Environmental Enrichment

Scientific Papers


© Rory Harper

Space Use and Enrichment in a North American River Otter (Lontra canadensis) Exhibit (Foerder et al., 2020)

May 10, 2020

Abstract: Exhibit design and environmental enrichment can influence the space use of captive animals. On May 2, 2014, the Tennessee Aquarium opened a new, expanded North American river otter (Lontra canadensis) exhibit, “River Otter Falls.” The exhibit housed 6 otters (5 male and 1 female). A group of three otters was rotated in the exhibit every 2-2 ½ hours. Using a scan sampling procedure with 30 second intervals, the location and number of the otters was marked in one 9 areas of the exhibit. The number of otters not visible was also counted. The study lasted for 4 months, with 43 sessions each lasting ~45 min. The results showed that the otters tended to use all areas of the exhibit rather than confining themselves to one or a few areas. (total SPI = 0.35) and were visible 98% of the time. G-tests showed that the otters were using the areas significantly different from chance with variations in how they are using each individual area of the exhibit. Comparisons of the visibility and location after enrichment showed that the otters tended to use the exhibit less uniformly during enrichment, but increased time spent in areas of the exhibit with greater visibility and proximity to guests. During enrichment sessions, otters were more visible in the areas of the tank that visitors may see most easily, empathizing the role that enrichment can have on space use of an enclosure and visibility of animals in captivity.

Photo credit: Tennessee Aquarium

Olfactory Enrichment in California Sea Lions (Zalophus californianus): An Effective Tool for Captive Welfare? (Samuelson et al., 2017)

December 04, 2019

Abstract: In the wild, California sea lions (Zalophus californianus) are exposed to a wide variety of sensory information, which cannot be replicated in captive environments. Therefore, unique procedures are necessary for maintaining physiological and psychological health in nonhuman animals in captivity. The effects of introducing natural scents to captive enclosures have been investigated in a variety of species, yet they have not been examined in marine mammals. This project explored the behavioral effect of scent added to the environment, with the goal of improving the welfare of sea lions in captivity. Two scent types were introduced: (a) natural scents, found in their native environment, and (b) non-natural scents, not found in their native environment. This study examined not only scent enrichment but also the possible evolutionary underpinnings of pinniped olfaction. Scent enrichment was found to significantly impact sea lion behavior as demonstrated by a reduction in pattern swimming, an increase in habitat utilization, and a reduction in stereotypical behavior. However, there were no differences in behavior between natural and non-natural scent conditions.

Photo credit: Smithsonian's National Zoo

Motion Illusions as Environmental Enrichment for Zoo Animals: A Preliminary Investigation on Lions (Panthera leo) (Regaiolli et al., 2019)

October 21, 2019

Abstract: Investigating perceptual and cognitive abilities of zoo animals might help to improve their husbandry and enrich their daily life with new stimuli. Developing new environmental enrichment programs and devices is hence necessary to promote species-specific behaviors that need to be maintained in controlled environments. As far as we are aware, no study has ever tested the potential benefits of motion illusions as visual enrichment for zoo animals. Starting from a recent study showing that domestic cats are spontaneously attracted by a well-known motion illusion, the Rotating Snake (RS) illusion, we studied whether this illusion could be used as a visual enrichment for big cats. We observed the spontaneous behavior of three lionesses when three different visual stimuli were placed in their environment: the RS illusion and two control stimuli. The study involved two different periods: the baseline and the RS period, in which the visual stimuli were provided to the lionesses. To assess whether the lionesses were specifically attracted by the RS illusion, we collected data on the number of interactions with the stimuli, as well as on the total time spent interacting with them. To investigate the effect of the illusion on the animals’ welfare, individual and social behaviors were studied, and compared between the two periods. The results showed that two lionesses out of three interacted more with the RS stimulus than with the two control stimuli. The fact that the lionesses seemed to be more inclined to interact with the RS stimulus indirectly suggests the intriguing possibility that they were attracted by the illusory motion. Moreover, behavioral changes between the two periods were reported for one of the lionesses, highlighting a reduction in self-directed behaviors and an increase in attentive behaviors, and suggesting positive welfare implications. Thus, behavioral observations made before and during the presentation of the stimuli showed that our visual enrichment actually provided positive effects in lionesses. These results call for the development of future studies on the use of visual illusions in the enrichment programs of zoo animals.

Photo credit: Parco Natura Viva

Chemosensory enrichment as a simple and effective way to improve the welfare of captive lizards (Londoño et al., 2018)

September 14, 2019

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.

Photo credit: Bernard Dupont 

Assessment of contrafreeloading preferences in giraffe (Giraffa camelopardalis) (Sasson-Yenor & Powell, 2019)

September 07, 2019

Abstract: Contrafreeloading is an intriguing phenomenon in which animals will work to obtain resources, such as food, when the same resource is simultaneously freely available. Multiple hypotheses exist for why animals might choose to contrafreeload. In this study, we assessed preferences for contrafreeloading in giraffe at the Bronx Zoo to determine whether they actually preferred to contrafreeload or were simply demonstrating a willingness to contrafreeload. Food was presented in a range of distributions between an easily accessed feeding device and a more challenging one and the giraffes’ feeding behavior at these two types of feeding devices was recorded. As the experiments progressed, more giraffe used these more challenging feeders. There was significant individual variation in the expression of preference for contrafreeloading and willingness to contrafreeload. Individual, phase of the experiment, and an interaction between these factors were significant predictors of challenge feeder use. Three foraging strategies emerged among the giraffe that we termed “freeloaders,” “contrafreeloaders,” and “opportunists.” The results of this study demonstrate that multiple indices of preference are necessary when assessing contrafreeloading behavior, and that giraffe are affected to different degrees by the factors that stimulate contrafreeloading. These results may shed light on why different individuals use complex feeding enrichment devices to varying extents.

Photo credit: Honolulu Zoo

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