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Burgers' Zoo


Joep Wensing (author)
Liz Carletta (translation)
Monika Fiby (editor)
Published 2002-10-16
deutsch , espaƱol



Schelmseweg 85 , NL-6816 SH Arnhem , Netherlands
Phone: 0031-26-4424534
Fax: 4430776
URL: http://www.burgerszoo.nl


Ecosystem, Immersion, Tropic Hall


Family:Species:Common Name:Capacity:
Aburria pipile grayiGray's Piping Guan
Aegithalos concinnusLong-tailed Tit
Anhinga rufaDarter
Arachnothera longirostraLittle spiderhunter
Argusianus argusArgus
Astronotus ocellatusOscar chichlid
Botia macracanthusClown Loach
Callonetta leucophrysRinged Teal
Caloenas nicobaricaNicobar pigeon
Chloropsis aurifronsGolden-fronted leafbird
Clarias grabinusLabyrinthic Catfish
Colius striatusSpeckled Mousebird
Colossoma brachyponumPacu
Cotinga cayanaSpangled Cotinga
Cyanerpes cyaneusRed-legged Honeycreeper
Dacnis cayanaTurquoise dacnis
Dendrocygna fluviataWhistling Duck
Epomophoreus gambianusEpauletted Fruit Bat
Eudocimus ruberScarlet Ibis
Euphonia violaceaViolaceous Euphonia
Eurypyga heliasSunbittern
Guttera pucheraniKenya Crested Guineafowl
Hydrochoerus hydrochaerisCapybara
Irena puellaFairy Bluebird
Jacana jacanaJacana
Loriculus vernalisMalay Lorikeet
Moenkhausia sanctae filomenaeMoenkhausia
Opopsitta diophthalmaTwo-eyed fig parrot
Orycteropus aferAardvark
Pericrocotus brevirostrisMinivets
Pitta sordidaBlack-headed Pitta
Potamotrygon brachyrrusRiver Ray
Protopterus dolloiAfrican Lungfish
Pteropus lyleiLyle's flying fox
Puntius tetrazonaSumatran Barb
Rollulus roulroulCrested wood partridge
Tangara arthusGolden Tanager
Tauraco leucotisWhite-cheeked tauaco
Tragulus javanicusLesser Malay Mouse Deer
Trichechus manatusManatee
Trichoglossus goldieiGoldie's lorikeet
Zosterops spec.White-eye


    2001 King William III Award for Innovations and Challenge Daring (for the Zoo)

    1989 European Steel Award (for BUSH)

    1988 National Steel Award (for BUSH)


For the first time in the history of zoos, a widely-functioning ecosystem similar to a tropical rainforest was attempted to be created. That means that the plants compete for light and nutrients, the animals have to share food, territory, nesting spots, etc., but also that organisms eat each other, harm each other, and even die and decay. On the other hand, animal species take care of pollinating many blossoms, spreading their seeds, eliminating garbage, and fighting parasitic diseases. Survival of the fittest and natural selection play a big role here; the plants and animals are supposed to thrive with each other with minimal human interference. A healthy equilibrium between predators and prey is very important for the BUSH. This type of exhibitry is called eco-display.

In Burger's BUSH, plants and animals from the tropical rainforests of South America, Africa, and Asia were combined. There are also traces of different cultures: a hut of the Asmat Papuas, a pygmy hut, a rope suspension bridge, and rice fields with a watering system.

The health management of the BUSH residents has had few problems. Since the animals have a lot of freedom and opportunities to move around, and can choose their food, their health is usually very good and their stress level is usually low. The immune system functions optimally in such an environment. The density of animals is low, and therefore the danger of contagious infections is smaller than in a conventional animal enclosure.

The roof consists of 765 cushions which are 3 by 6 meters. The cushions are made from Hostaflon layers which are transparent and permeable for all light wave lengths. The whole roof is suspended from eight giant beams which rest on heavy concrete blocks in the ground. An experimental building was errected in 1984 to test the construction of a free span building. Six ovens heat the air which flows in from both sides along the roof. The target temperature is between 22 and 24 degrees Celsius. In summer the air circulation is achieved by openings in the roof and by doors and windows in the walls. Two large fans and a 17 meter high waterfall control vertical air circulation granting an equal distribution of warmth. The waterfall also raises humidity.


The BUSH is 150 meters long, 95 meters wide and 20 meters high.

Space allocation in square meters:

useindoorsoutdoors     total exhibit    
accessible     total     accessible     total    



EUR 9,200,000 including n/a % for design.



1 June 1988


Beginning: 1984

  • Planning and design: Burgers' Zoo staff


Beginning: 1 August 1986

  • Construction: BAM, Arnhem, Netherlands
  • Roof: Bouwstaalbau, Barneveldt, Netherlands
  • Roof: Texlon, Bremerhaven, Germany
  • Statics: ABT, Velp, Netherlands


walter.gif This is a climatic diagram for the closest weather station.



Animals and plants listed are just a selection of species found in the BUSH at any given time. There are ongoing introductions and losses of species.

