Scratching under positive and negative arousal in common marmosets (Callithrix jacchus)

Abstract

Scratching has been widely used as an indicator of anxiety in many primate species. However, a handful of studies have shown no change in scratching under anxiety-provoking circumstances. In addition, the existing literature has investigated scratching only in relation to negative arousal (i.e., anxiety), even though anxiety and excitement (positive arousal) share important physiological and behavioral correlates, including increased heart rate, blood pressure, and locomotion. In the current study, we scored all instances of scratching in 11 outdoor-housed captive common marmosets (Callithrix jacchus) during three contexts that were intended to be negatively arousing and three contexts that were intended to be positively arousing during a baseline, manipulation, and post-induction period. Summed across the three negative arousal contexts, the results showed that subjects exhibited significantly lower scratching rates during the manipulation than during either the baseline or post-induction periods, and the pattern of means was the same for all three of those contexts. Under the three contexts of positive arousal, subjects exhibited different patterns of scratching rates during the manipulation periods (play = increases, foraging = decreases, food anticipation = no change). Data from the current study, and a close examination of data from studies showing no change in scratching under anxiety-provoking circumstances, suggest that the anxiety-scratching relationship may be more complex than has been reported previously. Our results raise a potential concern about the unchallenged use of scratching as a behavioral indicator of anxiety in captive non-human primates, with important implications for welfare and management of these species.

Effects of Enclosure and Environmental Enrichment on the Behaviour of Ring-Tailed Lemurs (Lemur catta)

“…Apart from promoting species-appropriate behaviours, environmental enrichment is also often used to reduce behaviours that may indicate poor welfare, e.g., abnormal and self-directed behaviours [41][42][43], but see Neal and Caine [44]. We did not record abnormal behaviours throughout the study period, but we did observe self-directed behaviours albeit at relatively low levels.…”

Vocal correlates of arousal in bottlenose dolphins (Tursiopsspp.) in human care

“…Daily arousal patterns which coincided with presence of staff and caretakers at the facility, specifically at the end of the day (last daily presentation) and early in the morning (food preparation and feeding), suggest excitement associated with these activities. Excitement is a positive arousal state [8,60], and is less commonly studied than negative arousal. Vocal responses indicating positive and negative emotional states are hard to differentiate as they may share vocal features [61].…”

Watching others in a positive state does not induce optimism bias in common marmosets (Callithrix jacchus), but leads to behaviour indicative of competition

“…Furthermore, these results might also, or in addition, be due to a lack of manipulation effect, and specifically, the JBT could have benefitted from a more realistic intervention rather than a static one (e.g., a simulation procedure, as in Adriaense et al 2019a ). Still, other studies have successfully used artificial toy predators as manipulation (see Neal and Caine 2016 , for examples). Moreover, most studies on cognitive bias focus on long-term moods through environmental changes (e.g., enrichment in pigs, Douglas et al 2012 ) or social behaviours (e.g., long-term grooming in Schino et al 2016 ), but effects of short-term social behaviour may show different results (e.g., immediate grooming showed no bias, in Schino et al 2016 ; though see e.g., Rygula et al, 2012 ; Adriaense et al 2019a , for short-term effects).…”

“…Scratching is commonly observed in primates in negative situations, for instance in occurrences of social conflict (Aureli and van Schaik 1991 ), contradicting motivations (Troisi et al 1991 ), or predatory threat (see Neal and Caine 2016 , for overview). Depending on the specific circumstances, scratching may thus reflect negative stress or anxiety, and therefore, scratching has been suggested as general indicator of a negative emotional state (Maestripieri et al 1992 ; Troisi 2002 ).…”