Anthropogenic changes to ecosystems have dramatically altered environmental processes such that native landscapes may be more susceptible to invasive species due to urbanization. This may particularly be the case on islands, where anthropogenic habitat alterations may alter available niche space that allows invasive species colonization and expansion. On Aruba, a small desert island with limited natural surface water, we examined how reproductive development, body size, body condition, and prevalence of pentastome parasites vary in the invasive Boa Constrictor (or simply, "Boa," Boa constrictor) between natural and urbanized habitats to test whether urbanization may alter the success of this species. Female B. constrictor from urban habitats had greater body mass, greater snout-vent lengths, greater ovary mass, and more ovarian follicles than those from natural habitats. Reproductive females were only found in urbanized habitats. Male body mass, body condition index, and testes mass also showed positive relationships with the number of buildings within their estimated activity range. Additionally, we compared the Boa anatomical dataset to recent prey consumption in the snakes we necropsied, which demonstrated a correlation between prey consumption and urbanization. Though limited by sample size of recently consumed prey items, large, endothermic, nonnative prey (e.g., Gallus domesticus, Rattus rattus, and Columba livia domestica) were only found in B. constrictor living in urbanized habitats; very few Boas in the natural ecosystem were found to have recently consumed prey, and of those, only small, native prey species were consumed by Boas. This study provides evidence that urbanized habitats may facilitate growth and reproduction in this large-bodied invasive snake and suggests that urban prey availability may be an important resource subsidy.

Chemoreception and recognition of specific prey are important sensory modalities for optimizing foraging success in snakes. Field observations suggest that cottonmouths are generalists, despite the specific epithet of the species (piscivorus) suggesting a fish prey preference. Because chemo-recognition of specific prey may reveal interesting evolutionary context for foraging strategy and if prey preference is either genetically or environmentally controlled, we investigated the prey cue preference of three experimental groups of Agkistrodon piscivorus (Northern Cottonmouths) with different diet histories. Two groups of captive snakes were acclimated to year-long diets of either fish (n = 11) or mice (n = 9) and a third group of recently wild-caught individuals served as a field diet group (n = 16). We investigated possible differences among diet history (fish, mouse, and field) and prey cue preference (control, fish, and mouse) and present results showing a significant difference among diet history with field snakes having significantly lower tongue-flick response. We also found a significant difference among prey cues, snakes within all diet histories showed a lower tongue-flick response to only the control scent cue. Both captive and field snakes showed no prey cue preference for either fish or mice. Because captive snakes did not show increased prey cue preference to their respective diet history, prey preference may be under genetic influence and not experience-based. Additionally, the lack of prey preference for fish or mice in the recently captured snakes in the field-diet group provides supporting evidence that A. piscivorus are generalists and opportunistic predators.

We sampled the vertebrate community of a 20-ha conservation easement in Venango County, PA, from April through August 2021. The restoration and management efforts on this easement were designed to improve the meadow habitat for one of the few remaining populations of Sistrurus catenatus (Eastern Massasauga Rattlesnake) in Pennsylvania, and our sampling efforts were focused on evaluating the potential prey base available to the rattlesnakes at this site. We identified 9 amphibian species, 10 reptile species, and 11 small mammal species. For amphibians, Anaxyrus americanus (American Toad) was the most abundant species, accounting for 32.6% of the total, followed by Notophthalmus viridescens (Red-Spotted Newt) with 30.6% of total abundance. Thamnophis brachystoma (Short-Headed Gartersnake) comprised more than half (53.7%) of all reptiles sampled, followed by Thamnophis sirtalis (Eastern Gartersnake; 22.7%). Peromyscus leucopus (White- Footed Mouse) was the most abundant mammal species, accounting for 37.4% of all mammals surveyed, followed by Microtus pennsylvanicus (Eastern Meadow Vole; 24.8%). Mammals had the greatest species richness (S = 11), while reptiles had the greatest total abundance (TA = 361), and amphibians had the greatest species evenness (E = 0.799). Species accounts for Venango County indicate that we sampled 40.9% (9/22), 37.0% (10/27), and 21.2% (11/52) of the known amphibian, reptilian, and mammalian species, respectively, within this restored meadow habitat. Our results suggest that the restoration efforts on this easement study site have been extremely effective in creating meadow habitat that supports a diversity of prey species for the Eastern Massasauga Rattlesnake.

Due to the impact and effects of Hurricane Harvey on several aquatic systems in southeast Texas, we investigated the potential impact of flood waters displacing individual cottonmouths (Agkistrodon piscivorus) from known site locations within Harmon Creek in Walker County, Texas. Using mark recapture data and GIS locations, we document that cottonmouths within our study area of Harmon Creek avoided potential displacement and mortality during unprecedented flooding. A comparison of distances between pre- (mean = 192.60 m, SE = 67.572, n = 7) and post- (mean = 97.91 m, SE = 24.953, n = 9) Hurricane Harvey snake locations did not differ and we recaptured 46 cottonmouths that were previously tagged in past sampling years prior to this unprecedented flood event. We finally discuss the importance of long-term monitoring programs that ultimately provide the data needed to evaluate the potential impacts of such disturbance events.

