RESEARCH ARTICLE

Behavioral Analysis of Tiger Night Housing PracticesAngela Miller, Katherine A. Leighty,* and Tamara L. Bettinger

Animals, Science, and Environment, Disney's Animal Kingdom®, Lake Buena Vista, Florida

The systematic evaluation of changes in animal management practices is critical to ensuring the best possible welfare. Here, weexamined the behavioral impacts of intermittently housing our six adult female tigers, who have been housed socially for muchof their lives, individually overnight to allow for specialized care required by their advancing age. We looked for behavioralchanges indicative of both positive and negative changes in welfare by monitoring time spent asleep, sleeping position, bodyposition while awake, as well as pacing, door pounding, self‐grooming, roaring, and chuffing while housed socially ascompared to individually overnight. Housing condition did not affect time spent asleep, sleeping positions assumed or themorepreferred body positions while awake. Further, pacing, door‐pounding, and roaring were infrequent and not altered by housingcondition. Self‐grooming did increase when housed individually but no evidence of over‐grooming was present and chuffing, aclose proximity social vocalization, was more likely to occur when socially housed. Taken together, these findings support thenotion that transitioning to individual housing as needed is a viable option for managing cats accustomed to beingmaintained ina social group. Zoo Biol. 32:189–194, 2013. © 2013 Wiley Periodicals Inc.

Keywords: management; solitary; social; welfare; Panthera tigris

INTRODUCTION

Wild tigers have historically been described as solitaryanimals, with the exception of a female with her dependentcubs, and infrequent observations of adult females in closeproximity were likely to result in aggression [Kleiman, 1974;Sunquist, 1981]. More recent accounts describe the formationof temporary social assemblages at large kill sites suggestingthat tigers may not be as solitary as often described [Sunquistand Sunquist, 1988; Thapar, 2004]. In zoological settings,tigers are typically housed alone or in small groups unless thereis clear evidence of mutual tolerance [Tilson et al., 2010], yetlittle research has been conducted to determine the impact ofsocial housing circumstances on their behavior. Interestingly,the few studies that have been conducted do indicate thepotential for tigers to be housed in social groupings successfully[see Miller and Kuhar, 2008; Miller et al., 2011]. Further, it isthought that many animals in zoos can be housed in a greaterdiversity of social groupings than in the wild due to the absenceor reduction of particular environmental constraints [Price andStoinski, 2007]. In fact, along with tigers, other felids speciesconsidered to be solitary in the wild are housed effectively associal groupings in zoos, including cheetahs and snow leopards[Wharton andMainka, 1997;Wielebnowski et al., 2002; Macriand Patterson‐Kane, 2011].

While successful social housing of solitary felids ispossible, the literature addressing the influences of social

versus solitary housing on their welfare is mixed andtherefore many felids are still housed alone or in small groupsdue to the perceived potential for social stress [Price andStoinski, 2007]. For example, De Rouck et al. [2005] foundthat tigers housed in pairs spent more time engaged in a widervariety of behaviors than singly housed animals, and alsopaced less than singly housed tigers as well as paired tigershoused adjacent to other tigers. On the other hand, a study ofsnow leopards demonstrated no difference in overall activityand amount of pacing between solitary and socially housedcats [Macri and Patterson‐Kane, 2011].

With six tigers at Disney’s Animal Kingdom®, we havethe opportunity to study slightly larger than average socialgroupings and to determine the impact of different housingscenarios on their behavior. In previous studies, wedocumented the long‐term social dynamics of these cats aswell as the impact of reduced exhibit access during a period ofconstruction [Miller and Kuhar, 2008; Miller et al., 2011].

*Correspondence to: Katherine A. Leighty, Animal Programs Administra-tion, P.O. Box 10000, Lake Buena Vista, FL 32830. E‐mail: katherine.leighty@disney.com

Received 26 June 2012; Revised 16November 2012; Accepted 29November2012

DOI 10.1002/zoo.21057Published online 15 January 2013 inWiley Online Library (wileyonlinelibrary.com).