The ground in the BUSH is made of coarse sand. This is nutrient-poor and lets water percolate well. Lack of nutrients is representative of almost all tropical rainforest floors. Most reused nutrients are stored in the plants themselves, not in the ground. In order to make the ground nutrient-rich in a natural way and to protect it from drying out or overheating, a layer of dried leaves, twigs, and bark was brought in. Dutch wood lice, ticks, springtails (Collembola,) snails, and millipedes take care of the decomposition of materials in the humus. They are aided by a few purchased tropical representatives of these organisms. Countless mineralizing fungi and bacteria came into the BUSH with the mulch. These irreplaceable organisms transform humus to useable plant nourishment. In addition to that, mushrooms live in symbiosis with plant roots and serve an important function in the nourishment of trees. After an introductory period, the tropical plants provide foliage and twigs so that the humus production continues. When necessary, horticulturists also fertilize the soil with elephant dung from the zoo.

A natural tropical rainforest is the product of an often centuries-long development. The different stages (from pioneer forest to secondary forest to primary forest) are marked by the special tree species, that are found in an increasingly higher, darker, moist, and wind-free forest, in which the micro-climate becomes more and more constant. In the BUSH, elements from all three stages of development were planted at the same time. A mosaic of quickly growing, broad-leaved pioneer species like umbrella trees (Cecropia,) balsa trees (Ochroma,) bananas (Musa,) and papayas (Carica) were combined, which quickly provided shade and protection for other delicate plants. Different fast-growing plants also live in the secondary forest, such as kapok (Ceiba) and cedar (Cedrela,) which were also planted, creating a dynamic and dense high forest after only two years. Diverse trees of the primary forest developed in the shade of these trees. In the deep darkness on the floor of a natural rainforest (only 1% of sunlight reaches the forest floor,) young trees grow slowly, if at all. Significant growth of height will happen only when a hole appears in the leaf cover. In the BUSH, there was enough light to guarantee that trees like durian (Durio,) rambutan (Nephelium,) shorea (Shorea,) and revea (Revea) quickly grew to be a few meters. In six years, the forest was so thick that lack of light made the natural growth of pioneer species impossible. As the artificial forest developed, not only the micro-climate but also the combination of species changed. Herbs that need light only grow along the sides of the paths or on the banks of wide bodies of water. Conversely, the number of species that prefer shade increases. Suitable spots for new plant species occur when trees mature. Epiphytes such as ferns, bromiliads, orchids, and others find their places on trees. They have to compete with creepers and vines. These "boisterous" quickly growing plants are introduced only with the greatest care.

In 1988, 15,000 individual plants of 1500 species representing 148 families were introduced.

The plant list specifies the Latin names of the plants used for this exhibit.


When introducing animals into the BUSH, management has to think carefully about the ecological consequences. What and how much does each animal eat? By which other animals can it be eaten? Are there opportunities for nest building? Is the animal an egg-stealer or a nest-destroyer? Does it dig or gnaw? Will it endanger the visitors? Is it territorial, nocturnal, or diurnal? Again and again, they have to consider if a niche, a place in the ecosystem, is available. Many of the introduced species have a biological function as food for other animals or pest control, others pollinate flowers, clean the water, or clean the ground of dead matter. To reduce the spread of disease-causing germs as much as possible, every new resident spends a quarantine period in an acclimation cage. Here, the animal can be observed for a few days and examined by a veterinarian. After it is released, the acclimation cage is still available. The animals can always find food there. This way, keepers can always dispense medication in the animal's food, if necessary.

As a consequence of the introduction of insect-eating birds, the population of insects decreased dramatically at first. This went so far that the loss of food threatened the survival of the lizards, turtles, and frogs. Now, flies are supplemented weekly. The flies that are used are mutants that cannot fly, and therefore are not of interest to the fly-catching birds. The different types of stinger-less bees (Melipona) have been able to survive the hunt of the birds so far. The bees are very important to the ecosystem as blossom pollinators.

The yellow-spotted Amazon River turtles (Podocnemis unifilis) share their pond with manatees. The turtles like to eat the manatees' poorly-digested excrement. The Asian small clawed otter (Aonyx cinera), the aardvark (Orycteropus afer), and the capybaras (Hydrochoerus hydrochaeris) are held in separate enclosure. The enclosure of the spectacled caiman (Caiman crocodylus) is also covered with a net to protect the birds. All other animals are free ranging in the hall.


Four horticulturists are in charge of the Bush.

The BUSH-keepers care for approximately 50 bird species by observing the feeding stations. Even the number of nestlings and fledglings is fairly well known. Such control is important in small populations in order to avoid inbreeding.


The visitor is an explorer; he must find his way himself. The visitor goes on the search for animals without much help of wayfinding signs, and sees only a small part of the available spectrum of animals. This type of searching, finding, and observing the animals in their surroundings that they belong in is not only thrilling, but also highly treasured. It is a powerful form of emotional pedagogy.

The restaurant in the middle of the tropics hall is Asian in design, and can be reserved for groups. The terrace lies among lusciously growing plants. The meals, which are often rice-based with tropical fruits, fit the environment.


