Individual differences in zoo‐housed squirrel monkeys' (Saimiri sciureus) reactions to visitors, research participation, and personality ratings

Abstract

Understanding individual differences in captive squirrel monkeys is a topic of importance both for improving welfare by catering to individual needs, and for better understanding the results and implications of behavioral research. In this study, 23 squirrel monkeys (Saimiri sciureus), housed in an environment that is both a zoo enclosure and research facility, were assessed for (i) the time they spent by an observation window under three visitor conditions: no visitors, small groups, and large groups; (ii) their likelihood of participating in voluntary research; and (iii) zookeepers, ratings of personality. A Friedman's ANOVA and Wilcoxon post-hoc tests comparing mean times found that the monkeys spent more time by the window when there were large groups present than when there were small groups or no visitors. Thus, visitors do not seem to have a negative effect and may be enriching for certain individuals. Through GLMM and correlational analyses, it was found that high scores on the personality trait of playfulness and low scores on cautiousness, depression, and solitude were significant predictors of increased window approach behavior when visitors were present. The GLMM and correlational analyses assessing the links between personality traits and research participation found that low scores of cautiousness and high scores of playfulness, gentleness, affection, and friendliness, were significant predictors. The implications of these results are discussed in relation to selection bias and its potential confounding effect on cognitive studies with voluntary participation.

Widespread Behavioral Responses by Mammals and Fish to Zoo Visitors Highlight Differences between Individual Animals

“…Previous studies have demonstrated that individuals can vary in their behavioral responses [ 21 , 51 , 52 ]. We found further evidence that individual animals of the same species in the same exhibit do not always respond in the same manner to humans.…”

“…Individual animals can vary in their responses to zoo visitors [ 21 , 51 , 52 ]. A study of three polar bears ( Ursus maritimus ) found one animal increased and two animals decreased stereotypical behavior during periods of higher visitor density [ 53 ].…”

Evaluating mood changes in response to anthropogenic noise with a response-slowing task in three species of zoo-housed primates

“…It is also likely that there are individual differences contributing to the results obtained here, and teasing out how personality or temperament influences responses to social stimuli is an important future direction. Related, there may have been selfselection among the subjects in that the subset of touchscreen trained animals who voluntarily participated during the Air and Water Show may have been willing to do so because they experienced less stress than groupmates (see Morton, Lee, & Buchanan-Smith, 2013;Polgar, Wood, & Haskell, 2017). However, that would have led us to underestimate the impact on mood for Japanese macaques.…”

How STRANGE are your study animals?

“… Self-selected participation in experiments was correlated with personality traits in squirrel monkeys 36 .…”