© 2013 Wiley Periodicals, Inc.

Zoo Biology 32: 189–194 (2013)

Historically, we housed the tigers in social groups on mostnights and on occasion housed them individually overnight togive them the opportunity to have bones and other highlyprized enrichment items. As our tigers have advanced in agein recent years, we found the need to separate individualsovernight more often to allow longer periods of time for sloweaters to consume the evening meal as well as to providepersonalized medications, training, and enrichment. Thus,our tigers now spend their overnight hours housed socially onmost nights but individually on approximately two nights perweek. Further, as the cats continue to age, it will likelybecome necessary to separate out individual cats when theyare ill and need specialized attention and monitoring.

Given these changes, questions arose as to whether thesolitary housing of these cats overnight, which have lived invaried social groups for much of their lives, would result inchanges to their welfare status. Therefore, in the presentstudy, we sought to investigate more closely the impacts ofsocial versus solitary overnight housing on behavior andwelfare. Following from methods utilized in welfare assess-ments of domestic cats in animal shelters [McCune, 1994;McCobb et al., 2005], and work with both lab rats [Abou‐Ismail et al., 2007] and dairy cows [Krohn and Munksgaard,1993; Haley et al., 2000], we documented their time spentasleep, sleeping position, and body position while awake,when housed in these conditions. Additionally, we monitoredrates of pacing and door pounding behavior as well as self‐grooming and production of the social vocalizations roar andchuff, changes in which might be reflective of frustrationlinked to inability to control access to social partners [Bashawet al., 2007]. Determining the impacts of such changes tohousing conditions will not only allow us to make informedmanagement decisions and contribute to the collectiveknowledge of felid housing practices but also may be appliedto the variety of other solitary species maintained in socialgroupings within zoos.

METHODS

Subjects

Disney’s Animal Kingdom’s® six adult female tigers(Panthera tigris hybrids) served as subjects for this study(individuals¼S, R, C, P, D, A). These tigers were born intothree litters at a private facility in Texas during the spring of1997. All subjects were hand‐reared beginning at 6 weeks ofage at which time they were housed as a single group. Thisgroup arrived at Disney’s Animal Kingdom® in the fall of1998 and their social relationships have been systematicallydocumented since 1999 [see Miller and Kuhar, 2008; Milleret al., 2011].

Housing and Maintenance

All six tigers spend the daylight hours in naturalisticoutdoor exhibits in varying groups of two, three, or fourindividuals. At the end of the day, the tigers are cued into a

holding area for the overnight hours. The night holdingfacility consists of six separate but inter‐connected stalls and atransfer chute (see Fig. 1). Upon return to the holding area, thetigers are separated into individual stalls for visual examina-tion, training and feeding. During the period of this study, onfive nights per week, when the tigers had finished eating, theywere put into two groups of either two, three, or fourindividuals. Each group spent the night with access to aportion of the stalls equal to the number of tigers in the group.On the remaining two nights per week, the tigers remainedindividually housed in separate stalls. All tigers were invisual, auditory, and olfactory contact at all times duringseparations.

Behavioral Data Collection and Analyses

A small group of night team keepers conducted theovernight behavioral observations for this study. Theseobservations took place for two alternating quarters ofthe calendar year (i.e., 3 months on followed by 3 months off)for 2 years (July 2009 through March 2011). During datacollection periods, the keepers conducted observations onfour nights per week: two in which the tigers wereindividually housed and two during which they weregroup‐housed. To control for behavioral differences attribut-able to different social groupings, we restricted nights onwhich they collected group‐housed data to the most frequentsocial grouping of SRC and PDA. Each observation nightincluded two 20min data collection sessions conductedbetween 20:00–21:00 and 24:00–01:00. We selected theseobservation times because they coincide with the regularlyscheduled checks of the area by the overnight animal carestaff and therefore would not result in alteration to theovernight routine for the animals.

