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Environmental enrichment for lorises and pottos

Behaviour supported:
Gauging / gnawing holes in tree bark; feeding on sap or gum
Under construction, incomplete
After finishing this part of the database, there will be index page for different enrichment methods and reviews of methods recommended for different lorisid species. This is just a first model for a possible form of our enrichment pages. Contributions and ideas for improvement would be appreciated.
Compiled by H. Schulze. Coauthors (in alphabetic order): Anne Miehs (Nocturnal Primate Reseach Group), Danielle Smith (London Zoo), Ulrike Streicher (Endangered Primate Rescue Center, Vietnam)

Content:

Behaviour supported by recommended enrichment methods

Enrichment methods, tested in lorises:
Live trees for harvesting fresh branches for gauging. Developed, tested by Ulrike Streicher, Endangered Primate Rescue Center, Vietnam.
Coconut shell with a section of apple inside. Developed and tested by Danielle Smith, London Zoo.
Melon shells hung up in the cage. Developed and tested by Danielle Smith, London Zoo.

Some safety and health considerations

Developed for other species, not yet tested in lorises:
Artificial gum tree. Literature reference, some details will be quoted later.

References
 


Behaviour supposed to be encouraged

Fresh tree sap and, to a lesser degree, gum (older, hardened sap) appear to be an important food item for most loris and potto species, maybe providing important nutrients like calcium, magnesium and potassium otherwise lacking in the diet (Barret 1984). In the wild, feeding on sap or gum, including some tree-bark gouging behaviour, has been described for most lorisid species.
Gum (old hardened sap) may be freely available and is an energy-rich food item for animals able to digest heteropolysaccharides. Digestion requires some adaptation of the intestine like enlarged, sacculated parts of the colon. Perodicticus potto edwardsi for instance are partly gum-eaters during dry season when other food is scarce (Oates, 1984) and have such adaptations (Osman Hill, Rewell 1948). Malaysian N. c. coucang lack the intestinal adaptation, gum-eating in the wild occurs, but apparently the gum is only partly digested (Wiens 2002).
Similar tree-gouging and feeding on sap or gum is also common in marmosets.
 

Nycticebus pygmaeus, Vietnam, gauging holes into tree bark. Photo from Streicher 2004. The same tree as in the left figure during day, showing the area where sap oozes out. Photo from Streicher 2004. Such gnaw marks (“gouges”) in the wild in a tree visited by N. pygmaeus have also been reported earlier by Tan (1994). Family group of pygmy marmosets gauging holes. The trunks and large branches of trees used this way are riddled with small and shallow holes which appear to be drilled, presumably gnawed by the marmosets themselves with the specialized lower anterior teeth. The animals spend a great deal of time moving up and down their tree, "sap-sucking". (Moynihan 1976; figure redrawn from Moynihan).
Lower anterior dentition of lorisids and marmosets. The toothcomb of lorises and pottos has apparently not only been developed for combing of the fur, but also for scraping holes into tree bark for obtaining the sap, an important food source in the wild. The strong lower premolars and upper canines may also play a role. Left: Nycticebus pygmaeus gauge hole, photo: Ulrike Streicher, EPRC, Vietnam. Right: gauge marks in dry old branches without sap, made by captive Nycticebus coucang (redrawn from twigs provided by K.-H. Schweigert)


Some initial general considerations
Gouging even on old dry branches in cages has been observed in captive, probably wildcaught slow lorises (K-H. Schweigert, pers. comm.); wooden substrate such as freshly cut branches of various sizes encouraged gauging at the Duke University Primate Center (Tan, Drake, 2001); at San Diego Zoo and at the Endangered Primate Rescue Centre gnaw marks by lorises on wooden substrates were found (U. Streicher, pers. comm.; Tan Drake 2001, quoting H. Fitch-Snyder, pers. comm.). Handreared animals lacking experience with foraging in the wild might need to learn how to gouge holes into substrates to obtain gum or sap; if so, some holes drilled into branches filled with preferred food might initially encourage learning. Information about gouging in unexperiences captive-reared lorises is still lacking.
There was evidence that N. pygmaeus can detect gums embedded in wooden blocks (Tan, Drake, 2001, quoting Fitch-Snyder, pers. comm.).
Lorises illegally sold, for instance in Indonesia or Vietnam, often get their teeth broken out to be sold as pets unable to bite (see our first aid page). They may be unable to use certain gauging devices. Research how such animals can be allowed to show halfways complete natural behaviour and feed approximately as they do in the wild, in spite of the lesions, is still lacking.

Safety and health tips:
Since lorises may get entangled in longer threads (see danger of accidents), safety in all hanging enrichment devices may be enhanced, for instance by pulling a flexible plastic tube (for instance the kind for sale for aquarium pumps) over the thread above the nutshell. Nealed wire may also be used, with joints made of loops if the animals should be able to bend or turn a device.
When offering enrichment devices including edible parts, care must be taken not to unbalance the animals´ diet, adjusting feeds accordingly (Craig, Reed 2003)


Enrichment method:
Live trees, fresh branches for gauging
Developed, tested by Ulrike Streicher, Endangered Primate Rescue Center, Vietnam

Live fresh trees or branches with genunine sap inside are of course the most natural enrichment method for this behaviour. Offering such natural food may be useful particularly in animals supposed to be released later.
Trees may be planted inside the cages or, in countries with adequate climate, may be cultured outside for harvesting fresh branches.

