Review of the Effects of Enclosure Complexity and Design on the Behaviour and Physiology of Zoo Animals

Abstract

The complexity of the habitat refers to its physical geometry, which includes abiotic and biotic elements. Habitat complexity is important because it allows more species to coexist and, consequently, more interactions to be established among them. The complexity of the habitat links the physical structure of the enclosure to the biological interactions, which occur within its limits. Enclosure complexity should vary temporally, to be able to influence the animals in different ways, depending on the period of the day and season and throughout the year. In the present paper, we discuss how habitat complexity is important, and how it can positively influence the physical and mental states of zoo animals. We show how habitat complexity can ultimately affect educational projects. Finally, we discuss how we can add complexity to enclosures and, thus, make the lives of animals more interesting and functional.

Keeping reptiles as pets in Brazil: keepers’ motivations and husbandry practices

“…In the wild, reptiles live in complex physical three-dimensional habitats composed of abiotic (e.g., soil, rocks, temperature, lighting, water features) and biotic components (e.g., different plant and animals species); a temporal dimension (e.g., climate and resource variations in time); and a social dimension (e.g. presence of individuals of the same and different species) [ 37 ]. Nonetheless, for reptiles kept in captivity as pets, the need for stimulating and changing environments is often underestimated [ 38 ].…”

“…Adding complexity to an enclosure (physical, social, environmental variation) is a form of environmental enrichment [ 37 ], and although it can be limited by the enclosure’s available space, its role is to create instances in which animals can express as many natural behaviors as possible. The presence of different substrates, vegetation cover, and physical structures such as burrows to afford shelter and retreat, rocks, perches, and other features to stimulate movement and exercise, can help individuals to reduce boredom, cope with the forced interaction of humans or other animals, and ultimately to thrive [ 45 ].…”

“…The presence of different substrates, vegetation cover, and physical structures such as burrows to afford shelter and retreat, rocks, perches, and other features to stimulate movement and exercise, can help individuals to reduce boredom, cope with the forced interaction of humans or other animals, and ultimately to thrive [ 45 ]. More complex enclosures result in more natural behaviors being displayed and more positive experiences, resulting in better animal welfare [ 37 , 38 ]. A proper enclosure complexity should consider the species’ habits (e.g., terrestrial, arboreal, semi-terrestrial) and natural habitat (e.g., humid or arid environment) [ 8 ].…”

“…On the other side, an arboreal rainforest reptile will prefer a moisture-retaining soil-based substrate, vertical space using branches and vines, foliage-covered areas, elevated water sources, higher humidity, and an adequate thermogradient. It is also important to consider the specimen characteristics (e.g., age, sex, size, how much it will grow, and social characteristics) to offer suitable space and adequate conditions [ 37 ]. For example, space that allows snakes to fully stretch to adopt rectilinear behavior/posture is important to their health and welfare [ 40 ].…”

Quantifying animals' perception of environmental predictability using anticipatory behavior

“…Some degree of unpredictability can be applied in captive settings to reduce boredom, and increase activity levels and exploration (Schneider et al, 2014; Shepherdson et al, 1993). Husbandry practices such as environmental enrichment allow animals to choose how to respond behaviorally to stimuli in their environments, and ideally allow them to exert control over the outcomes they achieve through expressing specific behaviors (de Azevedo et al, 2007, 2023; Maple & Perdue, 2013). A balance of predictable and unpredictable rewards has been proposed as an optimal strategy for supporting animal welfare in captive settings (Watters, 2014), however this approach has largely been tested under circumstances when animals have full control over the outcome they receive (i.e., the behaviors they express allow them to achieve a desired result such as attending to or avoiding enrichment items, Watters et al, 2011; Krebs & Watters, 2017).…”