Thamnophis Radix Research Articles

Relative Abundance of Snakes in Kansas

Forty-four samples of the Kansas ophifauna from localities well distributed over the state total 33,117 snakes of 34 species. Diadophis punctatus proved to be by far the most prevalent species. Others that are both widespread and numerous are Coluber constrictor, Thamnophis sirtalis, Pituophis catenifer and Nerodia sipedon. Thamnophis radix, Elaphe emoryi, Agkistrodon contortrix, Lampropeltis triangulum, Nerodia rhombifera, and Heterodon nasicus also are well represented in the state. However, a group of diminutive species of secretive and/or fossorial habits, including (besides Diadophis punctatus) Carphophis amoenus, Sonora semiannulata, Storeria dekayi, Tantilla gracilis, T. nigriceps and Tropidoclonion lineatum, all predators on invertebrates, were found to attain much higher densities (scores or even hundreds per hectare) than the larger kinds that prey on vertebrates.

The use of solar cues as migratory orientation guides by the plains garter snake, Thamnophis radix

The ability of adult plains garter snakes, Thamnophis radix, to use solar cues as orientation guides during their fall return to a communal hibernaculum in southern Canada was examined. Snakes were displaced from dens and tested in circular arenas that restricted their view of terrestrial landmarks. The results were analyzed by circular statistics. Snakes oriented along the homeward axis, indicating type II or type III orientation. A bidirectional pattern of responses suggests that polarized light may be an orientation cue.

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.

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

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

Responses by corn snakes (Elaphe guttata) to chemicals from heterospecific snakes

Young corn snakes,Elaphe guttata, were tested for responses to chemicals from heterospecific snakes. Corn snakes exhibited more tongue-flicks to swabs freshly rubbed against the skin of an ophiophagous kingsnake,Lampropeltis getulus, than to blank swabs. Responses toL. getulus and a nonophiophagous western plains garter snake,Thamnophis radix haydeni, did not differ significantly. Corn snakes exhibited more tongue-flicks to swabs treated with chloroform extracts of the shed skins ofL. getulus; an ophiophagous eastern coachwhip,Masticophis flagellum; and a nonophiophagous gray ratsnake,Elaphe obsoleta, than to blank swabs, but they did not discriminate between ophiophagous and nonophiophagous species in every case. Corn snakes, when offered shelters containing bedding from the home cages of a nonophiophagous water snake,Nerodia erythrogaster, an occasionally ophiophagous water moccasin,Agkistrodon pisdvorus; orL. getulus and untreated bedding, failed to reside under snake-scented shelters at a rate significantly different from that expected by chance. The responses of corn snakes are compared with those reported for other snakes presented with heterospecific snake chemicals.

Functional similarities in the mechanical design of the aorta in lower vertebrates and mammals

The mechanical properties of the aorta from the toad Bufo marinus, the lizard Gekko gecko and the garter snake Thamnophis radix were compared to those of the rat, by inflation of vessel segments in vitro. The arteries of the lower vertebrates, like those of mammals, were compliant, highly resilient, and non-linearly elastic. The elastic modulus of the artery wall was similar in the lower vertebrates and mammals, at their respective mean physiological pressures. We conclude that the aorta in each of these animals is suitably designed to function effectively as an elastic pulse smoothing component in the circulation; differences in the pressure wave transmission characteristics of lower vertebrates and mammals do not result from dissimilarities in arterial elastic properties, but from substantial differences in heart rate of these two groups.

Behavioural variation in natural populations. V. Morphological correlates of locomotion in the garter snake (Thamnophis radix)

A series of morphologieal and locomotor performance variables was measured in a population of newborn garter snakes to determine whether performance capacity has a significant morphological basis in these animals. Morphological traits measured were body length and mass, number of body and tail vertebrae and numbers of vertebral abnormalities. Locomotor performances included burst and mid-distance speed and distance and time crawled before anti-predator displays were assumed. All performance variables were repeatable in daily replicate trials (P < 0.001). Individual burst speed, mid-distance speed, and distance crawled were significantly correlated pairwise (P < 0.01). Most morphological and performance variables had a significant mass dependence (static allometry), although the effects were rather weak (r2 < 0.1, except for body length): larger animals performed better and had fewer abnormalities. There were significant associations between some morphological traits and locomotor performance. Morphological factors accounted for 19% of the variation in mid-distance speed and 14% of the variation in antipredator behavior by multiple regression analysis. Canonical correlation of all performance and morphological variables simultaneously accounted for 24% of the observed variation in performance. Numbers of body and tail vertebrae (assayed by scale counts) had an interactive effect on speed of locomotion.

