John C. Maerz

Diamondback terrapins (Malaclemys terrapin) are challenging to monitor in their salt marsh habitat. However, large-scale monitoring is needed to understand the status of populations and effectively apply targeted management. The Georgia Department of Natural Resources (GA DNR) is interested in developing a long-term monitoring program that it can use for tracking relative levels of terrapin abundance among creeks throughout the state to trigger varying intensities of management actions. The objective of this study was to investigate the potential of repeated head counts and binomial N-mixture models to inform the GA DNR's state-wide monitoring and management objectives. We used the unmarked repeated count method to categorize sites into 3 levels of relative abundance while accounting for uncertainty in estimates. However, relative abundance estimates were sensitive to the timing of sampling within the active season and location of sampling along the creek, indicating limitations of this method. Results also showed that as survey effort increased, the number of sites that could be confidently assigned to higher abundance categories also increased. Therefore, if an objective is to minimize the number of creeks requiring more intensive and potentially more restrictive management actions, a high level of survey effort is recommended. Because relative abundance estimates using head count methods varied with timing and location of sampling, survey methods would need to be standardized and consistent across years. If applied judiciously, a method using head count surveys and N-mixture models may be the most effective means of state- or region-wide monitoring of terrapins across large numbers of sites. Additionally, if integrated with ongoing, long-term capture–recapture studies at a smaller number of sites, the capacity for head count surveys to inform terrapin management decisions across large areas and many sites could be enhanced.

The Gopher Tortoise (Gopherus polyphemus) is a keystone species endemic to the Coastal Plain ecoregion of the southeastern United States. Gopher Tortoises excavate extensive burrows that are used by over 60 vertebrate and 300 invertebrate species. Our understanding of burrow commensals has generally been limited to Longleaf Pine (Pinus palustris) savanna and xeric uplands and shrublands, excluding private, working pine (Pinus spp.) forests that are known to harbor tortoise populations. Therefore, we used passive infrared wildlife cameras to document vertebrate burrow commensals and evaluate differences in composition across burrow classifications (i.e., abandoned, active, and inactive) within a private, working Loblolly Pine (Pinus taeda) forest located in the Upper Coastal Plain ecoregion of Georgia, USA. Our study showed that the composition of vertebrate commensals did not differ across abandoned, active, or inactive tortoise burrows, indicating that burrows, regardless of classification, may provide a similar suite of resources (e.g., refugia, forage) to vertebrate commensals. Also, we observed numerous species using burrows that typically occur in other landscapes with known tortoise populations (e.g., Longleaf Pine savannah). We encourage continued monitoring of tortoise burrows and other potential refugia within working forests to better understand how these structures contribute to species abundance and persistence within these forests.

The problem of global amphibian declines has prompted extensive research over the last three decades. Initially, the focus was on identifying and characterizing the extent of the problem, but more recently efforts have shifted to evidence‐based research designed to identify best solutions and to improve conservation outcomes. Despite extensive accumulation of knowledge on amphibian declines, there remain knowledge gaps and disconnects between science and action that hamper our ability to advance conservation efforts. Using input from participants at the ninth World Congress of Herpetology, a U.S. Geological Survey Powell Center symposium, amphibian on‐line forums for discussion, the International Union for Conservation of Nature Assisted Reproductive Technologies and Gamete Biobanking group, and respondents to a survey, we developed a list of 25 priority research questions for amphibian conservation at this stage of the Anthropocene. We identified amphibian conservation research priorities while accounting for expected tradeoffs in geographic scope, costs, and the taxonomic breadth of research needs. We aimed to solicit views from individuals rather than organizations while acknowledging inequities in participation. Emerging research priorities (i.e., those under‐represented in recently published amphibian conservation literature) were identified, and included the effects of climate change, community‐level (rather than single species‐level) drivers of declines, methodological improvements for research and monitoring, genomics, and effects of land‐use change. Improved inclusion of under‐represented members of the amphibian conservation community was also identified as a priority. These research needs represent critical knowledge gaps for amphibian conservation although filling these gaps may not be necessary for many conservation actions.

