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The emerging picture of non‐monophyly of scolecophidian snakes is increasingly indicative that fossorial lifestyle, myrmecophagous diet, and miniaturisation are powerful drivers of morphological evolution in squamate skulls. We provide a detailed description of the skull of Xenotyphlops grandidieri, with reference to the skulls of other scolecophidian snakes. The skull, which shows dramatic ventral inflection of the snout complex, is remarkably bizarre, and the mouth opening is more ventrally oriented than in other typhlopoids. The eyes are strongly reduced, and the enlarged and rather flat anterior head shield is covered in numerous sensillae. We put forward several potential explanations for the evolution of these unusual modifications. On the other hand, Xenotyphlops shares numerous synapomorphies with other typhlopoid snakes, including the highly specialized jaw mechanism. We argue that the key differences between the jaw mechanisms of Leptotyphlopidae, Anomalepididae, and Typhlopoidea provide compelling evidence for a strong role of convergence in the evolution of the scolecophidian bauplan, and these clades therefore cannot be interpreted as representative of ancestral anatomy or ecology among snakes. [ABSTRACT FROM AUTHOR]

Antipredator behaviours and the ability to appropriately assess predation risk contribute to increased fitness. Predator avoidance can be costly; however, so we expect prey to most strongly avoid predators that pose the greatest risk (i.e., prey should show threat sensitivity). For invasive species, effectively assessing the relative risk posed by predators in the new environment may help them establish in new environments. We examined the antipredator behaviour of introduced Asian house geckos, Hemidactylus frenatus (Schlegel), by determining if they avoided shelters scented with the chemical cues of native predatory snakes (spotted pythons, Antaresia maculosa [Peters]; brown tree snakes, Boiga irregularis [Merrem]; common tree snakes, Dendrelaphis punctulata [Grey]; and carpet pythons, Morelia spilota [Lacépède]). We also tested if Asian house geckos collected from vegetation vs. anthropogenic substrates (buildings) responded differently to the chemical cues of predatory snakes. Asian house geckos did not show a generalised antipredator response, that is, they did not respond to the chemical cues of all snakes in the same way. Asian house geckos avoided the chemical cues of carpet pythons more strongly than those of other snake species, providing some support for the threat‐sensitivity hypothesis. There was no difference in the antipredator behaviour of Asian house geckos collected from buildings vs. natural vegetation, suggesting that individuals that have invaded natural habitats have not changed their antipredator behaviour compared to urban individuals. Overall, we found some evidence indicating Asian house geckos are threat‐sensitive to some Australian predacious snakes. [ABSTRACT FROM AUTHOR]

At their range limits, animal populations are often small and endangered. Moreover, they may use habitats in different ways than core populations, making the determination of habitat requirements an important aspect for effective long‐term conservation of these populations. We assessed habitat requirements of the Aesculapian snake (Zamenis longissimus) in an isolated population at the northern limits of its range, southeastern Poland. We analyzed factors affecting the species' distribution at different spatial scales. We used the area of its current distribution (22,754 ha) in Poland to analyze macrohabitat patterns at the landscape scale and used the area currently occupied by the largest local population (2,192 ha) to analyze macro‐ and microhabitat use. Additionally, at 25 sites delimited around individual and clusters of snake records (140.7 ha), we characterized the detailed forest composition. Landscape‐scale analyses confirmed the Aesculapian snake's preference for deciduous forest. At the medium spatial scale, anthropogenic macro‐ and microhabitat features had a positive effect on the presence and abundance of the species. Its distribution was positively associated with warm river valleys, and we recorded the highest numbers of snakes in areas with average annual temperatures between 5.95°C and 6.30°C. At a fine scale, the relative abundance of the Aesculapian snake was negatively associated with dense deciduous forest cover but positively associated with open broad‐leaf woodlands. To conserve northern populations of the Aesculapian snake, clearings should be maintained in forest stands, tree planting and natural succession should be reduced in open areas, and alder forests (Alnetum incanae) and small beech forest (Dentario glandulosae‐Fagetum) stands should be protected. Active conservation should include the creation of artificial reproduction sites and permanent rocky shelters to assist dispersal and connectivity among subpopulations. © 2018 The Wildlife Society. Anthropogenic land cover types are the major limiting factor in the northern range of the Aesculapian snake. Effective conservation of the species should include the creation of artificial reproduction and shelter sites and the maintenance of clearings in forests. [ABSTRACT FROM AUTHOR]

