Refinement and Environmental Enrichment for Primates: Enrichment 5-9

Bibliographyon Refinement and Environmental Enrichment for Primates. Enrichment5-9

(5) PromotingArboreal Behavior

(5,1) The Importanceof Access to Vertical Dimension of Space

Bernstein IS, Draper WA 1964. The behaviour of juvenile rhesusmonkeys in groups. Animal Behaviour 12, 84-91
Subjects spent 48%-72% of the time in the upper one-third ofthe compound.

Bloomsmith MA, Lambeth SP, Haberstroh MD 1999. Chimpanzee useof enclosures. American Journal of Primatology 49, 36
Group-housed chimpanzees spent 43% of their time off the ground.

Buchanan-Smith HM 1991. A field study on the red-bellied tamarin,Saguinus l. labiatus, in Boliva. International Journalof Primatology 12, 259-276
Tamarins spent 90% of their time in the upper half of their186 cm-high cages when observations were made from a hide.

Clarence WM, Scott JP, Dorris MC,Paré M 2006. Use of enclosures with functional verticalspace by captive Rhesus monkeys (Macaca mulatta) involvedin biomedical research. JAALAS [Contemporary Topics in LaboratoryAnimal Science] 45(5), 31-34
"The monkeys visited more often and occupied for longertime regions at or above human eye level [perches and top homecage] than lower regions." The total percentage of time spentin the top home cage was found to be significantly greater thanin the bottom home cage."

European Commission 2002. The Welfare of Non-human Primates- Report of the Scientific Committe on Animal Health and AnimalWelfare. European Commission, Strasbourg, France
http://europa.eu.int/comm/food/fs/sc/scah/out83_en.pdf
"Enclosures for nonhuman primates should be equipped withone or more elevated resting surfaces (to a postion higher thanthe level at which they perceive threatening factors, e.g., humans)and installed in such a way that an animal can sit on them comfortably.Perches or shelves should be provided in all cages. Arboreal speciesshould be given adequate vertcial space to allow the expressionof normal locomotry behaviour. Primates should not be placed indouble-tiered caging unless the arrangement permits adequate verticalmovement for the animal."

Goff C, Howell SM, Fritz J, Nankivell B 1994. Space use andproximity of captive chimpanzees (Pan troglodytes) mother/offspringpairs. Zoo Biology 13, 61-68
"Results confirmed the importance of vertical cage dimensionand suggested the provision of horizontal substrates above theenclosure floor is important."

Home Office 1989. Animals(Scientific Procedures) Act 1986. Code of Practice for the Housingand Care of Animals Used in Scientific Procedures. HerMajesty's Stationery Office, London
"The use of space by primates means that cage volume isimportant. Virtually all show a vertical flight reaction. Cageheight should allow for this and should permit the animals tostand erect, jump and climb, and to sit on a perch without heador tail touching the cage."

International Primatological Society 1993. IPSInternational guidelines for the acquisition, care and breedingof nonhuman primates, Codes of Practice 1-3. Primate Report35, 3-29
"The vertical dimension of the cage is of importance [becauseof the vertical flight response] and cages where the monkey isable to perch above human eye level are recommended."

Kaumanns W, Schönmann U 1997. Requirements for cebids.Primate Report 49, 71-91
"Arboreal species need cages and enclosures which allowa differentiated moving in the vertical dimension. They shouldbe able to use spatial positions which are above the level ofthe position of certain groupmates and of threatening humans orpotential dangerous events in their environment. Cage positionsin a keeping room below the eye level of human can be a sourceof permanent stress, because they are incompatible with adaptivetendencies of arboreal primates to avoid risks by using higherparts of the habitat."

MacLean E, Roberts Prior S 2006. Viewfrom the top. AWI (Animal Welfare Institute) Quarterly55(3), 7
"Across both conditions, monkeys showed a strong preferencefor the upper-row cage indicating that elevation was more importantthan illumination in guiding location preference. Although monkeysdid increase the amount of time that they spent in the lower rowduring periods of reversed lighting, this trend was not significant.Nonetheless, we do not interpret this result as evidence thatsufficient lighting is not important to captive monkeys. Rather,we believe that monkeys' consistent preference for the upper-rowreflects the paramount importance of access to elevated space."
="http:>

National Research Council 1998. ThePsychological Well-Being of Nonhuman Primates. NationalAcademy Press, Washington
"Under natural conditions, many primates spend much oftheir lives aboveground and escape upward to avoid terrestrialthreats. Therefore, these animals might perceive the presenceof humans above them as particularly threatening. ... Even macaques,which some describe as semiterrestrial, spend most of the dayin elevated locations and seek the refuge of trees at night. ...Optimal use of available cage space might well depend more onthe placement of perches, platforms, moving and stationary supports,and refuges than on cage size itself."

Reinhardt V, Liss C, Stevens C 1996. Spacerequirement stipulations for caged nonhuman primates in the UnitedStates: A critical review. Animal Welfare 5, 361-372
"Having no stimulatory value, space alone does not enhancean animal's environment. ... Legal space requirements for non-humanprimates are not adequate unless they stipulate that sufficientheight be provided to accommodate properly placed elevated structures."

Ross SR, Lukasb KE 2006. Use of spacein a non-naturalistic environment by chimpanzees (Pan troglodytes)and lowland gorillas (Gorilla gorilla gorilla) . AppliedAnimal Behaviour Science 96, 143-152
"Chimpanzees preferred the highest tier of the enclosureand the gorillas preferred the floor level. Both species showedpreferences for doorways, corners and the mesh barriers adjacentto keeper areas."

Taylor L, Owens A 2004. Enclosureuse by aged squirrel monkeys (Saimiri sciureus). AmericanJournal of Primatology 62(Supplement), 85
A group of squirrel monkeys was translocated from an indoor exhibitto an outdoor enclosure. "The monkeys were scored most oftenamong the largest and highest branches in the tallest tree inthe enclosure (17.7% ). .. None were ever scored on the ground,despite the water source being there and the insect foraging opportunities."

Tecot S, Jensvold ML, Fouts R 1999. Evaluation of an enrichedphysical environment: space and structure utilization in Pantroglodytes. American Journal of Physical Anthroplogy Supplement264, 264
Ethological findings indicate that "access to verticalstructures is important to these [group of five] chimpanzees."

