J. Whitfield Gibbons's research while affiliated with University of Georgia and other places

Publications (246)

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According to a recent global literature survey, a total of 39 out of the 129 known spider families (30%) contain species capable of capturing vertebrate prey. The finding that the percentage of spider families engaged in vertebrate predation is so high is novel. Two groups of vertebrate-eating spiders are distinguished: habitual vertebrate-eaters v...
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Evolutionary theories predict major differences in life-history trait values of long- and short-lived organisms. Such comparisons have not been possible for chelonians because no short-lived turtle was known until research revealed that chicken turtles (Deirochelys reticularia; DR) have a maximum longevity of 21 yrs. Life-history trait values of DR...
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Exotic species are often vilified as “bad” without consideration of the potential they have for contributing to ecological functions in degraded ecosystems. The red-eared slider turtle (RES) has been disparaged as one of the worst invasive species. Based on this review, we suggest that RES contribute some ecosystem functions in urban wetlands compa...
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In this paper, we present an update on our knowledge on egg predation (oophagy) by spiders. Based on a survey of 233 reports, ghost spiders (Anyphaenidae), lynx spiders (Oxyopidae), jumping spiders (Salticidae), and yellow sac spiders (Cheiracanthiidae) were the most prominent groups of spiders engaged in oophagy. Around 75% of the reports referred...
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For many turtle species, life history traits such as body size, age at maturity, and somatic growth rate can vary among individuals and habitats and between the sexes. Therefore, it is important to consider factors that may influence growth when modeling (somatic) growth for turtles. Long-term capture-mark-recapture studies lend themselves to study...
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Visual acuity and sensitivity positively correlate to eye size in vertebrates, and eye size relates to the ecology of colubrid snakes. We investigated whether eye morphology of North American colubrids of the genus Nerodia correlates with ecology as well. Although all members of the genus utilize aquatic habits, they differ widely in the proportion...
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Turtles and tortoises (chelonians) have been integral components of global ecosystems for about 220 million years and have played important roles in human culture for at least 400,000 years. The chelonian shell is a remarkable evolutionary adaptation, facilitating success in terrestrial, freshwater and marine ecosystems. Today, more than half of th...
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Over 9000 articles have been published on turtles and tortoises (excluding sea turtles) since 1950 according to the Web of Science, including over 8000 contained in a personal bibliography that we analyze in this paper. Research had a slow start from 1900 to 1950, with mostly anecdotal additions to our knowledge until the contributions of F. Cagle...
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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 provisiona...
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This study focused on an estuarine wildlife species exhibiting high site fidelity and ubiquitous distribution in coastal environments along the Atlantic and Gulf coasts of the United States to monitor per- and polyfluoroalkyl substances (PFAS). A total of 75 diamondback terrapin (Malaclemys terrapin) plasma samples were collected from five creeks a...
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Of the 356 species of turtles worldwide, approximately 61% are threatened or already extinct. Turtles are among the most threatened of the major groups of vertebrates, in general, more so than birds, mammals, fishes or even the much besieged amphibians. Reasons for the dire situation of turtles worldwide include the familiar list of impacts to othe...
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Because body size affects nearly all facets of an organism’s life history, ecologists have long been interested in large-scale patterns of body-size variation, as well as why those large-scale patterns often differ between sexes. We explored body-size variation across the range of the sexually dimorphic Ratsnake complex (species of the genus Panthe...
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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 usin...
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The Eastern Mud Turtle, Kinosternon subrubrum (Family Kinosternidae), is a small (carapace length 85 to 120 mm) polytypic species of the eastern and central United States. All three historically recognized subspecies (K. s. subrubrum, K. s. steindachneri, and K. s. hippocrepis) are semi-aquatic turtles that inhabit much of the U.S. Atlantic and Gul...
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The ability to mark individual animals so that they can be identified when subsequently recaptured is crucial for conducting ecological, behavioral, population, and life-history studies. The osseous shells of most turtles provide an excellent medium for assigning relatively permanent and unique sets of marks to a large number of individuals. We pro...
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Because resources are finite, female animals face trade-offs between the size and number of offspring they are able to produce during a single reproductive event. Optimal egg size (OES) theory predicts that any increase in resources allocated to reproduction should increase clutch size with minimal effects on egg size. Variations of OES predict tha...
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Unlabelled: In evaluating conservation and management options for species, practitioners might consider surrogate habitats at multiple scales when estimating available habitat or modeling species' potential distributions based on suitable habitats, especially when native environments are rare. Species' dependence on surrogates likely increases as...
