Relationship between behavior, adrenal activity, and environment in zoo‐housed western lowland gorillas (Gorilla gorilla gorilla)

Reducing visual contact with visitors by using camouflage netting or one-way vision screens has been found to reduce intragroup aggression and stereotypic behaviours in Western lowland gorilla and Black-capped capuchins.

“For example, reducing visual contact with visitors by using camouflage netting or one-way vision screens has been found to reduced intragroup aggression and stereotypic behaviours such as repetitive teeth clenching, body rocking, pacing and self-scratching in Western lowland gorilla (Gorilla gorilla gorilla) and Black-capped capuchins (Sapajus apella) [22,23,24].”

Camouflage netting and one-way vision screens improved gorilla and black-capped capuchin welfare through reduction of visual contact with visitors and likely by reducing potentially threatening visitor behaviours.

“This is to some extent supported by previous studies that, while not measuring visitor behaviour specifically, found camouflage netting and one-way vision screens improved gorilla and black-capped capuchin welfare through the reduction of visual contact with visitors but also likely by reducing potentially threatening visitor behaviours as a result of the visual barriers being in place [22,23,24].”

Monitoring adrenal activity through non-invasive faecal hormone sampling is rapidly gaining popularity as a tool to assess zoo animal welfare.

“Monitoring adrenal activity through non-invasive faecal hormone sampling is rapidly gaining popularity as a tool to assess zoo animal welfare (Clark et al., 2012)”

To analyse whether the effect has physiological consequences for the animal, more direct measures of physiological stress and fitness consequences are required.

“However, to analyse whether the effect has physiological consequences for the animal, more direct measures of physiological stress and fitness consequences are required [61,62].”

An increase in the time spent alert to visitors was detected in gorillas, kangaroos, sika deer, koalas and Soemmerring's gazelle in response to higher numbers of visitors.

“An increase in the time spent alert to visitors was detected in various species including gorillas [61], kangaroos [86], sika deer [87], koalas [78] and Soemmerring’s gazelle [88] in response to higher numbers of visitors.”