Westlund K Preferenceof the vertical dimension of cyno pairs living in high cages.Laboratory Animal Refinement and Enrichment Forum (electronicdiscussion group), November 28, 2002
"In a quantitative study I did on pair-housed cynos theanimals spent 95% of their waking time in the upper part of thecage (being housed in a system that resembles a double-tier system,but with vertical access to upper and lower sections) - whichsuggests that their preference along the gradient of height isunequivocal! No bedding was provided on any of the cage floors,and all food was given in the bottom section. Even so, animalswould bring the food to the upper part and consume it there."

(5,2) Elevated Structures

Abee CR 1985. Medical care and management of the squirrel monkey.In Handbook of Squirrel Monkey Research Rosenblum LA, CoeCL (ed), 447-488. Plenum Press, New York
"Squirrel monkeys .... lack ischeal callosities and thereforeare prone to the development of sores if they are not providedwith suitable structures on which to climb and perch. Squirrelmonkeys prefer a flat, shelf-type surface for sleeping, but animalsusing such perches frequently develop pressure ulcers on the dorsalaspect of the tail. By using large-diameter plastic pipe (1.5inch), a highly desirable perch can be provided. These percheshave a broad surface yet are sufficiently contoured to avoid tailsores."

*Baumans V, CokeC, Green J, Moreau E, Morton D, Patterson-Kane E, Reinhardt A,Reinhardt V, Van Loo P 2007 Making Lives Easier for Animalsin Research Labs - Chapter4.17. Vertical Space Enhancement. Washington, DC: AnimalWelfare Institute
"Most of the primates' natural environment is "fixed."Even a tree is "fixed;" it's only at the end of brancheswhere a monkey in nature would have the sensation of anythinglike a swinging perch. A fixed perch is a great thing for a monkey.We used to hang numerous swings and movable raised structuresinto the enclosure of our group-housed cynos, but we could seevery clearly that they prefer the stable perches or platforms.Our animals very rarely used ropes or swings. The only ones usingthose elements were babies and juveniles.
In the caging systems we use there is no bottom tier. All cagesare 0.6 m off of the floor. Each cage is furnished with a 1 mhigh perch; so it is pretty much at human eye level 1.6 m height.It seems to me that the animals feel relaxed when they sit ontheir perch and can meet me at eye level. A low perch has littleor no value as a "safe" resting location from our monkeyspoint of view."

Bayne K, Hurst JK, Dexter SL 1992. Evaluation of the preferenceto and behavioral effects of an enriched environment on male rhesusmonkeys. Laboratory Animal Science 42, 38-45
"With simultaneous exposure, the single-housed subjectsspent the greatest portion of the interactive time [30 minute-observationsessions] on the perch [16.8%], the second greatest amount oftime spent divided approximately equally between interacting withthe Kong [5.0%] and Tug-A-Toy [4.9%], and the least amount oftime spent manipulating the grooming board [0.4%]."

Brinkman C 1998. Usefulness of swings for macaques . PrimateEnrichment Forum (electronic discussion group), (August 17,1998)
"I have used swings with cynos (socially and singly housed)and pigtails (socially housed). My impression is that adult animalsdo not really use them, that is, to 'swing'. Young animals likemoving things, be they swings, or other suspended items. My adultsdid not even use the swings much to perch on; my explanation isthat on a swing, you simply cannot easily relax. Animals cannotreally sit on them, and especially with the cynos, you can seealmost continuous movement in the tail, compensating in balance."

Crockett CM, Bellanca RU, Bowers CL, Bowden DM 1997. Grooming-contactbars provide social contact for individually caged laboratoryprimates. Contemporary Topics in Laboratory Animal Science36(6), 53-60
"Monkeys in upper cages averaged 48%±27% SD ofthe time on the perch, compared with 40%±25% SD for monkeysin lower cages."

Davis E 2006. Morefun with a barrel full of monkeys: A nonhuman primate swing madeby recycling plastic barrels. Laboratory Primate Newsletter45(3), 9-11
"The NIH Shared Animal Facilities' enrichment programhas developed a primate swing created from recycling our discardedplastic 30- and 55-gallon detergent barrels. These swings areeasy to construct and are effective in increasing our animals'behavioral repertoires. Additionally, these swings are safe, portable,non-toxic, easy to sanitize, and almost indestructible. We haveused these barrels in our socially-housed monkey runs for overthree years, and they are still going strong!"

Dexter SL, Bayne K 1994. Resultsof providing swings to individually housed rhesus monkeys (Macacamulatta). Laboratory Primate Newsletter 33(2),9-12
The single-housed adult test subjects manipulated the swingsbut showed little inclination to actually use them for swinging.

European Commission 2002. TheWelfare of Non-human Primates - Report of the Scientific Committeon Animal Health and Animal Welfare. European Commission,Strasbourg, France
Comprehensive updated recommendations on the species-appropriatecare of nonhuman primates.
"Enclosures for nonhuman primates should be equipped withone or more elevated resting surfaces (to a postion higher thanthe level at which they perceive threatenign factors, e.g., humans)and installed in such a way that an animal can sit on them comfortably.Perches or shelves should be provided in all cages."

Günther MM 1998. Influence of habitat structure on jumpingbehaviour in Galago moholi. Folia Primatologica69 (Supplement 1), 410
There was a statistically significant preference for woodenperches versus PVC perches and for high perches versus low perches."These results suggest that support material [perches], aswell as height, influences the behaviour of G. maholi and theseshould be taken into consideration in behavioural and biomedicalstudies as well as in the construction of cage facilities. Studieswhich do not take these factors into account are to some extentvitiated."

Howell SM, Mittra E, Fritz J, Baron J 1997. Theprovision of cage furnishings as environmental enrichment at thePrimate Foundation of Arizona. The Newsletter 9(2),1-5
"Adults infrequently used 'moving' furnishings (e.g.,swinging ropes, hanging tubes, etc...) and seemed to prefer 'stable'horizontal furnishings (e.g., benches, logs) above the enclosurefloor."

Kopecky J, Reinhardt V 1991. Comparingthe effectiveness of PVC swings versus PVC perches as environmentalenrichment objects for caged female rhesus macaques. LaboratoryPrimate Newsletter 30(2), 5-6
Single-housed subjects' "preference for perches was probablyrelated to the fact that perches, unlike swings, are fixed structurespermitting continuous relaxed postures rather than short-termbalancing. Moreover, perches, unlike swings, permit the animalsto sit right in front of the cage with optimal visual controlof the environment outside of the cage."