Many snakes are uniquely adapted to ingest large prey at infrequent intervals. Digestion of large prey is metabolically and aerobically costly, and large prey boluses can impair snake locomotion, increasing vulnerability to predation. Cessation of foraging and use of refugia with microclimates facilitating digestion are expected to be strategies employed by free‐ranging snakes to cope with the demands of digestion while minimizing risk of predation. However, empirical observations of such submergent behavior from field experiments are limited. The brown treesnake (Serpentes: Colubridae: Boiga irregularis) is a nocturnal, arboreal, colubrid snake that was accidentally introduced to the island of Guam, with ecologically and economically costly consequences. Because tools for brown treesnake damage prevention generally rely on snakes being visible or responding to lures or baits while foraging, cessation of foraging activities after feeding would complicate management. We sought to characterize differences in brown treesnake activity, movement, habitat use, and detectability following feeding of large meals (rodents 33% of the snake's unfed body mass) via radio telemetry, trapping, and visual surveys. Compared to unfed snakes, snakes in the feeding treatment group showed drastic decreases in hourly and nightly activity rates, differences in refuge height and microhabitat type, and a marked decrease in detectability by trapping and visual surveys. Depression of activity lasted approximately 5–7 days, a period that corresponds to previous studies of brown treesnake digestion and cycles of detectability. Our results indicate that management strategies for invasive brown treesnakes need to account for cycles of unavailability and underscore the importance of preventing spread of brown treesnakes to new environments where large prey are abundant and periods of cryptic behavior are likely to be frequent. Characterization of postfeeding behavior changes provides a richer understanding of snake ecology and foraging models for species that consume large prey. Many snakes exhibit remarkable physiological adaptations for ingestion of large prey; despite theoretical and laboratory‐based investigations of changes in snake behavior following ingestion of large meals, field experiments documenting such behaviors are limited. We document reduction in movement and changes in refuge site selection by invasive brown treesnakes on the island of Guam following experimental feeding of rodent mass equal to one third of the snake's body mass. These changes in postfeeding movement likely reflect evolution of behaviors favoring predator avoidance and meeting metabolic demands of digestion, and can reduce the effectiveness of invasive snake control tools based on snake foraging behavior for several days after ingesting a large meal. [ABSTRACT FROM AUTHOR]

Across the diversity of vertebrates, bite force has been studied and suggested to have important ecological and evolutionary consequences. However, there is a notable lineage of vertebrates that use this performance trait yet are missing from the bite-force literature: the snakes. Snakes often rely on biting during prey subjugation and handling. Many snakes bite and hold prey while a constriction coil is formed or while venom is being delivered, or both. Others use biting exclusively without employing any additional prey-handling behaviors. In addition to biting, constriction is an important predation mechanism. Here, I quantify bite force and constriction pressure in kingsnakes ( Lampropeltis getula). Furthermore, I explore the proximate determinants of bite force as well as the relationship between biting and constriction performance. Bite force increased linearly with all head and body measures. Of these, head height was the best predictor of bite force. Bite force in kingsnakes was within the range of values reported for lizards, but their relative performance was lower for their head size compared to lizards. Peak constriction pressure also increased with all body measures. Biting and constricting use 2 different parts of the musculoskeletal system and are positively and significantly correlated with one another. Future work targeting a greater diversity of snakes that rely more heavily on biting may reveal a greater range of bite performance in this diverse and successful vertebrate group. [ABSTRACT FROM AUTHOR]

Predation involves costs and benefits, so predators should employ tactics that reduce their risk of injury or death and that increase their success at capturing prey. One potential way that predators could decrease risk and increase benefits is by attacking prey at night when risks may be reduced and prey more vulnerable. Because some snakes are facultatively nocturnal and prey on bird nests during the day and night, they are ideal for assessing the costs and benefits of diurnal vs. nocturnal predation. We used automated radiotelemetry and cameras to investigate predation on nesting birds by two species of snakes, one diurnal and the other facultatively nocturnal. We predicted that snakes preying on nests at night should experience less parental nest defence and capture more adults and nestlings. Rat snakes (Pantherophis obsoletus) were relatively inactive at night (23-36% activity) but nearly always preyed on nests after dark (80% of nest predations). Conversely, racers (Coluber constrictor) were exclusively diurnal and preyed on nests during the times of day they were most active. These results are consistent with rat snakes strategically using their capacity for facultative nocturnal activity to prey on nests at night. The likely benefit is reduced nest defence because birds defended their nests less vigourously at night. Consistent with nocturnal predation being safer, rat snake predation events lasted three times longer at night than during the day (26 vs. 8 min). Nocturnal nest predation did not make nests more profitable by increasing the likelihood of capturing adults or removing premature fledging of nestlings. The disconnect between rat snake activity and timing of nest predation seems most consistent with rat snakes locating prey during the day using visual cues but waiting until dark to prey on nests when predation is safer, although designing a direct test of this hypothesis will be challenging. [ABSTRACT FROM AUTHOR]

