Melbourne Zoo
Gorilla Rainforest

Amanda Embury, Carlyn Worstell (authors)
Monika Fiby (editor)

Published 09 Jul 2018


PO Box 74 Parkville, Vict. 3052 Australia
Phone: 61 3 9285 9300
URL: http://www.zoo.org.au


Africa, animal behavior, electric fence, immersion, rainforest, visitor behavior


Family:Species:Common Name:Capacity:
Pongidae Gorilla gorilla Western Lowland Gorilla family of about 10


The primary objective of the design was to create an exhibit that promotes natural behaviour in the gorillas, as well as replicates their natural habitat. Visitors should gain an understanding of gorillas and their habitat. The exhibit has an undulating topography and includes waterfalls, rock outcrops, fallen logs, heated caves, and various canopy levels.

The first of several viewpoints is across a dry moat, looking onto a clearing favoured by gorillas early in the day as it attracts morning sun. The second vantage point is the major viewing area of a huge bay window. Another viewing window is framed by the buttress and root system of an artificial Moreton Bay Fig made from concrete. The concrete was carefully coloured, even including artificial lichen. By incorporation of some real root material, it is very deceptive. A waterfall and creek system moves through the roots of an artificial tree and flows down in front of the window.



An outdoor exhibit area of 1,600 m² is surrounded by a moat of 4 metres width and 4 metres depth (which was marginally reduced in some areas). Indoor rooms are 2,5m high. Staff facilities include a staff room of 12m², a kitchen of 40m² and a refrigerator of 16m², corridors of 32m². Gorillas use a communal den (approx. 32m²), two dens of about 10 and one of about 18m². Nursery quarters (20m²) are available.

Space allocation in square meters:

Use:Indoors:Outdoors:Total Exhibit:



AUS Dollars 2,100,000 including 10% for design.



April 1990


Beginning: 1986

  • Consulting: David Hancocks, Melbourne
  • Design: Green & Dale Associates, Melbourne
  • Horticulture Design: Michael de Oleveira, John Arnott, Melbourne Zoo


Beginning: 1988

  • Mock Rock/Tree Work: Environmental Images, John Barber, Melbourne, Australia


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



Creating a rainforest from barren soil is no mean feat. Consideration was given to the natural diet of gorillas, so that some food species, or closely related species, could be included. Pictorial references were consulted to gain an understanding of the composition of African rainforests.

Plants need to cope with Melbourne's climate and be resilient to the foraging of gorillas. Preference was given to plants that regenerated quickly after damage.

Preparation of growing medium was critical to enhance plant growth. Clay loam soil was chosen because it satisfied requirements for drainage and resistance to compaction. It is still important to maintain vegetation, organic material, or coarse sand over the soil in high-traffic areas. Drainage and irrigation systems keep moisture levels at optimum. Several thousand earthworms were added for aeration. The continued proliferation and lush nature of vegetation suggests that these preparations were justified. Two mature Moreton Bay Fig Trees (Ficus macrophylla) are the features of plantings within the exhibit. Many existing trees were retained for height - although these trees are neither African nor rainforest, they enhance rather than detract from the theme. Above the bridged entrance, a tree was heavily planted with epiphytic orchids. Irrigation sprays create humidity and misting. All of these features contribute to visitors feeling "the tropical rainforest experience".

To protect trees, two rings of 3 mm high-tensile wire, one at the base of the tree and one at a height of c. 1.8 m rings are attached to insulators that are nailed onto the tree. Several 2 mm thick strands of galvanized wire run from one ring to the other.

To create plant islands, one to three strands of wire on star pickets placed at a 60° angle are used for herbage protection. One strand placed at 400 mm height appears effective to protect other plants. Strands were placed at a height to exclude gorillas attempting to enter by crawling under, climbing over, jumping over, cartwheeling over or pulling branch down to short circuit and enable access.

Areas where vegetation was badly damaged by trampling have been mulched to avoid
problems associated with soil compaction. The mulch is an excellent medium in
which to hide food items and promote foraging activity.

Approximately 25% of the exhibit is not accessible to gorillas, leaving them with 1200 m² of usable area. The gorillas were familiarized with the effects of the hotwire in the old exhibit
before the move.