Millere KE, Laszlo K, Suomi SJ 2006.Usingrecycled barrel swings vs. Prima-Hedrons in primate enclosures.Laboratory Primate Newsletter 45(3), 12
"To document the utility of using recycled barrel swingsvs. Prima-Hedronsâ as enrichment objects, we observed asocially housed group of 28 tufted capuchins (Cebus apella). ..We found no significant difference in the average frequency ofuse of hanging Prima-Hedrons vs. hanging barrels."

Neveu H, Deputte BL 1996. Influence of availability of percheson the behavioral well-being of captive, group-living mangabeys.American Journal of Primatology 38, 175-185
"A total deprivation of perches yielded an increase inaggressive behaviors and locomotion, and a decrease in cohesiveness.Placing perches progressively in the experimental cage restoredthe level of all the variables to levels found in the controlcage [with five perches]. ... Therefore, perches constitute anecessary feature of an adequate environment for mangabeys."

O'Neill-Wagner PL 1994. Whentrying to get your monkeys to behave, try perches. In Touch1(2), 6-8
The group-housed animals preferred perches at high elevationover perches at low elevation.

Ochiai T, Matsuzawa T 1999. Environmental enrichment for captivechimpanzees (Pan troglodytes): Introduction of climbingframes 15 m high [Japanese text with English summary]. ReichoruiKenkyu/Primate Research 15, 289-296
"Tall climbing frames were introduced into an outdoorcompound for captive chimpanzees as a way of environmental enrichment.... Chimpanzees spent 81% of the observation time on the climbingstructures. ... All chimpanzees used the climbing structure throughoutthe day with little individual difference."

Phillippi-Falkenstein K 1998. Usefulness of swings for macaques.Primate Enrichment Forum (August 19, 1998)
"In group runs, corncribs and corrals, swings providea dimension of environmental complexity for rhesus and pig-tailedmacaques. The swings are primarily used by young animals, whileadults rarely use them. Tire swings seem to be the favorite. Ithas been my experience that the animals - even juveniles - donot benefit from swings when housed in 'small' standard cages:They simply don't use them."

Plesker R, Herzog A 2001. Primahedrons, puzzle feeders and television as environmental enrichmentfor captive African Green Monkeys. Primate Eye , 4
"The prima hedrons had no significant effect on any ofthe behaviours investigated. These were infrequently used as objectsfor playing, resting or observation."

Reinhardt V 1989. Evaluationof the long-term effectiveness of two environmental enrichmentobjects for singly caged rhesus macaques. Lab Animal18(6), 31-33
"The singly caged monkeys spent on average 28% of thetotal observation time [120 min] with the PVC pipes. ...Whileperching, the monkeys sat in front of the cage for 95% of thetime, in the middle or rear of the cage for 5% of the time. ...The proportion of time spent with the pipes was three times greaterfor animals living in lower-row cages than for animals livingin upper-row cages. ... In the elevated position, the light exposurewas increased, a fact that made the pipes of particular valuefor the lower-row cages animals."

Reinhardt V, Pape R 1991. Analternative method for primate perch installation. LabAnimal 20(8), 47-48
Modification of squeeze cages is described allowing the installationof a perch that does not interfere with the normal operation ofthe cage.

Reinhardt V 1990. Comparingthe effectiveness of PVC perches versus wooden perches as environmentalenrichment objects for singly caged rhesus monkeys. LaboratoryPrimate Newsletter 29(1), 13-14
"One half of each cage was provided with a PVC pipe, theother with an oak branch." Both perches had the same diameterand were installed in the same manner. During one-hour observationsessions, single-caged subjects showed no clear preference butspent on average 19% of the time on the PVC pipe and another 24%of the time on the oak branch.

Reinhardt V 1992. Environmentalenrichment branches that do not clog drains. LaboratoryPrimate Newsletter 31(2), 8
"More than 700 caged rhesus and stump-tailed macaqueshoused in 29 rooms have been exposed to red oak perches and/orloose branch segments for a period of six months. Drains did notclog in any of the 29 rooms during this time although the animalsgnawed the wood extensively."

Reinhardt V 1992. Spaceutilization by captive rhesus macaques. Animal Technology43, 11-17
"The area covered by the floor was 3 times larger thanthat covered by elevated structures; nonetheless the animals werelocated significantly more often (89.8% of 108 scan samples) onelevated structures than on the floor (8.6% of 108 scan samples).... The higher an animal's rank position, the more pronouncedwas its habit to utilize high-level (>130 cm above floor) structuresof the pen, while low ranking animals had to be content with low-levelstructures (40 cm above floor) and the floor. ..
All members of the group would inevitably take to elevated siteswhenever they heard or saw fear-inducing personnel. ... The animalshuddled together with regularity on high-level structures butnever on low-level structures or on the floor. ... It was concludedthat [group-housed] laboratory rhesus macaques prefer the verticaldimension over the horizontal dimension as primary living space."

Reinhardt V 2003. Legalloophole for subminimal floor area for caged macaques. Journalof Applied Animal Welfare Science 6, 53-56
"The USDA regulations pertaining to the minimum spacerequirements of nonhuman primates and the fitting of elevatedresting surfaces are contradictory. They implicitly condone theprevailing perch design that allows maximal usage of animal roomspace by stacking the cages on top of each other but fails toaddress the animals minimal spatial needs for normal posturaladjustments with freedom of movement. An amendment to the regulationsis needed to clarify that perches, ledges, swings, or other suspendedfixtures have to be installed in such a way that they do not blockpart of the minimum floor space that is needed by an animal tomake species-typical postural adjustments with freedom of movement."

Ricker RB, Williams LE, Brady AG, Gibson SV, Abee CR 1995.Environmental enhancement for laboratory-housed squirrel monkeys:Fifteen-year retrospective analysis of procedures. ContemporaryTopics in Laboratory Animal Science 34(4), 55
"Two types of perching material were tried: polyvinylchloride (PVC) and hemp (rope). The PVC was preferred by the animalsand was set up in multiple levels, allowing use of vertical aswell as horizontal space."

Schmidt EM, Dold GM, McIntosh JS 1989. A perch for primatesqueeze cages. Laboratory Animal Science 39, 166-167
Modification of single squeeze-cages is described allowingthe installation of a perch that does not interfere with the normaloperation of the cage. "The monkeys make use of their perchfor feeding, grooming and sleeping" for 30% to 95% of theday.

