Thomas Rainwater

• Project Manager at Clemson University

Among the Crocodylia, maternal females of most species are known to attend their nests during the egg incubation period. However, the ecological and environmental factors driving nest attendance in these reptiles remain poorly understood. In 2019, we conducted a study in coastal South Carolina, USA, to examine temporal patterns of nest attendance b...

Contaminant body burdens are determined by complex interactions between contaminant inputs into the environment, local ecological dynamics, and organismal ontogeny. Although a naturally occurring element, mercury (Hg) is a potent neurotoxin, commonly assessed in contaminant body burdens. Anthropogenic activity has impacted its spatial distribution,...

With 227,000 km of railways in the United States, wildlife-train collisions are more common than generally recognized and could be an important carrion source for Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura). We conducted a five-year study (2018-2022) in Dutchess and Putnam Counties, New York, USA to 1) estimate the biomas...

Crocodilians have diverse snout shapes ranging from the long, narrow snouts of the Indian gharial (Gavialis gangeticus) to the broad snout of the American alligator (Alligator mississippiensis). In addition, crocodilians possess the strongest bite force of all extant animals, with recorded values for adult alligators exceeding 9 kilonewtons (kN). J...

The Burmese Roofed Turtle (Batagur trivittata) is endemic to the major rivers of Myanmar. Once widespread and abundant, by the late 1990s B. trivittata was considered extinct until “rediscovered” in the Dokhtawady and Chindwin rivers during the early 2000s; the Dokhtawady has since been greatly altered by construction of the Yeywa Hydropower Dam an...

The Siamese Crocodile Crocodylus siamensis is considered one of the most imperiled and poorly-studied crocodilians in the world. Translocations (reintroductions) - often in conjunction with head-starting of juveniles - are a critical component of efforts to restore viable wild populations of C. siamensis. We here report the first confirmed nesting...

Maternal provisioning and the developmental environment are fundamental determinants of offspring traits, particularly in oviparous species. However, the extent to which embryonic responses to these factors differ across populations to drive phenotypic variation is not well understood. Here, we examine the contributions of maternal provisioning and...

Simple Summary The ecological roles and importance of crocodilians (alligators, caiman, crocodiles, gharials) are poorly understood. These large predators are considered to be “ecosystem engineers” because their modification of habitats (e.g., excavation of holes, dens, and tunnels; construction of nests) provides opportunities for vital life activ...

Many ectotherms rely on temperature cues experienced during development to determine offspring sex. The first descriptions of temperature‐dependent sex determination (TSD) were made over 50 years ago, yet an understanding of its adaptive significance remains elusive, especially in long‐lived taxa. One novel hypothesis predicts that TSD should be ev...

1. Many ectotherms rely on temperature cues experienced during development to determine offspring sex. The first descriptions of temperature-dependent sex determination (TSD) were made over 50 years ago, yet an understanding of its adaptive significance remains elusive, especially in long-lived taxa. 2. One novel hypothesis predicts that TSD should...

Mercury is a toxic and pervasive environmental contaminant that can be transferred from mother to offspring during development. Consequences of maternally-transferred mercury have been observed in vertebrate taxa, including reduced clutch viability, reduced offspring size, and behavioral alterations. These sublethal effects have been assumed to dec...

Population models often require detailed information on sex-, age-, or size-specific abundances, but population monitoring programs cannot always acquire data at the desired resolution. Thus, state uncertainty in monitoring data can potentially limit the demographic resolution of management decisions, which may be particularly problematic for stage...

Urban-living wildlife can be exposed to metal contaminants dispersed into the environment through industrial, residential, and agricultural applications. Metal exposure carries lethal and sublethal consequences for animals; in particular, heavy metals (e.g. arsenic, lead, mercury) can damage organs and act as carcinogens. Many bat species reside an...

The Khorat snail-eating turtle (Malayemys khoratensis) is a recently described (2016), poorly studied freshwater turtle known from the Khorat Plateau in Thailand and a small area near Vientiane, Lao People's Democratic Republic. We investigated the occurrence and natural history of M. khoratensis during field surveys of Xe Champhone Ramsar Site (XC...

As anthropogenic impacts on ecosystems increase, novel solutions are needed to mitigate increasing human–wildlife conflict. Aversive conditioning is one strategy that can reduce the risks of humans living alongside wildlife by modifying the behavior of animals through their experiences with humans. Although considered rare, American alligator (Alli...