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.

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.

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

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

Behavioural variation in natural populations. III: Antipredator displays in the garter snake Thamnophis radix

Recently born garter snakes ( Thamnophis radix) were subjected to a variety of threatening stimuli. The would crawl away from the investigator until high levels of lactate were attained, and then adopt one of a variety antipredator displays. These antipredator behaviours were surprisingly variable between individuals of a single population, but behaviours of individuals were consistent in replicate trials and in response to different stimuli. Snakes became more defensive when simulated predator attacks were more severe, but they became more offensive when tested at a lower temperature. Analysis of behavioural variation within and between 15 litters of full-sibling (172) snakes gave heritability estimates of 0.37 for single trials and 0.45 for the average of two replicate trials. This is the first study to examine the heritability of antipredator behaviour in any terrestrial vertebrate species.

Sex pheromone source location by garter snakes:

Male plains garter snakes,Thamnophis radix, tested in a 240-cm-long arena can detect directional information from a female pheromone trail only when the female is allowed to push against pegs while laying the trail. The female's normal locomotor activity apparently deposits pheromone on the anterolateral surfaces of vertical structures in her environment. The male sensorily assays the sides of these objects and from this information determines the female's direction of travel.

Effects of Chemical and Visual Stimuli upon Chemosensory Searching by Garter Snakes and Rattlesnakes

Many studies indicate that chemical cues activate garter snake feeding behavior whereas visual and/or thermal stimuli do so for rattlesnakes. However, no experiments have factorially combined chemical and visual cues for either of these taxa. The present work explored possible interactive effects of these stimuli on rate of tongue flicking (RTF) in garter snakes (Thamnophis radix haydeni) and rattlesnakes (Crotalus e. enyo, C. v. viridis, and Sistrurus catenatus tergeminus). In Experiments 1 and 2 snakes were exposed to four conditions represent- ing an orthogonal combination of presence vs. absence of visual and chemical stimuli arising from prey. RTF was recorded for 5 min under each condition. Garter snakes exhibited a significant elevation in RTF in the presence of chemical cues whether or not visual cues were present. There was also an effect of visual cues but no interaction between visual and chemical cues. Rattlesnakes did not respond to chemical cues; these snakes showed only an effect of visual cues. In Experiment 3, rattlesnakes were again observed as above, with the exception that test sessions were of 10 min duration. Behavior during the first 5 min was identical to that seen in Experiment 2, but during min 6-10 the snakes responded more in the condition containing visual plus chemical cues than in any other condition. Visual stimuli alerted rattlesnakes to the presence of potential prey and gave rise to elevated RTF which subsequently allowed these predators to utilize chemical cues that happened to be available. Hence, garter snakes and rattlesnakes use both chemical and visual information but differ in the sequence in which these stimuli are used.

Investigatory behaviour of plains garter snakes, Thamnophis radix (Reptilia: Colubridae), in tests of repellant chemicals.

Nineteen adult and 24 young Thamnophis radix, collected at two sites in southern Saskatchewan, were tested for avoidance to 10 common chemicals and commercial repellants. Avoidance was noted only to a repelling fumigant containing pyrethrum. Analysis of tongue flick rate showed that the adults used this part of searching behaviour significantly more than the young.

Stimuli influencing mating behavior in the garter snake, Thamnophis radix

1. Following copulation, female Thamnophis radix are unattractive to sexually active males for at least 48 h; the stimulus basis for this change is the mating plug produced by secretion from the male's renal sex segment. 2. The mating plug inhibits the courtship behavior of other, unmated males. 3. The effect of mating and the mating plug on female sexual attractivity and receptivity serves to maximize a male's reproductive success by minimizing the probability of multiple inseminations. 4. Loss of attractivity and mating-associated behavioral changes protect the female from subsequent courtships and copulations, thus minimizing predation dangers. 5. Inhibition of other male's courtship behavior confers a reproductive advantage on the mating male; this odor may be the stimulus underlying unsuccessful male dispersal from mating balls.