Seier JV 2000. Usefulness of wooden material for environmentalenrichment for rhesus macaques. Primate Enrichment Forum (February12, 2000)
"We have been using wood extensively in our vervetmonkey colony (about 300 monkeys, indoors) and communal cageswe make climbing apparatus from wood. Wood perches for restingwere also installed but they use the metal perches equally well....The vervets use the wood as described for other species, strippingthe bark and climbing. They eventually reduce and medium branchesto a single pole. We find this desirable since it keeps them occupiedfor hours. ... They do not loose interest in the wood as theydo in other objects which we have tried. ... There is obviouslythe problem of sanitation but we replace the wood regularly andautoclave it before we place inside the cage (luckily we havea very large autoclave). Clogging of drains and mould has notoccurred, neither have problems such as injury through splintering.... We consider wood as our most important enrichment tool."

Shimoji M, Bowers CL, Crockett CM 1993. Initialresponse to introduction of a PVC perch by singly caged Macacafascicularis. Laboratory Primate Newsletter 32(4),8-11
"Longtailed macaques ... exhibit a vertical flight responsewhen alarmed. Therefore, the height of the cage is important forallowing the animals to withdraw from potentially stressful oralarming situations. ..Single-housed "monkeys spent significantlymore time clinging to the cage wall ("suspended") inthe absence of the perch. ... Monkeys in lower level cages [26%of daytime] averaged somewhat more time on the perch than thosein upper cages [14% of daytime]. ... There was less stereotypywhen the perch was present."

Smith K, St. Claire M, Byrum R, Harbaugh S, Harbaugh J, ErwinJ 2003. Use of space, cage features, and manipulable objects bylaboratory primates: individual differences and species variability.American Journal of Primatology 60(Supplement), 76-77
http://www.asp.org/asp2003/abstractDisplay.cfm?abstractID=625&confEventID=514
"Rhesus (74%), longtailed (71%), vervets (94%), and patas(82%) significantly exceeded the expected rate of perch use (25%),while pigtailed (28%) did not differ from expectation."

Taylor LL 1998. Promoting species typical behavior in Coquerel'ssifakas (Propithecus Verreauxi Coquereli). AmericanZoo and Aquarium Association (AZA) Regional Conference Proceedings,599-603
"The sifakas rarely were observed on the ground, preferringto locomote on vertical substrates and rest on vertical and horizontalelevated substrates in all four size categories. Therefore, ifvertical surfaces were absent from captive habitats, these rarelemurs could not display their preferred mode of arboreal locomotion.Further, the rarity of ground use highlights the need for elevatedfeeding sites."

Taylor L, Owens A 2004.Enclosure use by aged squirrel monkeys (Saimiri sciureus).American Journal of Primatology 62(Supplement), 85
A group of squirrel monkeys was translocated from an indoor exhibitto an outdoor enclosure. "Static substrates were preferred(64.3%). Dynamic substrates, like rope walkways, were used primarilyduring locomotion (33.8%) from one static location to another."

van Wagenen G 1950. The monkeys. In The Care and Breedingof Laboratory Animals Farris EJ (ed), 1-42. John Wiley, NewYork
"Sitting on the board [approximately 1 m off the groundof the room], facing the center of the room, is the favorite positionof the monkeys. At this height these intensely alert animals havea better view of activities within the room, and they can meetvisitors on the same eye level. ... and they sleep on the boardat night."

Watson DSB 1991. A built-in perch for primate squeeze cages.Laboratory Animal Science 41, 378-379
Perch installation design for single squeeze-back cages isdescribed. "Independent of gender the monkeys were seen usingtheir perches more than 84% of the time."

Watson SL, Shively CA 1996. Effects of cage configuration onbehavior in cynomolgus macaques. XVIth Congress of the InternationalPrimatological Society/XIXth Conference of the American Societyof Primatologists, Abstract No. 674
"Stereotypies occurred more often in the STD [standardsingle cage] than in the VE [vertically-enhanced; probably withperche(s)]. ... The results indicate that VE cages provide moresuitable individual housing environments for nonhuman primatesthan STD cages."

Watson SL, Gray A, Taylor E, JohnsonB, Fahm B, McGee A, Bingham W, Banks P 2002. Efficacy of environmental enrichment for garnett'sbushbaby (Otolemur garnettii).American Journal of Primatology 57, 38-39)
"Bushbabies interacted with swinging/climbing apparatisignificantly more than with manipulanda.... All animals spentsignificantly more time at the top than at the bottom of theircages (t(17)=3.3, p=.004). ... These results suggest that provisionof vertical space and swinging/climbing opportunities may be moreeffective forms of enrichment for bushbabies than provision ofmanipulanda."

Williams LE, Abee CR, Barnes SR, Ricker RB 1988. Cage designand configuration for an arboreal species of primate. LaboratoryAnimal Science 38, 289-291
"Squirrel monkeys preferred a poly-vinyl-chloride pipeperch (rigid) over rope perches (non-rigid). For an arboreal animal,a higher perch may be perceived as safer." Additional perchesdecreased the propensity for development of tail ulcers associatedwith floor contact. "With only one perch level, males wereforced to spend a large percentage of their time sitting on thefloor rather than the main perches [which were occupied by females]."

Wolff A 1989. Polyvinylchloride piping as perch material for squirrel monkeys. LaboratoryPrimate Newsletter 28(1), 7
"An additional unexpected benefit of the PVC piping hasbeen a decrease in dorsal tail-head abrasions, frequently seenin squirrel monkeys that sit on the stainless steel flooring ofstandard primate cages."

Woodbeck T, Reinhardt V 1991. Perchuse by Macaca mulatta in relation to cage location.Laboratory Primate Newsletter 30(4), 11-12
Single-housed "animals living in lower-row cages spentan average of 31.6% of the time perching on their pipes whileanimals living in upper-row cages perched only 6.9% of the time.Access to the vertical dimension of the cage was more importantfor the lower-row caged monkeys who continuously live close tothe ground, in the horizontal dimension of the room."

