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Aug 2, 201812 min read

Is there a Difference in the Rate of Stereotypical Behavior...

Inquiry Project: Is there a difference in the rate of stereotypical behavior in tigers housed in a small or large enclosure?


This project required me to design and implement a term-long inquiry project. I needed to submit a research report that provided the contextual background, methods, results, and interpretation of my work.


This was created in my Foundations of Inquiry course in the Summer of 2018.


 

Abstract

This study focused on if there is a difference in the rate of tigers engaging in stereotypical behavior who are in a small or large enclosure. Three tigers in two enclosures were observed during nine hours on two separate days. The tigers were observed on a rotational basis in ten minute intervals, with a total of 18 observation periods for both enclosures. The criteria that the study focused on was if the tiger was engaged in active behavior, resting with eyes open, resting with eyes closed, vocalization, or engaged in stereotypical behavior. Most zoo guests always complain that the animals, specifically the tigers, do not have the adequate amount of space the guests believes the animal needs. Which makes this type of study crucial in order to know exactly how much space the tigers need in order to live a healthy and fulfilling life. That information can then be explained to the visitors so they know that the animal actually does have enough space. It is important to know how long tigers engage in stereotypical behavior and what size enclosure they are in to learn what else can be done to promote healthy behavior instead of behavior associated with stress.


Keywords

Stereotypical behavior


Introduction

Tigers live in large areas in the wild (SDZG, 2018) and that living space significantly decreases when they live in captivity. One study found that natural tiger home ranges can be as small as 14.2 km2, and as large as 294 km (McGinnis, 2015). Zoo guests hope the tigers and other animals are taken care of in the best possible way, especially by organizations that are a member of the Association of Zoos and Aquariums. The Association of Zoos and Aquariums (AZA) have animal welfare standards they must follow. According to the AZA, “animal welfare refers to an animal's collective physical, mental, and emotional states over a period of time, and is measured on a continuum from good to poor” (AZA, 2018). Although there are people who are against zoos and keeping animals in captivity, it's important to remember that "animals are in captivity for education, conservation, research, and recreation” (Pitsko, 2003). In recent years tigers’ home ranges in the wild continue to decrease in size.


According to the San Diego Zoo (2018), only about 1,400 Malayan tigers remain in the wild. Pitsko stated that animals need to carry out natural behaviors, such as swimming, climbing, stalking, and predation (Pitsko, 2003). These natural behaviors are believed to reduce stereotypical behavior. Enrichment is an important part of a captivate animal's life, and the San Diego Zoo gives their animals enrichment every day for every animal (SDZG, 2018). Enrichment for the tigers, at the San Diego zoo, are their swimming pool body of water, treats inside gourds, cow bones, logs, hills, plants and scents. Environmental enrichment has been shown to reduce stereotypic behavior (Mohapatra, 2014). It has been stated that in captive big cats remain inactive or engaged in frequent stereotypical behavior because they are in a different environment than they have evolved for (Mohapatra, 2014). It is important to note that animals behaving in a way different from their wild con-specific are not necessarily suffering or stressed (Veasey, 1996).


For this study the following behaviors are used and described. “Active” is defined as walking (not pacing), running, playing, engaging in enrichment, eating, or drinking. “Resting with eyes open” is defined as sitting, standing or laying down with eyes open, and “resting with eyes closed” is defined as sitting or laying down with eyes closed. “Vocalization” is defined as making sounds with the throat or mouth. “Stereotypical behavior” is defined as pacing (walking back and forth twice, similar to a figure-eight), excessive grooming (defined as engaging in the behavior for greater than 5 minutes), chewing of the paws or tail, and head bobbing.


The San Diego Zoo currently has three male Malayan tigers, who are all be brothers. The oldest tiger is Conner who is a seven year old male. His two younger brothers, Berani and Cinta, are both four year old males. According to a San Diego Zoo volunteer (2018), they were also all born in captivity, Conner at the San Diego Zoo and Cinta and Berani at the Fresno Zoo.

