Table Of ContentSelbyana 20(1): 186-190. 1999.
DEVELOPMENT OF CANOPY WALKWAYS BY ILLAR MUUL AND
ASSOCIATES: A BRIEF HISTORY
llLAR MUUL
Integrated Conservation Research, Inc., 5627 Woodlyn Road, Frederick, MD 21703 USA
ABSTRACT. Access to the canopy of tall tropical rain forests has been a challenge for scientists. Among
the many methods used, the canopy walkway system has the advantage of being the least physically
challenging, making the canopy accessible to people of all ages and of normal physical fitness. This system
thus lends itself to research and nature tourism. The first canopy walkway for research was installed in
Malaysia in 1968. Modified, lighter weight versions were developed by Andrew Mitchell in Zaire, Papua
New Guinea, and Malaysia in the late 1970s. Beginning in 1988, canopy Walkways were used by the author
and his colleagues both for research and nature tourism in Malaysia, China, Peru, Ghana, Costa Rica, and
Guyana.
Key words: canopy, walkway, history
INTRODUCTION considerably, stretching the chains that held the
ladders to the trunk as tight as guitar strings.
Mitchell (1982, 1986) has reviewed much of The expanding trunk had all but absorbed the
the history of attempts by scientists to reach the triangular spacers on the ladders that fixed them
canopy of the tropical rain forests. To his re to the bark. This resulted in very little space be
tween the rungs and the trunk for foot-hold
views, I would like to add the work of Marston
(more like toe-hold). The inadequate foot-hold
Bates and David Gillette. With support from the
and the slipperiness of the aluminum led me to
Rockefeller Foundation, Bates erected platforms
rely mainly on my arms, which most experi
at various heights in trees in Colombia to study
enced climbers know is a mistake. Upon reach
mosquito vectors of the yellow fever virus. Gil
ing the 90-ft platform, I would have given up,
lette, who worked for the London School of
but my colleague Fred Dunn urged me on.
Tropical Medicine and Hygiene, studied disease
At about 120 ft, the ladders, which were
vectors in West Africa. Together with the work
straight and stiff, could not be used. McClure
of Elliott McClure in Malaysia, the pioneering
solved the problem by driving railway spikes
studies of the canopy by Bates and Gillette
into the trunk and the first branches that flared
opened up a new frontier in research in the
out. McClure, a tall powerful man, had placed
1940s and 1950s.
the spikes within comfortable reach for him. I
In 1968, I had the privilege of being assigned
barely could reach them; plus they had been
to Malaysia. Lord Medway (now the Earl of
largely absorbed by the expanding trunk.
Cranbrook) was still using McClure's platform.
My problems were compounded by having to
Reaching the crown of the gigantic Meranti tree
hang nearly upside down from these minimal
(Dipterocarpacae) was an incredible feat for Mc
supports to hoist myself around to the top of the
Clure. Platforms were built at 40-,90-, and 147-
gigantic branch. I would not even consider doing
ft heights. Mong bin Tahir, a forest dwelling Ab
this now without a harness and safety rope.
origine, participated in the construction, together
Youth is better known for its bravado than its
with other native climbers. No modem climbing wisdom.
equipment was used, only safety ropes tied Finally reaching the platform, I announced to
around their waists. Mong told me later that he Fred that I was not going back down, which is
and the other climbers refused to go up beyond an even more difficult maneuver. I asked him to
the 90-ft platform, leaving McClure to complete make arrangements with my family to send up
the remaining 57 ft alone. provisions, and I would live up there forever.
Climbing McClure's ladder in 1968 frightened Fred patiently instructed me on my way
me deeply and inspired me to develop an easier down, and I kissed the ground once I reached
and safer way to access the canopy. The practice the base of the tree, thankful that I had not made
at the time was to free-climb the ladder, using the trip much faster in a free-fall. Reflecting
no safety equipment. Early morning dew on the back on this frightful yet exhilarating experi
rungs of the narrow aluminum forestry ladders ence, I thought, "There must be a better way!"
made footing very slippery. Moreover, since the While on the platform, I noted that the steep
installation 12 years earlier, the tree had grown embankment we descended to reach the base of
186
MUUL: DEVELOPING CANOPY WALKWAYS 187
the tree seemed to be as close as the base from weights, and age were recorded along with re
which we ascended. Pondering this, I thought, productive condition estimates.