Epidermal lipids serve as the primary barrier to cutaneous water loss (CWL) and play a significant role in water conservation and homeostasis. Previous studies have shown the correlation between increased aridity of habitats and the amount of epidermal lipids among species. Generally, increased amounts of epidermal lipids lower skin permeability. Species-specific differences in CWL and prey preferences between two sympatric snake species, the Northern Cottonmouth (Agkistrodon piscivorus) and the Eastern Copperhead (Agkistrodon contortrix), motivated us to question if prey-base can result in these observed species-specific differences in CWL. We experimentally controlled the diets for a captive colony of Northern Cottonmouths (A. piscivorus) by feeding either fish (Notemigonus crysoleucas) or mice (Mus musculus) to investigate if diet can affect the quantity and quality of epidermal lipids and the rates of CWL. Snakes fed mice gained consistently more mass, but diet treatments did not affect growth rate. We found no significant differences in quantitative lipid content or rates of CWL between diet treatments. An analysis for qualitative lipid content using infrared spectrophotometry also showed no diet effect, thus suggesting that lipid content and CWL are strong species-specific physiological performance traits not influenced by recent dietary history. While there is some evidence that epidermal permeability may be variable under certain environmental conditions (e.g., humidity), our findings show that diet has no effect and that a shift in prey preference may not influence or enhance physiological performance for decreasing CWL.

The Rio Grande Cichlid, Herichthys cyanoguttatus, is native to northeastern Mexico and southern Texas and has been introduced at many places in the US. Recent research has indicated that the true identity of at least some populations of Herichthys cf. cyanoguttatus in Louisiana is H. carpintis and not H. cyanoguttatus. In both their native and introduced ranges, H. carpintis seems to occupy a more lowland/coastal distribution than does Herichthys cyanoguttatus, suggesting that the two species may differ physiologically or ecologically in their ability to invade new environments. Previous research has found that Herichthys cf. cyanoguttatus from Louisiana (which were most likely H. carpintis) have a high tolerance to salinity and pose a threat to both fresh and brackish waters, but the osmoregulatory capacity of H. cyanoguttatus from Texas is unknown. To determine if H. cyanoguttatus from Texas might also have a high tolerance to salinity and pose a threat to both fresh and brackish waters, we performed three experiments to assess response to salinity challenges in H. cyanoguttatus from Texas and in H. carpintis from Louisiana. In response to acute moderate salinity challenge, we found a non-significant salinity*species interaction in change in body mass, a species difference in hematocrit, and no differences in plasma chloride or osmolality. In a 120-day chronic salinity exposure, salinity concentration was inversely related to growth rate, but there was no difference in growth between the two species. In an acute challenge, high salinity concentrations had a strong negative effect on survival, but survival was not different between the two species. Both species were highly tolerant of salinity, indicating that both species might be able to use brackish waters in coastal areas to expand their ranges in the US. Finally, we found that H. cyanoguttatus from Texas spent more time swimming than did H. carpintis from Louisiana, suggesting that the two species could differ in the way they interact behaviorally with native fish communities.

Invasive Boa Constrictors (Boa constrictor) have established a reproductive population on Aruba. High B. constrictor densities could stress prey populations on this small, faunally simplistic island. We examined diet, size, and condition of 501 B. constrictor at three periods over nearly 15 y: during early invasion, approaching the peak in encounters, and after 5 y of declining encounters. The 401 prey identified consisted of 32.9% mammals, 37.4% lizards, and 29.7% birds. Dietary proportion of these categories was consistent across sampling periods. Non-native prey were consumed in relatively high proportions. Despite a positive relationship between snake snout-vent length and prey mass, even the largest snakes consumed small prey. During the high encounter period, many snakes had empty digestive tracts, little abdominal fat, and low body mass, possibly due to a decline in prey availability; however, snakes from residential/agricultural areas had better body condition than those from natural areas. High population densities of the native Aruban Whiptail Lizard (Cnemidophorus arubensis) may provide a consistent food supply for B. constrictor in both natural and residential/agricultural areas, and domesticated prey near human habitation may subsidize the population in residential/agricultural areas. Improved body condition in the last sampling period suggests that the population is either stabilizing or poised for an increase. The endemic Aruba Island Rattlesnake (Crotalus durissus unicolor) and B. constrictor had similar, broad diets that overlapped heavily. Eradication of B. constrictor from Aruba is unlikely, but integration may be possible if the population can be stabilized at low densities. We recommend continued control efforts and systematic monitoring of prey populations.

