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Environmental enrichment

UFAW has done much to encourage enrichment of captive animal environments and the development of better housing and husbandry systems. Environmental enrichment is a term used to describe changing a captive animal’s environment in a way that improves the animal’s quality of life. Captive environments are often safer than the wild but can also be less challenging and stimulating. The goal of environmental enrichment is to make the environment more complex and dynamic, to provide more stimulating, cognitive challenges, and opportunities to make choices, control social interactions and behave in more diverse species-specific ways. Environmental enrichment is usually carried out using one of the following approaches: Social (contact or non-contact); Occupational (psychological, e.g. puzzles, and exercise e.g. mechanical devices or access to a run); Physical (enclosure design, e.g. size or complexity, and accessories, e.g. toys); Sensory (visual, auditory, olfactory, tactile, taste); Nutritional (delivery of food, e.g. frequency, schedule, presentation, and type of food e.g. novelty and variety) (1).

In 1987 UFAW funded one of the first research programmes into environmental enrichment – the aim of the study, carried out by Dr David Shepherdson, was to identify and provide sufficiently complex and stimulating environments so that animals could develop and display improved repertoires of natural behaviour. One of the biggest differences between the wild and the captive environment is the amount of time animals spend active – feeding, foraging and exploring their habitat.  In captivity, food is usually made available once or twice a day and in quantities that are sufficient to meet the animals’ daily dietary needs.  Dr Shepherdson’s work, carried out with the Zoological Society of London, resulted in the development of practical nutritional environmental enrichment options, including a puzzle feeder for orang-utans and simple cricket and mealworm feeders to enrich the environment of small carnivores such as meerkats. Wild animals also often spend much of their time protecting their territory, and another device developed as a result of this project was a system to play back calls from a neighbouring pair of gibbons (as would happen in the wild)

UFAW also produced a video on ‘Environmental Enrichment: Advancing Animal Care’ (1990), and published guidance on ‘Inexpensive Ways of Improving Zoo Enclosures for Mammals’. Additionally, following public concern about stereotypies (which are considered to be abnormal behaviours) in captive polar bears, UFAW supported research, and produced an educational video on the provision of enrichment for polar bears (2), as well as a report providing practical guidance and recommendations on the welfare and management of bears in zoological gardens.  A workshop on the subject was also held for zoo professionals.

Since 2000, UFAW has supported a range of research including projects on the causes of the development of stereotypies in captive carnivores; the welfare, housing and husbandry of elephants in UK zoos; the use of positive reinforcement training techniques on stress levels in chimpanzees; the use of puzzles to enhance the welfare of great apes; and the effects of management and climate on the behaviour of polar bears. Some of these projects have been carried out by students, so serving to train those who will work with or study these animals in the future and these can also provide useful information. For example, Fay Clark (Royal Veterinary College, UK) evaluated the enrichment effect of a novel cognitive challenge device for zoo-housed chimpanzees (Pan troglodytes). She designed a puzzle device that required chimpanzees to manoeuvre food items through a novel, grid-like maze using their fingers or tools. She found that the chimpanzees were engaged and used the device but it was most used and brought the greatest benefits when the task was less complex, more predictable and more controllable, that is, not so difficult as to cause frustration.

Similarly, Hannah Trayford of the University of Cambridge Wildlife Group examined the welfare of captive orang-utans in various rehabilitation centres in Indonesia, and found that providing complex and stimulating environments helped improve the psychological and physiological characteristics of the orang-utans. She suggested that enrichment should preferably be goal-directed and relevant to survival skills by, for example, developing the complex locomotor skills and ability to solve problems that these animals will need in their natural forest habitat.

For many years UFAW also sought to promote and encourage good examples and improvements in zoo animal housing and husbandry through the ‘Zoo Animal Welfare Award’, which later became the ‘UFAW Wild Animal Welfare Award’. This scheme ran from 1986 to 2010, and during this time various innovations and advancements were supported and celebrated.

Zoos raise funds to keep and care for captive wild animals by putting their animals on display; exposing them to large numbers of people that the animals, if they had the choice, would in most cases make great efforts to avoid. This ‘visitor effect’ can impact adversely on their welfare, with some species being particularly sensitive. In 2007 Chester Zoo won the UFAW Wild Animal Welfare Award for its environmental enrichment study determining the beneficial effects of using plants as a partial visual barrier between visitors and the glass front of a mandrill enclosure. Mandrills, the world’s largest species of monkey, were monitored at the zoo and it was found that the presence of visitors caused them to exhibit abnormal and aggressive behaviours such as banging the glass, baring teeth and hair plucking. Planting produced an immediate reduction in these stress-related behaviours and an increase in positive behaviours such as playing and feeding. Dr James Kirkwood, UFAW’s Chief Executive and Scientific Director at the time, said; “Studies of wild animals, in captivity and in the wild, are essential if, as the human population continues to rapidly expand, we are to find ways to co-exist without harming other species. These projects are excellent examples of scientific studies aimed at improving welfare in our interactions with other animals”.

