Live Toads Research Articles

NECROPHAGY IN TWO SNAKE SPECIES OF THE GENUS Leptodeira (SQUAMATA: DIPSADIDAE)

Snakes of the genus Leptodeira are known to be predators with a wide variety of prey known in their diet. The predation observations reported here were made in the state of Sinaloa, in northwestern Mexico. Our study reports the first record of L. splendida and L. septentrionalis consuming dead toads of the species Incilius mazatlanensis. In addition, we report the sighting of L. splendida feeding on a live toad of Rhinella horribilis. Therefore, this is the first report of necrophagy for both Leptodeira species. The possibilities of chemosensory signals for prey detection in these snakes and opportunistic predation when live prey is scarce are discussed.

Inter-group Transfer of Anti-alcoholic Effect of Nux vomica 200 CH through the Body of a Live Toad

Background: A homeopathic potency is usually given to the nursing mother for the treatment of her baby. Potencies above 12 CH cross the Avogadro number and are, therefore, too dilute to contain any original drug molecules. A potency is thought to be specifically structured water carrying the imprint of original drug molecules. It may convert the water structure in the body of the mother and through her milk reach the suckling baby. Using a toad model we have recently demonstrated that the antialcoholic effect of Nux vomica 200 CH could be transferred from one group of toads to another through capillary water which carries the information of Nux vomica. Homeopathic potencies show UV spectra distinct from its diluent medium of aquous ethanol. Does a potency remain effective even after passage through a living body? Objectives: To demonstrate that a potency effect can be transferred through the body of a live toad to other groups of toads connected through water to the live toad. Further, we want to see whether the UV spectra of drug solution and of water connected to the drug are similar in nature. Methods: A live toad was held vertically with one hind limb dipped in Nux vomica 200 CH solution in a beaker and another limb in distilled water in another beaker. The second beaker was connected by wet cotton threads encased in polythene tubes to 5 beakers, each of which contained adult toads in distilled water. A batch of toads was directly treated with Nux vomica 200 CH. An equal number of toads in distilled water served as the untreated control. After 30 min the control and the two batches of treated toads were kept separately in 209 mM ethanol solution. Toads, that stopped movement, were placed in supine position on a dry surface. Failure to assume a normal sitting posture within a cutoff time of 60 sec was regarded as loss of righting reflex (RR). The experiment was replicated using large number of toads. UV spectra of Nux vomica 200 CH solution and of water before and after connection with the drug were obtained. Results: The percentage of toads losing RR in the three groups of toads increased with time of exposure to 209 mM ethanol solution. The loss of RR was significantly delayed with the direct treatment group ( P < 0.001, chi square test) and the connected groups ( P < 0.01 , χ2 test ) as compared to the control. The two former groups did not differ from each other significantly. UV spectra of Nux vomica 200 CH solution were similar to that of water connected to the drug solution. Conclusion: The antialcoholic effect of Nux vomica 200 CH could be transferred through the body of a live toad to other groups of toads. The drug did not undergo denaturation during its passage through the living body. That water carries the information of original drug is further evidenced by the spectral properties of water connected to the drug solution through capillary water.

Qualitative and Quantitative Analysis of Tryptamines in the Poison of Incilius alvarius (Amphibia: Bufonidae).