This study can add to similar studies about enclosure size for tigers. For example, Sajjad’s study on the “Effects of captive environment on plasma cortisol level and behavioral pattern of Bengal tigers” mentions that, “environmental enrichment is strongly recommended for the maintenance of the physical and psychological behavior of captive animals” (Sajjad, 2011) . Enrichment is believed to reduce stereotypical behavior. A reduction in stereotypical behaviors may promote successful breeding of tigers and benefit the species survival plan to ensure that this species does not go extinct (Pitsko, 2003).


This study itself is important because it can help aid zoo staff and construction staff to know how big to make an enclosure for a particular animal. Zoo staff always cares about the well-being of animals; therefore, they would benefit from the knowledge of where the animal shows less stereotypical behavior, so it can be as healthy and as happy as can be.

This study will explore if there is a difference in the rate of stereotypical behavior in tigers who are in a small or large enclosure. This study will be focusing on the physical behavior and could in turn provide useful information and data to continue along this path of tigers physical behavior. This study can also aid in knowing how much room a tiger truly needs so room can be saved for them in the wild and made for them in managed care. The null hypothesis is that there is no difference in the rate of stereotypical behavior in tigers who are in a small or large enclosure. The alternate hypothesis is that tigers in a smaller enclosure will exhibit increased rates of stereotypical behavior.


Methods

This study focused on the three Malayan tigers (Panthera tigris jacksoni) in the two tiger exhibits along Tiger Trail, in the Lost Forest, at the San Diego Zoo. Each exhibit has a water feature, a log, and a cave (Tiger, SDZG, 2018). One study showed that tigers that have access to a clean water pool substantially enhances the tigers overall welfare (Biolatti, 2015). The large enclosure has a hill with a top and bottom part of the hill, while the small enclosure has a shelf and flat ground. The large enclosure also has several natural plants, while the small enclosure doesn't have any plants. The small exhibit has more trees around it than the large, so it has the potential of being more shady.


This study observed the behaviors of the tigers in each exhibit on a rotational basis in 10- minute intervals during a three hour period, for a total of 9 hours. Data was collected by observing each behavior the tiger exhibited and marking it down with the respective time that the behavior took place. One three-hour observation period took place on Thursday, July 19th from 9am-12:00pm. The second three-hour observation took place from 3pm- 6pm on Thursday, July 19th. The third three-hour observation took place from 12pm-3:00pm on Friday, July 20th. On Thursday, July 19th there were two tigers on exhibit: Berani was in the large enclosure and Conner was in the small enclosure. On Friday, July 20th there were three tigers on exhibit: Conner was in the large enclosure, and Berani and Cinta were in the small enclosure. There are two observation periods per exhibit per hour, giving a total of six scans per exhibit per three-hour observation period. This lead to a total of 18 observation periods for both enclosures. During each 10-minute observation interval, the study conducted ten 1-minute scans. Below are the criteria used to mark the respective behavioral categories for each tiger, one in the large enclosure and one in the small enclosure. After the collection of data the tigers in each enclosure were compared to see which one showed more stereotypical behavior.


The tiger’s behavior was recorded, including when the tiger is active, resting with eyes open, resting with eyes closed, vocalization, or engaging in stereotypical behavior


Results

The dependent variable is the number of times stereotypical behavior was displayed within the ten minute scans. Since this occured for ten minutes it is continuous, numerical (ratio) data. The independent variable is the enclosure size, large or small, which is a nominal variable. The SPSS test that was used to display the data was a non-parametric test, and the Mann-Whitney U test was used. This test was used because the data will be analyzed the difference between means of different yet similar data sets. Side-by-side bar graphs were used to show the data.


Through the Mann-Whitney test the mean for enclosure A was 11 and the mean for enclosure B was 8. The one tail test is significant because it is smaller and shows that stereotypical behavior is significant to enclosure A but not enclosure B.

The graph above shows the breakdown of each behavior for each enclosure. For this particular study it is clear from the graph that there is a difference in stereotypical behavior in tigers housed in a large or small enclosure. Based on the data, the null hypothesis for this study was incorrect and the alternate hypothesis was correct. There is a difference in stereotypic behavior in tigers with different enclosure size. As seen in the graph, enclosure A, the large enclosure, showed stereotypical behavior, while enclosure B, the small enclosure, did not show any stereotypic behavior. This study was conducted in nine hours with three tigers, so more time, data, and research is needed to come to a full understanding and conclusion of this. But for this study, it shows that the tigers in the large enclosure partake in stereotypical behavior.