Assessing numbers of leukocytes in salamanders and other amphibians can be useful metrics for understanding health or stress levels of individuals in a population. In this chapter we describe the procedures for obtaining blood samples from amphibians, preparing blood films for microscopy, counting, and identifying cells. We also provide reference values for amphibian leukocytes for use in interpreting leukocyte data. From our assessment of the published and unpublished literature, “non-stressed” salamanders would have a leukocyte profile where 60–70% of cells are lymphocytes, 17–30% are neutrophils, 1–4% are eosinophils, 4–12% are basophils, and 2–6% are monocytes. In Ambystoma spp., the eosinophil abundance can be notably higher (30% of all white blood cells), for reasons unknown. Finally, the neutrophil–lymphocyte ratio of most non-stressed salamanders tends to be between 0.3 and 0.4 (sometimes less), while the ratios of stressed salamanders tend to be over 1.0. Key words Leukocyte profiles Salamander White blood cells Neutrophil–lymphocyte ratios Stress indices Microscopy Blood smears Physiology

Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher diversity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.

Population models depend on reliable estimates of vital rates, yet for many taxa, such estimates and how they vary in response to spatial or temporal environmental gradients are lacking. The goal of this review was to determine whether existing estimates of vital rates for temperate, direct-developing plethodontid salamanders (subfamily Plethodontinae) could be used to reasonably project values for populations or species where such estimates are lacking, or whether current estimates are biased in a manner that limits their utility. We synthesized current knowledge of stage-specific survival rates, age- and size-at-maturity at first clutch, and clutch frequency. We tested for expected correlations among published vital rates (e.g., age at maturity and survival) and between vital rates and factors such as body size or latitude. We used matrix projection models to judge whether published estimates were reasonably possible for stable salamander populations. The largest number of published vital rates were for clutch size, clutch frequency (proportion of females with clutches), size at maturity or first clutch, and age at maturity or first clutch, though the latter vital rate is primarily inferred from size distribution and growth rate data. Among these vital rates, we found expected correlations with body size and latitude suggesting these rates were reasonable and somewhat predictable among species or populations. In contrast, there were few estimates of egg hatch rate or juvenile or adult survival. Hatch and survival rate estimates were widely variable; estimates seldom included measures of uncertainty, but when uncertainty measurements were included, they were generally high. Based on projection models, few survival estimates were likely unbiased or realistic for stable populations given other salamander vital rates. Additionally, few studies quantified how vital rates vary with spatial or temporal environmental gradients. We outline the key knowledge gaps that limit basic demographic modeling of these remarkably common, influential, and otherwise well-studied salamanders, and make recommendations for future research efforts.

Diamond-backed Terrapins inhabit coastal salt marshes along the eastern and Gulf coasts of North America. Terrapins are adapted to intermediate salinities yet frequently face saltwater-inundated marsh habitat exceeding 25 ppt (or grams/kilogram). We investigated the effect of salinity on the growth of hatchling terrapins and on their compensatory responses to salinity stress. We randomly assigned 30 terrapin hatchlings each to one of five salinity treatments (1, 5, 10, 20, or 35 ppt). Over 75 d, we regularly monitored behavior, appetite, and changes in growth; and calculated ratios of heterophils to lymphocytes (H:L ratio) to assess responses to prolonged salinity stress. Consistent with prior studies, chronic exposure to high salinity significantly reduced hatchling growth. Hatchlings in 20-ppt and 35-ppt salinities exhibited appetite suppression and saltwater avoidance and were more likely to show freshwater-seeking behaviors. H:L ratios were higher among hatchlings in 20- and 35-ppt salinities, consistent with a corticosterone-driven stress response to sustained high-salinity exposure, which may play a role in limiting growth. Our findings suggest hatchling growth and distribution among local habitats will vary spatially depending on habitat salinity and freshwater accessibility. The growth-limiting effects of chronically high salinity or limited access to freshwater could therefore increase hatchling mortality and be an important driver of spatial variation in terrapin demography and abundance. However, when freshwater sources are available, compensatory behaviors might reduce growth-limiting effects. Terrapin recruitment is likely to be impacted as rising sea levels, increased human water use, land development, and other anthropogenic changes alter freshwater inputs to coastal marshes.