Rising numbers of psychoactive tryptamine derivatives have become available on the drug market over the last decade, making these naturally occurring or synthetically manufactured compounds highly relevant for forensic analyses. One of these compounds is 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), a constituent of the dried poison of Incilius alvarius (Colorado River toad), which has a history of ritual and/or recreational use. Still, comprehensive and validated qualitative as well as quantitative analytical data on the psychoactive components of this poison are scarce. In this study, samples of the poison of Incilius alvarius were collected from live toads in the Sonoran Desert, Arizona (USA), and analyzed with a set of complementary methods. Acetone/water (70/30, v/v) proved to be the solvent of choice for the extraction of tryptamine derivatives. Trace compounds were enriched, and overload with 5-MeO-DMT was prevented by chromatographic separation of 5-MeO-DMT prior to qualitative analyses. The method for quantification was validated. Attenuated total reflection-Fourier transform infrared spectroscopy was suitable to identify 5-MeO-DMT as the main tryptamine in samples of the poison. The combined evaluation of analytical data gained from gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography-quadrupole time-of-flight high-resolution MS (HPLC-qToF-HRMS) and HPLC-MS-MS confirmed the presence of 5-MeO-DMT, 5-MeO-N-methyltryptamine, 5-MeO-tryptamine, 5-MeO-tryptophol, 2-(5-methoxy-1H-indol-3-yl)-acetic-acid (5-MIAA), 5-HO-N-methyltryptamine, bufotenin, DMT and tryptophan. For the first time, 5-MeO-tryptamine and two positional isomers of hydroxylated MeO-DMT were detected in the poison of Incilius alvarius. The tryptamine present in the highest concentrations was 5-MeO-DMT (mean ± SD: 410,000 ± 30,000 μg/g). Mean concentrations of 5-MeO-tryptamine (490 ± 260 μg/g), 5-HO-N-methyltryptamine (270 ± 120 μg/g), bufotenin (2,800 ± 1,900 μg/g) and DMT (250 ± 80 μg/g) showed a relatively high variability between individual samples. The comprehensive analytical reference data of Incilius alvarius poison presented here might prove useful for forensic chemists.

Road-killed toads as a non-invasive source to study age structure of spring migrating population

Development of road system causes worldwide barriers to wildlife movement and leads to mass road mortality which is a serious threat to the biodiversity, especially globally endangered amphibians. Animal carcasses, however, constitute an important non-invasive material for further research including species life history traits, but there is little known whether the road-killed animals are a representative sample of entire population. The aim of our research was to compare the age structures between road-killed and live individuals which crossed the road successfully during the breeding migration. As a model species, we used the common toad Bufo bufo which is a main amphibian traffic victim in Europe. We collected toe clips of dead and live toads during their breeding migration in four sampling sites located in the lowlands of western Poland. Phalanges were used for age determination by the skeletochronology. There were no significant differences in age distribution between live and dead individuals of the same sex in all populations studied. In compared groups, medians and mean ages were the same or differed marginally and confidence intervals for the mean age almost completely overlapped. Our results suggest that toads are killed on roads regardless of individual age, thus skeletochronological analysis of dead individuals is useful to study age structure of a live population. Our approach allows to avoid mutilation of amphibians and can be used to increase the knowledge of age structure of a given species living near the road as well as to study long-term road effect on amphibian demography. However, further comparative research on different species is required.

A diamond in the rough desert shrublands of the Great Basin in the Western United States: A new cryptic toad species (Amphibia: Bufonidae: Bufo (Anaxyrus)) discovered in Northern Nevada

We describe a new species of toad from the Great Basin region of northern Nevada belonging to the Bufo (Anaxyrus) boreas species complex. This cryptic species was detected through genetic analyses of toad populations sampled throughout the Great Basin and the morphological evidence was quantified through extensive sampling of live toads within the region. The new species has the smallest body size in the species complex, and can be further diagnosed from other species in the complex by its large tibial glands and unique coloration. The known distribution of the new species is restricted to an area less than 6 km2 in Dixie Valley, Churchill Co., Nevada. The Great Basin is an arid region where aquatic resources are both rare and widely scattered, making habitat suitable for anuran populations highly vulnerable to anthropogenic change. The habitat occupied by this newly described species is threatened by the incipient installation of geothermal and solar power development projects that require the water that defines its habitat.

Eliciting conditioned taste aversion in lizards: Live toxic prey are more effective than scent and taste cues alone

Conditioned taste aversion (CTA) is an adaptive learning mechanism whereby a consumer associates the taste of a certain food with symptoms caused by a toxic substance, and thereafter avoids eating that type of food. Recently, wildlife researchers have employed CTA to discourage native fauna from ingesting toxic cane toads (Rhinella marina), a species that is invading tropical Australia. In this paper, we compare the results of 2 sets of CTA trials on large varanid lizards ("goannas," Varanus panoptes). One set of trials (described in this paper) exposed recently-captured lizards to sausages made from cane toad flesh, laced with a nausea-inducing chemical (lithium chloride) to reinforce the aversion response. The other trials (in a recently-published paper, reviewed herein) exposed free-ranging lizards to live juvenile cane toads. The effectiveness of the training was judged by how long a lizard survived in the wild before it was killed (fatally poisoned) by a cane toad. Both stimuli elicited rapid aversion to live toads, but the CTA response did not enhance survival rates of the sausage-trained goannas after they were released into the wild. In contrast, the goannas exposed to live juvenile toads exhibited higher long-term survival rates than did untrained conspecifics. Our results suggest that although it is relatively easy to elicit short-term aversion to toad cues in goannas, a biologically realistic stimulus (live toads, encountered by free-ranging predators) is most effective at buffering these reptiles from the impact of invasive toxic prey.