"Why not hang the ladders horizontally from the Several problems in the epidemiology of
hillside, as a suspension bridge to reach the scrub typhus were resolved (Muul et al. 1975)
crown?" A few months later, we began instal and useful information was gained about poten
lation of the first canopy walkway using this tial malaria vectors (Andre pers. comm.).
principle (Muul & Lim 1970). Fleas collected from the mammals were sent
to Robert Traub who identified them, discover
ing many new species and a new genus. Lice
STUDY SITES were sent to K.C. Emerson, who also discovered
new species and genera. Ticks were identified
Our work in installing canopy walkways us
by Harry Hoogstraal; and chiggers by N. Nad
ing the suspension bridge principle has taken
chatram, who discovered an interesting forest
place in four phases characterized by funding
species that harbors the infectious agent respon
sources.
sible for scrub typhus (Rickettsia tsutsugamu
shi). This disease caused tens of thousands of
Phase I: Medical Research Walkway casualties during World War II.
Blood parasites were identified by Yap Loy
In reviewing the use of canopy walkways, Fong and c.P. Ramachandram. Yap discovered
Mitchell (1982, 1986) apparently was provided a new species of malaria parasite in a giant fly
some incorrect information: Our walkway was ing squirrel (Petaurista elegans) (Yap et al.
not designed by U.S. Army engineers, though 1970). Remarkably this parasite is similar in
the U.S. Army Medical Research and Develop morphology to Plasmodium jalciparum, which
ment Command provided the funding to install is responsible for the fatal cerebral malaria in
it. The design came from the footbridges found humans. A French team headed by Irene Landau
all over Southeast Asia that are used by native discovered dozens of new species of intestinal
inhabitants to cross rivers and steep valleys. We, parasites including Eimeria and Coccidia.
however, introduced the use of modem, strong, Hundreds of publications resulted from this
durable, and lightweight materials. The "back early probe into the canopy. Though most of the
bone, " formed by aluminum ladders about 30 studies had direct or indirect medical implica
cm wide, was suspended horizontally from 12- tions, many involved basic science, such as the
mm polyester ropes and 12-mm high-grade steel phenological studies conducted by Francis Ng of
cables. Planks were placed over the rungs for the Forest Research Institute of Malaysia. Fr
easier walking. ances DeSouza, University of London, studied
Another misconception in Mitchell's book tree shrews; and another example was our stud
(1986) was that because of its weight, the walk ies of intestinal morphology and types of diets
way created great strain on the supporting trees. of mammals (Muul & Lim 1978a).
Also contrary to what was stated, we did not The Bukit Lanjan canopy walkway in Malay
lose any of the support trees in the time that the sia can be considered as the first phase of our
walkway was used (1968-1975). In 1975, hav development of canopy walkways. Its sole pur
ing completed our studies, we offered the intact pose was to facilitate research. In addition to the
walkway to several local organizations. None dozens who worked there, hundreds of scientists
accepted, so the whole system was disassem from allover the world came to see this canopy
bled. We concluded that, although the walkway walkway and gain their first access to a new
was a wonderful tool for reaching and studying frontier. So many came that an idea was born to
the canopy, if left without proper management, use walkways in the future for nature tourism.
it had the potential to become a dangerous and
possibly lethal "toy." Phase II: Man and the Biosphere Walkways
Dozens of scientists from Malaysia and
around the world used our walkways in con The next opportunity to conduct canopy re
ducting research. On our own part, we captured search came nearly 12 years later. In 1987 Rob
hundreds of mammals in traps and mist nets in ert Hoffmann, then the new director of the U.S.
the canopy and on the ground directly below National Museum of Natural History, Smithson
(Muul & Lim 1978b). Each specimen was iden ian Institution, contracted me to establish new
tified, code marked on the ear and released after research stations in tropical China (Yunnan
examination for ectoparasites and endoparasites. Province) and in Borneo (Sabah, Malaysia). Part
Blood samples were taken to isolate disease-pro of the research plan was to develop models of
ducing rickettsia and viruses and antibodies. Vi ecologically sustainable, economic development
tal statistics such as body measurements, of the tropical rain forest (Muul 1989, 1993).
188 SELBYANA Volume 20(1) 1999
The idea was to demonstrate the potential ground-dwelling mammals at geographical ex
economic value of tropical rain forests to en tremes on a north-south gradient, of the most
courage policies that would conserve much larg prevalent types of tropical rain forests (Diptero
er tracts of land supporting these ecosystems carp) in Southeast Asia (Whitmore 1975). The
than what was possible through preservationist highest diversity of species in these types of for
strategies (Muul 1993). Funding for this phase ests occurs on the island of Borneo. One of the
of multidisciplinary research and conservation study areas was established in Borneo at the
was provided by the U.S. Man and the Bio edge of Kinabalu Park, Sabah, Malaysia. Borneo
sphere (MAB) Program with the assistance of has more than 3600 identified species of trees
Roger Soles, executive director. and 230 species of mammals.
The sustainable development strategy includ The other study area was set up in the south
ed developing part of the forests under study in ernmost tip of the Province of Yunnan, China.