Data collection methods consisted of group scansampling with a mixture of instantaneous and one‐zerotime sampling methods at 2min intervals across the 20minobservation periods. Physiological state (asleep, awake) wasdocumented via instantaneous time sampling to determinehow housing condition influenced sleeping patterns. Further,to provide a measure of the cat’s comfort/security in thehousing situation as well as overall activity level, theyrecorded the cat’s body position (back, locomotion, side,

Fig. 1. Schematic of tiger overnight holding facility at Disney’sAnimal Kingdom®.

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sitting, standing, sternal) in conjunction with the physio-logical state. One‐zero time sampling was used todocument other potential welfare indicators; pacing, doorpounding, self‐grooming, and vocalizations (roar, chuff;see Table 1 for ethogram). All data collectors obtaineda reliability criterion of 85% agreement prior to initiationof data collection. We utilized non‐parametric Wilcoxonsigned ranks tests to compare physiological states,body positions, behaviors, and vocalizations of catsacross the two housing conditions. Analyses were conductedusing SPSS 18.0 with two‐tailed alpha set to 0.05 for alltests.

RESULTS

Of the 369 total observations, the cats experiencedgroup‐housing in 179 and individual‐housing in 190 of thesesessions. The proportion of scans observed sleeping did notdiffer between the two housing conditions, with catsaveraging 73.40% of scans asleep while group‐housed and74.09% while individually housed (Z¼ 0.314, P> 0.05; seeFig. 2). Preference for particular sleeping positions (back,side, sitting, sternal) also did not differ between the twohousing conditions (Z¼ 0.105; 0.314; 1.363; �1.363,respectively, P> 0.05 in all cases; see Fig. 3). Sleeping ontheir side was the most preferred position with cats averaging83.37% sleeping scans in this position while in groups and85.35%while housed individually. Sleeping sternally was thenext most likely position with cats averaging 9.20% sleepingscans in this position while in groups and 6.29%while housedindividually. Cats slept on their backs an average of 7.27% ofsleeping scans while in a group and 7.98% while individuallyhoused. Sleeping while sitting up was the least likely sleepingposition observed with cats averaging 0.15% sleeping scansin this position while group‐housed and 0.40% whileindividually housed.

While awake, cats also preferred to be positionedsternally or on their side as they did while sleeping. Theirpreference for these body positions while awake also did notdiffer across the two housing conditions (Z¼ 0.524;�0.524,respectively, P> 0.05 in both cases) with cats lying awakesternally 47.10% and on their side 40.72% of awake scanswhile group‐housed and 50.05% sternally and 38.92% ontheir side while individually housed (see Fig. 4). Less likelyawake positions in cats while both group‐housed andindividually housed were locomotion (5.18% group‐housed,3.38% individually housed), lying on their back (3.71%group‐housed, 3.09% individually housed), and standing(2.50% group‐housed, 2.90% individually housed) with nosignificant differences in appearance of these behaviorsbetween housing conditions (Z¼�1.363; �0.734; 1.153,respectively, P> 0.05 in all cases). The least preferredposition while awake was sitting and cats sat significantlymore while awake (1.68% of awake scans) while individuallyhoused than they did while group‐housed (0.79% of awakescans; Z¼ 2.201, P¼ 0.028; see Fig. 4).

TABLE 1. Ethogram

Physiological statesAsleep Eyes closedAwake Eyes open

Body positionsBack Lying on back with both shoulder blades and/or both hips on the groundLocomotion Moving from one location to anotherSide Lying on side with one hip and one shoulder blade from the same side on the groundSitting Cat sits with all four paws and buttocks on the ground and abdomen off the groundStanding Body upright with all four feet on the ground and abdomen off the groundSternal Head upright with abdomen on the ground

Potential welfare indicatorsPacing Bouts begin at the beginning of the second turn as the animals’ transverse the path and end when

the animal paused in the same location for greater than 10 sec or broke away from the pathwaybeing transversed

Door pounding Bouts begin with the second foot touching the door and end when the animal paused 10 secGrooming self Licking and/or biting any part of own bodyChuffing A gentle puffing sound made by rapidly expelling air through their nostrils.Roaring A two‐toned sound like a‐a‐u‐u‐u or a‐o‐o‐o‐nh, produced by forcing air through the open mouth

while closing the jaws.