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The diamondback terrapin (Malaclemys terrapin) is a species of conservation concern that has experienced noticeable declines throughout its range. Mark-recapture studies have been conducted on terrapins at Kiawah Island, South Carolina since 1983 and during the early 1990’s this population began to decline. Our objectives were to evaluate current s...
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Despite the functional importance of isolated wetlands as supporters and sources of diverse assemblages of amphibians and reptiles, they lack federal protection and local protection is often insufficient to halt their destruction. A key step in guiding informed policy towards isolated wetlands is to understand their economic value. This study combi...
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The attainment of sexual maturity has been shown to affect measures of sexual size dimorphism (SSD) and adult sex ratios in several groups of vertebrates. Using data for turtles, we tested the model that sex ratios are expected to be male-biased when females are larger than males and female-biased when males are larger than females because of the r...
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Natural and sexual selection are frequently invoked as causes of sexual size dimorphism in animals. Many species of turtles, including the Diamond-backed Terrapin (Malaclemys terrapin), exhibit sexual dimorphism in body size, possibly enabling the sexes to exploit different resources and reduce intraspecific competition. Female terrapins not only h...
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I re-examine the phenomenon of delayed timing of emergence from the nest by hatchling turtles (known as overwintering in temperate climates) within the context of the original summary of the topic in an article by Gibbons and Nelson in 1978. I base the overview on cumulative data from research at the Savannah River Ecology Laboratory since 1968 and...
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Although evidence that reptiles exhibit indeterminate growth remains equivocal and based on inadequate data, the assumption that they do is still widely accepted as a general trait of reptiles. We examined patterns of variation in adult growth using long-term mark-recapture data on 13 populations of 9 species representing 3 families of freshwater t...
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An abundance of physical barriers and physiological challenges often prevent reptile and amphibian species from arriving at, and subsequently colonizing, barrier islands. Despite the high diversity of herpetofauna in the southeastern United States, only a small subset of those species persist on the myriad of barrier islands present just offshore....
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Of the more than 12,000 species and subspecies of extant reptiles, about 100 have re-entered the ocean. Among them are seven species of sea turtles and about 80 species and subspecies of sea snakes, as well as a few other species that are occasionally or regularly found in brackish waters, including various other snakes, the saltwater crocodile, an...
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Climate change has had a significant impact globally on the timing of ecological events such as reproduction and migration in many species. Here, we examined the phenology of reproductive migrations in 10 amphibian species at a wetland in South Carolina, USA using a 30 year dataset. We show for the first time that two autumn-breeding amphibians are...
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Understanding potential for range expansion is critical when evaluating the risk posed by invasive species. Burmese pythons (Python molurus bivittatus) are established in southern Florida and pose a significant threat to native ecosystems. Recent studies indicate that climate suitable for the species P. molurus exists throughout much of the souther...
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Activity levels throughout the year and movement patterns of individually marked slider turtles (Pseudemys scripta) were studied in three aquatic systems on the Savannah River Plant in South Carolina. An hypothesis was proposed to explain the differential movements and activity levels of the sexes, based on the assumption that reproductive strategi...
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Ecological studies were made on the Blanding's turtle, Emydoidea blandingi, in southwestern Michigan. Observations were made regarding population size and structure, seasonal activity, and reproductive potential and cycles. Reproductive cycles and periods of terrestrial activity were found to be coincident with those of the painted turtle, Chrysemy...
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Seasonal variation in the elimination rate constants of two radionuclides was examined in the yellow-bellied slider (Pseudemys scripta). Thirty-six turtles from waste ponds contaminated with cesium-137 and strontium-90 were placed in an uncontaminated 18 × 20 m experimental pond and fed ad libitum weekly. Total body burdens of the radionuclides wer...
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Quantifying diet is essential for understanding the functional role of species with regard to energy processing, transfer, and storage within ecosystems. Recently, variance structure in the stable isotope composition of consumer tissues has been touted as a robust tool for quantifying trophic niche width, a task that has previously proven difficult...
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Mercury contamination threatens many ecosystems worldwide. Methylmercury bioaccumulates at each trophic level, and biomagnifies within individuals over time. Long-lived turtles often occupy high trophic positions and are likely to accumulate mercury in contaminated habitats. Millions of turtles worldwide are sold in Asia for human consumption, and...
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There are currently ca. 317 recognized species of turtles and tortoises in the world. Of those that have been assessed on the IUCN Red List, 63% are considered threatened, and 10% are critically endangered, with ca. 42% of all known turtle species threatened. Without directed strategic conservation planning, a significant portion of turtle diversit...
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The causes and consequences of body size and sexual size dimorphism (SSD) have been central questions in evolutionary ecology. Two, often opposing selective forces are suspected to act on body size in animals: survival selection and reproductive (fecundity and sexual) selection. We have recently identified a system where a small aquatic snake speci...
