Immobility and supination in garter snakes (Thamnophis elegans) following handling by human predators

A common response of animals to physical restraint is tonic immobility. The authors observed the behavior of garter snakes, Thamnophis elegans, in the field to determine the frequency of immobility as a response to handling. Most snakes fled after release, but the remainder remained immobile, sometimes on their backs (supination), for up to 10 min. Immobility was seen most often in pregnant snakes, which also were more likely than other snakes not to have moved before capture. Failure to move, either before or after capture, might be a consequence of the limited locomotory ability of gravid snakes. However, the lack of observations of interactions between snakes and their natural predators impedes researchers' understanding of the antipredator value, if any, of tonic immobility.     

Neonate plains garter snakes (Thamnophis radix) are attracted to conspecific skin extracts

Several species of snakes aggregate in areas previously marked by conspecifics. However, species differences and sources of such chemical signals have received little attention. Methylene chloride-soluble substances from shed epidermis of adult plains garter snakes attracted neonate conspecifics, whereas similar extracts from a congener and a viperid did not. The functional significance of such conspecific aggregation may relate to location of hibernacula, foraging areas, osmoregulation, or predation avoidance.     

Social dynamics of group courtship behavior in male red-sided garter snakes (Thamnophis sirtalis parietalis)

Mating in red-sided garter snakes is characterized by the formation of mating balls. Up to 100 males simultaneously court single females. The social dynamics of the formation of these mating balls was examined to determine whether the mating balls are formed simply because of a common attraction to the female or whether males are stimulated by the mating balls themselves. A sexually attractive female garter snake appears to be even more attractive to a male when she is being courted by other males than when she is alone. Male garter snakes courted females more actively when other males were also courting the female than when they were alone with her. There is a positive correlation between the number of additional males present and the amount of courtship activity shown by the test male toward the stimulus female. The extent to which the courtship activity of the test males was stimulated by the presence of additional courting males was not influenced by how actively the additional males courted.     

Conditioned discrimination of airborne odorants by garter snakes (Thamnophis radix and T. sirtalis sirtalis)

For snakes, the nasal chemical senses are critical in intraspecific communication and prey recognition. Although it is known that garter snakes can respond differentially to airborne odorants, no previous study has demonstrated that snakes can learn a task with airborne odors as discriminative stimuli. In Experiment 1, 7 plains garter snakes (Thamnophis radix) were trained in a two-choice apparatus to move into a compartment containing lemon-scented chips for a food reward. All 7 snakes improved performance when the first 10 and last 10 trials of the 100 trials of conditioning were compared. Four of the snakes were subsequently trained to move away from the scented compartment into the unscented compartment. The 4 snakes rapidly learned this reversal. In Experiment 2, 7 common garter snakes (T. sirtalis sirtalis) were trained to traverse a two-choice maze with the presence or absence of amyl acetate odor as the conditioned stimulus. The snakes were pretested for odor versus nonodor preference and were trained to go to the initially nonpreferred stimulus. Of the 7 snakes, 5 achieved a predetermined criterion (two training sessions with cumulative correct responding above the .05 confidence level) within 85 trials.     

Effect of food competition on aggregation: evidence for social recognition in the plains garter snake (Thamnophis radix).

Competition for food and aggregating behavior were examined in plains garter snakes (Thamnophis radix), in 11 groups of 1 noncompetitor and 2 competitors. Aggregation data were obtained in 48 daily scans. During food competition, success at obtaining food was asymmetrical across pairs. For aggregation, competitors were mostly associated with noncompetitors. After removal of noncompetitors, competitors were more likely to be solitary, but associations between competitors increased. After a 5-month separation, 5 of the original groups were reconstituted; aggregation patterns similar to the 1st experiment were observed. In a 3rd experiment, unfamiliar animals with and without competitive experience did not aggregate preferentially. Garter snakes discriminate on the basis of sex and species; in this study individual relationships (prior competition) affected aggregation, and the data suggest individual recognition both occurs and persists over time.     

