<img class="aligncenter size-medium wp-image-825" title="enrichment_options" src="http://aecetia.net/gws/aazk/wp-content/uploads/enrichment_options-300x117.jpg" alt="enrichment_options" width="300" height="117" />

<em>By
Jennifer J. Elston, Ph.D., Curator of Conservation and Behavior
Fort Worth Zoo, Fort Worth, Texas</em>

<strong>Introduction</strong>

Traditional enrichment for reptiles has typically focused on enhancing environmental features of enclosures (e.g., plant variety, ground substrates, etc.), animal health (i.e., misting and soaking animals), and nutrition (i.e., provision of insects, variety in the diet).  These types of enrichments are important practices that can enhance an animal’s environment and well-being.  However, novelty in the form of foods, objects and scents may be equally stimulating and important for reptiles, as has been shown for mammals (Shepherdson, 2010) and birds (Elston and Plasse, 2008).

Studies regarding enrichments for chelonians are limited in the literature, though some published evidence exists regarding the benefits of enrichment for turtles.  Sea turtles increased investigative and grooming behaviors and reduced pattern swimming when enrichment devices were provided (Therrien et al., 2007).  A Nile soft-shelled turtle (Trionyx triunguis) sought out stimulation from objects and displayed “play” behavior previously only described for mammals and birds (Burghardt et al., 1996).

The objectives of this study were to introduce captive-housed tortoises to novel enrichments to determine the extent of their interaction with new and different items and to compare interactions among food, object and scent enrichment.  Additional goals were to compare tortoise behavior under routine management vs. novel enrichment presentation and also to determine the amount of contact between tortoises that were housed in pairs (a form of social enrichment).

<strong>Animals, Housing and Methods</strong>

This study took place from December 2011 through January 2012.  Three Burmese star tortoises (<em>Geochelone platynota</em>; two males, one female) and five Forsten’s tortoises (<em>Indotestudo forstenii</em>; three males, two females) were observed, for a total of eight tortoises.  Four tortoises were kept as male-female pairs, and four were kept separately.  The tortoises were housed in an off-exhibit greenhouse under both natural and artificial light, in either a run with cement and plywood sides (approximately 90 X 38 X 20 in., 1 pair and 1 single; or approximately 35 X 38 X 20 in., 1 pair) or a rubber tub (approximately 49 X 33 X 21 in., 3 single).  Cypress mulch was used as ground substrate and each enclosure contained a water bowl, food pan, heat source, and a shelter for privacy.  Tortoises were fed once daily in the morning a diet of mixed greens and vegetables with commercial biscuits (Mazuri® Tortoise Diet and Marion Leaf Eater® Food), and had access to their food throughout the day.  A HOBO® data logger (Onset Computer Corporation) was used to record temperature inside the greenhouse.

During each daily observation session, the behavior (Table 1) of each tortoise was recorded every minute for 40 minutes (Scan Sampling; Martin and Bateson, 2007).  Data collection took place between 1300 and 1600 hours.  Behavior was observed over six days under routine husbandry without novel enrichment to generate a baseline time budget before new enrichments were presented.  Following the baseline treatment, a randomly chosen enrichment item was presented during the observation session.  Six items that the tortoises did not have previous exposure to were used, representing three categories:  food, object and scent.  The foods were edible flowers (four total, ranging in size from 1 to 2 in.) and a fresh strawberry.  The objects were a ping pong ball and a wicker ball.  Because the tortoises had not been previously exposed to a ball, a ping pong ball and 2 in. wicker ball were chosen because their small size was expected to be less intimidating, and the tortoises were not large enough to accidentally swallow either type of ball.  The scents were a fresh herb (basil; one sprig, approximately 6 in. long and containing stem and leaves) or a spice (nutmeg; 3 shakes on a piece of cypress mulch).  One type of enrichment was presented per day and each enrichment item was presented twice, for a total of 12 days.  The enrichments were placed in the enclosures in locations where the tortoises could see them, typically within the center of the enclosure.  Each tortoise was offered the same amount of enrichment, whether housed singularly or in pairs.  After the enrichment treatment, behavioral data were collected for an additional six days in order to determine any changes in baseline behavior.

<strong>Results</strong>

During the enrichment treatment, tortoises spent an average of 13% of time interacting with the novel enrichments (Fig. 1).  Tortoises expressed natural behaviors toward the enrichments, including investigation and/or touching, and consumption of the edibles (Fig. 2).  Tortoises spent less time stationary during the enrichment treatment than before or after, and spent less time moving in general after the enrichment treatment (Fig. 1).  They also spent less time in their shelters when enrichments were present (38% of time during the enrichment treatment vs. 48% before and 58% after).  Tortoises spent the most time interacting with food enrichment (19% of time vs. 10% of time for objects and scents), primarily because of the strawberry.  The strawberry received the most interaction; the nutmeg received the least (Fig. 3).  <img class="alignright size-full wp-image-2515" title="figure-2-elston-fort-worth-zoo" src="http://aecetia.net/gws/aazk/wp-content/uploads/figure-2-elston-fort-worth-zoo.jpg" alt="figure-2-elston-fort-worth-zoo" width="677" height="561" />

The tortoises housed in male-female pairs spent an average of 49% of time in contact with one another over the course of the three treatments (56%, 31%, and 59% of time, respectively).  Temperature in the greenhouse was consistent throughout the treatments; average temperature was 72º F, reaching an average of 89º F during the day and 62º F at night.

<strong>Discussion</strong>

The tortoises spent the most time interacting with food enrichment, which was not surprising because food enrichments are often favored by animals in general (Young, 2003).  In a comparison of enrichments for an African serval (Leptailurus serval), the serval interacted more with edible enrichments than inedible enrichments, though both types did receive attention (Kunkel, 2011).  The tortoises spent a shorter amount of time interacting with the flowers primarily because of their small size, which made them easy to grasp and swallow.  Because some favored foods can be consumed fairly quickly by tortoises, if a goal for the enrichment is to increase time spent foraging (a natural behavior for tortoises), combining foods with objects that require manipulation to consume the food will lengthen interaction time.

The ping pong ball generated more interest than the wicker ball, possibly because its white color and smooth, round shape made it resemble a food item.  The tortoises that did interact with the ping pong ball spent most of their time biting at it.  Size of ball would need to be taken into consideration for larger tortoises to prevent any possible consumption.

Very little interaction occurred with the nutmeg; however, a great deal of time was spent with the fresh herb (basil).  In fact, the herb received the second highest amount of interaction after the strawberry.  Even though the herb was categorized as scent enrichment during this study, it became a combination of scent and food enrichment because it was consumed.  The palatability of the herb and its composition (leaves and stem, which required much biting and tearing to consume it) likely contributed to the lengthy interaction.  These attributes make fresh herbs an effective form of enrichment if goals are to increase foraging time and offer a novel gustatory and olfactory experience.

Once the enrichment treatment was underway the tortoises appeared to anticipate and expect to receive the enrichments.  For example, several tortoises began watching, moving toward and following the observer.  These behaviors began during the enrichment treatment and continued during the first part….

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