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                                                                                                 Hilda Tresz                          Global Volunteer Work
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Chengdu Zoo 

February 15-19, 2014                        


To provide information regarding exhibit improvements, zoo-wide animal training, basic husbandry and enrichment and to hold educational workshops                  

Chimpanzees (Pan troglodytes ?) Subspecies unknown

Suggestions: Subspecies needs to be determined by DNA testing.


Female 乖乖 (Guai guai) was born in Beijing on 26 January 2006; male 宝宝 (Bao bao) was born in Beijing on 9 January 2006. They were transferred to Chengdu on 20 September 2007.

Chimpanzee Exhibit

The chimpanzee exhibit was satisfactory in size with natural soil and plenty of climbing structures. The night house was large enough, made of concrete and metal. I was most happy to find the chimpanzees on substrate when kept inside. The animals were locked inside during the wintertime.






To further improve quality, permanent furniture needs to be installed, especially sleeping nests. The nests should be installed as high as possible both in the                                                                     on- and off-exhibit areas. Please review example pictures below.


Metal basket, hammock and platform for sleeping furniture both inside and outside 






The night houses could utilize three dimensions by adding large tree trunks, ropes, fire hoses, hammocks, wooden shelves, etc to increase space and allow opportunities for exercise, exploration and manipulation
Boomer ball products are not so easy to come by in China, but recycled household products (cereal boxes, ardboard boxes, plastic bottles, barrels, plastic cups, old plush toys, towels, clothing, tires, etc.) can be easily incorporated as enrichment/toys.
It would be preferable to add more windows or skylights to increase light. It would also be advantageous to build double sliding doors (one being solid and the other one built from bars and mesh) such that the night houses and the exhibit could be connected with a “Round Robin” system, allowing animals to move about in circular ways and not just a linear fashion. This system could be used for all other species as well and would help with introductions or with shifting animals more easily and quickly.
Chimpanzees can be allowed outside for limited time during the winter; however, they need to have access to inside heat and be provided with extra blankets. Some institutions keep to a temperature guideline and will only let their chimpanzees out if the temperature reaches 10-13 C, while others, such as Chimpanzee Sanctuary Northwest, USA, allow the chimpanzees to make their own decision. It is important, however, that chimpanzees truly have a choice to seek warmth if allowed outdoor access during cold weather. And there might be a temperature so low that outdoor access is inappropriate.Generally though, the only time these institutions don't allow chimpanzees outside is when heavy, wet snow reduces the voltage on their electric fences.  
Chimpanzees in Snow: Google Search
Wales Ape and Monkey Sanctuary, U.K  Snow day for the chimpanzees at Saint Louis Zoo: YouTube Saint Louis Zoo, USA  
General Propositions:    
Night Houses, Off-Exhibit Areas and Correct Substrate Use

Many animals (mostly carnivores and primates) were kept on sterile surfaces with reduced chance for exploratory behaviours. This practice likely originated out of good intent to keep a clean environment for the animals, as it appears to be a cultural inheritance that if an exhibit is not hosed frequently, than the animals are not being well cared for. However, this practice creates poor conditions for the animals. The problem was most prominent at the Children’s Zoo area, where small lambs were shivering on ice-cold, wet concrete in the middle of winter. Farm animals were covered with a mixture of water, urine and fecal matter up to their knees with no way of drying off or warming up.

Begin keeping animals off unyielding surfaces (brick, concrete, etc.),especially species that have sicknesses (Rhesus macaques with fur problems). The use of appropriate substrate (inside- paper products, hay or straw, etc.; outside- nonflammable materials such as grass, sand, soil, mulch, fresh browse, etc.) will make a significant difference not only in the animals’ mental and physical health, but also in improvement of the exhibit aesthetics. Using substrate will also reduce cleaning time and water consumption. Soaking, scrubbing and hosing dry waste takes much longer than spot cleaning due to substrate absorbing urine and covering feces. Reducing hosing and partially covering surfaces with substrate will overcome any of these obstacles and provide animals with a soft surface.
Solitary Primates
Several primate species were kept on bare concrete and also in solitary confinement without any visual or tactile opportunities with other primates. Social isolation and reduced space allowance have been documented to cause increased levels of aggression and stress levels in a range of captive wild animals from primates to dolphins.
Solitary primates need to be able to see, smell and touch other primates, even if it is a different species, until they are paired up with their conspecific. Please review laws and guidelines regarding social keeping of primates:

Title 9, Code of Federal Regulations, Subchapter A – Animal Welfare Part 3 Standards, Subpart D Specifications for the Humane Handling, Care, Treatment, and Transportation of Nonhuman Primates, Section 3.81

Sec. 3.81 Environment enhancement to promote psychological well-being.

