Accurate estimation of a species' size distribution is a key component of characterizing its ecology, evolution, physiology, and demography. We compared the body size distributions of five Pacific lizards (Carlia ailanpalai, Emoia caeruleocauda, Gehyra mutilata, Hemidactylus frenatus, and Lepidodactylus lugubris) from general herpetological collecting (including visual surveys and glue boards) with those from complete censuses obtained by total removal. All species exhibited the same pattern: general herpetological collecting undersampled juveniles and oversampled mid-sized adults. The bias was greatest for the smallest juveniles and was not statistically evident for newly maturing and very large adults. All of the true size distributions of these continuously breeding species were skewed heavily toward juveniles, more so than the detections obtained from general collecting. A strongly skewed size distribution is not well characterized by the mean or maximum, though those are the statistics routinely reported for species' sizes. We found body mass to be distributed more symmetrically than was snout–vent length, providing an additional rationale for collecting and reporting that size measure.

To obtain quantitative information about population dynamics from counts of animals, the per capita detectabilities of each species must remain constant over the course of monitoring. We characterized lizard detection constancy for four species over 17 yr from a single site in northern Guam, a relatively benign situation because detection was relatively easy and we were able to hold constant the site, habitat type, species, season, and sampling method. We monitored two species of diurnal terrestrial skinks (Carlia ailanpalai [Curious Skink], Emoia caeruleocauda [Pacific Bluetailed Skink]) using glueboards placed on the ground in the shade for 3 h on rainless mornings, yielding 10,286 skink captures. We additionally monitored two species of nocturnal arboreal geckos (Hemidactylus frenatus [Common House Gecko]; Lepidodactylus lugubris [Mourning Gecko]) on the basis of 15,212 sightings. We compared these count samples to a series of complete censuses we conducted from four or more total removal plots (everything removed to mineral soil) totaling 400 m² (about 1% of study site) in each of the years 1995, 1999, and 2012, providing time-stamped quantification of detectability for each species. Unfortunately, the actual population trajectories taken by the four species were masked by unexplained variation in detectability. This observation of debilitating latent variability in lizard detectability under nearly ideal conditions undercuts our trust in population estimation techniques that fail to quantify venue-specific detectability, rely on pooled detection probability estimates, or assume that modulation in predefined environmental covariates suffices for estimating detectability.

Transect surveys without some means of estimating detection probabilities generate population size indices prone to bias because survey conditions differ in time and space. Knowing what causes such bias can help guide the collection of relevant survey covariates, correct the survey data, anticipate situations where bias might be unacceptably large, and elucidate the ecology of target species. We used negative binomial regression to evaluate confounding variables for gecko (primarily Hemidactylus frenatus and Lepidodactylus lugubris) counts on 220-m-long transects surveyed at night, primarily for snakes, on 9,475 occasions. Searchers differed in gecko detection rates by up to a factor of six. The worst and best headlamps differed by a factor of at least two. Strong winds had a negative effect potentially as large as those of searchers or headlamps. More geckos were seen during wet weather conditions, but the effect size was small. Compared with a detection nadir during waxing gibbous (nearly full) moons above the horizon, we saw 28% more geckos during waning crescent moons below the horizon. A sine function suggested that we saw 24% more geckos at the end of the wet season than at the end of the dry season. Fluctuations on a longer timescale also were verified. Disturbingly, corrected data exhibited strong short-term fluctuations that covariates apparently failed to capture. Although some biases can be addressed with measured covariates, others will be difficult to eliminate as a significant source of error in long-term monitoring programs.

Terrestrial salamanders (Plethodontidae) are increasingly cited as important surrogates for monitoring forest ecosystem health and biodiversity. To accurately assess the ecological role of salamanders, total abundance is more relevant than the population subset available for sampling. Therefore, estimating detectability is important for generating unbiased population metrics, as abundance estimates average an order of magnitude greater than surface counts. The past two decades have seen a tremendous increase in analytical methods that account for imperfect detection. Terrestrial salamanders have unique physiological requirements and surface activity patterns that contribute to their inherently low detection levels, and variable terminology makes it difficult to compare detectability parameter values across species, regions, methods, and studies. It is important to use consistent terminology and explicitly state what specific components of detectability are being reported in a study. Availability is governed by the presence of individuals in the sampling area and the capacity of the search method to detect the targeted animals. Conditional capture probability is affected by survey methodology, observer experience level, habitat complexity, and species crypsis. Imperfect detection affects all population-related metrics, including abundance, occupancy, and species richness. Akin to capture–mark–recapture methods, population analysis via hierarchical modeling is a recently developed approach that can account for imperfect detection. Hierarchical models enable researchers to partition complex ecological systems into simpler component models and focus on the mechanisms underlying the observed data. With improved population analyses of terrestrial salamanders, monitoring and conservation efforts can become more precise and effective.