Shedding enhances the sexual attractiveness of oestradiol treated garter snakes and their untreated penmates

The courtship behaviour of male garter snakes ( Thamnophis radix) was tested with females who received or did not receive oestradiol benzoate (EB) injections prior to shedding, and with non-shedding females who received EB. Each female injected for 5 or more days prior to shedding was courted only after the shed. In addition, most penmates of the EB treated shedders were courted frequently after the treated female shed. Females who received no EB prior to shed showed little or no increase in sexual attractiveness. EB treated females who did not shed were inconsistently courted. It is most likely that shedding potentiates the release of a sexual pheromone from the dorsal skin of EB treated females, and this pheromone can then be spread to the backs of penmates.

The Efferent Connections of the Olfactory Bulb and Accessory Olfactory Bulb in the Snakes, Thamnophis sirtalis and Thamnophis radix

The efferent connections of the olfactory bulb and accessory olfactory bulb of two species of garter snakes, Thamnophis sirtalis and T. radix were studied with experimental anterograde degeneration techniques. Axons of cells located in the olfactory bulb terminate ipsilaterally in all parts of the anterior olfactory nucleus, olfactory tubercle and lateral pallium. In addition, some axons enter the ipsilateral stria medullaris thalami, cross the midline in the habenular commissure, enter the contralateral stria medullaris thalami and terminate in the contralateral lateral pallium. The axons of cells in the accessory olfactory bulb course through the telencephalon completely separated from the fibers of olfactory bulb origin and terminate predominantly in the nucleus sphericus. These results confirm previous reports of the separation between the central projections of the olfactory and vomeronasal systems in a variety of vertebrates. The totality of the separation between these two systems coupled with the extensive development of the vomeronasal-accessory bulb system in these snakes suggests that they may be ideal subjects for further research on the functional significance of the vomeronasal system.

Rate of tongue flicking by garter snakes ( Thamnophis radix haydeni) and Rattlesnakes ( Crotalus v. viridis, Sistrurus catenatus tergeminus, and Sistrurus catenatus edwardsi) during prolonged exposure to food odors

Garter snakes (Thamnophis radix haydeni) emitted more tongue flicks in environments containing fish or salamander odors than in a control environment. This indicates that appetitive searching (guided by the vomero-nasal system) can be activated by olfactory cues. Specimens of three taxa of rattlesnakes (Crotalus viridis viridis, Sistrurus catenatus tergeminus, and Sistrurus catenatus edwardsi) did not emit more tongue flicks in an environment containing mouse odors than in a control environment. Hence, the vomeronasal systems of these rattlesnakes were not activated by olfactory cues. A hypothesis is offered about the conditions required to stimulate tongue flicking in rattlesnakes.

Investigatory behavior inthe plains garter snake (Thamnophis radix) and several additional species

Garter snakes (Thamnophis radix), hognose snakes (Heterodon platyrhinos), and rattlesnakes (Crotalus species) flick their tongues and crawl about in an open field containing no food or sexual (i.e., reproductive) odors. As Experiment I shows, the taxa differ reliably in both rate of tongue flicking and rate of locomotion. In Experiment II, garter snakes (Thamnophis radix) placed into an open field for 5 min showed more tongue flicking than snakes that were handled and placed directly back into their home cages, indicating that the first group was exploring the apparatus rather than responding only to handling. During Minutes 3 through 5 (Experiment III) in the open field, garter snakes emitted fewer tongue flicks than they did during the first minute, and after 20 min, the rate of tongue flicking was virtually zero. However, snakes were capable of responding to presentation of new objects and/or odors, indicating that the previous response decrement was not derived from effector fatigue but rather from some habituatory process. Experiment IV revealed that satiated snakes habituated more rapidly than hungry snakes during exploration of the open field. Hence, exploratory behavior in these snakes is at least partially under the control of the same factors which mediate food-related appetitive activities.

Temperature and light effects on the circadian rhythm and locomotory activity of the plains garter snake(Thamnophis radix hayendi)

Abstract The Locomotory activity of the Plains Garter snake was determined under L/D: 12/12 conditions at five constant temperatures and three light intensities during the light period. The snakes were diurnal at low temperatures with nocturnal activity increasing in various amounts at higher temperatures. The different light intensities had relatively small effects on the activity rhythm. Activity was recorded under four constant light conditions at five constant temperatures and the characteristics of the free‐running rhythm measured. A comparison of the characteristics of the free‐running rhythm to Aschoff's circadian rule indicates that this snake is an exception to this rule. Increase light intensity decreased total activity under all conditions. Under a L/D: 12/12 cycle the decrease in activity was more pronounced during the dark period than the light period. It is suggested that crepuscular or nocturnal activity shown by snakes at high temperatures may be an effect the temperature level has on the ...