OBJECT MANIPULATIONIN CAPTIVEPOLAR BEARS

ALISONAMES, Universities Federationfor AnimalWelfare, 8 HamiltionClose, South Mimms, Potters Bar, Herts., EN6 3QD, England

Abstract:Data, with special reference to objectmanipulation, were collected on 14 polarbears (Ursusmaritimus) held in 8 in the British Isles. Morethan 1,200 hoursof observationswere collected from 1989 to 1991. Timescans were made at 5-minuteintervals and focal event samplingprovided information on objectselection, bout length, and behavior on land and in water. Analysesincluded individual and sex differencesin amount,frequency, and complexity of objectmanipulation. The male bears had higher levels of objectmanipulation overall, but 24%of the females'manipulative bouts were longer than those of the males. Boutfrequencies indicated an organizationaldifference between the sexes withall but 1 of the femaleshaving fewer sessions per hour. Responsesto a widerange of objectsand food itemswere recorded and categorized.Findings indicated that the behavioral repertoire of polarbears was morediverse than expected and that bears of all ages andboth sexes showeda high level of motivation,ability, and skill toward this kindof activity.

Int. Conf. BearRes. and Manage.9(1):443-449

Polar bears manipulateobjects and substratesin their were providedby A.D.B. Rimmer, and funding for the environment (Perry 1966, Jonkel et al. 1972, Kiliaan project came from the Universities Federation for 1974, Larsen 1985). This type of behavior occurs Animal Welfare, an animal welfare fund raised from during hunting, foraging, and the constructionof dens the readersof the Mail On Sunday, , Bristol and daybeds. Having recently evolved from brown Zoo, , , , and bears (Ursus arctos) (Kurtenand Anderson 1980), the Zoo. polar bear has retainedthe manipulativeabilities which have allowed the genus Ursidus to expand and adaptto a wide variety of habitats. Adaptationsfor coping with MATERIALSAND METHODS seasonal availability of food have occurred both Fourteen captive polar bears (8 F, 6 M) were behaviorally and morphologically. In dietary terms, observed over a 2-year period starting in September North Americanbears have diversified such that a wide 1989. The bears were housed in 7 different zoo variety of foods are exploited. Spatial knowledge of exhibits locatedthroughout the British Isles. More than seasonal foods and the physical abilityto forage for and 1,300 hours of data were collected using instantaneous process complex food sources have been a key to sampling techniques (Altmann 1974), at 5-minute evolutionary success in a variety of species (Parkerand intervals. At each data point, the gross state, the Gibson 1977, Chanin 1985, Schullery 1986, Gurell posture or locomotion, the activity, and the proximity 1987, Stirling and Derocher 1991). to other cage mates were recorded for each individual The aim of this researchis to examine the ability and (Table 1). interest of captive polar bears toward object The past histories of the bears differed widely with manipulation. Providing the bears with a variety of some animals being captive born, some wild caught, objects raised several questions. With no adaptive and in the case of 1 individual, having spent many pressures in captivity will the bears voluntarilyperform years in a circus (Table 2). Most of the bears were this type of activity? Are there sexual, individual, or kept in male-female pairs, but 2 females lost their age-relateddifferences in the amountand complexity of partners, and a trio is kept in 1 zoo. In addition, the object manipulation?Should the provision of objects age, and thus reproductivestatus, varied a great deal become a welfare priority for organizations holding among individuals. The youngest bear was 8 and the bears in captivity? oldest 31. The 8 enclosures were all very different, yet If curiosity and investigative behavior are innate some aspects of the design were similar. The major aspects of the nature of bears, we would predict that feature of all of the enclosures was the use of concrete captive individuals would respond actively to object and rock for construction. In 3 exhibits there was provision. If so, bears that are denied such behavioral minimal vegetation and in these it was not intentional. opportunitiesmay be considered deprived. None of the enclosures had soil, trees, or any natural Special thanks are owed to Maggie Redshaw for substrates. continual support, organization, and supervisionof the Sets of observationswere collected over a period of polar bear project. I received helpful commentaryfrom at least 10 days to obtain representativedata on the T.B. Poole, R. Hubrecht, C. West, D.M. Richardson, animals' activities. The time spent on observations G. Law, and A.J.R. Bushby. A computerand software during each of these periods usually totalled 60 hours, 444 Int. Conf.Bear Res. and Manage.9(1) 1994

Table 1. Glossary of behaviors.