China and Malaysia for nature tourism (eco At this northernmost distribution of Dipterocarp
tourism). In each area, two separate canopy forests, the number of species is less than half
walkway systems were installed-one for re that in Borneo. Yet because of the relatively high
search only and another primarily for nature diversity in these Dipterocarp forests, the Prov
tourism. The ecotourism set also was used for ince of Yunnan has more species in most fami
research, in part to determine the effects of tour lies of plants and animals than all the other prov
ists on the ecosystems providing the attraction. inces of China combined.
Because of the multiple use made of these Among the mammals captured in China, we
walkways, additional safety measures were tak found a new species in the canopy and possibly
en. The basic design remained the same as that a new species and genus from the ground level.
used earlier in Bukit Lanjan, Malaysia (Muul & Both the numbers of species and individuals
Lim 1970). The walkway, however, was en captured were remarkably lower than those cap
closed with strong fish netting. The netting ex tured by the same methods in Malaysia. The
tends from the supporting horizontal ropes like scarcity of animals also was corroborated
a giant hammock. The vertical support ropes are through direct observations in the canopy, both
woven through the mesh to stabilize the netting during the day and night.
horizontally. Vertically the netting is wrapped These meager results, however, are extremely
around and tied to the horizontal support ropes informative. The documented relative scarcity of
at waist height or greater. One scientist remarked mammals both in the canopy and ground levels
that, "It would require great imagination to be of the Dipterocarp forest in China is probably
able to falloff." the result of the recent (last 100 years) fragmen
Safety has always been the primary factor in tation of these forests. The largest intact area we
installation, maintenance, and management of could find was about 35 ha. The total of the
our canopy walkways. As a result, our walkways remaining fragments may not add up to more
may seem "overbuilt." The design and materials than 200 ha. By contrast, Kinabalu Park in Bor
selected, however, should allow the systems to neo consists of about 75,000 ha, of which low
be used for decades with minimal maintenance land Dipterocarp forest comprises about 7000 ha
and repair. (still not very much for long-term survival of
Again dozens of scientists with international the diversity now found there). These are valu
interests joined the studies, particularly in Ma able clues to what is likely to occur in the future,
laysia. Most came from various universities in as forests increasingly are fragmented and re
Germany. Studies by German researchers were duced into smaller parcels.
coordinated by Eduard Linsenmaier, University
of Wurzburg, who was president of the German
Phase III: LocallInternational Walkways
Tropical Ecological Research Society. In China,
logistical problems limited the use of the walk Based on the success of the Yunnan and Kin
ways for research by many outsiders. After com abalu demonstration sites, requests came to us
pleting our own studies in 1992, we added ma for additional walkways to be developed pri
terials from the research walkway to extend the marily for nature tourism and education. These
walkway used for tourism. included two additional sites in Malaysia: the
I cannot determine whether research use of Forest Research Institute of Malaysia near Kuala
the walkways or use for tourism has been more Lumpur (1991) and the Taman Negara National
successful. Each of these uses has different ob Park (1992), with its more than 1200 square
jectives. miles of uninterrupted rain forests. The Taman
The research purpose of our own studies, sup Negara walkway was fully funded by the Ma
ported by the National Geographic Society and laysian Government. Modified versions of these
GEO, involved comparisons of canopy and canopy walkways were developed by others in
MUUL: DEVELOPING CANOPY WALKWAYS 189
Danum Valley in Sabah (Borneo) and in Sara magnet to attract tourism. Admission charges are
wak in 1992. minimal and do not reflect the true local eco
Other government-supported and internation nomic situation. The growing number of canopy
ally funded tourism walkways were designed walkways being installed evidences government
and installed by our group in Peru (1990) and recognition of the value of nature tourism. The
in Ghana (1994). These walkways have been a walkway at Taman Negara in Malaysia has been
major factor in promoting tourism to tropical visited by that country's King and Queen and by
rain forests. the prime minister. A wedding was performed
Additional walkways have been discussed for on the walkway at Kinabalu Park.
other areas in Malaysia, the Philippines, Irian The canopy walkway in Peru receives fewer
Jaya, Thailand, and Burma. visitors, but is the best known in the world be
cause of its use as an advertising centerpiece by
Phase IV: Private Ecotourism Walkways International Expeditions (IE), the largest nature
tourism company in the world. IE provided
The most gratifying trend lately has been the much of the support to install this system on the
interest shown in nature tourism and use of can Napo River, near the Amazon, and helped create
opy walkways by private investors. Privately the Amazon Center for Environmental Educa
funded development began in Costa Rica in tion and Research (ACEER).