Imperfect detectability in animal studies has been an acknowledged problem for several decades. A number of analytical approaches (e.g., capture–mark–recapture, distance sampling, occupancy analyses), have been developed to deal with the problem and estimate biological parameters of interest. These different analytical approaches can be implemented through various software programs, each with its own graphical user interface (GUI), data input format, and graphing capabilities. Although GUIs and mouse clicks might be convenient to conduct analyses, mouse clicks are difficult to replicate and archive in the long term. Using programming environments such as the R open source project along with a text editor yields flexibility and leaves a paper trail after the analyses are conducted. Such environments also provide statistical and graphical tools for further treatment following the analyses. In this article, I use R to conduct classical analyses to estimate demographic parameters in four case studies. The examples feature interacting with certain software such as MARK, as well as using recent R packages designed to implement specific analyses in both a frequentist and a Bayesian framework. The case studies present all the steps to conduct the analyses, including data importation, model selection, and multimodel inference, as well as the graphical presentation of results. Such an integrative approach provides a flexible alternative to using GUIs, while keeping everything in the same environment and documenting precisely how an analysis was conducted. These are the basic ideas behind reproducible research.

On reconnaît depuis plusieurs décennies le problème de la probabilité de détection imparfaite lors de l'étude de populations animales. Afin d'aborder le problème et d'estimer les paramètres biologiques d'intérêt, plusieurs approches analytiques ont été développées, telles que les approches de capture–marquage–recapture, l'échantillonnage de la distance et les analyses d'occupation de sites. On peut appliquer ces différentes approches à l'aide de divers logiciels, chacun avec sa propre interface graphique, son format d'entrée des données et ses capacités à traiter les données. Les interfaces graphiques et les clics de souris sont pratiques, mais difficiles à archiver. Une alternative consiste à utiliser un environnement de programmation tel que le projet libre R en combinaison avec un éditeur de texte, ce qui amène flexibilité et permet de documenter une analyse pour la répliquer plus tard. De tels environnements offrent des outils statistiques et graphiques pour le traitement ultérieur des données. Dans cet article, je présente quatre études de cas afin d'illustrer l'usage de l'environnement R pour effectuer des analyses classiques permettant d'estimer les paramètres démographiques. Les exemples documentent en détail toutes les étapes de l'analyse, incluant l'importation des données, la réalisation des analyses, la sélection de modèle et l'inférence multimodèle ainsi que la présentation graphique des résultats. De plus, je présente comment appeler certains logiciels à partir de R, tel que MARK ou des logiciels bayésiens. Une telle approche intégrative s'avère une alternative intéressante à l'usage des environnements graphiques. Ainsi, toutes les étapes de l'analyse sont documentées de façon transparente dans un seul environnement de travail pour un usage ultérieur. Ce sont les idées de base derrière la recherche reproductible.

Fragmentary fossils have been tentatively attributed to Alligator from the Eocene of Wyoming, North Dakota, Saskatchewan, and Utah. The earliest definitive temporal and geographic range of Alligator has been limited to the late Eocene and early Oligocene Chadron and Brule Formations of the White River Badlands in South Dakota, represented by fossils of Alligator prenasalis. New fossils from the Chadron Formation in northwestern Nebraska expand the definitive geographic range of Alligator during the late Eocene. Results from a cladistic analysis of 28 alligatoroid species using 181 morphological characters support the identification of the new specimens as representing the most basally divergent taxon within Alligator, suggesting that they likely represent A. prenasalis; however, a lack of diagnostic features in the Nebraska specimens prevents a definitive assignment to this species. Limited occurrence data may indicate that Alligator experienced a reduction in biogeographic range following global cooling around the Eocene-Oligocene transition, although this may be an artifact of low sample size for Oligocene alligators in the Great Plains.