Dealers, exhibitors, and research facilities must develop, document, and follow an appropriate plan for environment enhancement adequate to promote the psychological well-being of nonhuman primates. The plan must be in accordance with the currently accepted professional standards as cited in appropriate professional journals or reference guides, and as directed by the attending veterinarian. This plan must be made available to APHIS upon request, and, in the case of research facilities, to officials of any pertinent funding agency. The plan, at a minimum, must address each of the following:


(a) Social grouping. The environment enhancement plan must include specific provisions to address the social needs of nonhuman primates of species known to exist in social groups in nature.

Individually housed nonhuman primates must be able to see and hear nonhuman primates of their own or compatible species unless the attending veterinarian determines that it would endanger their health, safety, or well-being.


Canadian Council on Animal Care, Olfert ED, Cross BM, McWilliam AA 1993. Guide to the Care and Use of Experimental Animals, Volume 1, 2nd Edition. Canadian Council on Animal Care, Ottawa
"The social needs of animals used in research, teaching, or testing, should be given equal consideration with environmental factors such as lighting, heating, ventilations and containment (caging). Particularly in the case of singly housed animals, daily observation provides an alternative from of social contact for the animal and commonly facilitates handling in that the animal becomes accustomed to the human presence. .. Most animals should not be housed singly unless required by medical condition, aggression, or dictates of the study. Singly housed animals should have some degree of social contact with others of their own kind. ... In the interest of well-being, a social environment is desired for each animal which will allow basic social contacts and positive social relationships. Social behaviour assists animals to cope with circumstances of confinement."

European Commission 2002.The Welfare of Non-human Primates - Report of the Scientific Committe on Animal Health and Animal Welfare. European Commission, Strasbourg, France
"Primates should not be housed singly unless fully justified by health considerations (for the animal and human handler) or research procedures, as advised following an ethical review process. If primates have to be singly housed, the animals should have visual, olfactory and autitory contact with conspecifics.”

International Primatological Society 1993. IPS International guidelines for the acquisition, care and breeding of nonhuman primates, Codes of Practice 1-3. Primate Report 35, 3-29
" A compatible conspecific probably provides more appropriate stimulation to a captive primate than any other potential environmental enrichment factor. ... Monkeys should, unless there are compelling reasons for not doing so, be housed socially. ... Young monkey should not normally be separated from its mother at an early age (i.e., at 3-6 months) but should remain in contact for one year to 18 months, in most species. There is unlikely to be any greater productivity through early weaning, in seasonally breeding species, such as rhesus monkeys. Even in non-seasonal breeders, any slight increase in productivity must be offset against the resulting behavioural abnormalities of the offspring."

National Research Council 1996. Guide for the Care and Use of Laboratory Animals, 7th Edition. National Academy Press, Washington
"Animals should be housed with the goal of maximizing species-specific behaviors and minimizing stress-induced behaviors. For social species, this normally requires housing in compatible pairs or groups."

National Research Council 1998. The Psychological Well-Being of Nonhuman Primates. National Academy Press, Washington
"Social interactions are considered to be one of the most important factors influencing the psychological well-being of most nonhuman primates. ... The common practice of housing rhesus monkeys singly calls for special attention [p. 99] ... Every effort should be made to house these [singly caged] animals socially (in groups or pairs), but when this is not possible, the need for single housing should be documented by investigators and approved by the IACUC. ... The animal technician's and caregiver's roles are pivotal to the social support of primates, particularly animals that are singly caged."


Immediate improvements:

         At the Carnivore area, a keeper started to make immediate changes and the animals showed instant positive response.

         At the Primate area a single housed male squirrel monkey was immediately introduced to two other squirrel monkeys.

         Farm area staff refused any collaboration with the consultant.




The zoo has a large amount of edible vegetation available on grounds that can provide fresh, leafy branches (browse).


Browse should be provided at least every 2-3 days, but if possible, every day for animals that need it. The zoo can plant edible trees, bushes and even crops inside and outside of exhibits, along visitor pathways and resting areas that will provide future browsing materials for growing collection demands. Whether cut by staff or available by natural damage, fallen vegetation can be used rather than wasted.