GROSSSTATE Lift mouth: to raiseoff the groundby using the mouth. Active: awakeand movingabout the enclosureor performingan Carrymouth: to transportan objectwithin the mouth. activity. Toss: to projectan itemthrough the air fromthe mouth. Vigilant: alertbut not active. Lick: to pass the tongueover. Inactive: eyes closedand probably asleep. Bite: to sinkthe teethinto an object. Chew: to workthe jaws andteeth in orderto grind. Nudge nose: slightlymoving an item by pushingalong with the POSTUREOR LOCOMOTION nose. Lie: weightnot carriedon the feet, can be downon belly, side or Carry/wearhead: transportan item on topof thehead or aroundthe back. neck. Sit: headheld up andweight resting on frontpaws and rear. Rub head: pushthe headback and forth against an object. Stand: weightcarried on all 4 pawswhile remaining stationary. Hold down: pushan objectagainst the groundwith the paws. Walk: move alongon all 4 pawsat a moderaterate. Pushagainst side: holdingagainst a walland applying pressure with Run: move alongon all 4 pawsat a rapidrate, i.e. gallop. the paws. Climb: moveup, over, or onto a steepslope. Lift paws: raisean objectoff the groundwith paws. Bathe: in the waterwith no particularform of locomotion. Carry paws: transportan item by holdingbetween the paws or Swim: movingalong in the water. betweena paw andthe body. Pace: any locomotorstereotypy which is executedon land. Nudgepaw: slightlymove an itemby softlypushing it witha paw. Stereotypic swimming: any locomotor stereotypywhich is Bounceon: to repeatedlyjump up anddown on somethingwith the performedin the water. pawscoming in contactwith the object,and the hindlegs remaining on the ground. Scratchat: to scrapethe surfaceof an objectwith the claws. ACTIVITY Throw: lift an objectwith the forepawsand project it into the air. Look around: visuallyscanning the area,inside or outsideof the Hit: to strikean objectwith force. enclosure. Lie on: to putthe bodyon, over, or acrossan object. Watch: to look at or observea conspecific. Rub against: to pushthe bodyback and forth across an item. Feed Drink Manipulate: to handleor use objects. OBJECTHANDLING-ACTIONS WITH OBJECTS Groom: to cleanand keep fur andbody clean. Stack: to set 1 itemon top of another. Scratch: to scrapewith paws or claws, as to relieveitching. Include: to put 1 iteminside of another. Rub: to movebody, with pressure, along, over, or againsta surface. Incorporate: to manipulatemore than 1 objectat a time. Smell: olfactoryinvestigation of a conspecificor aninanimate object. Hoard: to collecta numberof itemstogether in 1 area. Scent: to smellthe air. Insert: to pushan objectinto a hole or gap. Defecate Urinate GAMES Tug-of-war: two or moreindividuals pull an objectback and forth PROXIMITY betweeneach other. andthen it. Contact: touchingeach other. Stalk: set an itemin position,back off, charge Arms reach: withina bear'sarm reach of eachother. Grapple: two or moreindividuals engaging in roughand tumble Body length: a bear'sbody lengthaway. play. or hit an item and then on it. Body length plus: morethan a body lengthapart. Retrieve: to throw away, jump Out of sight: out of visualcontact.

OBJECTHANDLING-ACTIONS ON OBJECTS Hold mouth: to have or keep an objectbetween the teeth. OBJECTMANIPULATION IN CAPTIVE POLAR BEARS * Ames 445

