The Impact of Visitors on Non-Primate Species in Zoos: A Quantitative Review

Abstract

Visitors are a prominent feature in the lives of zoo animals, and their presence can cause a range of impacts on zoo animals (typically classed as positive, negative or neutral impacts), commonly referred to as the 'visitor effect'. This paper quantitatively collates the literature on the visitor effect in non-primate species, investigates the types of measures used to assess impacts of visitors on animals and considers whether impacts vary across non-primate species in zoos. In total, there were 105 papers which had investigated the impact of zoo visitors on 252 non-primate species/species groups. There has been a steady increase in visitor effect research in zoos since 2012 and this body of work incorporates species from avian (28% study species), reptilian (9%), amphibian (2%), fish (4%) and invertebrate taxa (1%). However, there is still a bias towards mammalian species (56%). The response to visitors varied across taxa. Amphibians responded negatively to visitors more frequently than would be expected by chance (p < 0.05), birds responded neutrally more frequently than would be expected by chance (p < 0.05) and fish responded neutrally and 'unknown' more frequently than would be expected by chance (p < 0.05). This review highlighted a number of animal-based metrics which have been used to assess the impacts of visitors on animals, with measures used varying across taxa. Moving forwards, it is recommended that moving forwards researchers incorporate a suite of measures, incorporating those which are meaningful in terms of being representative of individual animal experiences and animal welfare, collected in a manner which should capture those metrics accurately.

Keywords: non-primate species; visitor effect; zoo animal welfare; zoo visitors.

Figure 1

An overview of the process undertaken to identify and review relevant literature for the searches.

Figure 2

An overview of the number of papers produced per study year from 1992 to 2022.

Figure 3

An overview of taxa represented in the study papers from 1992 to 2022.

Figure 4

An overview of the orders represented in papers published on the visitor effect on zoo animals from 1992 to 2022.

Figure 5

Range of visitor variables and number of times they were studied in the reviewed papers.

Figure 6

A breakdown of the number of behavioural, physical and physiological animal-based measures and how they varied across the animal groups.

Figure 7

An overview of the number of times different responses were reported to zoo visitors across the taxa.