The effects of zoo visitors on a group of Western lowland gorillas Gorilla gorilla gorilla before and after the birth of an infant at Dublin Zoo

Abstract

Increasingly, it is understood that one must take into consideration all aspects of the zoo environment when assessing visitor effects. One of the unexplored topics in this area is the impact of a new group member in combination with the visitor effect on primates. Here, we investigate the effect visitors have on a group of Western lowland gorillas Gorilla gorilla gorilla before and after the birth of an infant. Observational data were obtained through scan sampling before and after the infant's birth and during different visitor conditions. Results indicate that the birth of the infant lessened some of the negative visitor effects previously observed in this group of gorillas. Particularly when in the ‘high’ visitor numbers category, the adult ♂ foraged more, was less inactive and more social after the infant's birth than he had been before. However, certain negative behaviours associated with increased visitor number, such as aggression and ‘back to viewing window’, were not diminished with the birth of the infant. Although results varied between individuals, there are indications that an event such as the birth of an infant may lessen negative visitor effects.

The effect of visitors on the behavior of zoo‐housed western lowland gorillas (Gorilla gorilla gorilla)

“…Likewise, increased intragroup aggression can create social instability, with consequent stress (Cheney & Seyfarth, 2009; Judge & Mullen, 2005; Schino & Sciarretta, 2015), and may also increase rates of physical injury (Lambeth, Bloomsmith, & Alford, 1997). Increased locomotion has also been reported (Chamove et al, 1988; Collins & Marples, 2016); while some studies interpret this as negative (Collins & Marples, 2016), the overall significance of this increase is unclear. Increases in “abnormal” or “stress‐related” behaviors with increased visitors have also been found in a number of studies (Carder & Semple, 2008; Clark et al, 2012; Wells, 2005).…”

“…), the overall evidence for visitor effects and their impact is generally inconclusive; some authors report pronounced responses to large crowd conditions (Carder & Semple, 2008; Wells, 2005), while others find little effect (Carder & Semple, 2008; Ross et al, 2010). Discrepancies may result from a number of differences between collections including enclosure design (Davey, 2007; Stoinski, Jaicks, & Drayton, 2012), husbandry styles (Stoinski et al, 2012), habituation (Chamove et al, 1988), and group composition or changes therein (Collins & Marples, 2016). Many studies have small sample sizes, so individual differences in response may be a strong explanatory factor.…”

Studying primate personality in zoos: implications for the management, welfare and conservation of great apes

“…Changes in group structure, such as the birth of an infant, may also have an effect on how gorillas react to visitors (e.g. Collins & Marples, 2016). Visitor density is not a stressor for all individuals (Hosey, 2000), and crowd size may or may not have an effect on behaviour in various species in zoos (Ross et al, 2007;Bonnie et al, 2016;Jones et al, 2016;Martin, R. A., & Melfi, 2016;Polg ar et al, 2017).…”

The Social Rank of Zoo-Housed Japanese Macaques is a Predictor of Visitor-Directed Aggression

“…While most research has focused on how the characteristics of the visitor crowds affect the animals, it is also becoming apparent that characteristics of the animals themselves, such as their age or sex, play a role in explaining their reactions to zoo visitors [11,13,21]. There is growing interest in identifying additional factors given the amount of individual variation that has been observed [11,22,23,24]. One key dimension on which most individual primates vary within any given social group is social rank [25,26,27], yet the impact of rank on primate reactions to zoo visitors has not yet been explored.…”