(6) PromotingObject-oriented Behavior

(6,1) Commercial Toys

Anonymous 1991. The psychological well-being of primates. PrimateNews 25(Fall), 3-5
"The problems with all these devices is that they areexpensive to purchase (foraging boards cost $60 each) and to maintain(they require many hours to fill and clean). "That is toughon an institution like ours," says Dr. Kelley, "thathas a large colony of animals. We could live with the expenseif we were certain that these devices really improve the well-beingof the animals. It seems, however, that after a short time theanimals lose interest in foraging boards, and fleece boards, justas they lose interest in balls and toys."

Bayne K 1989. Nylonballs re-visited. Laboratory Primate Newsletter 28(1),5-6
"Approximately 10% of the [single-housed] monkeys in aroom utilize the ball [Nylaball®]at any given time."

Bayne K, Hurst JK, Dexter SL 1992. Evaluation of the preferenceto and behavioral effects of an enriched environment on male rhesusmonkeys. Laboratory Animal Science 42, 38-45
"With simultaneous exposure, the single-housed subjectsspent the greatest portion of the interactive time [30 minute-observationsessions] on the perch [16.8%], the second greatest amount oftime spent divided approximately equally between interacting withthe Kong [5.0%] and Tug-A-Toy [4.9%], and the least amount oftime spent manipulating the grooming board [0.4%]."

Bayne K, Dexter SL, Hurst JK, Strange GM, Hill EE 1993. Kongtoys for laboratory primates: Are they really an enrichment orjust fomites? Laboratory Animal Science 43, 78-85
"The use of simple toys for environmental enrichment oflaboratory primates is an economical means of increasing the complexityof the cage environment to a limited degree. The limitations presentedby this method of enrichment include the finite ways in whicha simple device can elicit normative behaviors and the relativelyrapid habituation to the device." It was demonstrated thatmicrobial growth can persist on enrichment devices - such as Kongtoys - after they have been sanitized in a commercial cagewasher.

Bloomsmith MA, Finlay TW, Merhalski JJ, Maple TL 1990. Rigidplastic balls as enrichment devices for captive chimpanzees. LaboratoryAnimal Science 40(3), 319-322
"The mean percentage of ball-use time for all subjectsduring the study [first ten hours after initial presentation]was 7.1%. ... Age and housing effects were obtained, with youngeranimals and those housed in more barren environments exhibitinghigher levels of ball use. It is concluded that the balls wereworthwhile additions to the chimpanzee environments with use stabilizingat a mean of 2.5% of the subjects' time."

Brent L, Stone AM 1998. Destructible toys as enrichment forcaptive chimpanzees. Journal of Applied Animal Welfare Science1, 5-14
Nine singly caged chimpanzees were provided with eight differenttoys made of plastic, vinyl, or cloth one at a time or severalat once. The toys remained in the cages an average of three days."The chimpanzees varied greatly in their interest in thetoys. One subject rarely contacted the toys and others used thema great deal and quickly destroyed them."

Cardinal BR, Kent SJ 1998. Behavioraleffects of simple manipulable environmental enrichment on pair-housedjuvenile macaques (Macaca nemestrina). LaboratoryPrimate Newsletter 37(1), 1-3
"The teddy bear was preferred as a manipulable toy overthe pink teething ring and the green teething ring. Toy use declinedwith time, indicating that rotation of toys, at least in the shortterm, may increase use."

Crockett CM, Bielitzki JT, Carey A, Velez A 1989. Kongtoys as enrichment devices for singly-caged macaques. LaboratoryPrimate Newsletter 28(2), 21-22
"Providing objects such as Kong toys to macaques in single-animalhousing with little or no opportunity for manipulation is mildlyenriching to some of the monkeys. Periodically removing and reintroducingthe toys would increase their enrichment value."

Hamilton P 1991. Enrichment toys and tools in recent trials.Humane Innovations and Alternatives in Animal Experimentation5, 272-277
"When toys were left with an animal for several days,the individual became accustomed to and desinterested in the toy."

Kessel AL, Brent L 1998. Cage toys reduce abnormal behaviorin individually housed pigtail macaques. Journal of AppliedAnimal Welfare Science 1, 227-234
"Providing multiple manipulable toys as enrichment for[single-caged] pigtail macaques was effective in reducing abnormalbehavior" during 30-min observation session. "The useof the toys was reduced over time."

Line SW, Markowitz H, Morgan KN, Strong S 1989. Evaluationof attempts to enrich the environment of single-caged non-humanprimates. In Animal Care and Use in Behavioral Research: Regulation,Issues, and Applications Driscoll JW (ed), 103-117. AnimalWelfare Information Center, Beltsville
"Our experience with cage toys suggests that after a veryshort time (a few days or less), most macaques will lose interestin the objects that are offered."

Novak MA, Musant A, Munroe H, O'Neill PL, Price C, Suomi SJ1993. Old, socially housed rhesus monkeys manipulate objects.Zoo Biology 12, 285-298
"More than 10% of the [group-housed] females' time wasspent in object [toy] manipulation. ... Socially housed rhesusmonkeys ranging in age from 14 to 22 years showed steady ratesof object manipulation, and their interest in familiar objectsdid not appear to wane over time. .... Several factors [for interpretinghigher interaction rates in groups-housed than in single-housedanimals] should be considered, the first of which is social facilitation... Failure to manipulate objects in rhesus macaques appears tobe more a function of individual housing than of old age."

Paquette D, Prescott J 1988. Use of novel objects to enhanceenvironments of captive chimpanzees. Zoo Biology 7, 15-23
"Following their familiarization with the novel objects[rubber or plastic toys for small children], the [group-housed]chimpanzees' manipulation frequency decreased whereas self-groomingand abnormal behaviors were increased." The importance ofa periodical substitution of the objects was suggested to enhancetheir usefulness.

Plesker R, Heller-Schmidth J, HackbarthH 2006. Environmental enrichment objects for the improvementof locomotion of caged rhesus macaques (Macaca mulatta). Laboratory Primate Newsletter 45(1),7-10
Juveniles used the mobile objects [treadmill and rotatingbarrel] more than the adults. "Due to the increase in locomotion,the amount of time spent in aggressive behavior significantlydecreased."

Pruetz JD, Bloomsmith MA 1992. Comparingtwo manipulable objects as enrichment for captive chimpanzees.Animal Welfare 1, 127-137
"Paper was used a mean 27 per cent of the available time[one hour], while the Kong Toys were used a mean 10 per cent ofthe available time. ... Object use steadily declined over thefirst hour of exposure. ... Object use when the Kong Toy was presentdeclined over the course of the study, but use of the paper remainedconsistent. ... The destructible wrapping paper was more worthwhileenrichment object than the indestructible Kong Toy for the [group-housed]captive chimpanzees of this study."