Table 2. A list of the polar bears held in zoos in the British also providedto stimulateexploratory and manipulative Isles. activity. A wide range of objectsvarying in shape, size, andtexture were in orderto increasethe Wildor provided behavioral available. Identity Age Sex captiveborn Location opportunities Thewide geographical separation of theparticipating Nina 32 F CB Bristol zoos, andthe needto collectadequate blocks of dataon Misha 28 M W? Bristol the study animalsprior to enrichment,resulted in the Bonnie 10 F CB Chessington programbeing initiatedin a staggeredfashion. As a data were collectedand the enrichment Clyde 10 M CB Chessington consequence, programbegun at differenttimes of year at each zoo. Mandy 16 F W? Flamingoland At some zoos, events or features of current Marcus 16 M W? Flamingoland managementdelayed observations: at 1 zoo the male Sabrina 24 F CB Chester polar bear was housed with a brown bear while the femalereared her cub; at another,the maleand female Sally 29 F CB? Glasgow were separatedwhile the female rearedher cub in Winston 28 M W Glasgow anotherarea; 2 femaleswere dennedup during the Mercedes 11 F W Edinburgh wintermonths. Oneold, malebear died after the initial but beforethe effects of the intervention Barney 15 M CB Edinburgh observations, couldbe examined. Wash 10 F CB Belfast Althoughall the zoos weregiven the sameguidelines Tumble 10 F CB Belfast and suggestions,quality of enrichmentvaried at each Dudley 12 M CB accordingto enclosuredesign, characteristicsof individualbears, and of the onset of the Spunky 13 F W Dublin timing enrichmentprogram. Some enclosureshave filtration Ootek 13 M W Dublin systemsthat providebears with clean waterbut limit the type of objectsthat animalscan receive. A glass barrieralso resultedin restrictionsby limitingobjects butless whenthere was only 1 animalto observe. Data to thosethat cannot be used to breakglass. Keepersin werecollected with observations distributed evenly over some zoos had greatdifficulty in changingthe objects the hoursof 0700-1900 hours,under varying weather in the enclosurebecause bears preferred not to enterthe conditions and at different times of the week. dens. Antiquatedfacilities with slides that did not work Observationsat eachzoo werecollected during different quicklyand easily exacerbatedthis problem. All of seasons to identify seasonal influences upon the these differencescontributed to differencesin quality animal's behavior. The seasons were defined as of the enrichmentprogram. summer = June, July, and August; autumn = This paperis focusedon the abilityand interestof September, October, and November; winter = captivepolar bears to manipulateobjects. Priorto the December,January, and February;spring = March, study, captive bears did not receive a supply of April, and May. moveableobjects, and as a resultwere unable to exhibit Data were analyzedby tabulatingdata points for manipulativebehavior. Following object provision, the selectedbehaviors. With such a small samplesize, animalsexhibited a morediverse behavioral repertoire, repeatedmeasures were collected and the data has been and it is this increasein behavioralopportunities that presented as case studies. Data were analyzed using will be detailed. nonparametrictests. Post-enrichmentobservations were not carriedout An enrichment program was initiated at all of the immediately.A key goal of the studywas to measure zoos, whichencompassed a 2-foldstrategy with changes the effectivenessof the enrichmentprogram and not the in feedingroutines (Law et al. 1986) andprovision of effectsof noveltyon the bears. Followinga 3-month objectsfor manipulationand exploration. Guidelines interval,the post-interventiondata were collected. The for feedingroutines were aimedat makingfeeds more datawere examinedfor seasonaland sex differencesin interestingfor the bears. A greater variety and totalamount of manipulation.The initiationsof object complexityof food items, such as wholecrabs or food handlingsessions were identifiedand