TRITRICHOMONAS BATRACHORUM PERTY FROM SOME COLOMBIAN TOADS

The Colombian toads Bufo marinus, B. typhonius ockerdeni, B. guttatus and B. blombergi were infested with Tritrichomonas batrachorum. Samples of feces obtained directly from live toads and cultures made of the flagellates. Uninfected B. marinus were kept with individuals of B. typhonius ockerdeni harbouring small T. batrachorum. After 42 days all B. marinus were infested with T. batrachorum of the large strain, originally isolated from that host species. Ingestion of trophozoites and cysts is considered to be the normal route of entry. The trichomonads fit the original description of T. batrachorum and the difference in size is considered to be due to host adaptation. T. batrachorum has not yet been recorded for Colombia, and all toads except B. marinus are new hosts.

Chemical suppression of embryonic cane toads Rhinella marina by larval conspecifics

Summary Mechanisms that evolved to suppress the development of potential competitors may offer novel methods for species‐specific control of invasive organisms. The tadpoles of cane toads Rhinella marina compete for limited food resources in small ponds and older tadpoles eliminate competitors not only by eating newly laid eggs, but also by releasing a chemical that suppresses development of conspecific eggs. We conducted laboratory trials to assess the magnitude and generality of this suppression effect and to identify the developmental stages capable of producing the suppressor cue and those that are vulnerable to its presence. In all clutches that we tested, the suppressor cue reduced larval growth, development and survival (>95% mortality vs. <50% in controls). The suppressor exerts a general effect on larval development, rather than causing malformations of specific organ systems. Free‐swimming tadpoles of all developmental stages produce the cue (but are not affected by it), whereas embryos do not produce the cue, but are vulnerable to it. Tadpoles produce the cue consistently rather than facultatively (e.g. in response to detecting eggs). A preliminary trial shows that the cue is effective in natural spawning ponds as well as in the laboratory. Synthesis and applications. Our data have strong implications for current methods of toad control (culling tadpoles will remove suppression effects on the next generation, so it may be better to maintain live toad tadpoles in secure containers rather than removing them from the pond). Longer‐term, understanding the chemical basis of this powerful mechanism for intraspecific competition may facilitate invader control.

Modeling amphibian energetics, habitat suitability, and movements of western toads, Anaxyrus (= Bufo) boreas, across present and future landscapes

Effective conservation of amphibian populations requires the prediction of how amphibians use and move through a landscape. Amphibians are closely coupled to their physical environment. Thus an approach that uses the physiological attributes of amphibians, together with knowledge of their natural history, should be helpful. We used Niche Mapper™ to model the known movements and habitat use patterns of a population of Western toads ( Anaxyrus (= Bufo) boreas) occupying forested habitats in southeastern Idaho. Niche Mapper uses first principles of environmental biophysics to combine features of topography, climate, land cover, and animal features to model microclimates and animal physiology and behavior across landscapes. Niche Mapper reproduced core body temperatures ( T c ) and evaporation rates of live toads with average errors of 1.6 ± 0.4 °C and 0.8 ± 0.2 g/h, respectively. For four different habitat types, it reproduced similar mid-summer daily temperature patterns as those measured in the field and calculated evaporation rates (g/h) with an average error rate of 7.2 ± 5.5%. Sensitivity analyses indicate these errors do not significantly affect estimates of food consumption or activity. Using Niche Mapper we predicted the daily habitats used by free-ranging toads; our accuracy for female toads was greater than for male toads (74.2 ± 6.8% and 53.6 ± 15.8%, respectively), reflecting the stronger patterns of habitat selection among females. Using these changing to construct a cost surface, we also reconstructed movement paths that were consistent with field observations. The effect of climate warming on toads depends on the interaction of temperature and atmospheric moisture. If climate change occurs as predicted, results from Niche Mapper suggests that climate warming will increase the physiological cost of landscapes thereby limiting the activity for toads in different habitats.