In the wild licking and tree gauging was observed observed in the following tree species:
In Vietnam: N. pygmaeus were observed gouging on Sapindus sp., Vernicia montana, Euphorbiaceae, Himalayan Ambarella Spondias axillaris, Anacardiaceae, and sorrow-less tree Saraca dives, Caesalpiniaceae. (U. Streicher, pers. comm.; Streicher 2004); Tan and Drake (2001) observed gouging on trees of the family Burseraceae.
In Malaysia: N. c. coucang were observed gouging on Albizia sp., Leguminosae (Barrett 1984).
In India: L. t. lydekkerianus were observed gouging on trees of the family Mimosoidae: Prosophis glandulosa, Azadirachta indica, Acacia leucophlora, Acacia ferruginea, and Prosophis juliflora (Nekaris 2000).

Captive enrichment in cages:
Lychee, Litchi chinensis Sonn. (Nephelium litchi Cambess), Sapindaceae, was tried successfully at the Endangered Primate Rescue Centre (U. Streicher, pers. comm.;  Streicher 2004).
Red maple, Acer rubrum, Aceraceae, and sweet gum Liquidambar styraciflua, Hamamelidaceae (both exudate producing species) were preferred for gouging at the Duke University Primate Center, USA (Tan, Drake, 2001)

Evaluation / purpose of method
Entertainment / physical training, health / mental training, skills / providing natural or near-natural food or forageing opportunities / Simulation of natural environments for diminishing unnatural selective pressure in captive breeding programs or for pre-release training / supported behaviour is known to be important for the eco-system
Practically tested in: Nycticebus pygmaeus


Enrichment method:
Artificial gum tree
McGrew, W.C., Brennan, J. A. and Russell, J.,1986: An artificial "gum-tree" for marmosets (Callithrix jacchus). Zoo Biology, 5: 45-50. ISBN / ISSN 0733-3188
Some details will be provided here soon

Evaluation / purpose of method
Entertainment / physical training, health / mental training, skills / providing natural or near-natural food or forageing opportunities / Simulation of natural environments for diminishing unnatural selective pressure in captive breeding programs or for pre-release training / supported behaviour is known to be important for the eco-system
Practically tested: no information about tests in lorises or pottos.



Enrichment method: 
Coconut shells with apple inside
Developed, tested by Danielle Smith, London Zoo 

One of the current devices which are occasionally used for lorises in London is a halved coconut shell with a section of apple attached inside with a thread and plug. See photo for details. 
They animals are only able to get food out of the coconut by holding the shell with the hands and scraping out some apple with the teeth (see below) 
This device may be placed best in the upper part of the cage, particularly in slender lorises who generally prefer higher branches where they feel safest. 

Detail: how to attach the apple in the coconut shell. 
Photo: Danielle Smith
 
A slow loris is eagerly engaged in gauging apple out of the nutshell, the other one awaits his turn. Photos: Danielle Smith Apple after use. 

Evaluation / purpose of methods
Entertainment / physical training, health / mental training, skills / providing natural or near-natural food or forageing opportunities / Simulation of natural environments for diminishing unnatural selective pressure in captive breeding programs or for pre-release training / supported behaviour is known to be important for the eco-system
Practically tested in: slow lorises, lesser slow lorises and slender lorises;
   other species: fat tailed dwarf lemurs (Cheirogaleus), marmosets and tamarins.


Enrichment method:
Melon shells hung up in the cage
Developed, tested by Danielle Smith, London Zoo

Sections of water melon, with a lot of the flesh removed, may be hung up in the cage. The lorises then use their teeth to scrape the fruit out of the shell.
(See also safety and health consideration above)

Evaluation / purpose of methods
Entertainment / physical training, health / mental training, skills / providing natural or near-natural food or forageing opportunities / Simulation of natural environments for diminishing unnatural selective pressure in captive breeding programs or for pre-release training / supported behaviour is known to be important for the eco-system
Practically tested in: Lorises


References

Barrett, E., 1984: The ecology of some nocturnal, arboreal mammals in the rainforests of peninsular Malaysia. Ph.D. Thesis, Cambridge University

Craig, J.; Reed, C., 2003: Diet-based enrichment ideas for small primates. International Zoo News 50 (1): 16-20.

McGrew, W.C.; Brennan, J. A.; Russell, J., 1986: An artificial "gum-tree" for marmosets (Callithrix jacchus). Zoo Biology 5: 45-50.   ISBN / ISSN 0733-3188

Moynihan, M., 1976: The New World primates: Adaptive radiation and the evolution of social behavior, languages, and intelligence. Princeton University Press, New Jersey

Nekaris, K. A. I., 2000. The socioecology of the Mysore slender loris (Loris tardigradus lydekkerianus) in Dindigul, Tamil Nadu, South India. Dissertation, Washington University, Department of Anthropology.

Oates, J. F., 1984: The niche of the potto, Perodicticus potto. Int. J. Primatol. 5 (1): 51-61.

Osman Hill, W. C.; Rewell, R. E., 1948: The caecum of primates. Trans. Zool. Soc. Lond. 26: 199-256.

Streicher, U., 2004: Aspects of Ecology and Conservation of the Pygmy Loris Nycticebus pygmaeus in Vietnam. Inaugural-Dissertation, Institut für Zoologie, Fischkrankheiten und Fischereibiologie der Tierärztlichen Fakultät der Ludwig-Maximilians Universität München.

Tan, C. L.; Drake, J. H., 2001: Evidence of tree gouging and exsudate eating in pygmy slow lorises (Nycticebus pygmaeus). Folia Primatol 72: 37-39.

Wiens, F., 2002: Behaviour and ecology of wild slow lorises (Nycticebus coucang): social organisation, infant care system, and diet. Dissertation, Faculty of Biology, Chemistry and Geosciences, Bayreuth University.
 

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Loris and potto conservation database - captive care / nutrition  Last amendment: 8 December 2004

 

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