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)
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.