Abstract. Habitat selection is dependent on several abiotic and biotic factors which have influence at multiple spatial scales. Dependence on specific habitat characteristics for thermoregulation could make habitat selection by herpetofauna especially subtle. Enhancing knowledge of habitat selection by herpetofauna is critical for completely understanding natural histories and improving future habitat management strategies. We conducted a year-long telemetric habitat selection study on two Northern Cottonmouth (Agkistrodon piscivorus) populations in northeast Texas. We used a use–availability approach and investigated intersexual differences at three spatiotemporal scales: home range selection within the study site (home range selection); habitat selection within the home range (macrohabitat selection); and fine-scale local habitat selection (microhabitat selection). The home range selection of both males and females exhibited selection for edges and avoidance of pasture. Males only exhibited macrohabitat selection in the summer, when they selected edge and wetland. Females did not exhibit any macrohabitat selection. Males and females selected microhabitats with thick vegetation in the spring and summer. However, in the fall, male microhabitat selection was influenced by lower temperatures and female microhabitat use appeared to be driven by parturition. Although our study suffered from small female sample size and a short time frame, we provide insight into the complex habitat selection of Cottonmouths in northeast Texas.

We conducted a yearlong telemetric study on 44 northern cottonmouths (Agkistrodon piscivorus) and recorded their weekly spatial position and use at two different and unconnected wetlands: Cooper Wildlife Management Area (Cooper WMA) and Texas A& M Commerce Wetland Area (Commerce WA). These wetland sites differed in size, but were nearly identical in general locality, structure, hydrology, vegetative composition, available resources, and biodiversity. Home ranges for male cottonmouths at the larger Cooper WMA (n = 16; 95% kernel density estimate (KDE) (X) over bar = 54.69 ha +/- 9.36; 100% minimum convex polygon (MCP) (X) over bar = 22.9 ha +/- 4.19) were significantly larger than those at the smaller Commerce WA (n = 10; 95% KDE (X) over bar = 19.88 ha +/- 4.71; 100% MCP (X) over bar = 8.98 ha +/- 2.27). The home ranges of males (n = 26; 95% KDE (X) over bar = 41.3 ha +/- 6.84; 100% MCP (X) over bar = 17.55 ha +/- 3.00) were also significantly larger than those of females (n = 7; 95% KDE (X) over bar = 7.04 ha +/- 1.81; 100% MCP (X) over bar = 3.08 ha +/- 0.82) at both sites. We found no relationship between body size and home range size at either study site. Average weekly distance traveled by males ((X) over bar = 110.07 m +/- 10.80) was significantly greater than that of females ((X) over bar = 45.04 m +/- 4.34), and male movement rates were bimodal in distribution with peaks of movement in the spring and fall. These peaks in movement rates coincided with the spring and fall migrations for mating, thermoregulation, parturition, and access to hibernacula and food resources. We found home ranges within these two-dimensional wetlands to be larger than those reported for linear or one-dimensional riparian sites. We discuss how wetland size and the size-dependent dispersion of potential resources within similar wetlands may influence movement patterns and home range sizes. Such information may serve to evaluate effective wetland size for the conservation and management of wetland species.

Quantifying temporal and spatial occurrence of road crossing activity by amphibians and reptiles has become increasingly important in conservation efforts. By documenting both the common times (hot moments) and places (hot spots) of individuals, species, and assemblages, effective conservation strategies can help to mitigate road mortality. We conducted a 1-y survey of a snake assemblage on U.S. Highway 51 along the Joyce and Manchac wildlife management areas and the Manchac Land Bridge Area between Lake Pontchartrain and Lake Maurepas, Louisiana, USA. We made 78 road-cruising surveys, which allowed us to investigate both the temporal and spatial patterns of snake road crossing activity. We found 409 snakes representing 11 species within two families, Colubridae and Viperidae. Hot moments occurred in late spring or early summer, potentially coinciding with the breeding season and mate-searching behavior in many colubrid species. Hot spots along Highway 51 were detected at the assemblage level and some species-level hot spots were also detected due to large sample sizes. Both peak times and areas of snake activity along U.S. Highway 51 may help to inform potential management efforts for reducing wildlife road mortality.

A classic paper detailed conceptual analyses of behavioral thermoregulation (Huey and Slatkin, 1976) and has served as the theoretical foundation for hundreds of investigative studies. Most recently, investigators have revisited this theoretical presentation to offer additional interpretation for both heterogeneity and spatial structure of temperature and how it may influence energetic costs (Sears and Angilletta, 2015). Interestingly, this foundational presentation by Huey and Slatkin, over 40 years ago, has never received formal computational analyses to address mathematically the postulates of this conceptual model. Here we use functions that closely mimic those that were described by Huey and Slatkin to provide both a theoretical and computational analysis for the cost and benefits of lizard thermoregulation. We demonstrate both the utility and inherent accuracy of their analyses using a model that was developed conceptually without the use of now readily available computational tools. But contrary to Huey and Slatkin's analyses, we provide a mathematical proof that perfect thermoregulation is never an optimal strategy and show by computational analysis that thermoregulatory strategy (k) may decrease, not increase, with increasing cost.