Predation on toxic cane toads (Bufo marinus) may imperil bluetongue lizards (Tiliqua scincoides intermedia, Scincidae) in tropical Australia

Context. Detecting ecological impacts of invasive species can be extremely difficult. Even major population declines may be undetectable without extensive long-term data if the affected taxon is rare and/or difficult to census, and exhibits stochastic variation in abundance as a result of other factors. Our data suggest such a situation in an iconic Australian reptile species, the bluetongue lizard. Originally restricted to Central and South America, cane toads (Bufo marinus) are rapidly spreading through tropical Australia. Most native predators have no evolutionary history of exposure to the toads’ distinctive chemical defences (bufadienolides), and many varanid lizards, elapid snakes, crocodiles and marsupials have been killed when they have attempted to consume toads. Aims. Scincid lizards have not been considered vulnerable to toad invasion; however, one lineage (the bluetongues, genus Tiliqua) consists of large omnivores that may be affected. Our field and laboratory research aimed to elucidate this concern. Methods. Nightly surveys for bluetongue lizards (Tiliqua scincoides intermedia) and cane toads were conducted along two adjacent roadways on the Adelaide River floodplain of the Northern Territory. Scent discrimination trials in the laboratory assessed lizard responses to chemical cues from three food types (native frogs, cane toads and ‘preferred foods’) by counting tongue-flicks and biting elicited by cotton swabs. A subset of lizards was presented with live toads. Key results. Numbers of bluetongues encountered during standardised field surveys in the Darwin region declined soon after toads arrived, and we have not recorded a single lizard for the last 20 months. In the laboratory, foraging responses of bluetongues were as intense to cane-toad scent as to the scent of native frogs, and many of the lizards we tested attempted to consume toads, and were poisoned as a result. Conclusions and implications. The population decline of bluetongues in this region appears to have been the direct result of fatal ingestion of toxic cane toads. Our studies thus add a scincid lizard species to the list of native Australian predators imperilled by cane-toad invasion, and point to the difficulty of detecting invader impact even for an iconic species in a system subject to detailed survey work.

Aggressive mimicry in neonates of the sidewinder rattlesnake, Crotalus cerastes (Serpentes: Viperidae): stimulus control and visual perception of prey luring

Aggressive mimicry in vertebrates remains understudied relative to other categories of mimetic systems, such as Batesian mimicry. Prey attraction through caudal luring (CL) is a type of aggressive mimicry that constitutes a tripartite relationship in which a predator (mimic, S2), typically a snake, produces a highly specific tail display in the presence of a prey species (receiver or operator, R) to produce a resemblance to a prey animal (model, S1), such as a worm or insect, that the receiver mistakes for food and attempts to capture. Most reports of CL in snakes, however, are not hypothesis-based and provide limited information on the cognitive interplay between predator and prey. In two experiments, CL was studied using a large sample (N = 40) of neonatal sidewinder rattlesnakes (Crotalus cerastes) and lizards (N = 12 species) to investigate stimulus control and visual perception. In experiment 1, CL was elicited in 110 trials using lizards that were either syntopic (N = 6 species) or nonsympatric (N = 6 species) to C. cerastes, and CL occurred at a significantly greater frequency when using syntopic taxa. Similarly, syntopic lizards were attracted to luring snakes significantly more than their nonsympatric counterparts. The presence of CL in C. cerastes was not ubiquitous and we provide preliminary evidence that this behaviour varies geographically and thus has a genetic basis. In experiment 2, a potential predator (live toad) was introduced to subjects that had been stimulated to lure by means of a prey-dummy and, in all (N = 8) trials, there was an immediate shift in the behaviour of the snakes. The most notable changes were termination of CL and a transition to species-typical defensive displays, which included rapid tail vibration and audible rattling in individuals with two (or more) rattle segments. We discuss future directions of CL research in snakes, especially with regard to expanding the types of cognitive tests. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 81–91.