Simple Summary Immunoglobulin Y (IgY) was purified from American alligator, Alligator mississippiensis, serum and used to develop a monoclonal antibody (mAb AMY-9) specific for the heavy chains of IgY. This antibody tool was then used to develop an ELISA for quantifying serum antibody responses against whole bacterial pathogens in alligators sample...

Amended version of 2021 assessment of Crocodylus acutus, American crocodile, for the IUCN Red List of Threatened Species

Cattle Egrets (Bubulcus ibis) are active foragers that typically pursue and capture insects flushed by grazing mammals. Arboreal foraging by Cattle Egrets has occasionally been reported, although this behavior appears to be rare, poorly documented, and not well understood. We observed Cattle Egrets arboreally foraging at 2 locations in Myanmar: Yan...

American Crocodile Crocodylus acutus has most recently been assessed for The IUCN Red List of Threatened Species in 2020. Crocodylus acutus is listed as Vulnerable under criteria A2cd.

The nuclearfollower relationship is a specialized interspecific foraging association in which the nuclear species excavates the substrate while foraging, and follower species access food items flushed or uncovered by the nuclear species. We observed a nuclearfollower association between Apalone spinifera (Spiny Softshell Turtle) and fish (Micropter...

The Central American river turtle Dermatemys mawii is a critically endangered species that has incurred substantial losses over the last several decades due to overhunting. This species is now being considered for head-starting programmes (i.e., captive breeding of turtles for wild release). However, relatively little is known about their life hist...

Rice Oryza sativa ecosystems provide foraging and nesting habitat for a variety of birds. Myanmar is a major rice-producing nation and yet bird use of rice ecosystems remains largely unstudied. We present the results of a case study of avian species richness in a traditional rice ecosystem at Limpha Village in upper Myanmar. The rice field at Limph...

The environment experienced during embryonic development is a rich source of phenotypic variation, as environmental signals have the potential to both inform adaptive plastic responses and disrupt normal developmental programs. Environment-by-embryo interactions are particularly consequential for species with temperature-dependent sex determination...

The mechanisms connecting environmental conditions to plasticity in biological aging trajectories are fundamental to understanding individual variation in functional traits and life history. Recent findings suggest that telomere biology is especially dynamic during early life stages and has long-term consequences for subsequent reproduction and sur...

Despite the general perception that crocodilians exhibit indeterminate growth, recent long‐term field studies and laboratory investigations have independently suggested that growth in these animals is determinate. In this study, we had the unique opportunity to examine skeletal growth in a wild adult American alligator (Alligator mississippiensis)...

Morelet’s crocodile (Crocodylus moreletii) and hybrid crocodiles (C. moreletii × acutus) are mound-nesting crocodilians found in the lowlands of northern and southern Belize, respectively. Nests of both crocodilians consist of large mounds of soil, vegetation, leaf litter, and in some cases sand. We here report on the fauna associated with nest mou...

Contaminants such as mercury are pervasive and can have immunosuppressive effects on wildlife. Impaired immunity could be important for forecasting pathogen spillover, as many land‐use changes that generate mercury contamination also bring wildlife into close contact with humans and domestic animals. However, the interactions among contaminants, im...

Models relating morphological measures to body size are of great value in crocodilian research and management. Although scat morphometrics are widely used for estimating the body size of large mammals, these relationships have not been determined for any crocodilian. To this end, we collected scats from Siamese Crocodiles (Crocodylus siamensis) and...

The Burmese Roofed Turtle (Batagur trivittata Duméril & Bibron, 1835) is a large (straight-line carapace length [CL] to 620 mm; Platt et al., 2019), aquatic, herbivorous turtle endemic to the major river systems of Myanmar (Smith 1931; TTWG 2017). Although historically widespread and apparently abundant, long-term population declines resulted from...

Contaminants such as mercury are pervasive and can have immunosuppressive effects on wildlife. Impaired immunity could be important for forecasting pathogen spillover risks, as many land-use changes that generate mercury contamination can also bring wildlife reservoir hosts into close contact with humans and domestic animals. However, the interacti...

Species displaying temperature-dependent sex determination (TSD) are especially vulnerable to the effects of a rapidly changing global climate due to their profound sensitivity to thermal cues during development. Predicting the consequences of climate change for these species, including skewed offspring sex ratios, depends on understanding how clim...

Runt (abnormally small) eggs are widely reported in the avian literature, but the few reports available for crocodilians are ambiguous. From 1992 to 2000, we examined 3015 Crocodylus moreletii (Morelet’s Crocodile) eggs from 117 nests in northern Belize; 9 of these eggs met the criterion for runt eggs. Runt eggs occurred at frequencies (per egg an...