Awareness and appreciation of the tropical ecosystem is raised in visitors through the enjoyment of the BUSH.

Only a few signs were erected in the BUSH to leave the landscape undisturbed. There is information available at special information spots and in an extensive exhibition on the Amazon in a small building next to the entrance.

Special tours and brochures are offered to those with more interest.


Unlike other projects, like Biosphere II in Tucson, Arizona, the BUSH is an open system: the visitors produce varying amounts of carbon dioxide daily. On warm days, the inside of the building is cooled with outside air. Some animals need outside nourishment to survive. Water is also supplemented from outside, because the water used to water the plants just runs through the ground and isn't used again. The nightly drizzling of water (about 200 mm/year) occurs with the help of a sprinkler system that is installed in the ceiling.

In order to preserve the biological diversity of plants and protect the sensitive roof, about 20,000 kg of plant material are removed from the "leaf ceiling" each year, with the knowledge that these holes will be filled again within a few months. But the cutting-back in the winter allows extra light for the undergrowth. The clippings are spread over the ground to keep the nutrient cycle going.

There are also some damaging species that are introduced along with the plants. Since no pesticides can be used, biological agents must be applied. Various insects and mold species are available for such purposes. Besides that, small-beaked, insect eating birds were introduced. Important representatives are white-eyes (Zosterops,) honey creepers (Cyanerpes,), later sunbirds (Nectarinia) and spider hunters (Arachnothera.) With the help of these bird species, a stable situation, in which the plants were mostly parasite-free, was reached in the course of two years.

Banana moths cannot be controlled by the birds, since their eggs, larvae, and pupas live hidden in plant stems. Because of that, traps with UV lights were set up, which attract and catch the banana moths at night. The population of these parasites has remained at an acceptably low level for many years.

A short time after the opening of the BUSH, the number of ants kept growing. Ants are important scavengers, but must also be controlled. In searching for a biological enemy, it was clear that woodpeckers were not an option, since they would have ruined the system. Dragonflies (Draco) were not efficient enough. Toads are an important ant predator. In the BUSH, African square marked toads (Bufo regularis,) whose young eat only ants, were introduced. Open water is necessary for breeding, but the tadpoles are also hunted by fish and birds. The toads have the best chance for survival in the water, where water lilies block the view of the fishing birds. In this way, water lilies have proven to be an important controlling agent of ants.

Cockroaches are useful humus-builders and provide an important food source for insectivores, especially in the winter. But they can also damage living plants, so their population cannot be left unchecked. The adult roaches are eaten by many game fowl, dwarf kingfishers, lizards, and turtles. Besides that, wasp species that parisitize cockroaches were introduced.


Keepers attempt to ID as many animals as possible with a leg band or a microchip, in order to make animal inventory and research possible.

The University of Utrecht collaborates with the University of Costa Rica on research on stingless bees.

With the help of the Department of Animal Ecology of the Catholic University of Nimwegen, a sampling of the activity pattern and the eating habits of the African square marked toads (Bufo regularis) was made possible.


Burgers' Zoo supports the International Tropical Conservation Foundation (ITCF), the foundation golden arch (De Gouden Ark), the Lucy Burgers' Foundation and the World Tree Fund.


Preferably, local companies are contracted for construction works.

The water for irrigating the tropics hall comes from tanks collecting storm water from neighbouring roofs.

©Burgers' Zoo, 2002

Site Plan
©Burger's Zoo, 2002

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small wonder (1)
©Joep Wensing, 2000

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Dryer for Eyeglasses (2)
©Monika Fiby, 2002

entering the bush . . . (2)
©Monika Fiby, 2002

visitors search for wildlife (3)
©Monika Fiby, 2002

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To other biomes . . . (4)
©Monika Fiby, 2002

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Pelican Flower (5)
©Joep Wensing, 2000

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Common Iguana Roams Free (6)
©Monika Fiby, 2002

Identifying Birds and Butterflies (7)
©Monika Fiby, 2002

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A bridge with character (8)
©Monika Fiby, 2002

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Victoria Crowned Pigeon (9)
©Monika Fiby, 2002

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Careful Crossing (10)
©Joep Wensing, 2000

Kaiman (11)
©Monika Fiby, 2002

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Family Adventure (12)
©Monika Fiby, 2002

view from behind the waterfall (13)
©Monika Fiby, 2002

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A Papuan House (14)
©Joep Wensing, 2000

Red-footed Tortoise (15)
©Monika Fiby, 2002

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Aardvark Exhibit (16)
©Monika Fiby, 2002

Informative Signage (17)
©Monika Fiby, 2002

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A Thriving Ecosystem (19)
©Joep Wensing, 2000

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Manatee Food (20)
©Joep Wensing, 2000

Manatee Pond (21)
©Monika Fiby, 2002

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Turtles (22)
©Monika Fiby, 2002

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A Place to Break (23)
©Monika Fiby, 2002

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Forest Floor Exhibit (24)
©Monika Fiby, 2002

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Innovative Roof (25)
©Monika Fiby, 2002



You are visitor number 24534 to this exhibit presentation.

Revised 2010-07-25
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