Phenology is an important dimension of vertebrate reproductive strategies. Characterizing a species' reproductive phenology is a fundamental step in directing studies of influences on reproduction within and among populations throughout its range. Eastern Diamond-Backed Rattlesnakes (Crotalus adamanteus; EDBs) are endemic predators of the imperiled longleaf pine (Pinus palustris) ecosystem of the southeastern United States, and the species currently is under review for listing under the Endangered Species Act. Conservation and management of this imperiled species will greatly benefit from research on its basic biology, and particularly from information that will assist management for adult survival and population viability. Here, we present long-term data on EDB breeding and reproductive phenology from several populations in the South Carolina Coastal Plain. We summarized the phenology of EDB breeding and reproduction using observations of free-ranging, radiotelemetered rattlesnakes in South Carolina from 1997 to 2011. Breeding activity occurred from 10 July to 14 October, with a mean of 28 August. There was one outlying observation of spring breeding (18 March). Females moved to birthing sites as early as 26 June and as late as 28 August, with a mean of 15 August. Neonates were born around 31 August, with birth dates between 10 August and 14 September. We also noted six unique observations of apparent clutch size: 8, 10, 11, 11, 12, and 13 neonates. This information will contribute both to our current knowledge and conservation efforts of EDBs, and also facilitate future long-term comparative investigations throughout their geographic range.

Male slider turtles change coloration ontogenetically, becoming melanistic as they age and approach the body size of sexually mature females. Several investigators have suggested that melanism is favored by sexual selection, although there is little evidence to support this hypothesis. We conducted experiments in enclosures to test whether melanism in male Red-Eared Sliders is a visual signal favored by sexual selection. In female preference trials, females showed no preference for either nonmelanistic or melanistic males. Melanistic and nonmelanistic males associated together instead of being aggressive toward each other in trials testing male–male competition. Neither result supports the hypothesis that male melanism is a product of sexual selection. Our observations of nonaggressive interactions between melanistic and nonmelanistic males suggest that melanism in male slider turtles may function as sex recognition to avoid mistaken courtship of large males.

This study investigated the influence of seasonality on diet and foraging behavior of the whiptail lizard Ameivula (Cnemidophorus) ocellifera in the Caatinga of northeastern Brazil. Diet composition was identified through stomach analysis of lizards collected monthly by active search during 2009 (rainy and dry seasons) and half of 2010 (rainy season). Foraging behavior was investigated during one rainy and one dry month of 2012, allowing us to determine the percent of time spent moving (PTM), number of movements per minute (MPM), and number of successful attacks on prey by lizards during foraging activity. Analysis of stomach contents showed significant seasonal differences in diet: insect larvae, Coleoptera, and Orthoptera predominated during the two rainy seasons (2009 and 2010); insect larvae, Hemiptera, Araneae, and Orthoptera predominated in the dry season. Prey movement index was lower during rainy seasons, mainly because of more insect larvae consumed during those periods. Population niche breadth was broader in the dry season, but individual niches did not differ significantly between seasons. When foraging, the average PTM was 61.1 ± 15.1%; MPM was 2.03 ± 0.30; and prey items captured/min was 0.14 ± 0.14. PTM for A. ocellifera was similar to values found for North American whiptails (Aspidoscelis), but MPM was relatively higher. Seasonal differences were observed in PTM, which were significantly higher in the rainy season. This difference may represent a behavioral adjustment in response to differences in seasonal food availability.

The Greenhouse Frog (Eleutherodactylus planirostris) is one of the most widespread frog species in the world. Because of its high population densities, widespread distribution, and consumption of native invertebrates in some invaded sites, understanding its impacts in Hawaii is important. We analyzed stomach contents of 397 frogs from 10 study sites in Maui. Results suggest Greenhouse Frogs are active, ant-specialist predators in the leaf litter. Ants (Formicidae) were the dominant prey found in stomachs in both number and volume. Furthermore, only ants were consumed in a higher proportion than they were sampled in the environment. Because ants dominated their diets, and because all ants are nonnative to Hawaii, this means Greenhouse Frogs consumed primarily nonnative invertebrates (>80%) in the areas sampled. Although results suggest that most native taxa are not at risk from Greenhouse Frog predation, the only locations where we could currently find Greenhouse Frogs were in human-dominated lowlands, which have a lower proportion of native species. Greenhouse Frogs may consume more native species if they invade more native-dominated habitat. Alternatively, nonnative ants are known to impact negatively many native invertebrates in Hawaii, and their possible reduction through Greenhouse Frog predation could affect other species positively. Our research highlights the need to understand better the effects of Greenhouse Frog predation on both native and nonnative invertebrates in Hawaii.