Below is a table chart to show the tigers and the number of times the behavior was observed during the entire time the tiger was in an exhibit. This chart shows each tiger and the number of times they were observed doing each respective behavior. This data includes the times for the individual tigers. Berani and Conner were both on exhibit longer than Cinta was, which explains why Cinta’s numbers are much lower than Berani’s and Conner’s. Berani was the only tiger to show signs of stereotypical behavior, and it all occurred while he was in enclosure A, the large enclosure. Berani and Conner were active mainly due to the morning bone they received on Thursday morning, and all three tigers spend most of their time napping, which is not surprising for a member of the cat family, since they are mostly nocturnal.


Discussion

The results show that there is a difference in the rate of stereotypical behavior in tigers who are in a small or large enclosure. The researcher conducting this study overheard several zoo visitors discuss how animals need the most room possible and they are quick to mention how small the enclosures are. In this study the researcher observed that the tigers’ behavior did not appear to be affected by the size of the enclosure.This study observed three tigers, all of which seemed to be well taken care of. There was enrichment, food, and water for them to interact with, which is what they would have access to out in the wild, to some extent.


Pitkso (2003) stated that tigers in a more natural and complex enclosure performed less stereotypical behavior and performed more exploratory and natural behavior. This study shows the exact opposite of that statement. Whichever tiger was in enclosure A engaged with the plants, but there was also stereotypical behavior only observed in that same enclosure. Enclosure B didn't have any plants for the tigers to engage with and yet there were no stereotypical behaviors observed in that enclosure.


It's hard to say the reasoning behind this, but this is one major difference that occurred since the majority of the literature states that a more natural environment reduces the occurrence of stereotypical behavior. It has been said that stereotypical behavior is associated with poor welfare (Mohapatra, 2014). However, the tigers at the zoo get enrichment every day, get health checks, get moved between the enclosures depending on what day it is, and are overall cared for and cared about. Mohapatra also stated that environmental enrichment has been shown to reduce stereotypical behavior. This study shows the opposite, which shows how beneficial enrichment is and how the zoo does everything they can to reduce stereotypical behavior. One study that can be further researched is if age has anything to do with the the difference in presenting stereotypical behavior. Berani was the only tiger who showed signs of stereotypical behavior, which occurred for roughly 15 observational looks. Conner is three years older than Berani; however, Cinta and Berani are the same age, and Cinta wasn't observed engaging in stereotypical behavior at all. Berani was alone in the enclosure when he was observed engaging in stereotypical behavior, so possibly he missed being with his brother Cinta, but that is another study in itself.


There two tigers observed on Thursday, July 19th were Berani and Conner. Berani was in the large enclosure, which was determined to be enclosure A, and Conner was in the small enclosure, which was determined to be enclosure B. Both tigers had access to their entire respective enclosure, they were also both given large cow bones to chew on. A good chunk of their morning they spent engaged in being active, largely due to the bone they were both eating. Conner did walk around his enclosure and test out other sources of enrichment, smelling scents sprayed on logs and cat scratching his nails. Berani decided to take his bone and start eating it while sitting in the pool of water. After they were done with their bones, they both decided to rest. During the entire three hour morning observation period, there were only five minutes that observed pacing, from Berani in the large enclosure. Berani was also vocal during the morning. Unfortunately, he was vocal when the observation on him was not taking place.

The mid-day observation on Friday the 20th had a unique challenge in that there were two tigers in one exhibit and one in the other. Conner was alone in enclosure A, and Berani and Cinta were in enclosure B. On this day there were no observations of any stereotypic behavior or vocalization. For the most part the tigers remained at rest. There was a couple minutes where Conner was engaged with his keeper where treats were given through the fence. There was a previous study done that focused on whether differences in social conditions cause significant differences in the behaviors performed in captive tigers. This study proved that there are significant differences between tigers that are paired together and tigers that are alone (Rouck, M.D., 2005). This plays an important role in this study about stereotypical behavior and enclosure size, because one tiger is normally paired together and was alone during the observation of all of his stereotypical behavior.