The forked tongue and edge detection in snakes (Crotalus oreganus): an experimental test

Many stimulus-detection systems are lateralized to allow for simultaneous comparison of paired stimuli. It has been hypothesized that the deeply forked tongue of snakes and some derived lizards functions as a chemical edge detector where cues gathered by each tine are kept separate to provide two points of lateral odor assessment by the central nervous system via vomeronasal input. While following a chemical trail, one time can be on the trail, the other off, and such differential information prompts the snake to turn back to the trail. The authors tested this hypothesis in rattlesnakes within a predatory context by unilaterally severing the vomeronasal nerves. If edge detection is used by snakes during prey trailing, then unilateral denervation should disrupt trailing ability. The authors found no change in the seven separate trailing parameters measured. Therefore, they found no support for the edge detection hypothesis as it applies to prey trailing behavior. Instead, the deeply forked tongue may represent a chemosensory specialization to increase odor-sampling area, with snakes and derived lizards detecting only the concentration of chemical trails.     

Evolutionary persistence of chemically elicited ophiophagous antipredator responses in gartersnakes (Thamnophis sirtalis)

The ability to detect and respond to potential predators is key for the survival of individuals, but this ability is sometimes lost via relaxation of antipredator behavior when prey species are separated from predators. Adult and predator-na?ve neonate gartersnakes (Thamnophis sirtalis) from mainland and insular sites where they do and do not occur with ophiophagous (snake-eating) snakes were tested to determine if responses to such predators have been lost, reduced, or retained, and what might be causing differences in such responses. Our data indicate that, overall, adult snakes from populations syntopic with ophiophagous milksnakes are more responsive to chemical stimuli from milksnakes than adults from areas where they are not syntopic with milksnakes, whereas there were few differences with neonate gartersnakes. Experiments with neonates with or without periodic ophiophagous snake chemical experience over several weeks showed that gartersnakes with such experience became more responsive to ophiophagous cues rather than habituating to them. Such evidence of both genetic and experiential factors underlying the antipredator responses to ophiophagous snakes indicates that antipredator responses have persisted despite separation of predator and prey.     

How mediation (and other) approaches may improve ethics consultants' outcomes

Articles in this issue of JCE recommend a number of approaches to clinical ethics consultation. Given these various approaches, how should ethics consultants proceed?     

Heidegger and the source(s) of intelligibility

Wittgensteinian readings of Being and Time, and of the source of the intelligibility of Dasein's world, in terms of language and the average everyday public practices of das Man are partly right and partly wrong. They are right in correcting overly individualist and existentialist readings of Heidegger. But they are wrong in making Heidegger into a proponent of language or everydayness as the final word on intelligibility and the way the world is disclosed to us. The everydayness of das Man and language are partial sources of intelligibility but only insofar as they are comprehended within the greater unitary structure of care and temporality. Care and temporality constitute the foundational underpinnings for disclosure and the intelligibility ofthat wherein Dasein dwells.     

Partial mediation of strange-male-induced pregnancy blocks by sexual activity in mice (Mus musculus)

Novel male house mice (Mus musculus) can disrupt early pregnancy in females. Previous research focused on pheromonal rather than behavioral mediation of this phenomenon. In Experiment 1, novel males were housed with females shortly after insemination. Litter production was negatively correlated with the males' sexual activity. Experiment 2 replicated this finding with a larger sample. In Experiment 3, females were exposed to castrated males. Testosterone-treated males completely blocked pregnancy, whereas untreated males did not. In Experiment 4, castrated testosterone-treated males were presented at intervals after insemination. Pregnancy was totally blocked at Days 3 and 4 and mostly blocked at Days 1 and 2 but was less affected at Days 5 and 6. In Experiment 5, females were exposed through a wire-mesh grid to castrated males. Pregnancies occurred in all conditions, even with testosterone-treated males. These data suggest a role for sexual activity in male-induced pregnancy blocks.     