Correct Furniture




During the winter, animals (especially tropical animals) need to spend large amounts of time in front of heating units. Resting areas (platforms, baskets, etc.) in front of the heating units are preferred. They are more comfortable for the animals and less of a safety and burn hazard. Heating units should be elevated to higher parts of exhibits for arboreal animals, such as squirrel monkeys.

Mixed Species Exhibits

Mixed species exhibits can be created in order to free up space and develop a more esthetic, complex exhibition. This type of exhibit also resolves certain problems associated with housing otherwise social species alone until they are paired paired with a conspecific. Please review the photos of Phoenix Zoo mixed exhibits.



Pet Trade

Outside vendors selling pets at the front gate should not be encouraged. These animals are kept in substandard circumstances such as small, sterile cages without shelter from the elements (fish in Ping-Pong ball size containers, guinea pigs freezing during winter without substrate, etc.). Chengdu Zoo, as one of the top four zoos in China, did a great job on animal conservation and education, while such vendors just send wrong message to visitors and could easily hurt Chengdu Zoo’s reputation.



Extending Foraging Time


All animals need to be fed in a way that their foraging time is extended and proper species-specific behaviors are encouraged. If no one can be appointed for this position, staff can be scheduled to cut browse and chop diet on a rotation basis.


Keepers were often observed smoking, some of them inside the night house right next to the animals.


The zoo should change its smoking policy by creating designated smoking areas for visitors with tables, chairs, ashtrays and garbage cans. All visitors that want to smoke should be directed to these areas. In addition, keepers should no longer smoke in front of visitors and absolutely should not smoke inside the animals' night houses and/or next to the animals. Keepers must also have designated smoking areas behind the scenes, out of visitor view. Keepers should only smoke during their breaks. 


The following PowerPoint presentations were given to all staff: 

         Lack of Substrate Use in Zoos addresses the easy fix of empty cages and shows how much benefit there is in the animals’ lives when provided with substrate (i.e., when they do not have to sit inside of empty, concrete cages). This is probably the most important animal welfare presentation to give out of the five.

         Contra Freeloading at the Phoenix Zoo talks about extending foraging times by making animals work for their food in ways similar to their wild counterparts, instead  of eating diet in short periods of time from provided dishes.

         The Beneficial Browse presentation provides guidelines on how to develop a low cost, zoo-wide browse program in the middle of the Sonoran Desert. It also addresses the major changes that fresh, leafy greens can make in the animals’ lives.

         Let Them Be Elephants addresses the changes the Phoenix Zoo made in our elephants’ lives, how we helped their behaviors by teaching them how to correctly forage and behave like normal females. It also talks about basic husbandry, enrichment ideas and health care.

 Presentations are available at htresz@thephxzoo.com.

I would like to thank the Chengdu Zoo’s director and staff, as well as the Chinese Association of Zoological Gardens (CAZG), for their incredible hospitality — making me feel so welcomed.

I would also like to thank Animals Asia Foundation for funding and organizing this trip and to establish such a wonderful, working relationship between the Jane Goodall Institute, the Phoenix Zoo and the Chengdu Zoo.



Harris,S. & Lossa, G & Soulsbury, S.D. A review of the welfare of wild animals in circuses

School of Biological Sciences, Woodland Rd, University of Bristol, Bristol, BS8 1UG http://www.rspca.org.uk/ImageLocator/LocateAsset?asset=document&assetId=1232714755621&mode=prd

Hemsworth, P.H. & Barnett, J.L. (2000) Human-animal interactions and animal stress. In: The biology of animal stress (eds. Moberg, G.P. & Mench, J.A.), pp. 309-335. CABI.Publishing, Oxon, UK

Morgan, K.N. & Tromborg, C.T. (2006) Sources of stress in captivity. Applied Animal Behaviour Science doi: 10.1016/j.applanim.2006.05.032

Moberg, G.P. (2000) Biological response to stress: implications for animal welfare. In: The biology of animal stress (eds. Moberg, G.P. & Mench, J.A.), pp. 1-21. CABI. Publishing, Oxon, UK

Tresz,H. (2011). The lack of substrate use in zoos, ICEE.

CNN Wire Staff (2011). Animal performance ban looms in China

Morgan, K.N. & Tromborg, C.T. (2006) Sources of stress in captivity. Applied Animal Behaviour Science 10.1016/j.applanim.2006.05.032http://www.reed.edu/biology/professors/srenn/pages/teaching/2008_syllabus/2008_readings/1_MorganTromborg2008.pdf











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