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Harvesting timber is a common form of land use that has the potential to cause declines in amphibian populations. It is essential to understand the behavior and fate of individuals and the resulting consequences for vital rates (birth, death, immigration, emigration) under different forest management conditions. We report on experimental studies co...
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We compared the effectiveness of five amphibian sampling methods in nine isolated wetlands in Baker County, Georgia, USA. Overall, aquatic funnel traps yielded the most species, although the number detected using frogloggers (automated frog call recording devices), funnel traps, dipnetting, and PVC pipe refugia was not significantly different among...
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Although diamondback terrapins appear to be declining throughout much of their geographic range, more information is required to evaluate population trends. Unfortunately, sampling terrapin populations is both time and labor intensive. We initiated studies to examine the efficacy of using head counts in tidal creeks as a rapid-assessment technique...
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1.Many turtle species frequently suffer major injuries due to attempted predation or anthropogenic factors. Diamondback terrapins (Malaclemys terrapin) are one species known to be affected by anthropogenic activity, but little is known about the causes of injuries. In declining diamondback terrapin populations, learning more about causes and result...
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Summary 1. Habitat loss is a leading cause of global amphibian declines. Forest removal is a particularly significant threat because an estimated 82% of amphibians rely on forests for part of their lives. 2. Biphasic amphibians rely on suitable terrestrial habitat to support their post-metamorphic growth and survival and also to maintain appropriat...
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Chicken turtles (Deirochelys reticularia) were studied at Dry Bay, a Carolina bay wetland in South Carolina, USA, between 1994 and 2005. A total of 461 individual turtles was marked from 1993–1998. Minimum ages at maturity for males and females were 2 and 5 yr, respectively. All females reproduced each year, and 60% of reproductive females produced...
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Several pathogens affect amphibians, but a chytridiomycete fungus, Batrachochytrium dendrobatidis, is of particular interest because this pathogen is linked to localized amphibian population declines and extinction of species. Species-specific infections and pathogen distribution are poorly understood, particularly in members of Caudata. We found B...
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Conservation of isolated wetlands is critical for maintaining regional biodiversity within the southeastern U.S. However, relatively little is known about the ecological communities of these wetland systems, particularly within the karst wetlands of the southeastern Coastal Plain. In southwestern Georgia seasonal isolated wetlands include marshes,...
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There are very few comprehensive studies of the ecology of small-bodied snakes. Here, we describe the ecology and demography of the Southeastern Crowned Snake (Tantilla coronata) based on 1,640 captures on the Savannah River Site in the Upper Coastal Plain of South Carolina, USA from 1951-2007. Female T. coronata were significantly longer, heavier,...
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Altered habitats have been suggested to facilitate red imported fire ant (Solenopsis invicta) colonization and dispersal, possibly compounding effects of habitat alteration on native wildlife. In this study, we compared colonization intensity of wood cover boards by S. invicta among four forest management treatments in South Carolina, USA: an unhar...
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ABSTRACT Population-level responses of amphibians to forest management regimes are partly dictated by individual behavioral responses to habitat alteration. We examined the short-term (i.e., 24-hr) habitat choices and movement patterns of 3 amphibian species—southern leopard frogs (Rana sphenocephala), marbled salamanders (Ambystoma opacum), and so...
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The evaluation of appropriate sampling methodologies is critical for accurately determining the distribution and status of herpetofaunal populations. We report the results of a year-long drift fence study, using multiple trap types (large pitfall traps, small pitfall traps and funnel traps), of a species-rich herpetofaunal community (59 species) su...
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Although recent reports of global amphibian declines have received considerable attention, reptile declines have gone largely unreported. Among reptiles, snakes are particularly difficult to quantitatively sample, and thus, most reports of snake declines are based on qualitative or anecdotal evidence. Recently, several sources have suggested that E...
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Diamondback terrapins (Malaclemys terrapin) are thought to be declining throughout their range. Although many factors have been proposed to contribute to terrapin declines, including increased predation of nests and adults, habitat loss and degradation, road mortality, commercial harvest for food, and mortality as bycatch in crab traps, few studies...
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The gopher tortoise (Gopherus polyphemus) occurs in the southeastern Coastal Plain and has experienced widespread decline due to habitat loss and other human impacts. The largest remaining populations occur on private lands and military installations. Proper management at these sites will be critical to the success of the species. The goal of this...
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Few studies have examined the spatial and temporal migration patterns of snakes to and from active-season habitats. We conducted a year-long population-level analysis of cottonmouth Agkistrodon piscivorus migration patterns by monitoring snakes entering and leaving a Carolina bay wetland that was encircled by a continuous terrestrial drift fence. C...