Androgen mediation of conditioned rhythmic cloacal sphincter movements in Japanese Quail (Coturnix japonica)

Demonstrations of increased reproductive success due to sexual conditioning in Japanese quail (Coturnix japonica) have been reported, although the mechanisms that underlie these effects have remained elusive. One possible mechanism is conditioned rhythmic cloacal sphincter movements (RCSM). Two experiments were conducted with male quail to determine whether associations between a conditioned stimulus (CS) and a hen would result in the ability of the CS to elicit RCSM, and to explore the androgen mediation of conditioned RCSM. The results suggest that a focal CS paired with visual access to a female will elicit RCSM via a representation of the hen activated by the CS. Further, the available evidence indicates that conditioned RCSM is androgen mediated and that this learning may transfer across breeding seasons.     

Quantity estimation and comparison in western lowland gorillas (Gorilla gorilla gorilla)

We investigated the quantity judgment abilities of two adult male western lowland gorillas (Gorilla gorilla gorilla) by presenting discrimination tasks on a touch-screen computer. Both gorillas chose the larger quantity of two arrays of dot stimuli. On some trials, the relative number of dots was congruent with the relative total area of the two arrays. On other trials, number of dots was incongruent with area. The gorillas were first tested with static dots, then with dots that moved within the arrays, and finally on a task where they were required to discriminate numerically larger subsets within arrays of moving dots. Both gorillas achieved above-chance performance on both congruent and incongruent trials with all tasks, indicating that they were able to use number as a cue even though ratio of number and area significantly controlled responding, suggesting that number was not the only relevant dimension that the gorillas used. The pattern of performance was similar to that found previously with monkeys and chimpanzees but had not previously been demonstrated in gorillas within a computerized test format, and with these kinds of visual stimuli.     

Understanding source effects in ADHD rating scales: reply to DuPaul (2003)

G. J. DuPaul (2003) offered two suggestions for additional research to understand the strong source effects reported by R. Gomez, G. L. Burns, J. A. Walsh, and M. A. de Moura (2003) in attention-deficit/hyperactivity disorder (ADHD) rating scales. The first suggestion was to determine whether the source effects represent mostly bias or accuracy. The second suggestion was to minimize source effects through the development of better ADHD rating scales. Because source effects can represent bias or accuracy, it is important to minimize the bias aspect through content validation procedures prior to attempts to determine whether source effects better reflect bias or accuracy. This comment offers various suggestions to reduce the bias in ADHD rating scales.     

Horse (Equus caballus) whinnies: a source of social information

Many animal species that rely mainly on calls to communicate produce individual acoustic structures, but we wondered whether individuals of species better known as visual communicants, with small vocal repertoires, would also exhibit individual distinctiveness in calls. Moreover, theoretical advances concerning the evolution of social intelligence are usually based on primate species data, but relatively little is known about the social cognitive capacities of non-primate mammals. However, some non-primate species demonstrate auditory recognition of social categories and possess mental representation of their social network. Horses (Equus caballus) form stable social networks and although they display a large range of visual signals, they also use long-distance whinny calls to maintain contact. Here, we investigated the potential existence of individual acoustic signatures in whinny calls and the ability of horses to discriminate by ear individuals varying in their degree of familiarity. Our analysis of the acoustic structure of whinnies of 30 adult domestic horses (ten stallions, ten geldings, ten mares) revealed that some of the frequency and temporal parameters carried reliable information about the caller’s sex, body size and identity. However, no correlations with age were found. Playback experiments evaluated the behavioural significance of this variability. Twelve horses heard either control white noise or whinnies emitted by group members, familiar neighbours or unfamiliar horses. While control sounds did not induce any particular response, horses discriminated the social category of the callers and reacted with a sound-specific behaviour (vigilance and attraction varied with familiarity). Our results support the existence of social knowledge in horses and suggest a process of vocal coding/decoding of information.     

