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The effect of visitors on the behavior of zoo‐housed western lowland gorillas ( Gorilla gorilla gorilla )
Author(s) -
Lewis Rebecca N.,
Chang YuMei,
Ferguson Amanda,
Lee Tracey,
Clifforde Lisa,
Abeyesinghe Siobhan M.
Publication year - 2020
Publication title -
zoo biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.5
H-Index - 54
eISSN - 1098-2361
pISSN - 0733-3188
DOI - 10.1002/zoo.21552
Subject(s) - gorilla , crowds , visitor pattern , biology , demography , captivity , aggression , zoology , social psychology , psychology , statistics , mathematics , computer science , paleontology , sociology , programming language
Abstract Primates, especially apes, are popular with the public, often attracting large crowds. These crowds could cause behavioral change in captive primates, whether positive, neutral, or negative. We examined the impact of visitors on the behavior of six western lowland gorillas ( Gorilla gorilla gorilla ), observing the troop over 6 weeks during high season (4.5 hr/day, 35 days, May–July 2016). We used focal scan sampling to determine activity budget and enclosure usage, and focal continuous sampling to identify bouts of anxiety‐related behavior (visitor‐directed vigilance, self‐scratching, and aggression). Both daily zoo‐entry numbers (V GATE ) and instantaneous crowds at the exhibit (V DENSITY ) were measured. Overall, V GATE had little effect across behaviors. However, consistent with the more acute time frame of measurement, V DENSITY was a better predictor of behavior; at high crowd volumes, we observed significant group‐level changes in activity budget (increased inactivity, increased locomotion, and decreased environment‐related behaviors), increase in some anxiety‐related behaviors, and decreased enclosure usage. Although contributing similar effects, it could not be determined if crowd numbers, composition, or noise most affected the troop, nor any chronic effects of exposure to large crowds. Nevertheless, our findings suggest that measures to minimize the impacts of large crowds at the exhibit would be beneficial. Furthermore, we highlight potential discrepancies between common methods for measuring visitor numbers: V GATE is less sensitive to detecting visitor effects on behavioral indices than V DENSITY . Future studies should appropriately match the biological time frame of welfare indicators and visitor measures used to ensure the reliability of findings.