Movement patterns in animals have been studied extensively, but differences in sampling frequencies produce datasets that are not always directly comparable. Because information is collected as point coordinates, measures of movement generally underestimate actual distances moved, especially when sampling frequency is low. Many animals, including most snakes, move from one location to another in discrete bouts of movement interspersed by relatively long periods of immobility. The impact of sampling interval on measures of movement in such studies remains poorly quantified, severely limiting appropriate contrasts among species, populations or individuals. We collected data during telemetry studies of four African snake species (Bitis arietans, B. schneideri, Python natalensis and Gonionotophis capensis) to assess the impact of sampling frequency on two measures of movement (mean daily displacement, MDD; moves per month, MM), which we assessed by subsampling our datasets to simulate different sampling frequencies. For each species, we analysed two subgroups defined by their movement profiles yielding eight experimental species groups. We found significant effects of sampling interval on MDD and MM with the magnitude of the effect (b) of sampling interval ranging from −0.025 to −0.138 among species groups, producing errors of up to 10%. For MM, b estimates ranged between −0.313 and 0.032, yielding error estimates of up to 40%. Our study reveals the potential for sampling interval to significantly impact measures of movement. Moreover, this error can vary dramatically among species, sexes or seasons, emphasizing the importance of taking cognizance of sampling interval in movement studies. We propose a method whereby researchers explicitly account for such effects by reporting measures of displacement and movement frequency corrected to a standardized daily sampling interval to account for this error and better facilitate meta-analysis. This will facilitate a more holistic understanding of the movement ecology of infrequently moving animals. [ABSTRACT FROM AUTHOR]

Almost all snakes swallow their prey whole. However, a few species are known as exceptions. Two species of Asian crab-eating snakes tear off crab legs and ingest them one at a time to eat prey that is otherwise too large. Two species of leptotyphlopid blindsnakes break off the head of termites or suck abdominal contents of termites, discarding remains of termites. Here, we show that a typhlopid blindsnake I ndotyphlops braminus decapitates its termite prey and consumes only the thorax and abdomen. In our feeding trials, I . braminus decapitated a median of 47% of termites they eat, while swallowing the remaining termites whole. Decapitation did not affect ingestion speed, and therefore, it is unlikely that decapitation assists for fast ingestion. Ingested termite heads often remain undigested in the feces, implying that the decapitation functions to remove an indigestible part of termites. Decapitation might also be related to circumvention of chemical defenses of termites because termite heads often contain toxic compounds. These observations showed unusual feeding behavior used by a basal snake, which could be associated with removal of indigestible and/or toxic parts of prey items. [ABSTRACT FROM AUTHOR]

Assemblage structure, diversity measures and diversity/dominance patterns of snakes were studied between 1996 and 2013 in three types of plantation in the Niger River delta of southern Nigeria. The investigated plantation types were pineapple, banana/plantain, and cassava/yam. Over 74% of the census species ( n = 27) were found in all three plantation types, with, overall, just two singletons ( Bitis nasicornis, Lamprophis olivaceus) being observed. Despite an overall similarity in the taxonomic species composition, a principal component analysis placed the three plantation types in distinct zones of the multivariate space. Diversity/dominance diagrams for the three plantation types showed that banana/plantain and cassava/yam were nearly identical in terms of evenness profile, whereas the pineapple plantation had a higher evenness. [ABSTRACT FROM AUTHOR]

SUMMARY Mimicry, where one species resembles another species because of the selective benefits of sharing a common signal, is especially common in snakes. Snakes might be particularly prone to evolving mimicry if all species share some of the same proximate mechanisms that can be used to produce aposematic/mimetic signals. We evaluated this possibility by examining color pigments in 11 species of snakes from four different families, three species of which participate in a coral snake mimicry complex involving convergence in coloration. We found that all 11 species used combinations of two pteridine pigments and melanin in their coloration, regardless of whether or not they were mimics. Furthermore, the presence or absence of red pteridines was strongly correlated with the relative excitation of medium- and long-wavelength photoreceptors in birds, thereby linking shared pigmentation to perception of those pigments by likely agents of selection. Thus, precise color mimicry might be relatively easy to evolve among snakes owing to symplesiomorphies in pigmentation. [ABSTRACT FROM AUTHOR]