measuredwhen frozenin blocksof ice, wereprovided so thatbears had animalsfirst came into physical contact with 1 or more to work harderin orderto obtainfood. Objectswere objects. Terminationsof sessionswere defined by a 5- 446 Int. Conf.Bear Res. and Manage.9(1) 1994 minute break in manipulationaccompanied by a change Session Parameters in behavior. Breaks of less than 5 minutes were used The median session lengths varied from 3 to 12 to identify the termination of object handling bouts. minutes, while ranges varied from 1 to 96 minutes. Sessions were comprised of 1 or more manipulative The distributionof medians and ranges did not appear bouts. to be influenced by sex. However, analysis indicated Furtherdetailed analyses were conducted in order to that there was a difference in the distributionof session identify composition, organization, and intensity of lengths. In order to identify male-female differences, behavior directed toward objects. For measures of session lengths were plotted by frequency, which session length, frequency of sessions, and body parts showed the male's distributiondropping off at sessions used in manipulation,data were limited to observations > 15 minutes (Fig. 2). The female bear's distribution collected during summer months since males and was more prolonged with a further24 % of the sessions females appearedequally affected by seasonal variation. having lengths > 15 minutes. During these months both sexes exhibited similar levels The frequency of sessions was examined in order to of object manipulation. Past research on captive polar obtain a comprehensive view of the amount of object bears indicates that seasonal behavior and species manipulation. Session length was shorter for males, management, in regards to reproduction,have marked while the total amount of manipulation hardly varied effect upon various aspects of their behavior (Ames and between the sexes. It was thus hypothesized that the Redshaw 1990). male bears would have more frequent sessions and this was found to be a significant difference (Mann-Whitney;P < 0.05). The frequency of male RESULTS sessions ranged from 0.2 to 0.8 sessions per hour with a mean score of 0.4 sessions per hour (n = 4). Female Total Amount of Manipulation manipulationranged from 0.02 to 0.6 sessions per hour Levels of manipulationremained fairly constantover with a mean score of 0.2 sessions per hour (n = 7). the seasons, for the female bears (Wilcoxon test; NS), All but 1 of the females had fewer sessions per hour with a difference of only 1.5% of total observationtime than the male bears. between the highest and lowest recordings. The male bears however, showed seasonal variation (Wilcoxon Session Composition test; P < 0.10) with manipulationat a low of 2.1 % in Much of the manipulative activity observed had an the spring and a high of 14.6% of total observation organized structureinvolving repeatedsegments, minor time in the autumn (Fig. 1). In all seasons except the variants, and elaborations (Ames and Redshaw 1990). spring, male bears had higher levels of manipulation. For example, an animal would knock a barrel with It was thought that the age of the bears might have an punctureholes into the pool, jump onto it, hold it under inverse relationship with levels of object handling but the water and when it was full, lift it out, wait until it no such relationshipwas found (Spearman;NS). emptied and then climb out, knock it into the water, jump onto it and so on, repeating the sequence with variations. With a wide range of objects, repeated LEVELS OF MANIPULATION tossing, dropping, and throwing were common play elements that appearedafter visual inspection, olfactory - 20- El MALES (n=6) t FEMALES I (n =8) MANIPULATIVE SESSIONS 60 ? - /^ x 50 ;' 50- nE3 MALES (n=4) 10- I i ,~~~40,,-^^~~ - FEMALES(n=7) CL2 30 - F-1711 * , , a, ' A 20 , , .1/,,,. (AVMco vt : %t, tn a r A . ,r, ', .A . , 0 , " "" r WINTER 10 .-" '', 5- SPRING SUMMERAUTUMN 1-5 6-10 11-15 16-20 21-25 26-30 31-35 36-40 41-45 46-50 MINUTES