Physically modeling operative temperatures and evaporation rates in amphibians

(1) We designed a physical model that simulates the thermal and evaporative properties of live Western toads ( Bufo boreas). (2) In controlled tests, the model tracked the body temperature of live toads with an average error of 0.3±0.03 °C (test range=4–30 °C). (3) It estimated the evaporative water loss of live toads with an average error of 0.35–0.65 g/h, or about 14% (test range=0.7–9 g/h). (4) Data collected with this physical model should provide an effective way for biologists to better understand habitat selection in toads and other amphibians

Shelter Microhabitats Determine Body Temperature and Dehydration Rates of a Terrestrial Amphibian (Bufo marinus)

Abstract Selection of diurnal shelter sites varies significantly with season in the cane toad (Bufo marinus), and the aim of this paper is to determine how hydric and thermal conditions of shelter microhabitats changed with season and whether those changes explained seasonal differences in toad behavior. Body temperatures of cane toads were measured by telemetry, and dehydration rates and thermal conditions of shelter microhabitats were measured by using preserved toads as environmental probes. Live toads and preserved toad models were monitored monthly over a 18-month period. Laboratory experiments showed that toad models dehydrated at the same rate as live toads. In the field, dehydration rates varied significantly between seasons and shelter microhabitats, but dehydration rates were always significantly less in shelters compared to a nonshelter control. Daily average body temperature of toads was 16–30°C, and it changed seasonally in proportion to model temperature. Diurnal model temperature was signif...

Shelter Microhabitats Determine Body Temperature and Dehydration Rates of a Terrestrial Amphibian (Bufo marinus)

Selection of diurnal shelter sites varies significantly with season in the cane toad (Bufo marinus), and the aim of this paper is to determine how hydric and thermal conditions of shelter microhabitats changed with season and whether those changes explained seasonal differences in toad behavior. Body temperatures of cane toads were measured by telemetry, and dehydration rates and thermal conditions of shelter microhabitats were measured by using preserved toads as environmental probes. Live toads and preserved toad models were monitored monthly over a 18-month period. Laboratory experiments showed that toad models dehydrated at the same rate as live toads. In the field, dehydration rates varied significantly between seasons and shelter microhabitats, but dehydration rates were always significantly less in shelters compared to a nonshelter control. Daily average body temperature of toads was 16–30°C, and it changed seasonally in proportion to model temperature. Diurnal model temperature was significantly lower in shelters compared to the nonshelter control, but there were significant seasonal differences between shelter sites. It appears that access to suitable diurnal shelter sites is essential for survival of cane toads outside the wet season and that seasonal changes in environmental conditions influence shelter microhabitat selection.

Preliminary Observations on the Nutritive Value of Toad Meal in Broiler Starter Diets

A 21-day feeding trial was conducted to determine the nutritive value of toad meal as protein supplement in broiler starter diets. Live toads were harvested from different ponds, knocked unconscious with a metal rod, eviscerated to remove the offals and later smoke-dried at a temperature of 40 ºC for 3 days. They were crushed and milled to produce toad meal (TM). Toad meal contained 59.06% crude protein, 10.50% either extract, 12.7% total ash, 5.61% crude fibre and 5.24 kcal/g GE. Three broiler starter diets were formulated such that they contained toad meal (TM) at 0%, 5% and 10% respectively. Three hundred, 14-day old Hubbard broiler chicks were divided into three groups of hundred birds each and randomly assigned to the three treatment diets in a completely randomized design (CRD). Each treatment was replicated four times, giving 25 birds per replicate. Data were collected on feed intake, body weight gain, fed conversion ratio and internal organ analysis. There was no significant (P

Movement of Water over Toad Skin: Functional Role of Epidermal Sculpturing

When live toads (Bufo) are placed on a water-saturated surface, it can be demonstrated that a film of water moves upward over the sides of the body and, in some individuals, reaches the dorsal midline. Movement of water over the skin follows interconnecting channels which characterize the outer epidermis of many terrestrial species. It was demonstrated that such water movement may replenish evaporative losses from skin surfaces and act to retard both cutaneous desiccation and elevated temperatures in individuals which are forced to bask in the laboratory. Observations and experiments suggest the possibility that epidermal sculpturing of terrestrial Bufonidae may have a functional role in relation to water uptake, thermoregulation and the prevention of integumentary desiccation.