Animals failing to deter predation are eaten. Among the many deterrents to predation, antipredator behaviors are perhaps the most variable, ranging from active (fight or flight) to passive (immobility). We assessed variation in the expression of a passive defensive behavior, death-feigning, in Plains Hog-nosed Snakes ( Heterodon nasicus) and predicted that intrinsic and extrinsic factors would influence the duration of this behavior and the latency to its onset. We simulated predatory attacks on 27 snakes encountered in the field, and analyzed the behavioral responses of snakes as a function of differences among individuals (sex and size) and environmental factors (temperature and microhabitat). Larger snakes death-feigned for longer durations than smaller ones; this relationship was stronger for female snakes than for males. Death feints were initiated sooner when snakes were encountered at higher temperatures. Extrinsic factors had a greater influence on latency to death-feigning behavior, whereas intrinsic factors more strongly influenced its duration. Because our results involved wild snakes, they provide an improved, highly relevant understanding of individual and environmental factors that regulate the expression of immobile defensive behavior. Furthermore, additional hypotheses can now be proposed that address the evolution of defensive behaviors that leave animals prone to attack. [ABSTRACT FROM AUTHOR]

Injuries are common in animals of diverse taxa and are usually attributed to encounters with predators. Although often non-lethal, injuries nevertheless represent effects of predators that can have negative consequences for demography and fitness (e.g. reproductive costs). However, encounters with predators also represent experience through which animals can learn and positively adapt their future behaviour, potentially mitigating, at least partly, the negative effects of prior exposure to predators. I predicted that injured grass snakes ( Natrix natrix), which presumably had been handled previously by a predator, would be more likely to move before capture than uninjured snakes. This prediction was borne out. Snakes with injuries also had lower body condition than uninjured snakes, although the effect was non-significant. Snakes that had been previously captured also were significantly more likely to move before capture than snakes that had never been caught before. These results provide strong evidence for the role of experience and learning in modifying the antipredator behaviour of snakes. [ABSTRACT FROM AUTHOR]

Small mammals have a number of means to detect and avoid predators, including visual, auditory and olfactory cues. Olfactory cues are particularly important for nocturnal or fossorial species where visual cues would not be as reliable. The Cape ground squirrel ( Xerus inauris) is a semi-fossorial, diurnal mammal from southern Africa. Cape ground squirrels encounter multiple species of predatory snake that pursue individuals underground where visual and social cues are limited. We assessed whether Cape ground squirrels use odours to discriminate between snakes by presenting a non-venomous snake, a venomous snake and a control odour collected on polyethylene cubes to 11 adult female squirrels from 11 different social groups. Cape ground squirrels responded by inspecting the cube, displaying snake harassment-associated behaviours and decreasing time spent in close proximity to snake odours when compared with a control. They also displayed discrimination between two snake species by increasing the frequency of cube inspection and increasing harassment behaviours with venomous snake odours when compared with non-venomous snake odours. We conclude that Cape ground squirrels respond with snake-specific antipredator behaviours when presented olfactory cues alone. Olfactory discrimination may be maintained by the decreased utility of other methods of predator detection: sight and group detection, in below-ground encounters. [ABSTRACT FROM AUTHOR]