1995 with the Rainmaker Group, which has pur Richard Humphrey, a developer of lUXury rain
chased 1500 acres of rain forest for conservation forest resorts in Guyana, immediately recog
near Manuel Antonio National Park. The group nized the value of canopy walkways as part of
has plans to purchase more land for rain forest nature tourism facilities. He has said, "Any na
conservation and sustainable development in the ture tourism attraction in the tropical rain forest
future. is as incomplete without a canopy walkway as
. In another project begun in 1996 in Guyana would be a beach resort without a swimming
for the Hotel Tower Group, investors leased land pool and tennis courts."
in the spectacular Great Falls area on the De In providing consulting and design services,
marara River. The canopy walkway is built, and we always stress that the canopy walkway is
completion of trail systems and accommodations only the "hardware" part of a package. Devel
awaits additional funding. opment of a strong nature interpretation program
Plans are underway for privately funded can provides the "software." Both need to be de
opy walkways to be used primarily to support veloped together. Our demonstration projects in
nature tourism in Uganda, Peru, and Belize. training nature interpreters were funded by the
United Nations Educational, Scientific and Cul
tural Organization (UNESCO) MAB Program
DISCUSSION
with the assistance and guidance of Malcolm
Canopy walkways have proven themselves a Hadley, executive director.
valuable research tool. By providing easy access In most cases, the nature interpreters we train
to the canopy level, the walkways also have be are former poachers. This ironic situation yields
come a popular tourist attraction. several advantages. Since the na~e interpreters
In both China and Malaysia (Kinabalu Park), are local forest inhabitants, a participatory at
the canopy walkways are visited by more than mosphere is established in the local community;
10,000 tourists per year. At this level of visita and the project is not viewed as entirely foreign.
tion, they have the potential to bring in large Income to the local people provides tangible ev
amounts of revenue. In China, tourists pay an idence of the economic value of the conserva
admission fee equal to a day's wage for a gov tion efforts. Time and effort formerly devoted to
ernment worker. At that rate, rain forest tourism poaching are now used to earn better income.
has the potential to earn more money, per hect Also poachers usually know more about the for
are of land use, than logging operations or con est and its inhabitants than do others, including
version of the land to rubber plantations. Con academically trained people with only book
firming this potential, the Yunnan Provincial knowledge who do not feel comfortable in the
Government decided in 1991 to stop deforesta forest.
tion being carried out to clear the land for rubber From among potential candidates for the
estates. Instead investments were concentrated training programs, we try to select those with
in building the tourism infrastructure. Currently, good communication skills. Naturally, training
the provincial government is interested in de increases the value of nature interpreters in the
veloping additional sites for nature tourism, in minds of the tourists. We try to put the inter
cluding canopy walkways. preters' specific knowledge into the context of
In Malaysia the national parks are used as a scientific information about the forest and to em-
190 SELBYANA Volume 20( 1) 1999
power them to discuss conservation matters 1993. Tropical Forests. Integrated Conserva
from various sides of the issue. tion Strategies and the Concept of Critical Mass.
Satisfied tourists, after experiencing interpre MAB DIS, UNESCO, Paris.
Muul. I. and B.L. Lim. 1970. Vertical zonation in a
tive programs, have been heard to say, "We nev
tropical forest in Malaysia: method of study. Sci
er realized how much is going on in these for
ence 169:788-789.
ests," and "We are going to encourage our
---. 1978a. Comparative morphology, food habits
friends to make such a trip." Such satisfied cus and ecology of some Malaysian arboreal rodents.
tomers are instrumental in making nature tour Pp. 361-368 in G.G. Montgomery and J.E Eisen
ism (ecotourism) the fastest growing segment in berg, eds. The Ecology of Arboreal Folivores.
the tourism industry. Smithsonian Institute Press. Washington, D.e.
The growth of ecotourism is an essential part ---. 1978b. Small mammal populations in zoo
of any strategy to demonstrate the economic val notic and toxicological studies. Pp. 208-223 in
D.P. Snyder, ed. Populations of Small Mammals
ue of ecologically sustainable development in
under Natural Conditions. Special Publication Se
tropical rain forests.
ries, Pymatuning Laboratory of Ecology, Univ.
Pittsburgh.
LITERATURE CITED Muul, 1. and I.S. Walker. 1975. Mammals and scrub
typhus ecology in Peninsular Malaysia. Trans. of
Mitchell, A.W. 1982. Reaching the Rainforest Roof-A the Royal Society of Tropical Medicine and Hy
Handbook on Techniques of Access and Study in giene 69: 121-130.
the Canopy. Leeds Phil. and Litt. Soc./UNEP' Whitmore, T.e. 1975. Tropical Rainforests of the Far
---. 1986. The Enchanted Canopy. Macmillan East. Clarendon Press, Oxford, UK.
Pub!. Co. New York. Yap, L.E, 1. Muul and B.L. Lim. 1970. A Plasmodium
Muul, 1. 1989. Use them or lose them: a recipe for sp. from the spotted giant flying squirrel in West
sustainable use of tropical forests. UNESCO C 1: Malaysia. Southeast Asian Journal of Tropical
29-33. Medicine and Public Health 1: 418.