Prosocial attitudes and empathic behavior in emotional positive versus negative situations: brain response (ERPs) and source localization (LORETA) analysis

The present research firstly investigated the neural correlates (ERPs, event-related potentials) of attitudes to engage in prosocial-helping behaviors, and secondly, it analyzed the relation between these brain-based potentials and personal profile (high vs. low empathic profile). It was considered the subjects’ behavior in response to specific emotional situations (positive vs. negative) in case it was required a possible prosocial intervention. Thirty-one subjects were invited to empathize with the emotional contexts (videotapes that reproduced two person’s exchanges) and to decide whether to intervene or not to support these persons. BEES questionnaire for empathic behavior was submitted to the subjects after the experimental session. ERP acquisition and LORETA source analysis revealed a negative ongoing deflection (N200 effect) more prefrontally distributed (dorsolateral prefrontal cortex) in response to prosocial intervention options mainly for negative and positive contexts. Moreover, a significant positive correlation was found between high-empathic profiles, intervention behaviors (higher frequency of interventions) and N200 amplitude (higher peak). These results highlight the role of emotions in prosocial behavior, since the N200 effect was considered a marker of the emotional significance of the interpersonal situation. Secondly, the empathic trait may explain the prosocial decisional processes: Higher empathic trait contributes to induce subject’s intervention behavior which in turn appears to be directly related to the cortical responsiveness within the prefrontal areas.     

Death feigning by grass snakes (Natrix natrix) in response to handling by human "predators."

Death feigning, a variant of tonic immobility, is usually interpreted as a last-resort antipredator measure. The authors describe death feigning in grass snakes (Natrix natrix) and test some of its potential correlates. Death feigning was seen in 66% of wild-caught snakes but was not seen in hatchlings from laboratory-incubated eggs. Minimal indication of death feigning was mouth gaping, often with the tongue hanging free, but more dramatic cases involved voluntary supination and/or lack of muscle tone. Aside from hatchlings, which did not feign death, there was little variation in frequency or intensity of death feigning with body size. There was no effect of body temperature on death feigning nor were snakes that were moving when caught less likely to feign death than those that were not moving. Interpretation of the adaptive value of death feigning in grass snakes or in other animals is hampered by lack of evidence of this behavior in the field in response to natural predators.     

The narrow fellow in the grass: human infants associate snakes and fear

Why are snakes such a common target of fear? One current view is that snake fear is one of several innate fears that emerge spontaneously. Another is that humans have an evolved predisposition to learn to fear snakes. In the first study reported here, 9‐ to 10‐month‐old infants showed no differential spontaneous reaction to films of snakes versus other animals. In the second study, 7‐ to 18‐month‐old infants associated snakes with fear: As predicted, they looked longer at films of snakes while listening to a frightened human voice than while listening to a happy voice. In the third study, infants did not look differentially to still photos of snakes and other animals, indicating that movement is crucial to infants’ association of snakes with fear. These results offer support for the view that humans have a natural tendency to selectively associate snakes with fear.     

Similarities and differences between western cultures: Toddler temperament and parent-child interactions in the United States (US) and Germany

Parents play a critical role in shaping social-emotional development, particularly in early childhood; however, children’s influence on their own development is equally important. Parent-child interactions, fundamental to secure attachment and social schemes, represent a critical area of social-emotional development subject to child effects associated with temperament. The present study explores these effects through a cross-cultural lens via comparisons of dyads from the United States (US) and Germany. Specifically, cross-cultural differences in toddler temperament were evaluated via the Early Childhood Behavior Questionnaire (ECBQ; Putnam et al., 2006), with cross-cultural variability in parent-child interactions examined as well, along with differences in child temperament effects on the quality of these interactions. Ratings of temperament were generally similar between the two cultures; however, US toddlers were rated higher in attention shifting, whereas German children were rated higher on soothability and perceptual sensitivity. Additionally, dyadic interactions in the US were rated as more stimulating and demonstrating greater partner engagement than those in Germany. Differential contributions of temperament to interaction quality and complexity were also observed. Higher ratings of toddler discomfort and perceptual sensitivity predicted more stimulating interactions overall in the US but not Germany. In contrast, higher ratings of toddler low-intensity pleasure predicted more stimulating interactions in Germany but not the US. Overall, the present study identifies many similarities between US and German toddlers and supports theories describing children as active agents in shaping their own development, in what appears to be a different manner across cultures.