ABSTRACT Snakes have long been thought to drink with a two-phase buccal-pump mechanism, but observations that some snakes can drink without sealing the margins of their mouths suggest that buccal pumping may not be the only drinking mechanism used by snakes. Here, we report that some snakes appear to drink using sponge-like qualities of specific regions of the oropharyngeal and esophageal mucosa and sponge-compressing functions of certain muscles and bones of the head. The resulting mechanism allows them to transport water upward against the effects of gravity using movements much slower than those of many other vertebrates. To arrive at this model, drinking was examined in three snake species using synchronized ciné and electromyographic recordings of muscle activity and in a fourth species using synchronized video and pressure recordings. Functional data were correlated with a variety of anatomical features to test specific predictions of the buccal-pump model. The anatomical data suggest explanations for the lack of conformity between a buccal-pump model of drinking and the performance of the drinking apparatus in many species. Electromyographic data show that many muscles with major functions in feeding play minor roles in drinking and, conversely, some muscles with minor roles in feeding play major roles in drinking. Mouth sealing by either the tongue or mental scale, previously considered critical to drinking in snakes, is incidental to drinking performance in some species. The sponge mechanism of drinking may represent a macrostomatan exaptation of mucosal folds, the evolution of which was driven primarily by the demands of feeding. J. Exp. Zool. 317:152-172, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Social interactions often play a significant role in determining patterns of spatial use. Although snakes are generally thought of as asocial, recent spatial dispersion studies suggest that the spatial ecology of snakes may be more strongly influenced by social interactions than previously thought. We investigated the spatial behavior patterns of a western cottonmouth ( Agkistrodon piscivorus) population in east Texas by uniquely combining radio-telemetry studies on free-ranging snakes with experimental arena trials with captive individuals from the same population. Observations from the radio-telemetry study on free-ranging A. piscivorus indicated that females were more gregarious than males. In the follow-up study, spatial dispersion data from captive snakes maintained in experimental field arenas yielded similar results to spatial behavior patterns of free-ranging individuals. When compared to random experimental controls, these data suggest that observed spatial behavior patterns are related to mechanisms associated with both active avoidance among males and conspecific attraction among females. In addition to uniquely combining both free-ranging and captive observations, this is the first snake study to demonstrate sex differences with both of these divergent (attraction and avoidance) spatial patterns within a single population. Thus, similar to other vertebrate groups, a growing body of literature suggests that social interactions in snakes should be strongly considered in interpretations of spatial ecology and behavior. [ABSTRACT FROM AUTHOR]

Tentacled snakes ( Erpeton tentaculatum) are aquatic predators that feed exclusively on fish. They have a unique pair of tentacles projecting from the face and an unusual J-shaped hunting posture. These features have been the subject of speculation for over a century. In a series of behavioral studies, tentacled snakes were found to exploit fish escape responses by startling fish toward their strike. This remarkable, deceptive behavior takes advantage of the stereotyped C-start escape response of fish. For some fish approach angles, snakes predicted future fish behavior and accurately struck at their moving head. These findings suggest tentacled snakes are acting as 'rare enemies'-taking advantage of prey behavior that is usually adaptive for the prey species. Anatomical and physiological analysis showed the tentacles are densely innervated by the trigeminal nerve and are sensitive mechanoreceptors that respond to water movements. Mechanosensory information from the tentacles projects to the optic tectum in approximate register with vision, providing a mechanism for integrating visual and mechanosensory cues for identifying, localizing, and capturing prey. [ABSTRACT FROM AUTHOR]

Dispersal is a fundamental attribute of species in nature and shapes population dynamics, evolutionary trajectories and genetic variation across spatial and temporal scales. It is increasingly clear that landscape features have large impacts on dispersal patterns. Thus, understanding how individuals and species move through landscapes is essential for predicting impacts of landscape alterations. Information on dispersal patterns, however, is lacking for many taxa, particularly reptiles. Eastern foxsnakes ( Mintoinus gloydi) are marsh and prairie specialists that avoid agricultural fields, but they have persisted across a fragmented region in southwestern Ontario and northern Ohio. Here, we combined habitat suitability modelling with population genetic analyses to infer how foxsnakes disperse through a habitat mosaic of natural and altered landscape features. Boundary regions between the eight genetic clusters, identified through assignment tests, were comprised of low suitability habitat (e.g. agricultural fields). Island populations were grouped into a single genetic cluster, and comparatively low F values between island and mainland populations suggest open water presents less of a barrier than nonsuitable terrestrial habitat. Isolation by resistance and least-cost path analysis produced similar results with matrices of pairwise individual genetic distance significantly more correlated to matrices of resistance values derived from habitat suitability than models with an undifferentiated landscape. Spatial autocorrelation results matched better with assignment results when incorporating resistance values rather than straight-line distances. All analyses used in our study produced similar results suggesting that habitat degradation limits dispersal for foxsnakes, which has had a strong effect on the genetic population structure across this region. [ABSTRACT FROM AUTHOR]

The article presents information on the striking capability depicting the velocities and accelerations of huge snakes in comparison to small ones. It focuses on the study of heavy-bodied snakes, puff adders known as Bitis arietans which had a striking velocity of 72 m/sec². It presents the findings of the examination and evaluation of the mechanistic basis of the strike using high-speed video with electromyographic (EMG) analysis through the extensors in vertebral column, semispinalis, and longissimus.

