber open population models did not provide definitive evidence regarding changes in population size over the study period. The tendency for this introduced species to establish populations primarily within urban centers may suggest that negative impacts associated with this northerly expansion are minor. Nonetheless, a high potential for range expansion suggests a need to assess a potentially growing suite of ecosystem interactions.

To forage, mate, or thermoregulate: Influence of resource manipulation on male rattlesnake behavior

Abstract Male animals should preferentially allocate their time to performing activities that promote enhancing reproductive opportunity, but the need to acquire resources for growth and survival may compete with those behaviors in the short term. Thus, behaviors which require differing movement patterns such as ambushing prey and actively searching for mates can be mutually exclusive. Consequently, males that succeed at foraging could invest greater time and energy into mate searching. We radio‐tracked sixteen male massasauga rattlesnakes (Sistrurus catenatus) and supplemented the diets of half the snakes with mice across an active season. We tested the predictions that reduced foraging needs would allow fed snakes to move (i.e., mate search) more, but that they would consequently be stationary to thermoregulate less, than unfed controls. Contrary to our first prediction, we found no evidence that fed snakes altered their mate searching behavior compared to controls. However, we found controls maintained higher body temperatures than fed snakes during the breeding season, perhaps because fed snakes spent less time in exposed ambush sites. Fed snakes had higher body condition scores than controls when the breeding season ended. Our results suggest the potential costs incurred by devoting time to stationary foraging may be outweighed by the drive to increase mating opportunities. Such instances may be especially valuable for massasaugas and other temperate reptiles that can remain inactive for upwards of half their lives or longer in some cases, and for female rattlesnakes that generally exhibit biennial or more protracted reproductive cycles.

Invasive Plant Management Creates Ecological Traps for Snakes

Exotic plant management often begins only after introduced taxa become widespread and problematic. Control efforts at this stage have a higher potential to lead to unintended outcomes in native systems. We explored the impacts of ongoing invasive plant management on a native ectotherm, the copperhead (Agkistrodon contortrix), in a landscape heavily impacted by multiple nonnative plant species. We found that habitats undergoing invasive plant control are preferred by snakes over other available habitats, but these individuals are at greater risk of injury and mortality owing to policy-driven methods of control. At the same time, we show that management can reverse invader impacts, notably reclaiming thermoregulatory opportunities for ectotherms, thus offering benefits as well as challenges for such animals. This introduces a key dilemma for conservation as invasive plant management can reclaim critical resources while policy-driven control methods can undermine the success of these efforts. We outline several simple and direct solutions that may easily be incorporated into management plans.

VERTEBRATE FAUNA IN CAVES OF EASTERN TENNESSEE WITHIN THE APPALACHIANS KARST REGION, USA

More than one-fifth of the documented caves in the United States occur in Tennessee. The obligate subterranean biota of Tennessee is rich and diverse, with 200 troglobionts reported from over 660 caves. Fifty troglobionts are known from just 75 of the 1,469 caves in the Appalachian Valley and Ridge physiographic province of eastern Tennessee. Tennessee’s Valley and Ridge has been under-sampled relative to other karst areas in the state, limiting our knowledge of cave and karst species diversity and distributions and compromising our ability to identify habitats and species potentially at risk from anthropogenic threats, such as urban sprawl near the metropolitan area of Knoxville. Knowledge of nontroglobiontic species inhabiting caves, including vertebrates, is particularly sparse in this region. Although caves have long been recognized as critical habitats for several bat species, the importance of caves for other vertebrate taxa has received less attention. Caves are important habitats for many other nontroglobiontic vertebrates and should be considered in the management and conservation of these species. Our decade-long study bioinventoried 56 caves in 15 counties and begins to address knowledge gaps in distributions and cave use by vertebrates in the Valley and Ridge and adjacent Blue Ridge Mountains of eastern Tennessee within the Appalachians karst region. In addition, we conducted a thorough review of the literature and museum databases for additional species-occurrence records in those provinces of eastern Tennessee. From these sources, we present an annotated list of 54 vertebrate taxa, including 8 fishes, 19 amphibians (8 anurans and 11 salamanders), 6 reptiles, 3 birds, and 18 mammals. Three species are included on the IUCN Red List of Threatened Species, while six species are at risk of extinction based on NatureServe conservation rank criteria. Ten bat species are known from 109 caves in 24 eastern Tennessee counties. Our bioinventories documented five bat species in 39 caves, including new records of the federally endangered Gray Bat (Myotis grisescens). We observed visible evidence of whitenose syndrome caused by the fungal pathogen Pseudogymnoascus destructans at four caves in Blount, Roane, and Union counties. We documented two new localities of the only troglobiontic vertebrate in the Valley and Ridge, the Berry Cave Salamander (Gyrinophilus gulolineatus). Despite these efforts, significant sampling gaps remain—only 7.7% of known caves in the Valley and Ridge and Blue Ridge Mountains of eastern Tennessee have records of vertebrate-species occurrence. Moreover, few caves in eastern Tennessee have experienced repeated, comprehensive bioinventories, with the exception of periodic surveys of hibernating bats at selected caves. Future bioinventory efforts should incorporate multiple visits to individual caves, if possible, and more efforts should focus on these understudied areas of eastern Tennessee.