Shefferly N, Fritz J, Howell S 1993. Toysas environmental enrichment for captive juvenile chimpanzees (Pantroglodytes). Laboratory Primate Newsletter 32(2),7-9
"Whereas contact with the indestructible toy ball decreasedover time, destructible objects maintained a consistent levelof interest throughout the toys lifespan. ... Provision of bothtypes of toys did not result in significant differences in thetime individuals spent in abnormal, or aggressive behavior. ...There were no health problems or injuries associated with thedestructible objects. No pieces of plastic were found in feces,indicating that none had been ingested."

Weick BG, Perkins SE, Burnett DE, Rice TR, Staley EC 1991.Environmental enrichment objects and singly housed rhesus monkeys:Individual preferences and the restoration of novelty. ContemporaryTopics in Laboratory Animal Science 30(5), 18
"We found that the extent of physical contact with the[Kong toy, Nylabone ring and Nylabone ball] toys habituated duringa short time. ... The introduction of a different toy every Mondaywas accompanied by a restoration of the apparent novelty of thetoys."

(6,2) Wooden Objects

*Baumans V, CokeC, Green J, Moreau E, Morton D, Patterson-Kane E, Reinhardt A,Reinhardt V, Van Loo P 2007 Making Lives Easier for Animalsin Research Labs - Chapter4.10. Wooden Objects. Washington, DC: Animal Welfare Institute
"I give our single-caged baboons 20 cm long gnawing sticksmade of pecan branches. They love them! It takes one totwo weeks for a stick to be "widdled" down to abouthalf of its size."

Eckert K, Niemeyer C, Anonymous , Rogers RW, Seier J, IngersollB, Barklay L, Brinkman C, Oliver S, Buckmaster C, Knowles L, PyleS 2000. Woodenobjects for enrichment: A discussion. Laboratory PrimateNewsletter 39(3), 1-4
"It seems that there is a general consensus that woodenobjects provide inexpensive, safe, long-term and effective stimulationfor the expression of non-injurious, species-typical behaviorssuch as perching, gnawing, gouging, manipulating and playing"without causing health and hygienic problems.

Hienz RD, Zarcone TJ, Turkkan JS, Pyle DA, Adams RJ 1998. Measurementof enrichment device use and preference in singly caged baboons.Laboratory Primate Newsletter 37(3), 6-10
"Baboons generally interacted less with Kongs than withlogs or swings. This trend, however, was not consistent for eachindividual animal. Of the six baboons, three clearly "preferred"the log (i.e., moved the log more than the other two devices),two preferred the swing, and one preferred the Kong. Thus thetrends expressed in the averaged data can be quite misleading."
="http:>

Hienz RD, Pyle DA, Frey JJ, Zarcone TJ, Adams RJ, Turkkan JS2000. Enrichmentdevice use by baboons during long-term vs. intermittent availability.Laboratory Primate Newsletter 39(2), 1-3
"Four of the six baboons increased their [cherry] loguse over the exposure period [104 days], while the remaining twobaboons decreased their interactions with their logs over thisperiod. ...When the logs were available only every other day,or every fourth day, log use was considerably enhanced on thosedays. When the logs were withheld longer, log use declined tothe same level of use observed when the logs were continuouslyavailable. These results suggest that leaving enrichment devicesout of a monkey's cage for extended periods would not be beneficialfor generating greater use."

Hienz RD, Jones A, Pyle DA, JohnsonJ 2002. Effectivenessof enrichment devices during brief periods of social restrictionin singly housed baboons. Laboratory Primate Newsletter41(3), 1-3
"Data were collected on the animals' (three singly cagedadult males) daily biscuit intake and activity levels as wellas log activity prior to, during, and following social restriction(housed in separate room in which no other animals are present),and also in the absence and presence of a log (hand-cut cherryhardwood logs; 9 cm diameter x 35 cm long). .. All three baboonsin the current study showed a marked decrease in activity duringthe brief periods of social restriction when the log enrichmentdevices were not available. However, once these devices were provided,general activity increased again, with two of the three baboonsincreasing their activity levels to near-normal. .. These findingspresent further support for the importance of enrichment devicesfor laboratory primates, showing that in the presence of suchdevices, the behavior of the animal is positively influenced.While the devices themselves were not manipulated greatly in thisstudy, their presence affected the activity of the baboons."

Line SW, Morgan KN 1991. The effects of two novel objects onthe behaviour of singly caged adult rhesus macaques. LaboratoryAnimal Science 41, 365-369
Single-housed subjects engaged in stick use 5.8% of 15 minute-observationsessions. The corresponding figure for nylon ball use was 2%."No adverse health effects of stick ingestion were notedamong the subjects."

Reinhardt V 1990. Time budget of caged rhesus monkeys exposedto a companion, a PVC perch and a piece of wood for an extendedtime. American Journal of Primatology 20, 51-56
"Sixty animals were continuously exposed for at least1.5 years to a compatible companion for social interaction, asuspended plastic pipe for perching, and a branch segment forgnawing." Individuals spent an average of 23.5% of the timeinteracting with the companion, 10.4% with the plastic pipe and4.8% with the branch segment.

Reinhardt V 1997. TheWisconsin Gnawing Stick. Animal Welfare Information Center(AWIC) Newsletter 7(3-4), 11-12
The sticks consist of branch segments cut of dead red oak trees.They are used by caged macaques about 5% of the time - more byyoung animals, less by adult animals - for gnawing, manipulatingand playing. "All caged rhesus macaques (more than 700 animals)and all caged stumptailed macaques (approximately 36 animals)have continual access to gnawing sticks since that time [1989].... Long-term exposure to the sticks has resulted in no recognizablehealth hazards."

