Investigation in snakes (Garter, and others)

Investigatory behavior in-the plains garter snake (Thamnophis radix) and several additional species- Chiszar et al. 1976

• Abstract: When observing the tongue flick rate of multiple snakes, they found that different taxa differ in their tongue flick rates as well as their locomotion within an open arena.
• The second experiment showed that garter snakes showed exploration within the arena even after mitigating for the effects of handling.
• The tongue flick rate of the garter snakes became virtually zero after a 20min period, and the presentation of objects increased the tongue flick rate, showing that the snakes were not displaying fatigue, but a form of habituation. – > (check out Thompson and Spencer, 1966)
• Hungry snakes took longer to habituate to the arena than recently eaten snakes, thus hinting that exploration behaviour is influenced by the same factors that control food related activities
• Aim: to investigate how tongue flick rate is affected by the presentation of non-naturalistic stimuli as well as the absence of stimuli to provide a baseline. Second is to investigate curiousity in these animals.
• Method:
• 1. N= 8 garter snakes, 8 rattlesnakes, 2 eastern hognose snakes. Snakes were placed in the center of the arena and observed for 5 minutes by 2 observers counting distance via squares and tongue flicks per minute
• 2. N= 10 garter snakes, observed tongue flick rate in home environment, and then after placement in the arena. Second group was observed in home environment, and then held for 3 seconds before being placed back in their home environment.
• 3. N= 6 garter snakes, raised in a single terrarium. Snakes were individually placed in the centre of the arena, and their tongue flick rates were observed for a 20min period. At the 20min mark, a dish of water or water with fish flesh was placed within the arena and observed for another 20min period. 
• 4. N= 9 garter snakes, same procedure as the first experiment with an empty arena, except with three feeding regimes.
• Results:
• 1. All the snakes significantly decreased in tongue flick rate and squares traveled, all species were significantly different from one another as well.
• 2. The handling did significantly increase tongue flick rate compared to before handling, however the tongue flick rate of the open arena was significantly more than what the handling could produce. The snakes in the arena also decreased tongue flick rate over successive days. The younger snakes also had a significantly higher rate compared to older snakes.
• 3. The snakes showed similar rates of decline until the stimulus was added, and all snakes showed significantly more responses within the 5 minutes of exposure. However there was no significant difference between the treatment groups
• 4. There was an obvious effect of feeding regime on exploration with less exploration displayed by snakes that were well fed. However there was no significant decline over the ten days.
• Discussion:
• 1. The significant difference between snake species should not be regarded as a species-specific characteristic, because tongue flick rate has been shown to differ based on age and food-deprivation in the following experiments
• 2. The snakes showed that they investigated the open arena out of curiousity since the tongue flick rate was higher than just handling and returning back to the home enclosure. Factors such as consumable stimuli were controlled for by using an empty arena, and the decline of tongue flick rate over time hints at habituation.
• 3. The response of an increased tongue flick rate and movement after the stimulus was presented shows that the snakes were habituating rather than tired. The fact that both groups showed similar levels of interest is odd since one of the stimuli was food oriented. This may be because of a small sample size, or because food deprivation has a larger role in exploration than first assumed.
• 4. The study shows that the exploration of an open arena is partially dependent upon hunger, with hungry snakes exploring more with hopes of bumping into food. Also the tongue flick rate was always significantly higher during the initial minutes of the study showing that the investigation aspect was independent of hunger.