Personality in Nonhuman Animals by Jennifer Vonk Alexander Weiss & Stan A. Kuczaj

Author:Jennifer Vonk, Alexander Weiss & Stan A. Kuczaj
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Consistency of Behavior Across Situations

Another marker of temperament/personality is consistency of behavior across situations. There has been less research on behavioral consistency across situations in snakes, and the evidence for this consistency is mixed, as will be reviewed below.

Behavioral Consistency Across Temperatures

Brodie and Russell (1999) tested northwestern gartersnakes, T. ordinoides, at different temperatures (15, 22.2, 30 °C) representing the range encountered by these snakes in the wild. Temperature affected distance traveled, reversals, and speed, with cooler temperature resulting in a decrease in all measures; however, snakes were relatively consistent in their rankings across temperatures. Specifically, snakes with relatively faster crawling speeds at one temperature were likely to have faster speeds at the other temperatures. In a field study of almost 200 adult Eastern gartersnakes, T. sirtalis, Passak and Gillingham (1997) also found changes in antipredator responses across temperatures ranging from 6 to 40° C. These rather cold-tolerant north temperate snakes were either physically grabbed or mock grabbed after being exposed from under cover objects. Individuality was shown in which of five responses were displayed by grabbed snakes (body flattening, mouth gaping, biting, cloacal discharge, or no antipredator behavior), with flight also recorded for the mock-grabbed snakes. Flight was more common at higher temperatures, but other behaviors such as body flattening and cloacal discharge, which could occur singly or in combination, did not vary by temperature. Although these snakes were not retested, there were individual differences in behavior not explained solely by temperature. Mori and Burghardt (2001) tested 24 adult Japanese tiger keelback snakes, Rhabdophis tigrinus, under three temperature conditions (14, 22, 30 °C). In the tests, snakes were briefly pinned with a snake hook, and the occurrence of eight different antipredator behaviors was measured; some of the behaviors (e.g., “neck arch”) exposed nuchal glands that excrete toxic secretions. Temperature affected antipredator behavior overall, with snakes exhibiting more passive behaviors and behaviors that exposed the nuchal glands at the lowest temperature; when the snakes were tested under higher temperatures, they, as with T. sirtalis above, showed more active fleeing from the stimulus. The behaviors were sorted into three factors through principal component analysis, and the factors were, for the most part, individually consistent across the temperature conditions (Kendall’s coefficient of concordance: PC1 static threatening response. W = 0.75, p < .001; PC2 immobility W = 0.48, p = .09; PC3 active threatening response, W = 0.55, p < .05). An example of behavioral consistency of a non-natricine snake was described by Citadini and Navas (2013) who found consistent individual variation of antipredator behaviors across different temperatures in the neotropical snake, Tomodon dorsatus (Dipsadidae). Snakes consistently displayed behaviors classified as aggressive, passive, or evasive in the different temperature conditions; these initial classifications interacted with behavioral tendency, i.e., cooler temperatures increased aggressive behaviors only in those snakes previously classified as having aggressive dispositions. Thus, there is good evidence that snakes show consistent individual variability in antipredator behavior across different temperatures.

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