Recently the keepers began a process to work on separating the two younger tigers, so some days they are together and other days they are alone. This is considered normal behavior since tigers are solitary animals, except during mating and a mother and her cubs (Tiger, SDZG, 2018). For two observation periods there are only two tigers being observed, one in each exhibit. For the third observation period there are three tigers being observed, which alters the data a little.


During the afternoon observation on Thursday July 19th Berani and Conner were in the same enclosure they were in that morning, enclosure A held Berani and enclosure B held Conner. Both Conner and Berani spent most of the afternoon resting. Berani did spend about 10 minutes, out of the three hour observational period, engaging in stereotypical behavior, while in the large enclosure. Berani always used to be put in an enclosure with his brother Cinta, but since they are both entering adulthood the keepers decided to separate the two tigers. It is unknown when this separation first started, or if one day they are out together and the next they are kept separate. This could play a role in why Berani was behaving the way he was, and why he was so vocal, while Conner didn't make a sound during the six hours of observation on this day.


There were a two unforeseen events that occurred that could have affected the outcome of this study. One event was the temperature difference on Thursday and Friday. Thursday was sunny, warm, and humid. Friday was cloudy, not warm or cold, and there was no humidity. Another event was with Berani being alone on Thursday and then being with Cinta on Friday, which leads to the question of does he act differently when he is with Cinta versus alone? That is an entirely other study though.


There were a couple limitations this study had. One main limitation was lack of time. Nine hours isn't enough time to fully understand if enclosure size affects tigers rate of stereotypical behavior. This study is a good start to answering that question; however, more data is needed to have a firm answer. Another limitation was that Berani and Cinta are beginning to spend time alone as well as apart in the outside enclosures, and Berani being alone one day and with Cinta the next could play a role in his behavior.

Literature Cited


Animal Welfare Committee. (n.d.). Retrieved from


Biolatti, C., Modesto, P., Dezzutto, D., Pera, F., Tarantola, M., Gennero, M. S., . . . Acutis, P. L.

(2015, July 17). Behavioural analysis of captive tigers (Panthera tigris): A water pool

makes the difference. Retrieved from

file:///C:/Users/reedt/Downloads/Behavioural_analysis_of_captive_tigers_P%20(1).pdf


McGinnis, L. (2015). Tigers and territory: The issues we see with home range size and

conservation in these big cats. Retrieved from https://wp.natsci.colostate.edu/finding

porpoise/tigers-and-territory-the-issues-we-see-with-home-range-size-and-conservation-in-these-big-cats/


Mohapatra, R. K., Panda, S., & Acharya, U. R. (2014). Study on activity pattern and incidence of

stereotypic behavior in captive tigers. Journal of Veterinary Behavior: Clinical Applications and Research,9(4), 172-176. doi:10.1016/j.jveb.2014.04.003


Pitsko, L. E. (2003, April 25). Wild tigers in captivity: a study of the effects of the captive

environment on tiger behavior. Retrieved from https://vtechworks.lib.vt.edu/bitstream/


Rouck, M. D., Kitchener, A., Law, G., & Nelissen, M. (2005). A comparative study of the

influence of social housing conditions on the behaviour of captive tigers (Panthera tigris).

Animal Welfare,14(962), 7286th ser., 229-238. Retrieved from

f.


Sajjad, S., Farooq, U., Anwar, M., Khurshid, A., & Bukhari, S. A. (2011). Effect of captive



Veasey, J. S., Waran, N. K., & Young, R. J. (1996). On comparing the behaviour of zoo housed

animals with wild conspecifics as a welfare indicator. Animal Welfare,5, 13-24.


Retrieved from file:///C:/Users/reedt/Downloads/Wildcomparedtocaptiveanimals-anim

alwelfare.pdf.


Appendix

Appendix A: Enclosure A: Large enclosure



Appendix B: Enclosure B: Small enclosure


Appendix C: Berani


Appendix D: Cinta



Appendix E: Conner



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