I conducted anuran vocalization surveys in cranberry bogs, drainage ditches, and reservoirs of three active and three abandoned cranberry farms in the New Jersey Pinelands to examine the distribution of four anuran species in three consecutive years. I then applied a multinomial model to quantify their calling intensity and assess the influence of cranberry cultivation activities on each anuran species. I discovered that four species naturally inhabiting the Pinelands exhibited varied responses to cranberry cultivation. The responses ranged from positive to negative depending on the life history characteristics, disturbance tolerance, and especially the breeding season of the species in question. Green frogs (Lithobates (=Rana) clamitans) showed a high abundance in the bog habitats of active farms, where they exhibited prolonged courtship calls in late summer. Fowler's Toads (Anaxyrus (=Bufo) fowleri) exhibited high abundance in the ditches of active farms and the reservoirs of abandoned farms. On the other hand, Southern Leopard Frogs (Lithobates sphenocephalus) and Carpenter Frogs (Lithobates virgatipes) showed a reduced occurrence and calling intensity in active farms, probably because of the intensive water management that coincides with their breeding or wintering season, respectively. My findings indicate that wetlands in agricultural settings with diverse habitats can potentially be used as breeding habitats by anurans, but only if agricultural activities do not interfere with the anuran's breeding and wintering patterns.

Boa constrictor was first documented on the Caribbean island of Aruba in 1999. Despite intensive efforts to eradicate the snake from the island, B. constrictor has established a stable, reproductively successful population on Aruba. We generated mitochondrial sequence and multilocus microsatellite data for individuals from this population to characterize the origins and means of introduction to the island. Phylogenetic analyses and measures of genetic diversity for this population were compared with those for invasive B. constrictor imperator from Cozumel and B. constrictor constrictor from Puerto Rico. Cozumel populations of B. c. imperator had significantly higher numbers of alleles and significantly higher values for F_IS than the Puerto Rico and Aruba populations. Observed, expected, and Nei's unbiased heterozygosities, as well as effective number of alleles, were not significantly different. The effective population sizes from Aruba and Puerto Rico were generally lower than those for either of the Cozumel populations; however, there were broad confidence intervals associated with published estimates. We conclude that the present B. constrictor population on Aruba most likely resulted from the release or escape of a small number of unrelated captive snakes originating from South America (B. c. constrictor) and are phylogenetically distinct from introduced boas on Puerto Rico and Cozumel. This study adds to the growing body of evidence suggesting the ease with which a small number of relatively slow-maturing B. constrictor can quickly invade, become established, and avoid eradication efforts in a new location with suitable habitat.

Synchronous hatching occurs in many reptiles that lay multi-egg clutches, but this phenomenon and its potential environmental cues are poorly documented for species that lay their eggs singly, such as Anolis lizards. We tested for a circadian hatching rhythm in 196 Brown Anole (Anolis sagrei) eggs maintained in social isolation under a 12 : 12 L : D photoperiod with constant temperature and humidity. Hatching occurred exclusively in the morning and was approximately normally distributed around the transition from dark to light, with most (94%) eggs hatching ±1 hour from the onset of light. Hatching times differed significantly between sexes, such that most males hatched after the onset of light (71%), whereas only half of all females hatched after the onset of light (52%). That a substantial proportion of eggs (38% across sexes) hatched in the dark suggests circadian entrainment to photoperiod, rather than a direct behavioral response to light. Whether this reflects a natural circadian rhythm of hatching or an artifact of increased light exposure in our artificial incubation environment is presently unknown. If this circadian rhythm of hatching is a natural phenomenon, then its potential fitness benefits (e.g., optimal timing for predator avoidance, prey detection, water balance, or thermoregulation) warrant further attention.

Environmental conditions to which amphibians are exposed can influence embryonic development and physiology and thus alter later life-history traits. We exposed Ambystoma maculatum eggs to oxygen partial pressures (PO₂) of 1.6, 3.5, 7.9, 12.4, and 18.1 kPa. No eggs survived in the 1.6-kPa treatment, but 94% of the eggs incubated at greater PO₂s survived to hatching. We reared the resulting larvae individually in the laboratory until metamorphosis. Larvae from the 3.5-kPa treatment had reduced posthatching survival. Exposure to hypoxia while in the egg resulted in slowed growth early in the larval period. As a consequence, larvae from the 3.5-kPa treatment averaged 11 d longer to reach metamorphosis than larvae from the 18.1-kPa treatment. Additionally, larvae from an intermediate level of hypoxia (7.9 kPa) were larger at metamorphosis than larvae from eggs reared at either greater or lesser PO₂s. Overall, our results indicate that environmental conditions to which eggs are exposed have the potential to alter future development and survival, even if the effects appear relatively minor at the time of hatching. They also point toward the need for further studies to understand the developmental and physiological mechanisms behind these effects.