American alligators are exposed to mercury (Hg) throughout their natural range and may maternally transfer Hg into their eggs. Wildlife species are highly sensitive to Hg toxicity during embryonic development and neonatal life, and information on Hg transfer into eggs is critical when attempting to understand the effects of Hg exposure on developin...

Herein, we describe a sand flinging behavior that appears commonplace among captive B. trivittata.

Mercury is a widespread, naturally occurring contaminant that biomagnifies in wetlands due to the methylation of this element by sulfate-reducing bacteria. Species that feed at the top trophic level within wetlands are predicted to have higher mercury loads compared to species feeding at lower trophic levels and are therefore often used for mercury...

Dermatemys mawii (Central American River Turtle) is one of the 25 most endangered turtle species in the world and has been locally extirpated from much of its historical range in southern Mexico, lowland Belize, and northern Guatemala. As the sole living member of the primitive Dermatemydidae family, D. mawii, is unique and possesses some uncommon...

Batagur trivittata is a critically endangered, highly aquatic turtle endemic to the large rivers of Myanmar (Ernst and Barbour. 1989. Turtles of the World. Smithsonian Institution Press, Washington, D.C. 313 pp.; Stanford et al. 2018. Turtles in Trouble: The World’s 25+ Most Endangered Tortoises and Freshwater Turtles - 2018. IUCN Tortoise and Fres...

While puberty is an animal commonality, little is known of its timing or process in crocodylians. Males copulate with an intromittent phallus that has a distinct glans morphology which directly interacts with the female cloaca, putatively effecting effective semen transfer and ultimately increased fecundity. Here we present, during the Morelet's cr...

Multiple paternity is relatively common across diverse taxa; however, the drivers and implications related to paternal and maternal fitness are not well understood. Several hypotheses have been offered to explain the occurrence and frequency of multiple paternity. One set of hypotheses seeks to explain multiple paternity through direct and indirect...

Toxic trace element exposure occurs through release of the ubiquitous and naturally occurring elements arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). The unique environmental conditions of the wetland ecosystems along the southeastern Atlantic coast of the United States lead to the accumulation of Hg which is greater than in most other ec...

Dioxins and related contaminants are highly pervasive in aquatic systems and elicit deleterious effects in exposed organisms. Because dioxins exhibit a proclivity to bioaccumulate, long-lived predatory species are particularly vulnerable to their persistence in the environment. We have previously reported elevated expression of CYP1A2, a biomarker...

From June 2015 through August 2018, we examined 258 neonate D. mawii at the Hicatee Conservation and Research Center (HCRC) in the Toledo District of southern Belize. Here we report morphometric measurements, describe coloration, and present representative photographs of these turtles.

We critically evaluated a published historic account purported to be a new size record for A. mississippiensis (American Alligator). According to a newspaper article published in 1885, this large alligator was killed in Natchitoches, LA, and reportedly measured 823 cm (27 ft) in length and weighed 355.3 kg (783.5 lbs). We compared the reported valu...

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...

The herpetofauna of Myanmar remains one of the least studied and poorly known in Asia, and even basic distributional and natural history data are lacking for many species. This situation is particularly alarming given the need for such data when prioritizing conservation action and crafting effective management plans. Furthermore, ethnobiological i...

Elephants are widely recognized as ecosystem engineers. To date, most research on ecosystem engineering by elephants has focused on Loxodonta africana and Loxodonta cyclotis , and the role of Elephas maximus is much less well-known. We here report observations of anuran eggs and larva in water-filled tracks (n=20) of E. maximus in Myanmar. Our obse...

Dermatemys mawii (Central American River Turtle), locally known in Belize as the "Hicatee" and in Guatemala and Mexico as Tortuga Blanca, is a large, highly aquatic freshwater turtle that has been extirpated from much of its historical range of southern Mex-ico, northern Guatemala, and lowland Belize. Throughout its restricted range, Dermatemys has...

We conducted an interview-based survey to investigate the conservation status of large (adult carapace length >400mm) Softshell Turtles (Amyda ornata, Chitra vandijki, and Nilssonia formosa) in the Irrawaddy Dolphin Protected Area (IDPA) of Myanmar during November 2015. Our objectives were to: (1) determine which species of Softshell Turtles occur...

Mercury (Hg) is a persistent and widespread heavy metal with neurotoxic effects in wildlife. While bioaccumulation of Hg has historically been studied in aquatic food webs, terrestrial consumers can become contaminated with Hg when they feed on aquatic organisms (e.g., emergent aquatic insects, fish, and amphibians). However, the extent to which di...