Natriferic and hydrosmotic effects of neurohypophysial peptides and their analogues in augmenting fluid uptake by Bufo melanostictus.

1. The effect of intramuscular injection of 8-arginine vasotocin, 8-arginine vasopressin, 8-lysine vasopressin, oxytocin, 8-ornithine oxytocin and 8-ornithine vasopressin on fluid uptake across the skin was studied in the live toad, Bufo melanostictus, bathed either in distilled water or in NaCl solution (0.1 g/100 ml.).2. When the bathing solution was distilled water, 8-arginine vasotocin was the most potent, 0.14 nmole/kg augmenting the rate of fluid uptake by 50%. Compared with it the others had relative potencies of: 8-arginine vasopressin 0.8, 8-lysine vasopressin 0.8 x 10(-3), oxytocin 0.8 x 10(-3), 8-ornithine oxytocin 0.8 x 10(-2), 8-ornithine vasopressin < 1.4 x 10(-4).3. When the bathing solution contained 0.1% NaCl, 8-arginine vasotocin was again the most potent, 0.06 nmole/kg augmenting the rate of fluid uptake by 50%. Compared with it the others had relative potencies of: 8-arginine vasopressin 0.3, 8-lysine vasopressin 0.3 x 10(-3), oxytocin 0.3 x 10(-2), 8-ornithine oxytocin 0.8 x 10(-2), 8-ornithine vasopressin < 0.6 x 10(-4).4. Dose-response curves for each peptide showed that in the case of 8-arginine vasopressin, 8-lysine vasopressin and 8-ornithine vasopressin the augmentation of rate of fluid uptake did not differ in the absence or in the presence of NaCl in the bathing solution; whereas in the case of 8-arginine vasotocin, oxytocin, and 8-ornithine oxytocin the augmentation was greater in the presence of sodium chloride.5. Support has been found for the postulate of a binary action of some neurohypophysial peptides on amphibian skin, arginine in position 8 being correlated with hydrosmotic effect, and isoleucine in position 3 with natriferic effect.

Water uptake by Bufo melanostictus, as affected by osmotic gradients, vasopressin and temperature.

1. The rate of water uptake across the skin was studied in the live toad, Bufo melanostictus. When toads were kept in distilled water at 29 degrees C the uptake of water amounted to 16.9 +/- 1.3 mul./cm(2)/hr; when bathed in sucrose or urea solutions, the water uptake diminished with increasing osmotic pressure. There was no water uptake observed when toads were kept in 200 m-osmolar sucrose or urea.2. Intramuscular injections of vasopressin increased the rate of water uptake from distilled water. There was a good relation between doses and responses over various time intervals. A dose of 4 m-u. vasopressin/g body wt. doubled the rate of water uptake over a period of 1 hr. The same dose of vasopressin doubled the rate of water uptake when the toads were kept in solutions of sucrose or urea of different osmolarity.3. The rate of water uptake when the toads were bathed in sodium chloride solutions was consistently 8 mul./cm(2)/hr greater than when bathed in sucrose or urea solutions of equal osmolarity. There was no water uptake when the sodium chloride solution was 285 m-osmolar.4. Vasopressin (4 m-u./g) injected intramuscularly doubled the rate of water uptake from sodium chloride solutions of different osmolarity.5. With solutions of potassium chloride, sodium nitrate, and potassium nitrate, in concentrations up to 150 m-osmoles/l., the rate of water uptake was found to be the same as with solutions of sodium chloride of the same osmolarity. Similarly, it was doubled by injection of vasopressin (4m-u./g).6. The effect of temperature on the rate of water uptake before and after injection of vasopressin was investigated in toads kept in distilled water, sucrose, or sodium chloride solutions. For temperatures between 20 and 37 degrees C, vasopressin (4 m-u./g) reduced the activation energy involved in the process of water uptake by 4000 cal.7. The results agree with the view that water uptake follows a diffusion process which is facilitated by vasopressin, possibly as a result of increasing the size or number of available pores.

Notes on the Giant Toad, Bufo Marinus (L.),In Puerto Rico

The distribution, life-history, and habits are given so far as known; a detailed study of the food-habits in Puerto Rico is summarized, indicating the large quantities of injurious insects consumed; the shipment of live toads to Hawaii and their initial successful establishment there is noted.