(6,3) Mirrors

*Baumans V, CokeC, Green J, Moreau E, Morton D, Patterson-Kane E, Reinhardt A,Reinhardt V, Van Loo P 2007 Making Lives Easier for Animalsin Research Labs - Chapter4.5. Mirrors. Washington, DC: Animal Welfare Institute
"All of our single-housed long-tailed macaques have mirrorsmounted on swivels that are attached to the outside of their cages,low enough so that an animal can chose to either bend down andintentionally look into the mirror or to make no extra effort,hence not be confronted bothered? by the mirror reflection. Ourmonkeys use their mirrors frequently.
Our rhesus love mirrors too. They like to check us out by lookingat us through the mirror. I guess they don't feel so threatenedwhen they can look at us without being seen. They also like tocheck out the room, by looking at the reflections in the mirror.We have one male who never looks at people directly, but holdsup a polished stainless steel mirror to watch people who havejust entered the room. Of course, we named him Mirror Man.
We have found an acrylic sheet mirror that we can cut into different-sizepieces. Some get hung on the walls, using double sided tape, whileother pieces get hung right inside the enclosures, using zip ties.We also cut small pieces and give these directly to the primates.Our rhesus macaques often combine the wall and hand mirrors toget extra viewing advantage! It's really fun to watch them. Theacrylic leaves no sharp edges when it breaks; this means it issafe for the animals. We never encountered a problem.
Our singly housed baboons get the most enjoyment from their mirrors,while pair- and group-housed animals show little interest in them.
I have a male olive baboon in my charge who regularly sits forlong periods at a time looking at himself in a mirror. He is housedwith two females but appears to prefer looking at his own mirrorreflection versus the nice tumescent females hovering around him!He also uses his mirror to see reflections of what is going onbehind him, sitting diagonally with his back facing the main trafficarea for techs, as if he was spying on us! I do believe he isentertaining himself quite a bit with the mirror."

Brent L, Stone AM 1996. Long-term use of television, balls,and mirrors as enrichment for paired and singly caged chimpanzees.American Journal of Primatology 39, 139-145
"Chimpanzees used televisions, balls, and mirrors for0.27-1.53% of the observation time after several years of exposureto the enrichment items. Television and ball use were significantlyhigher than mirror use."

Goode TL, McPherson H, Hughes J, Conboy T, Smith S, Bone A,Zimmerman W, Holder D, Klein H 1998. Evaluation of stainless steelreflective discs as enrichment devices for rhesus monkeys (Macacamulatta) housed in a toxicological facility. ContemporaryTopics in Laboratory Animal Science 37, 100
"The enrichment device was used [probably by single-cagedsubjects] primarily for manipulation and banging. ... The usageof polished stainless steel discs declines over time and thereforealternative methods of environmental enrichment and rotation ofenrichment devices should be considered."

Harris H 2002. Mirrorsas enrichment for monkeys. Laboratory Animal Refinementand Enrichment Forum (electronic discussion group), November13, 2002
"Our African green monkeys (all males) and cynomolgusmacaques use the mirrors more than the rhesus and squirrel monkeys... The mirrors are utilized by singly-caged, paired and grouphoused monkeys. They use them to look at themselves and at otherthings inside and outside the room. We have had a few (less than10) occurrences where the monkeys were too fearful or self-aggressiveto keep a mirror on their cage, but by far, the majority benefitfrom them. The mirrors, in my opinion, are one of our most usefulobject enrichment items."

O'Neill PL, Wright AC, Weed JL 1997. Curious response of threemonkey species to mirrors. American Zoo and Aquarium Association(AZA) Regional Conference Proceedings, 95-101
One mirror was hung on the front of each subject's cage andremained in place for a two-week study period. Pig-tailed macaquescontacted the mirror at a fairly constant rate of 12-18 timesper hour. Rhesus macaques were initially interested in the mirror,but contact rate per hour progressively dropped to only 6 at theend of the second week. Long-tailed macaques showed little interestin the beginning, but contact rates reached those of pig-tailedmacaques at the end of the study.

(7) Promoting Curiosity Behavior

(7,1)Television and Videos

Bloomsmith MA, Lambeth SP 2000. Videotapes as enrichment forcaptive chimpanzees (Pan troglodytes). Zoo Biology19, 541-551
"Individually housed subjects watched the videotapes morethan socially housed subjects. When viewing time was averagedacross all videotapes, the chimpanzees watched the monitor a meanof 38.4% of the time available. ... Subjects habituated to repeatedpresentations of the videotapes, although the effect was smallnumerically. Although this type of enrichment did not extensivelyalter behavior, it did occupy a significant portion of the subjectsactivity budget."

Bloomsmith MA, Lambeth SP, Perlamn JE, Hook MA, Schapiro SJ2000. Control over videotape enrichment for socially housed chimpanzees.American Journal of Primatology 51, Supplement 1, 44-45
Social behavior and solitary play were higher in subjects withcontrol over the onset of videotapes, while scratching [generallyregarded as a sign of tension] was higher in those groups wholacked control. "The results indicate that giving chimpanzeescontrol over videotaped enrichment had limited, but positive,effects on behavior."

Harris LD, Briand EJ, Orth R, Galbicka G 1999. Assessing thevalue of television as environmental enrichment for individuallyhoused rhesus monkeys: A behavioral economic approach. ContemporaryTopics in Laboratory Animal Science 38(2), 48-53
"The negative demand curve suggested that TV is not avalued commodity" for single-caged rhesus macaques.

Lambeth S, Bloomsmith M, Baker K, Perlman J, Hook M, SchapiroS 2001. Controlover videotape enrichment for socially housed chimpanzees: Subsequentchallenge tests. American Journal of Primatology 54(Supplement1), 62-63
"The lower expression of stressrelated behaviors by chimpanzeesthat took advantage of the opportunity to control the videotapeapparatus implies that exerting control over the environment mayhave a generalized effect by lessening disturbance caused by mildlychallenging situations."

O'Neill-Wagner P 2001. Videotapeexposure may facilitate recovery for monkeys in a clinical setting.American Journal of Primatology 54(Supplement 1), 59
"During videotape exposure monkeys did not remove theirsutures. Animals that had previously withdrawn from food wereobserved eating during videotapes showing primates eating."

Platt DM, Novak MA 1997. Videostimulation as enrichment forcaptive rhesus monkeys (Macaca mulatta). Applied AnimalBehaviour Science 52, 139-155
The animals spent substantially more time watching selectedvideotapes than manipulating the joystick.

Plesker R, Herzog A 2001. Primahedrons, puzzle feeders and television as environmental enrichmentfor captive African Green Monkeys. Primate Eye, 4
"The access to television (mainly nature films) enhancedthe observation behaviour of the whole group for a short time.Again, the adult males, but also the youngest offspring did notappear to be interested."