The article presents a study which investigates the association between snake behavior and nest predation in a Midwestern bird community. The activity of rat snakes Elaphe obsoleta and racers Coluber constrictor that prey on nests and 300 songbird nests in forest edges are monitored using radiotelemetry to evaluate predation risk. Results show that predation risk increases when rat snakes are more active, however, there is no evidence of increased predation risk to nest at forest edges.

Aim To analyse the global patterns in species richness of Viperidae snakes through the deconstruction of richness into sets of species according to their distribution models, range size, body size and phylogenetic structure, and to test if environmental drivers explaining the geographical ranges of species are similar to those explaining richness patterns, something we called the extreme deconstruction principle. Location Global. Methods We generated a global dataset of 228 terrestrial viperid snakes, which included geographical ranges (mapped at 1° resolution, for a grid with 7331 cells world-wide), body sizes and phylogenetic relationships among species. We used logistic regression (generalized linear model; GLM) to model species geographical ranges with five environmental predictors. Sets of species richness were also generated for large and small-bodied species, for basal and derived species and for four classes of geographical range sizes. Richness patterns were also modelled against the five environmental variables through standard ordinary least squares (OLS) multiple regressions. These subsets are replications to test if environmental factors driving species geographical ranges can be directly associated with those explaining richness patterns. Results Around 48% of the total variance in viperid richness was explained by the environmental model, but richness sets revealed different patterns across the world. The similarity between OLS coefficients and the primacy of variables across species geographical range GLMs was equal to 0.645 when analysing all viperid snakes. Thus, in general, when an environmental predictor it is important to model species geographical ranges, this predictor is also important when modelling richness, so that the extreme deconstruction principle holds. However, replicating this correlation using subsets of species within different categories in body size, range size and phylogenetic structure gave more variable results, with correlations between GLM and OLS coefficients varying from –0.46 up to 0.83. Despite this, there is a relatively high correspondence ( r = 0.73) between the similarity of GLM-OLS coefficients and R2 values of richness models, indicating that when richness is well explained by the environment, the relative importance of environmental drivers is similar in the richness OLS and its corresponding set of GLMs. Main conclusions The deconstruction of species richness based on macroecological traits revealed that, at least for range size and phylogenetic level, the causes underlying patterns in viperid richness differ for the various sets of species. On the other hand, our analyses of extreme deconstruction using GLM for species geographical range support the idea that, if environmental drivers determine the geographical distribution of species by establishing niche boundaries, it is expected, at least in theory, that the overlap among ranges (i.e. richness) will reveal similar effects of these environmental drivers. Richness patterns may be indeed viewed as macroecological consequences of population-level processes acting on species geographical ranges. [ABSTRACT FROM AUTHOR]

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We evaluate predictions concerning the evolutionary and ecological consequences of color polymorphisms. Previous endeavors have aimed at identifying conditions that promote the evolution and maintenance within populations of alternative variants. But the polymorphic condition may also influence important population processes. We consider the prediction that populations that consist of alternative "ecomorphs" with coadapted gene complexes will utilize more diverse resources and display higher rates of colonization success, population persistence, and range expansions, while being less vulnerable to range contractions and extinctions, compared with monomorphic populations. We perform pairwise comparative analyses based on information for 323 species of Australian lizards and snakes. We find that species with variable color patterns have larger ranges, utilize a greater diversity of habitat types, and are underrepresented among species currently-listed as threatened. These results are consistent with the proposition that the co-occurrence of multiple color variants may promote the ecological success of populations and species, but there are also alternative interpretations. [ABSTRACT FROM AUTHOR]

Current foraging models limit the decision-making process of animals to the food searching and consuming phase. The post-consummatory phase of feeding may influence optimal meal size for some species as a morphologic change often results from feeding. In snakes, a single prey item can lead to abrupt increases in body mass, thus influencing locomotor performance. Identifying factors affecting locomotor performance can help predict behaviors that should maximize an animal's chance of evading predators. Although many snakes ingest large percentages of their body mass, not much work has examined the post-consummatory effects of ingesting bulky prey differing in relative mass. I examined the locomotor performance and antipredator tactics of hatchling trinket snakes ( Elaphe helena) after subjecting snakes to mice prey varying by relative mass differences of 20–35%, 50–59% or 70–79% of an individual hatchling's body mass. Snakes in treatment groups were compared with snakes in a control group (0%). Meal size-affected locomotor parameters such as burst speed, endurance, and endurance times for hatchlings that ingested 50–59% and 70–79% of their body mass (p < 0.001). Recent feeding also affected the types of antipredator modes employed. Hatchlings in the 0% and 20–35% treatments exhibited behaviors that were categorized as active and threatening, while hatchlings in the 50–59% and 70–79% treatments exhibited stationary, neutral, and cryptic behaviors. Although snakes may become more reclusive following a meal, this study demonstrates that relative prey mass affects the ability of hatchling trinket snakes to flee from a predator. In turn, these results suggest that the post-consummatory effects of foraging should be considered in optimal foraging models for organisms that consume a substantial portion of their body mass during a single feeding. [ABSTRACT FROM AUTHOR]