We tested the hypothesis that salamanders growing at different rates would have allocation patterns that differ among male and female metamorphic and larval salamanders.We raised individual axolotls, Ambystoma mexicanum, on four food regimes: constant high growth (throughout the experiment), constant low growth (restricted throughout the experiment), high growth switched to low growth (ad libitum switched after 140 d to restricted), and low growth switched to high growth (restricted switched after 140 d to ad libitum). Because axolotls are obligate paedomorphs, we exposed half of the salamanders to thyroid hormone to induce metamorphosis. We assayed growth and dissected and weighed gonads and fat bodies. Salamanders that were switched from restricted to ad libitum food regime delayed metamorphosis. In all treatment groups, females had larger gonads than males and males had larger fat bodies than females. The association between storage and reproduction differed between larvae and metamorphs and depended on sex.

Current knowledge on sexual dimorphism and population structure in the genus Odontophrynus is limited. We studied age structure, age at maturity, and longevity in Odontophrynus cf. barrioi, with skeletochronology. We also determined whether sexual dimorphism in body size exists in this species, and evaluated its relation to demographic life history traits. We found that females were larger in four variables corresponding to the morphology of the head. In addition, females of O. cf. barrioi have a longer tibia-fibula and femur than males. Nevertheless, Odontophrynus cf. barrioi shows no sexual dimorphism in snout–vent length. We suggest the possibility that sexes have different growth trajectories after the onset of reproduction, as they are exposed to different selection pressures, or even predation rate, because of size differences.

The Radiated Tortoise (Astrochelys radiata) is one of Madagascar's four critically endangered tortoise species that has been heavily impacted by poaching. Despite successful captive breeding programs for this species, within Madagascar and internationally, little information is available detailing their reproductive ecology in the wild. In this study, I compare the characteristics of this species' reproduction and reproductive success in 1) a wild population (WP) within their natural habitat in Tsimanampetsotsa National Park, and 2) a captive population (CP) that is exposed to regional climatic conditions in southwest Madagascar. Breeding activities were seasonal, with egg depositions from February until October and mean (±SD) clutch sizes of 3.4 ± 1.6 eggs (CP) and 2.5 ± 0.5 eggs (WP). I found egg mass to be positively correlated with female body mass, and the CP tortoises were larger than in the WP. Egg masses in the CP (36.6 ± 6.4 g) were higher than in the WP (30.1 ± 4.0 g). Incubation time was between 132 and 271 d for the CP hatchlings, and incubation time in the WP was 210–292 d. Hatchlings from the CP emerged in December and January, whereas emergence was restricted to December in the WP. Hatchling body mass did not differ between the two populations. My results suggest that removing large individuals from wild populations (as a result of poaching pressure to support the local bush meat trade) may compromise the reproductive output and long-term survival of this species in the wild.

Growth rates can be used as an indicator of overall turtle population health and provide a baseline against which to compare the quality of, or changes in, the conditions in foraging habitats. Previous studies of Green Turtles (Chelonia mydas) in the waters of the Galápagos Archipelago in the late 1970s revealed some of the slowest growth rates ever reported for immature Green Turtles. In this study, we evaluate whether growth rates have changed since the earlier study and the effects of color morph, body size, recapture interval, year, and site of capture on growth rates for Green Turtles at four key foraging grounds in the Galápagos Islands between 2003 and 2008. Results of this study confirm that somatic growth in Galápagos Green Turtles is very slow. In addition, somatic growth is significantly affected by morph, body size, and spatial variation. Mean growth rates generate implausibly long estimates of 133–200 yr for Galápagos Green Turtles to grow from 40-cm straight carapace length to sexual maturity. We also present some data for growth in Hawksbills (Eretmochelys imbricata), representing the first information of growth rates for Hawksbills in the Archipelago.

