Chemosensory enrichment as a simple and effective way to improve the welfare of captive lizards

Abstract

Environmental enrichment has proven to be a useful and effective welfare tool in order to evaluate and enhance the well‐being of captive animals, but only when it is based on detailed knowledge of each species' natural behaviour. Chemoreception is fundamental to many aspects of reptilian biology; however, sensory enrichment with chemical stimuli has rarely been applied to reptiles. In this study, we evaluate the use of chemosensory enrichment as a method to enhance the welfare of Podarcis liolepis. For seven weeks, we exposed field‐caught males to scents from donor conspecific males collected on pieces of filter paper (i.e., “enriched” group, n = 18), and compared their behaviour to that of control males provided with unscented pieces of filter paper (n = 18). We measured the occurrence of normal (e.g., locomotion) and abnormal (escape attempts) behaviours each day for three weeks. In addition, we conducted two exploration tests and a visual barrier test. Compared to controls, enriched lizards showed a consistent long‐term decrease (29%–38%) in the occurrence of escape attempts. During exploration tests, enriched lizards spent less time performing escape attempts and devoted more time to perching than controls. As expected, both control and enriched lizards showed a reduction of time in locomotion and an increase in the time spent perching between the first and second exploration test, but these changes were significantly more pronounced for enriched animals. Taken together, our results suggest improved welfare of enriched animals, as they spent less time engaging in abnormal behaviours, more time in normal behaviours, and showed signs of faster habituation to a novel environment. Chemosensory enrichment is a relatively simple enrichment strategy that could potentially be applied to improve the welfare of a wide range of captive lizards, and reptiles at large.

The Effect of Enrichment on Leopard Geckos (Eublepharis macularius) Housed in Two Different Maintenance Systems (Rack System vs. Terrarium)

“…In this study, of all the applied enrichment items, the new object (rubber dog toy) aroused the least interest in the lizards. Perhaps applying an additional stimulus, e.g., a scent on the new object, would increase their reaction [ 40 , 51 , 52 ]. It is worth mentioning that the containers in the rack system used in this study were much larger than typical containers used by mass breeders of this species.…”

Overlooked and Under-Studied: A Review of Evidence-Based Enrichment in Varanidae

“…Despite the attention bias, this is a developing field (Figure 1), and the studies that have been published in peer-reviewed journals support the notion that reptiles benefit from enrichment [21,[26][27][28][29][30][31] and that it is in fact essential [32]. Evidence for enrichment as a beneficial practice with reptiles is documented through an increase in natural behaviors and relaxed postures under structural enriched environments [33,34].…”

“…Evidence for enrichment as a beneficial practice with reptiles is documented through an increase in natural behaviors and relaxed postures under structural enriched environments [33,34]. Additionally, the use of chemosensory enrichment (scent of conspecifics, based upon the species natural ecology) significantly (p < 0.001) reduced the occurrence of abnormal behavior (escape attempts) in wild-caught brown wall lizards (Podarcis liolepis) by 38% [27]. Similarly, the use of fishscented enrichment cups resulted in a reduction in escape behaviors of aquarium-housed, freshwater turtles (Trachemys scripta and Pseudemys concinna), although there was an increase in aggression, which demonstrates the need to assess the efficacy of any new techniques before implementation [35].…”

“…While large sample sizes are important for generalizability to the wider population as a means of predicting the most effective enrichment methods [36], there is also value in studies with small sample sizes [37,38], typically true of zoos [18]. While different complexities in enclosure design [39], confounding factors of sex, age [27], and individuality and the measures used to evaluate the enrichment [40] can lead to issues in generalization of the design, enrichment studies, in many cases, require an individual approach [41,42]. Differing past experiences, temperament, genetics, and coping mechanisms may lead to different preferences, while some individuals may, for example, choose tactile stimulation, others may choose food rewards [43].…”

Identification of Animal-Based Welfare Indicators in Captive Reptiles: A Delphi Consultation Survey

“…A number of these studies have examined the behavioral responses to provision of enrichment, as a method assumed to improve animal welfare. The occurrence of abnormal repetitive behaviors, such as escape behaviors [23], increased locomotor exploration, [24][25][26], increased foraging behaviors [24][25][26], behavioral response to novelty [25], along with increased visibility and loose-coiling whilst resting in snakes [27], have all been proposed as useful methods to ascertain welfare. Other behaviors suggested as indicators of stress in reptiles include body inflation and hissing, aggression directed towards conspecifics and humans, and interaction with transparent boundaries [28][29][30].…”