Numerous species are known for their tendency to approach and confront their predators as a group. This behavior is known as mobbing. Snakes seem to be one of the more consistent recipients of this type of predator-directed behavior. This paper explores individual differences (sex and age) in the mobbing behavior of the spectral tarsier toward live and model snakes. This study was conducted at Tangkoko Nature Reserve (Sulawesi, Indonesia) during 2003-2004. During this research, 11 natural mobbing events and 31 artificially induced mobbing events were observed. The mean number of individuals at a mobbing was 5.7. The duration of mobbing events was strongly correlated with the number of assembled mobbers. Adults were more likely than other age classes to participate in mobbings. Males were more likely than females to participate in mobbings. Mobbing groups often contained more than one adult male, despite the fact that no spectral tarsier group contains more than one adult male. No difference in body size between extragroup males and resident males was observed, refuting the "attract the mightier" hypothesis. The number of mobbers did not affect whether the tarsier or the snake retreated first, countering the "move-on" hypothesis. The "perception advertisement" hypothesis was tentatively supported, in that live snakes were rarely seen in the area following mobbing calls, in comparison to when tarsiers either ignored the snake or alarm call. [ABSTRACT FROM AUTHOR]

To effectively ambush prey, sit-and-wait predators must locate sites where profitable prey are likely to return. One means by which predators evaluate potential ambush sites is by recognizing high-use areas through chemical cues deposited inadvertently by their prey. However, it is unknown whether ambush predators can use chemical cues associated with past prey items in the assessment of potential ambush sites. I examined selection of ambush sites by timber rattlesnakes ( Crotalus horridus) exposed to trails made from chemical extracts of the integument of various prey species. I evaluated the role of feeding experience in ambush site selection by comparing the behavior of timber rattlesnakes before and after feeding experience with different sized prey items. Timber rattlesnakes are more likely to select ambush sites adjacent to chemical trails from prey with which they have had feeding experience, but only those fed relatively large prey showed an increase in responsiveness. Increased responsiveness after feeding experience was exhibited in experiments using integumentary extracts of mammals (the natural prey of timber rattlesnakes), but not in those using extracts of fish. These results indicate that ambush predators may learn to recognize chemicals on the integument of profitable food items, and use that experience when subsequently selecting ambush sites. Additionally, these findings provide evidence that size-dependent predation by snakes may be, in some species, a result of active prey selection. [ABSTRACT FROM AUTHOR]

Many contextual factors affect the anti-predator behaviour of animals. In ectotherms, in which most physiological activities depend on body temperature, ambient temperature is one of the most important of these factors. We examined the effects of temperature on the anti-predator behaviour of an ectotherm, the Japanese grass snake (Rhabdophis tigrinus). This species has a large repertoire of anti-predator behavioural responses. Among these responses are several anti-predator displays that appear to be unique to this species and perhaps others in a small group of closely related species possessing nuchal glands containing toxic secretions that may be derived from their toxic toad diet. Snakes were tested at room temperatures of 14, 22 and 30°C with order of temperatures balanced. A long wand modified to simulate initial contact by a predator was used as the stimulus. Snakes exhibited rather passive responses (neck flatten, body flatten, neck arch and immobile) more frequently at low temperatures, and fled more frequently at high temperatures. The dorsal facing posture, a characteristic posture directed against the stimulus, was observed more frequently at low temperatures. Threatening, assertive responses such as strike were rarely observed. These results showed that R. tigrinus shifts its anti-predator behaviour from multiple passive responses to active flight responses with increasing temperature. This snake species thus appears to rely more on its nuchal glands as a predator deterrent at low ambient temperatures. Consistent individual variation was also observed, and its adaptive and causal bases are discussed. [ABSTRACT FROM AUTHOR]

Examines how autotomy-induced shifts in the behavior of a diurnal lizard, Lampropholis guichenoti and natural snake predators, Demansia psammophis and Rhinoplocephalus nigrescens influence the outcome of predatory interactions. Estimation of consumption order of tailless and intact tails lizards; Responses of snakes to chemical cues of potential prey items.