Fig. 1. Proportion of time captive polar bears spent manipulating objects during different seasons. Fig. 2. The distribution of session lengths for the sexes. OBJECTMANIPULATION IN CAPTIVE POLAR BEARS * Ames 447 andoral exploration,and attemptsat destruction. socialplay with objectsoccurred in 50% of both male The use of differentbody partswas dividedup into and femalebears. 3 sections:mouth-muzzle, paws, and body (Fig. 3). Theamount of timespent manipulating objects on the Data showed that males and femalesalike used their land or in the water indicatedthe bears' substrate paws, 46.7% and42% respectively,slightly more than preference. Duringthe summer,both sexes spentthe theirmouth-muzzle, 40.9% and 40.7%, duringobject majorityof their manipulationtime in the water manipulation.However, this was not a significant (Wilcoxon;P < 0.05). It was foundthat 80.8% of the difference(Wilcoxon; NS). Activitieswith the objects females'and 67.7% of the males'object handling was were divided into 4 sectionsas relatedto degree of done in the water. Furtheranalysis was done in order complexity:(1) actionson objects, such as biting or to identifythe seasonalvariation in the pool use (Fig. smelling;(2) actionswith objects,such as carryingor 4). Lower levels of water-basedmanipulation were throwing;(3) actions with objects on self, such as recordedin winterthan in summer,however, object wearingan objector puttingthe paws or head inside; handlingon landremained at a lowerlevel thanthat in and (4) actionswith objectson otherobjects, such as water,regardless of season(Wilcoxon; P < 0.05). stackingobjects or puttingone insidethe other. The scores indicatedthat althoughthe majorityof activity was comprisedof actionson objectsfor bothmales and DISCUSSION females, 44.2% and 43%, female polar bears If polarbears have an intrinsicability and motivation performedmore complex object manipulation.The to manipulateobjects, 2 resultsare expected. First, femaleswere foundto performactions with objects on manipulationwould occur regardlessof seasonor sex themselves10.7% of totalmanipulation time, whilethe differences. This expectationwas realizedin every maleswere found to do this only 6.2% of theirtime. case over a 2-yearperiod of observations.Second, the Eightpercent of the manipulationof femalesinvolved amountof manipulationmight reduce with an increase actions with objects on other objects. The males in age, butlevels would still be recorded.Reduction in exhibited this type of behavior in 6.5% of their play behaviorwith age has been recordedin a number manipulativebouts. These differenceswere not highly of species(Hediger 1950, Fagen1981, Poole 1987),but significant(Mann-Whitney; NS). in this sampleof polarbears, manipulativeability was All of the polarbears have been seen manipulating independentof age. objects. The sex differenceswere most notable. Althoughthe medianscores for sessionlength were Manipulationinvolving more than 1 object,as well as similar for males and females, the distributionof the organizationof game structureswas observedin sessionlengths clearly indicated that differences in the 75% of the femalesand only 33% of the males,while gross organizationof object manipulationwere object manipulation involving the individual's occurring. Male polar bears were exhibitingshorter surroundingsoccurred with 62% of the femalesand session lengths than females. Total levels of 33% of the males. Bearscoming together in boutsof manipulationdid not reflectthis discrepancyhowever, withmales manipulating objects at meansummer levels POLAR BEAR MANIPULATION of 4.5% and femalesat 4.3% of the total observation time. Objectmanipulation appears to be organizedin 50 -