Rumbaugh DM, Washburn DA, Savage-Rumbaugh ES 1989. On the careof captive chimpanzees: Methods of enrichment. In Housing,Care and Psychological Wellbeing of Captive and Laboratory PrimatesSegal EF (ed), 357-375. Noyes Publications, Park Ridge
"Television can be a great source of environmental enrichmentif the chimpanzee can perceive the relevance of what it sees onthe screen to the world it knows."

(7,2)Windows

*Baumans V, CokeC, Green J, Moreau E, Morton D, Patterson-Kane E, Reinhardt A,Reinhardt V, Van Loo P 2007 Making Lives Easier for Animalsin Research Labs - Chapter4.7. Windows. Washington, DC: Animal Welfare Institute
"We expose our squirrel monkeys to natural daylight viabig windows during the summer. This is supplemented with artificiallight in late fall and early spring, when the days are short,and throughout the winter. Some of our squirrel monkeys will lieas close to the window as possible and let the sun rays danceon their belly.
I've seen the same behavior in our marmosets. As soon as the sunlighthits the window, the animals stop what they are doing, run overto the window ledge, and start stretching out and basking in thesunrays. There is no doubt in my mind that exposure to naturallight, especially sunlight, is highly appreciated by the animals.
All our rhesus macaques have access to one-way glass exteriorwindows mounted high above ground level. I very often see theanimals gather up, attentively gazing out of the windows towardsthe source of some noise, at caretakers, activities in the gardenand birds. One would think that exposure to daylight and the naturaldiurnal rhythm couldn't be anything else but a good thing forthese animals."

Lynch R, Baker D 2000. PrimateEnrichment: A room with a view. Laboratory Primate Newsletter39(1), 12
Pairs were transferred to a play room with windows for 1½hours every ten days. "During the past year, we have observedthat the primates spend about an hour of their time looking outthe windows."

(8) Safety Concerns

Eckert K, Niemeyer C, Anonymous , Rogers RW, Seier J, IngersollB, Barklay L, Brinkman C, Oliver S, Buckmaster C, Knowles L, PyleS 2000. Woodenobjects for enrichment: A discussion. Laboratory PrimateNewsletter 39(3), 1-4
"It seems that there is a general consensus that woodenobjects provide inexpensive, safe, long-term and effective stimulationfor the expression of non-injurious, species-typical behaviorssuch as perching, gnawing, gouging, manipulating and playing"without causing health and hygienic problems.

Etheridge MA, O'Malley J 1996. Diarrhea and peritonitis dueto traumatic perforation of the stomach in a rhesus macaque (hardwaredisease). Contemporary Topics in Laboratory Animal Science35(5), 57-78
"Abdominal radiographic views indicated ingestion of approximately20 pieces of wire that came from an old automobile tire hung inthe outdoor monkey pen to provide environmental enrichment."

Hahn NE, Lau D, Eckert K, Markowitz H 2000. Environmental enrichment-relatedinjury in a macaque (Macaca fascicularis): Intestinal linearforeign body. Comparative Medicine 50, 556-558
"As a result of this incidence [ingested sisal rope piecesleading to multiple ulcerations, perforations, septic peritonitis]sisal rope enrichment devices were immediately removed from allmacaque cages in the facility."

Mahoney CJ 1992. Some thoughts on psychological enrichment.Lab Animal 21(5), 27,29,32-37
"Facilities must exercise caution when installing suchclimbing devices as vertically hanging or horizontally suspendedropes and chains - these must not crisscross or be too slack,because an animal can strangle its neck, limbs, or other bodyparts."

Murchison MA 1993. Potentialanimal hazard with ring toys. Laboratory Primate Newsletter32(1), 1-2
"Recently one animal, a 2-year-old pigtail macaque (Macacanemestrina), approximate weight 3.1 kg, became trapped insidea Nylaring. The ring went around the neck, across the body, andunder one arm. Since the animal was apparently unable to removethe ring, he was anesthetized and the ring manually removed."

Novak MA, Rulf A, Munroe H, Parks K, Price C, O'Neill PL, SuomiSJ 1995. Using a standard to evaluate the effects of environmentalenrichment. Lab Animal 24(6), 37-42
Monkeys maintained on pine wood shavings for a long periodof time showed an increase in agonism, scratch, and stereotypy.

Reinhardt V 1997. TheWisconsin Gnawing Stick. Animal Welfare Information Center(AWIC) Newsletter 7(3-4), 11-12
"All caged rhesus macaques (more than 700 animals) andall caged stumptailed macaques (approximately 36 animals) havecontinual access to gnawing sticks since that time [1989]. ...Long-term exposure to the sticks has resulted in no recognizablehealth hazards."

Shefferly N, Fritz J, Howell S 1993. Toysas environmental enrichment for captive juvenile chimpanzees (Pantroglodytes). Laboratory Primate Newsletter 32(2),7-9
"Whereas contact with the indestructible toy ball decreasedover time, destructible objects maintained a consistent levelof interest throughout the toys lifespan. ... There were no healthproblems or injuries associated with the destructible objects.No pieces of plastic were found in feces, indicating that nonehad been ingested."

Tresz H 1997. Providing enrichment at no cost. The Shapeof Enrichment 6(4), 1-4
"Green pine cones can cause severe diarrhea. Keepers shouldwork only with old, opened-up pinecones."

Regulationsand Guidelines

American Society of Primatologists2000. American Society of Primatologists guidelines for the ethicaltreatment of nonhuman primates. ASP Bulletin 24(4), 4
"ASP members hold the following general principlesin common:
1. The most important of these principles is that we accept theresponsibility of stewardship for nonhuman primates, and thisresponsibility must [sic] be reflected in our husbandrypractices and research protocols whether in field, laboratory,or other setting.
3. Research with nonhuman primates should avoid pain and distressat every opportunity.
5. We should make use of information on a species natural historyto improve management and enrich environments, because physicaland psychological well-being are essential not only to the healthof the animals but also to the validity of the research results.
6. Finally, we recognize that our concern should be extended tononhuman primates once they have become 'surplus' to our researchneeds. This obligation entails ensuring quality care to the endof their natural lives whenever possible. .. While recognizingthat some professional believe euthanasia is an acceptable wayto deal with surplus animals in some cases, we strongly u

Share This!