Studies black rat snakes' movements to determine potential ways to minimize their depredation on nesting birds and small mammals. Familiarity with habitat features within their home range; Use of forest edge, residential, hedgerow, and herbaceous/brush habitats; Low frequency of movement within forest interior and residential areas; Recommendations on minimizing snake predations.

Habituation of defensive attacks directed toward a threatening stimulus was investigated in neonatal garter snakes. The focus of the experiments was on differential effects of a simple experimental process in relation to species, litter, sex, and individual. In Experiment 1 newborn Thamnophis melanogaster from four liters and newborn Thamnophis butleri from three liters were given daily tests in which snakes were confronted with a nonmoving and moving human hand. Over five successive test days the T. melanogaster neonates showed a decline in number of strikes directed toward the stimuli. When retested 10-13 days later the animals showed significant response recovery. Although some of the T. butleri newborns demonstrated significant habituation, there was no overall habituation of strike scores in this species. The T. melanogaster had high strike scores, more rapid habituation to moving than nonmoving stimuli, and significant liter differences in habituation rates. The T. melanogaster, but not the T. butleri neonates, showed significant habituation of flight responses over the five tests. In T. butleri, but not T. melanogaster, males were more prone to attack than were females. In both species there were large differences in both overall strike scores and habituation rates of individual newborn animals. In Experiment 2, T. melanogaster 2-months old, were tested for short-term habituation to either a moving or nonmoving stimulus for 10 successive tests on one day. Habituation of strikes was similar to both stimuli, but more animals confronted with the moving stimulus showed an initial increase in strikes, lending support to the dual-process theory of habituation. As in Experiment 1, there were large individual differences in habituation rates. The results are discussed in terms of the ecological and methodological implications for developmental studies. [ABSTRACT FROM AUTHOR]

This article describes and assesses the utility of combat in the common vipers, Vipera berus berus, thereby attempting to assign a role to aggression. A captive viper population was housed and observed in a circular, open-air enclosure. Detailed analysis of intermale combat (which can last up to 60 minutes and always involved two males) reveals that it consists of an initial investigation phase (tongue flicking as seen in courtship and predatory behavior is rare here), followed by a raising of the anterior third of the body. A positive association between body size and success in agonistic encounters over potential mates and food seems suited to poikilothermic, seasonal breeders.

The article is a study on the behavior of juvenile snakes. According to the authors, the habitat choice for juvenile snakes is based more on finding a place of very little disturbance than a place with out predators. The authors have taken into account the role played by the lyre birds in the experiment that they have conducted to study the extent of biotic disturbance and predation on the juvenile snakes in the wild. The authors have also taken into account the probability of lyrebirds attacking the juvenile snakes.

The article presents ouroboros, an ancient symbol depicting a snake eating its own tail, and how placing the tube's tip during pre-oxygenation of the patient's lungs may overcome the problem of achieving sufficient anterior flexion of a Ring-Adair-Elwyn preformed tracheal tube.

An introduction is presented in which the editor discusses various reports within the issue on topics including the drinking behavior of snakes by David Cundall and colleagues and upregulated genes in aphids by Asano Ishikawa and colleagues.

The article reports on the brown tree snakes introduced to the Pacific island of Guam during the 1950s. The introduction resulted to the extinction of several birds and lizard species and the economic losses from power outages that had reached $4.5 million per year. According to the experts the expansion of military presence on Guam has worried them that the associated increase could help the invasive snake establish populations on other island. Moreover, Pacific Islands Invasive Species Coordinator with the US and Fish and Wild Service in Honolulu, Hawaii, Earl Campbell, states that the impending ramp-up in shipping to and from Guam poses a big challenge to the team now trying to restrain and contain the invasive snakes.

The article comments on the study conducted by Webb and Whiting on the relationship between Lyrebird and Juvenile snakes. The article highlights the logical fallacies in their methodology. The author argues that since both the researchers have not seen the superb lyrebirds disturbing the rocks while foraging nor of the lyrebirds attacking the plasticine models of the juvenile snakes, they can not claim that these birds feed on juvenile snakes. The author urges the researchers to observe the phenomenon of the lyrebirds displacing rocks and attacking the plasticine models of the snakes by themselves before they certify the role of the birds.