40 - SEASONALITY 0 MALES (n=4) ;I. M FEMALES(n=7) SUMMER 30 - WINTER 23.91% - c 20 LAND 38.33% am' !l > A ?3 WATER 10- IC r 61.67% \\,>^ , I,,/ vt 0 76.09% MOUTH/MUZZLEPAWS OTHER

Fig. 4. Results show the bears preference of area for Fig. 3. The different body parts used in manipulative bouts. manipulative bouts (n = 11). 448 Int. Conf.Bear Res. and Manage.9(1) 1994 differentways in the 2 sexes. Male bears spend shorter both the short and long term. Day-to-day husbandry periods object handling yet manipulativesessions occur routines should be modified in such a way that bears more frequently. Female bears perform longer, less have a steady supply of movable objects. This frequent sessions. provisioning should be implementedon a daily basis to This differentiation was further identified when provide captive bears with novel objects. activities in object handling sessions were examined. It The majority of object manipulationand rough and was hypothesized that if females were having longer tumble, social play seen in captive polar bears occurs in session lengths their object handling would become the water. This substratepreference is most likely the more complex. Male polar bears had a more limited result of inappropriateenclosure design with the bears repertoire of activities while females performed a having no other soft substrates in which to play. If greater number of activities involving multiple objects. significant, natural areas, such as sand, soil, or bark Activities involved with puttingobjects on oneself, i.e., litter, were included in captive enclosures, bears would putting the head or a paw inside, involved a greater be able to build daybeds, dig dens, and forage as they understandingof an object in relationto the individual. would in the wild (Ames 1993). Efforts to recreate Female bears also performed more of this type of superficialaspects of the Arctic have left captive polar behavior than the male bears. bears in a traditionalconcrete pit, allowing only a tiny Although females developed their object handling fragmentof their behavioralrepertoire to be expressed. more than males did, both sexes were found to be Such managementcan only be considereddeprivational. capable of delicate, complex manipulation. Data In terms of captive management,polar bears need to be relating the amount of different body parts used in considered primarily as bears, with corresponding object handling sessions show that even males were still behavioraland psychological needs. using their paws more than their mouth-muzzle. Captive polar bears do not simply tear objects apart. Mentally and physically, they are capableof deliberate, LITERATURECITED focused, and agile object manipulation. ALTMANN,J. 1974. Observationalstudy of behavior: Observationsand video recordingsshowed thatmuch samplingmethods. Behavior49:227-267. of the manipulativeactivity had an organized structure AMES, A., AND M. REDSHAW. 1990. The managementand involving repeated segments (Ames and Redshaw welfareof polarbears in captivity.Paper presented for the 1990). In many ways these are reminiscentof the play BritishVeterinary . Unpubl.rep. 19pp. behavior of young primates. Initial investigations of AMES,A. 1993. The behaviorof captive polar bears. new objects involved visual and oral explorationbut as UFAW Animal Welfare Research Report No.5. the bears established the properties of an object, they UniversitiesFederation for AnimalWelfare, Potters Bar, would begin to "handle" and manipulate the item. England. 67pp. Some bears were observed to create games for CARLSTEAD, K., SEIDENSTICKER,J., AND BALDWIN, R. themselves and other individuals. Placing objects in 1991. Environmentalenrichment for zoo bears. Zoo Biol. just the right area so that they could be stalked and 10:3-16. attackedwas a game that was developed on land and in CHANIN,P. 1985. The naturalhistory of otters. Christopher the water. On several occasions, bears were seen to HelmLtd., Bromley,Kent. 179pp. play games of tug-o-war. FAGEN,R. 1981. Animalplay behavior. OxfordUniversity Press, New York, N.Y. 684pp. GURNELL, J. 1987. The naturalhistory of squirrels. MANAGEMENTIMPLICATIONS ChristopherHelm Ltd., Bromley,Kent. 201pp. Polar bears are more skilled and dexterous in object HEDIGER,H. 1950. Wild animals in captivity: an outline of manipulationthan previously describedor expected. In the biology of zoological gardens. Dover Publications, evolutionary terms, such ability is a reflection of New York, N.Y. 207pp. intelligence that has allowed all species of bears to JONKEL,C.J., G.B. KOLENOSKY,R.J. ROBERTSON,AND R.H. adapt to a wide variety of habitats in the wild. RUSSELL. 1972. Further notes on polar bear denning Potential for manipulation and object related activity habits. Pages 142-158in S. Herrero,ed. Bears-Their appears to be an indicator of behavioral and Biol. and Manage. Int. Union for the Conserv. of Nat., psychological needs in captivity (Jordan 1982, Law et n.s., no. 23. Switzerland. al. 1986, Tripp 1985, Carlstead et al. 1991, Pellis JORDAN, C. 1982. Object manipulation and tool use in 1991). Such requirementscan and should be met in captive pygmy chimpanzees (Pan paniscus). J. of Human OBJECTMANIPULATION IN CAPTIVE POLAR BEARS * Ames 449

Evol. 11: 35-39. PELLIS,S.M. 1991. How motivationallydistinct is play? A KILIAAN,H.P.L. 1974. The possibleuse of tools by polar preliminarycase study. Anim. Behav. 42: 851-853. bears to obtaintheir food. Yearbookof the Norwegian PERRY,R. 1966. The worldof the polarbear. Casselland PolarInst. CompanyLtd., London. 195pp. KURTEN,B., AND E. ANDERSON. 1980. Pleistocene POOLE,T.B. 1987. Social behavior of a group of orangutans mammalsof NorthAmerica. ColumbiaUniversity Press, (Pongo pygmaeus)on an artificialisland in Singapore New York, N.Y. 443pp. ZoologicalGardens. Zoo Biol. 6:315-330. LARSEN, T. 1985. Polarbear denning and cub production in SCHULLERY,P. 1986. The bears of Yellowstone. Roberts Svalbard,Norway. J. of Wildl. Manage.49:320-326. RinehartInc., Colo. 263pp. LAW, G., H. BOYLE,AND J. JOHNSTON.1986. Notes on STIRLING,I. ANDA.E. DEROCHER.1991. Factors affecting polar bear managementat . Ratel 13(2): theevolution and behavioral ecology of the modernbears. 56-58. Int. Conf. BearRes. andManage. 8:189-204. PARKER,S.T., AND K.R. GIBSON. 1977. Object TRIPP,J.K. 1985. Increasingactivity in orangutans: manipulation,tool use, and sensorimotorintelligence as provisionof manipulableand ediblematerials. Zoo Biol. feedingadaptations in cebusmonkeys and great apes. J. 4:225-234. of HumanEvol. 6:623-641.