Fig. 2. Average proportion of scans tigers were observed asleepwhen housed in a social group as compared to when housed theywere individually.

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Overall, cats showed a low rate of pacing behavior inboth housing conditions with cats pacing during an average of2.1% of awake scans (0.47% of all scans) while group‐housedand 2.75% of awake scans while housed individually (0.61%of all scans). Door pounding was extremely uncommon,occurring in only 0.14% of awake scans when group‐housedand 0.07% when individually housed. Housing condition didnot significantly alter pacing or door pounding behavior(Z¼ 0.524; �1.342, respectively, P> 0.05 in both cases).Cats did groom themselves significantly more when housedindividually (16.15% of awake scans) as compared to whilegroup‐housed (13.64% of awake scans; Z¼ 1.992,P¼ 0.046; see Fig. 5). The cats also chuffed more oftenwhile group‐housed (1.80% of awake scans) than they didwhen housed individually (0.28% of awake scans; Z¼�2.023, P¼ 0.043; see Fig. 5). Roaring behavior did notdiffer across conditions with cats roaring in 0.84% of awakescans while group‐housed and 0.43% while individually‐housed (Z¼�1.826, P> 0.05).

DISCUSSION

The ability tomake changes to management practices isan essential component of maintaining animals in azoological setting over time. Yet, as such managementchanges take place, it is critical to evaluate animal welfare inorder to ensure that we are providing the best possible care.

We previously conducted such evaluations of changes to ourtiger management practices documenting the behavioralimpacts of a long‐term exhibit closure as well as the additionof visual barriers between neighboring social groups [Milleret al., 2008, 2011]. In the situation described here, theadvancing age of our tigers, which have been socially housedover the course of their lifetimes, necessitated that they behoused individually overnight a few nights per week to allowfor medical treatments, training, and specialized feeding andenrichment. We therefore evaluated how this change tohousing practices influenced their sleeping behavior, sleepingpostures, and activities while awake.

Contrary to our initial concerns regarding the potentialimpacts of this management change, we found that the tigersdid not significantly alter their sleeping behavior whenhoused individually as compared to their more typicalovernight housing in social groups. Sleeping behavior is acomponent of welfare assessments of domestic cats[McCune, 1994; McCobb et al., 2005] and from that scoringsystem we thought that stress resulting from individualhousing could have resulted in decreased time spent asleepbut this was not the case. In fact, the data revealed that thetigers in either housing condition were asleep in nearly ¾ ofscans taken at two different periods during the overnighthours. This finding suggests that the tigers did not experiencean increase in stress as a result of this management change to adegree that lead to a change in the time they spent sleeping.

To look for more subtle impacts of housing conditionon the cats’ sleeping behavior, we looked at the bodypositions they assumed while asleep when housed alone ascompared to in a social group. Consistent with our hope thatthis management change would not decrease welfare, the catsslept in the same positions with the same degree of frequencyin both housing conditions. We had suspected that cats whenhoused alone might be more likely to sleep on their backssince assuming this position while socially housed couldleave them more vulnerable within their social group, but infact, this positioning remained a non‐preferred position whenhoused individually as it was when housed socially. Sleepingon their side was the most preferred position in both housing

Fig. 3. Average proportion of sleeping scans tigers were observedin each body position when housed in a social group as compared towhen housed they were individually.

Fig. 4. Average proportion of awake scans tigers were observed ineach body position when housed in a social group as compared towhen housed they were individually.

Fig. 5. Average proportion of awake scans tigers were observed toengage in potential welfare indicator behaviors when housed in asocial group as compared to when housed they were individually.