Recent evidence suggests that morphological divergence of the American crocodile (Crocodylus acutus) occurred in Greater Antilles under conditions of prolonged isolation and hybridization with the Cuban crocodile (C. rhombifer). We investigated morphological diversity in C. acutus in the coastal zone of the Yucata´n Peninsula, where isolation and h...

Environmental contamination resulting from the production or release of harmful chemicals can lead to negative consequences for wildlife and human health. Perfluorinated alkyl acids (PFAAs) were historically produced as protective coatings for many household items and currently persist in the environment, wildlife, and humans. PFAAs have been linke...

Exposure to perfluorinated alkyl acids (PFAAs) has been linked to many harmful health effects including reproductive disorders, developmental delays, and altered liver and kidney function. Most human exposure to environmental contaminants, including PFAAs, occurs through consumption of contaminated food or drinking water. This study uses PFAA data...

Mercury (Hg) is a pervasive heavy metal that often enters the environment from anthropogenic sources such as gold mining and agriculture. Chronic exposure to Hg can impair immune function, reducing the ability of animals to resist or recover from infections. How Hg influences immunity and susceptibility remains unknown for bats, which appear immuno...

Supplementary figures and tables showing model averaging results, full model comparison, site and year effects on bat hair THg, relationships between sampling year and bat immunity, and temporal patterns in rainfall across years.

Predictors and immunological correlates of sublethal mercury exposure in vampire bats: Online Supplemental Information

This study aimed to quantify concentrations of fifteen perfluoroalkyl acids (PFAAs) in the plasma of American alligators (Alligator mississippiensis) inhabiting wetlands surrounding the Kennedy Space Center (KSC) in Florida, USA located at Merritt Island National Wildlife Refuge (MINWR). Approximately 10 male and 10 female alligators (ntotal = 229)...

Historically, Belize has used large quantities of organochlorine (OC) pesticides for agriculture and disease-vector control, yet few tools exist for noninvasive assessment of OC contaminant loads in Belize wildlife. Crocodile caudal (tail) scutes are clipped as a marking technique in wildlife management programs and may also have utility as a minim...

The perception that crocodilians exhibit indeterminate growth is common in the general reptilian literature. However, this assumption is frequently based on observations of immature and young adult animals and therefore lacks a complete understanding of adult growth patterns. Long-term mark-recapture studies appear to be the most certain method of...

This study aimed to quantitate 15 perfluoroalkyl acids (PFAAs) in 125 adult American alligators at 12 sites across the southeastern US. Of those 15 PFAAs, 9 were detected in 65% - 100% of the samples: PFOA, PFNA, PFDA, PFUnA, PFDoA, PFTriA, PFTA, PFHxS, and PFOS. Males (across all sites) showed significantly higher concentrations of four PFAAs: PFO...

We conducted a dietary study of the Rough-footed Mud Turtle (Kinosternon hirtipes) at Plata Wetland Complex (PWC) in Presidio County, Texas, USA, from 2007-2008. We collected feces from 88 turtles, including 42 males, 14 females, and 32 juveniles. Items recovered from fecal samples included filamentous algae, vegetation, seeds and fruits, aquatic,...

Kinosternon hirtipes is among the least-studied North American turtles and little is known concerning reproduction. In the United States, K. hirtipes occurs at < 10 sites within a single creek drainage in Presidio County, Texas where it is considered a threatened species. We investigated the reproductive ecology of one of these populations at Plata...

The genus Crocodylus comprises 12 currently recognized species, many of which can be difficult to differentiate phenotypically. Interspecific hybridization among crocodiles is known to occur in captivity and has been documented between some species in the wild. The identification of hybrid individuals is of importance for management and monitoring...

An unusually large Alligator mississippiensis (American Alligator) was harvested in Alabama in 2014. We report on the animal's length and mass, and document the techniques used to obtain those measurements. We compare our measurements to other extreme lengths and weights reported for the species. We show that the size of the American Alligator is c...

Despite the widespread occurrence of environmental sex determination amongst vertebrates, our knowledge of the temporal dynamics by which environmental factors act on this process remains limited. In many reptiles, incubation temperature determines sex during a discrete developmental window just prior to and coincident with the differentiation of t...

The Arakan forest turtle (Heosemys depressa) is a critically endangered, poorly known chelonian endemic to western Myanmar. Previously known only from the Rakhine ( = Arakan) Hills, we here report a significant northward range extension into the southern Chin Hills, verify the occurrence of H. depressa in Kyauk Pan Taung Wildlife Sanctuary, and pre...