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

Examined the social dynamics of the formation of mating balls (gatherings of males) during the mating period of red-sided garter snakes 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. Nine test males and 9 stimulus females were used in tests, along with 55 other males, to measure the effect of other courting males. Results show that male Ss courted females more actively when other males were also courting the female than when they were alone with her, suggesting that the female is more attractive to the male when courted by other males. A positive correlation was observed 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. Results suggest that males are intrinsically stimulated by mating balls. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of lesions of the vomeronasal and olfactory nerves on garter snake (Thamnophis sirtalis) responses to airborne chemical stimuli.

The roles of the main (MOS) and accessory (AOS) olfactory systems of garter snakes in response to airborne chemicals were investigated. Preoperatively, all snakes responded to airborne odors with increased tongue-flick rate and duration. Postoperatively, sham-operated snakes responded to airborne odors with increased tongue-flick rates, but snakes with main olfactory nerve cuts failed to respond to the odors, and snakes with vomeronasal nerve cuts responded to nonprey odors only. Preoperatively, exposure to earthworm odor produced more frequent and shorter duration tongue-flicks during locomotion compared with exposure to water. Postoperatively, only sham-lesioned snakes exhibited differential responding to earthworm odors. This study demonstrates that the MOS is critical for the initiation of tongue-flick behavior in response to airborne odors and that discrimination of odors with biological significance requires a functional AOS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of antipredator responses in snakes: I. Defensive and open-field behaviors in newborns and adults of three species of garter snakes (Thamnophis melanogaster, T. sirtalis, T. butleri).

A comparative study of defensive behavior in multiple litters of newborn garter snakes and adult female garter snakes from 3 species was conducted in the laboratory. In Exp I, 241 1-day-old Ss, roughly equally divided among the 3 species, were tested for defensive behaviors directed toward a moving or nonmoving stimulus. T. melanogaster babies were the most reactive in terms of strikes, bites, and defensive tongue flicks. T. sirtalis and T. butleri were less reactive and not significantly different from each other. In Exp II, 32 adult females reacted in ways similar to the neonates, except that the T. sirtalis females were more reactive toward the moving stimulus than were the T. butleri females. Exp III showed large and significant differences in open-field behavior among the newborn of the 3 species but few significant correlations between open-field measures and antipredator responses. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)