Assessing preferences of two zoo‐housed Aldabran giant tortoises (Aldabrachelys gigantea) for three stimuli using a novel preference test

Abstract

Recent research has uncovered many complex cognitive traits and affective processes in many reptile species, such as the ability to make choices that are rewarding or pleasurable. The investigation herein was initiated after many years of anecdotal reports, and preliminary observations, that the two male Aldabran giant tortoises (Aldabrachelys gigantea), Wilbur and Little John, at Melbourne Zoo (Melbourne, Australia) would approach the fence‐line of their enclosure, sometimes multiple times daily, to “solicit” interactions from zoo visitors and/or zoo staff. Following other research with Galapagos giant tortoises (Geochelone nigra), this experiment was a novel preference test with two male Aldabran giant tortoises to assess their individual preferences for three stimuli: (1) human interaction (shell and neck rubs provided using hands); (2) food (highly palatable carrot pieces); and (3) an “enrichment” ball (a red “boomer ball”). The results found that Wilbur highly preferred human interaction and food over the ball; whereas Little John preferred food, and showed some initial interest in the ball, but did not approach the human on any of his 13 human interaction trials. These results reflect previous published findings, that human interaction is a preferred “enrichment,” but is dependent upon a multitude of other contextual factors, and is not preferred at all times by all individuals. Individual variation may be very important to understand to have greater positive effect on the welfare‐related needs of each giant tortoise housed in captivity. Further research is clearly required to enhance the welfare and well‐being of many types of zoo‐housed reptiles.

Using a novel ethogram of tuatara behaviour to evaluate the impact of interactions with zoo visitors

“…Additionally, differences in home habitat conditions (as described in section Home habitats and husbandry) and stage of life (as described in section Animal information) meant it was not appropriate to pool the data of the three individuals. This approach aligns with some of the studies that are cited in the Introduction (Mehrkam and Dorey 2014;Mehrkam and Dorey 2015;Baird 2018;Learmonth et al 2021) as they used single subject design analysis to evaluate data that couldn't reasonably be pooled across individual animals. As such, we used standard visual analysis techniques to evaluate the effect of visitor contact on animals (Cooper 2013).…”

“…Reptile species are commonly used for visitor-animal interactions (e.g. National Reptile Zoo 2017) and there is a growing body of literature to understand how these animals interact with their handlers; two studies of tortoises found that animals showed a preference for interaction with their handlers when given the choice of varying types of enrichment and also highlighted important individual differences (Mehrkam and Dorey 2014;Learmonth et al 2021). While these studies provide some insight into the impact of interactions with humans for this reptile species there have been no studies to date to understand how visitor interactions impact on zoo-housed tuatara (Sphenodon punctatus).…”

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

“…This renders the goal of creating a welfare assessment tool, with a broad range of positive and negative descriptors, currently challenging. There clearly needs to be more focused research on this topic utilizing methods such as judgement bias [46,49], or preference testing [50], to corroborate determinations on positive emotions associated with behaviors identified. Alternately, the employment of habitat modifications expected to be positive, with evaluation of a suite of indicators before and after the change might be an alternate validation strategy; see, e.g., [24].…”

Animal Training, Environmental Enrichment, and Animal Welfare: A History of Behavior Analysis in Zoos (Preprint)

“…Applied behavior analysts have a long history with increasing behavioral repertoires to the benefit of the participants involved, and zoo animals should be no exception to this approach. While zoos already use environmental enrichment for this purpose, behavior analysts could increase the effectiveness of these enrichment practices by drawing inspiration from human studies on factors such as schedules of reinforcement, habituation, preference, variation, and choice (e.g., Hanratty & Hanley, 2021;Mehrkam & Dorey, 2014;Learmonth et al, 2021;Ringdahl et al, 1997;Tarou & Bashaw, 2007;Woods et al, 2020). Additionally, training practices could be combined with environmental enrichment (e.g., to shape more complex behaviors that allow for increased engagement with enrichment devices.…”