Las tasas de crecimiento pueden ser usadas como un indicador de la salud global de una población de tortugas marinas y así proporcionar una línea base con la cual comparar la calidad o los cambios en la condición de los hábitats de forrajeo. Estudios previos en la tortuga verde (Chelonia mydas), llevados a cabo en las aguas del Archipiélago de Galápagos a fines de 1970, revelaron las tasas de crecimiento más lentas que se han reportado para especímenes inmaduros de tortuga verde. En el presente estudio, evaluamos si las tasas de crecimiento han cambiado desde la realización del estudio anterior, y si el color del morfo, tamaño corporal, intervalo de recaptura, año y sitio de captura, tienen algún efecto sobre las tasas de crecimiento de tortugas verdes en cuatro sitios clave de forrajeo de las islas Galápagos entre los años 2003 y 2008. Los resultados de este estudio confirman que las tortugas verdes de Galápagos tienen un crecimiento somático muy lento. Además, el crecimiento somático es significativamente afectado por el morfo, el tamaño corporal y la variación espacial. Las tasas promedio de crecimiento registradas generan largas e inverosímiles estimaciones de 133 a 200 años de vida para las tortugas verdes de Galápagos que, crecen desde los 40-cm de largo recto caparazón hasta la madurez sexual. También presentamos aquí algunos datos para el crecimiento de tortugas carey (Eretmochelys imbricata), representando éstos la primera información sobre tasas de crecimiento de tortugas carey en el Archipiélago.

Many species of animals employ camouflage to render them inconspicuous. Selection to precisely match cryptic color patterns to the background substrate should result in geographic variation in relation to substrate type. We tested this premise by examining color pattern variation in relation to substrate surface in Fowler's Toad (Anaxyrus fowleri), a noxious and cryptically colored amphibian that is widespread in eastern North America and frequently associated with sandy habitats. We quantified total dorsal spot area, number of spots, and size of the four largest dorsal spots among 330 specimens of Fowler's Toads (89 live, 241 preserved) in 14 samples from Canada and the United States. We found no significant difference in the extent or number of spots between males vs. females or between living vs. preserved specimens after compensating for variation in snout–vent length. However, toads from freshwater habitats with extensive areas of open sandy terrain had significantly smaller and fewer dorsal spots than toads from either seacoast localities with open sands present or toads from freshwater habitats with open sands absent. Because saltwater seaside beaches and sand dunes are generally uninhabitable by amphibians, we take this as evidence consistent with the presence of adaptive background pattern matching coloration in this species.

Although our understanding of the behavior of frogs during breeding events is substantial, a gap exists in our knowledge of the behavior and physiology of these animals during nonreproductive periods. We used field sampling of Gray Treefrogs, Hyla versicolor, to measure body condition and steroid hormone levels of breeding and dispersed nonbreeding frogs throughout the active seasons for this species. Gray Treefrog females in the act of breeding showed the greatest elevation of all measured steroids, and females that dispersed away from breeding ponds had greater plasma estradiol and testosterone during the breeding season relative to the nonbreeding season. There was no relationship between progesterone levels and season for dispersed females. Dispersed females were not more likely to show elevated levels of gonadal steroids if they were found closer to the breeding pond and did not move to refugia closer to the breeding ponds as breeding time approached, supporting the hypothesis that migration to breeding ponds is a rapid event in this species. Body condition of females captured during the breeding season did not significantly differ from those captured after the season, and body condition was not correlated with reproductive steroid levels. Our findings suggest that for female Gray Treefrogs, breeding migrations are rapid, and reproductive activity is not strongly condition-dependent in this species.

Chronic stress can result in an elevation of circulating levels of glucocorticoid (GC) hormones in vertebrates, which may affect their fitness. To isolate the effect of GCs on stressed organisms, one approach consists of manipulating circulating levels of GCs. We investigated the usefulness of two corticosterone (CORT) administration methods, Silastic^® implants and cocoa butter injections, in chronically elevating circulating CORT levels in Painted Turtles (Chrysemys picta). First, free-living turtles received subcutaneous Silastic implants for 2 mo. We observed no significant difference in baseline CORT levels between two doses of CORT and sham-treated turtles. Then, captive turtles received a subcutaneous Silastic implant for 28 d. We observed no effect on baseline CORT levels, hormonal stress response, or body mass, suggesting that sealed and perforated Silastic implants of CORT may not be an effective way to elevate CORT in Painted Turtles. Second, we tested injections of CORT-laden cocoa butter for the first time in an ectothermic tetrapod. Free-living turtles received an epicoelomic injection of liquid cocoa butter mixed with CORT and were recaptured in the field over 2 mo. Despite large interindividual variation, we found that this injection approach generally kept circulating CORT levels elevated for up to 3 wk. Achieved CORT concentrations were probably physiologically and ecologically relevant for the species, although concentrations possibly remained elevated longer than would be the case in wild animals. Cocoa butter injections, but not sealed or perforated Silastic implants, can be used in Painted Turtles to chronically elevate CORT. Further, this represents a promising method for other temperate ectotherms such as amphibians and reptiles.