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conditions (observed on>80% of sleeping scans). Work withdomestic cats suggests that this body position of being on theside with the belly fully or partially exposed is reflective of arelaxed state [McCune, 1994; McCobb et al., 2005].

While it was clear that housing condition did not affectsleeping behavior, which occupied nearly ¾ of the overnightscans, we thought it was important to also address thepositions the cats assumed and behaviors they engaged inwhile awake during this period. Interestingly, there were nodifferences in body position while awake (back, side,standing, sternal, locomotion) across the two housingconditions with the exception of times observed awake in asitting position. The cats exhibited this position more oftenwhile awake when individually housed (1.68% of awakescans) than when housed in a group (0.79% of awake scans),but this was the least preferred position assumed while awakein both housing conditions and thus we do not believe thisdifference reflects a significant impact to welfare.

In addition to the positions they assumed while awake,we also selected a few key behaviors (pacing, door pounding,self‐grooming, chuffing, and roaring) that could serve asindicators of both positive and negative welfare. Pacing is acommon stereotypic behavior that has been well‐documentedin captive felids [Swaisgood and Shepherdson, 2005] anddoor pounding was a behavior observed on occasion in thesecats in the past. Increases in either of these behaviors wouldbe a welfare concern, but both pacing and door poundingoccurred quite rarely (pacing < 3%, door pounding < 1% ofawake scans) and did not differ across housing conditions.We observed self‐grooming (as an indicator of positivewelfare), while also monitoring for signs of over‐groomingthat could reflect a possible stress response to separation.Self‐grooming was present and did increase when housedindividually as compared to when they were in a social group(approximately 16% vs. 14% of awake scans) but no physicalindicators of over‐grooming were present. We documentedchuffing and roaring to look for increases in contact callingbehavior when separated from social partners. Roaringbehavior did not change across housing conditions and asexpected chuffing occurred at significantly higher rates whensocially housed. Chuffing, also called prusten, is a closeproximity vocalization in tigers that is known to be social innature and thus more likely in that context [Thapar, 2004].Finally, while not systematically documented as part ofthis study, discussions with animal care staff indicatedthat they did not detect differences in aggression betweentigers when reunited with other cats following individualovernight housing as compared to when they moved into adifferent social grouping of cats after a night being group‐housed.

Taken together, our findings demonstrate the success ofmanagement changes made to our tiger overnight housingpractices. Specifically, we found that housing cats individu-ally rather than in a social group a few nights per week did notalter their time spent sleeping, sleeping position, lead toincreased pacing or door pounding, or cause any other

behavior changes indicative of a welfare concern. While weconducted this assessment with tigers accustomed to socialhousing, we feel that the findings are more broadly applicableas social housing of solitary species is an accepted practice inzoological institutions [Wharton and Mainka, 1997; Wie-lebnowski et al., 2002; Price and Stoinski, 2007; Macri andPatterson‐Kane, 2011]. In fact, this practice is likely toincrease in popularity in the future as we continue to learnmore about the flexibility of animal social systems in bothwild and captive environments, and as the potential welfarebenefits are revealed. Systematic evaluation of changes tomanagement practices is a key step to ensuring that we aremaximizing the welfare of animals in our care and from thedata presented here, we can conclude that housing our adultfemale tigers individually overnight is an effective manage-ment strategy.

CONCLUSIONS

1. Tigers accustomed to social housing can acclimate torecurrent individual overnight housing.

2. Transitioning to recurrent individual housing did notsignificantly impact time spent sleeping, sleeping position,lead to increased pacing or door pounding, or cause anyother behavior changes indicative of a welfare concern andhas afforded us the opportunity to provide specialized carefor our aging cats.

ACKNOWLEDGMENTS

Our thanks go to Disney’s Animal Kingdom’s® NightAnimal Care Team for their commitment to these animals andtheir assistance with this project. Specifically, our thanks goout to Lois Johannes, Gretchen Mueller, Melissa Olivenica,Shawna Riddle, and Wendy Steiner for their help in datacollection.

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