As well as supporting and recognising valuable research, UFAW also seeks to publish and disseminate information and in 2003 UFAW published the first book in the UFAW Wiley Animal Welfare series. ‘Environmental Enrichment for Captive Animals’, by Robert J Young has proven to be an important educational resource, drawing attention to the importance of enrichment, especially for zoos where the ultimate aim may be reintroduction of animals into complex natural environments. Young also provided practical exemplars and discussed how to research and assess enrichment to ensure that it really does improve animal welfare. Many articles on captive wild animal welfare have also been published in the UFAW journal Animal Welfare.


  • Young RJ. 2006. Environmental Enrichment for Captive Animals. UFAW Animal Welfare Series. Blackwell Publishing. 240pp.
  • Ames A. The Behaviour of Captive Polar Bears. UFAW Animal Welfare Research Report No. 5. UFAW. A4. 67pp

Selected papers on environment enrichment published in the UFAW Journal, Animal Welfare:

Hacker CE, Miller LJ, Schulte BA. 2018. Examination of enrichment using space and food for African elephants (Loxodonta Africana) at the San Diego zoo safari park. Animal Welfare, 27(1): 55-65. UFAW.

Troxell-Smith SM, Whelan CJ, Magle SB, Brown JS. 2017. Zoo foraging ecology: development and assessment of a welfare tool for captive animals. Animal Welfare, 26(3): 265-275. UFAW.

Suárez, P; Recuerda, P; Arias-de-Reyna, L. 2017. Behaviour and welfare: the visitor effect in captive felids. Animal Welfare, 26(1): 25-34. UFAW.

Martínez-Macipe M, Lafont-Lecuelle C, Manteca X, Pageat P, Cozzi A. 2015. Evaluation of an innovative approach for sensory enrichment in zoos: semiochemical stimulation for captive lions (Panthera leo). Animal Welfare, 24(4): 455-461. UFAW.

Haspeslagh M, Stevens JMG, De Groot E, Dewulf J, Kalmar ID, Moons CPH. 2013. A survey of foot problems, stereotypic behaviour and floor type in Asian elephants (Elephus maximus) in European zoos. Animal Welfare, 22(4): 437-443. UFAW.

Mallavarapu S, Bloomsmith MA, Kuhar CW, Maple TL. 2013. Using multiple joystick systems in computerised enrichment for captive orangutans. Animal Welfare, 22(3): 401-409. UFAW.

Phillips CJC, Jiang Z, Hatton AJ, Tribe A, Le Bouar M, Guerlin M, Murray PJ. 2011. Environmental enrichment for captive Eastern blue-tongue lizards (Tiliqua scincoides). Animal Welfare, 20(3): 377-384. UFAW.

Bicca-Marques JC. 2011. The effect of environmental enrichment and visitors on the behaviour and welfare of two captive hamadryas baboons (Papio hamadryas). Animal Welfare, 20(4): 573-579. UFAW.

Kistler C, Hegglin D, Würbel H, König, B. 2010. Structural enrichment and enclosure use in an opportunistic carnivore: the red fox (Vulpes vulpes). Animal Welfare, 19(4): 391-400. UFAW.

Wells DL, Irwin RM. 2008. Auditory stimulation as enrichment for zoo-housed Asian elephants (Elephas maximus). Animal Welfare, 17(4): 335-340. UFAW.

Tarou LR, Kuhar CW, Adcock D, Bloomsmith MA, Maple TL. 2004. Computer-assisted enrichment for zoo-housed orangutans (Pongo pygmaeus). Animal Welfare, 13(4): 445-453. UFAW.

Blaney EC and Wells DL. 2004. The influence of a camouflage net barrier on the behaviour, welfare and public perceptions of zoo-housed gorillas. Animal Welfare, 13(2): 111-118. UFAW.

Pepperberg IM. 2004. Cognitive and communicative capacities of Grey parrots – implications for the enrichment of many species. Animal Welfare, 13(Suppl. 1): 203-208. UFAW.

Birke L. 2002. Effect of browse, human visitors and noise on the behaviour of captive orangutans. Animal Welfare, 11(2): 189-202. UFAW.

Hosey GR. 2000. Zoo animals and their human audiences: what is the visitor effect? Animal Welfare, 9(4): 343-357. UFAW.

Schapiro  SJ, Bloomsmith MA, Suarez SA, Porter LM. 1997. A comparison of the effects of simple versus complex environmental enrichment on the behaviour of group-housed, subadult rhesus macaques. Animal Welfare, 6(1): 17-28. UFAW.

Robinson HM. 1998. Enriching the lives of zoo animals, and their welfare: where research can be fundamental. Animal Welfare, 7(2): 151-175. UFAW.

Gilloux I, Gurnell J, Shepherdson D. 1992. An enrichment device for Great apes. Animal Welfare, 1(4): 279-289. UFAW.


Other UFAW publications:

Ames A. 1993. The Behaviour of Captive Polar Bears. UFAW Animal Welfare Research Report No. 5. UFAW. A4. 67pp

Dickie LA. 1994. Environmental enrichment in captive primates: A survey and review. UFAW. A4. 88pp