The relationship between host density and parasitism depends on a parasite's life history. The abundance of a directly transmitted contagious parasite should increase with host density, whereas the abundance of a directly transmitted parasite that seeks its host might decrease due to the encounter-dilution effect. For parasites with complex life cycles, previous studies have found no association between parasite abundance and host density. We tested the relationship between host density and metacercarial abundance of a trematode parasite (Posthodiplostomum minimum) in two species of centrarchid fishes (Lepomis macrochirus and L. auritus) from eight small creeks. We found that host density was negatively associated with parasite abundance. Thus, our study represents the first evidence of the encounter-dilution effect for a parasite with complex life cycle in a natural system. We also report a positive association between total P. minimum population abundance and Lepomis spp. density, indicating that at low host density, cercarial mortality could moderate the encounter-dilution effect.

Deviations in bilateral symmetry or fluctuating asymmetry of an organism may result under environmental stressors that reduce developmental homeostasis and stability. Anthropogenic stressors such as increased urbanization can negatively impact environmental quality of aquatic ecosystems. Researchers have stressed the value in finding easy, accurate and inexpensive methods for assessing potential stress within ecosystems. Here we use fluctuating asymmetry (FA) as a useful quantitative tool in assessing the environmental quality and potential urban-based stressors within eight creeks of the Bull and Upatoi Creeks Watershed within the larger watershed of the Middle Chattahoochee. Using Geographic Information System (GIS), we characterize land-use patterns and a decreasing urbanization gradient as related to each creek's eastward position from Columbus, Georgia. We collected two common fishes (redbreast sunfish; Lepomis auritus and bluegill; Lepomis macrochirus), measured both metric and meristic traits and investigated if the degree of FA in these two common fishes correlated with the urbanization gradient across creeks. We found significant differences in FA among creeks with one of the highest FA measures for the most urban creek. Principal component analysis (PCA) scores of urbanization and water chemistry were regressed against FA scores. We found no significant relationship between urbanization and FA nor environmental water chemistry and FA among creeks. We comment on the use of FA as a potential response variable and biological indicator of environmental stress within this watershed.

Forensic taphonomy is an essential research field; however, the decomposition of human cadavers at forensic science facilities may lead to nutrient loading and the introduction of unique biological compounds to adjacent areas. The infrastructure of a water retention system may provide a mechanism for the biogeochemical processing and retention of nutrients and compounds, ensuring the control of runoff from forensic facilities. This work provides a proof of concept for a hydrologic retention system and an autonomous water quality monitoring program designed to mitigate runoff from The Southeast Texas Applied Forensic Science (STAFS) Facility. Water samples collected along a sample transect were analyzed for total phosphorous, total nitrogen, NO3-, NO2-, NH4, F-, and Cl-. Preliminary water quality analyses confirm the overall effectiveness of the water retention system. These results are discussed with relation to how this infrastructure can be expanded upon to monitor additional, more novel, byproducts of forensic science research facilities.

The island of Aruba is home to several endemic species, and has been colonized recently by the invasive boa, Boa constrictor. We present data for a multiple-year sampling effort on one of Aruba's endemic species, the Aruban Whiptail Lizard (Cnemidophorus arubensis). Our sampling began before the invasion of B. constrictor and ended after their firm establishment, thus affording us the unique opportunity to document the potential effects of this invasive snake on the endemic lizard. Additionally, we compare our data with earlier studies with an average lizard density of 235.1/ha (SE = 73.42, n = 11). After the invasion of the B. constrictor we calculated densities of C. arubensis as high as 2,185/ha. Although B. constrictor regularly preys upon C. arubensis, the relationship between B. constrictor and C. arubensis likely represents ecological facilitation of the lizard species. Herein, we further develop a hypothesis that may explain how the invasive B. constrictor has caused an increase in the population of this endemic lizard. Additionally, we suggest and discuss a few alternative hypotheses that may also account for this observed pattern of increased density. This study identifies a need for continued monitoring of Aruba's native fauna, as well as the need for further experimental approaches to understand the mechanism by which invasive predators ecologically interact with native prey.

Predation on Notophthalmus viridescens viridescens (Red-spotted Newt) is rare due to their toxic skin excretions, which provide chemical defense against potential predators. Here we document the occurrence of the Red-spotted Newt in the stomach contents of Lepomis macrochirus (Bluegill) and L. auritus (Redbreast Sunfish), common sunfishes within an urban watershed in Columbus, GA.