The vegetation is principally managed for the well being of the gorillas.

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


The landscaping of the enclosure gives the gorillas access to both morning and afternoon sun. Landscaping also enables the gorillas to gain visual isolation both from zoo visitors and other gorillas. High points created by mock rock work enable gorillas to gain an elevated view of their surroundings. Other features incorporated into the enclosure include heated caves that provide the gorillas with shelter from the elements and warmth.

Off-exhibit there is a small window from the communal night den to the exhibit enabling gorillas to look in and keepers or gorillas to look out. Gorillas regularly make use of this window. Three small dens and a communal den form the nocturnal holding quarters for the gorillas. The larger communal den provides extra space for days when the gorillas cannot go on exhibit. Each den is made from welded mesh on steel supports. Within each den is a heated sleeping bench. The floor of the dens has considerable slope to aid collecing urine that is analysed to determine oestrus cycles of females. The dens are serviced by a keeper corridor.

Feeding of gorillas works via hinged "feeding buckets". A food bin is swung open, food placed within it, then swung back and locked flush with the wall of the den. The gorilla complex is connected to previously existing ape facilities via a weldmesh raceway. The raceway passes through the ape nursery which enables infant gorillas to have access to their mothers if they require hand-rearing.



The gorilla complex features an extensive food preparation area with stainless steel work benches and shelving. Adjacent to the food preparation area is a cold room that is accessible both from within and external to the building. Provisions can be offloaded from a vehicle directly into the cold room. A dishwasher is provided so that keepers have more time available for tasks other than scrubbing food trays. The food preparation area has two large windows with one looking into the communal night den.

Keeper exhibit access is between the individual night dens and communal dens. Doors connecting dens and holding facilities to the enclosure are operated by a mechanical winch system.

Staff amenities are also provided within the building. Because the complex proved to be extremely noisy, with sounds of gorillas and dishwashers reverberating on concrete and stainless steel, it was necessary to introduce sound proofing. A series of baffles are used to absorb noise.



At the first viewing area, visitors can see gorillas across a raised planted strip which obscures a moat. A post and rail fence prevents parents from lifting their children up onto the planted strip. On busy days, zoo personnel patrol the area to ensure that no problems arise.

The main viewing area is a 10.1 m long semi-circular window with six glass viewing panels (Plate 1). Each 1.6 m wide and 3-6 m high panel is constructed of three layers of 13 mm thick glass, separated by 1 mm thick perspex, resulting in a five-layer laminated glass that is 42 mm thick.

Another viewing window with two glass panels 1.9 x 2.1 m is framed by the buttress-root system of an artificial Moreton Bay fig tree (Ficus macrophylla). Made from cement, the tree has been artfully coloured, even including artificial lichen, and with the addition of some real root material gives a realistic appearance. A waterfall and creek system runs through the roots of the artificial tree and flows across in front of the window.

Other glimpses of the exhibit can be obtained from various points along the perimeter pathway which winds through lush vegetation. The pathway also leads to the food preparation area where the visitors can see staff at work.



Interpretative material to demonstrate the major characteristics of gorillas and provide an insight
into their natural habitat, are positioned at 11 points along the pathway. The signs contain basic details such as scientific name, distribution, diet, an introduction to the African rain forest, information about fieldwork, and the impact of crop production and increasing human populations on the habitat.

A "Research Hut" is included to enable visitors to experience the life of a field worker. The hut is staffed by volunteers and offers views of the enclosure, information about individual gorillas, and various artefacts for handling. To demonstrate the effects of agriculture on natural habitat an area of plantings was developed to look like a "slash and burn area" featuring crop plants such as banana, hotmint, maize, okra, gourds and tobacco. Visitors also have the opportunity to ask keepers about gorillas during the afternoon feed which is often done from public viewing areas. A space that can be used for teaching is located not far from the Research Hut. Logs and rocks have been carefully placed to form natural seats.

Additional interpretive material is available from both the Zoo's Education Service and retail outlets. A booklet describing some of the plants used in the Gorilla Rainforest is available. Zoo education staff produced a series of books as a resource for school teachers for classroom activities focusing on rainforests.



The exhibit is maintained on a daily basis both by keepers and gardeners. Faeces and bedding material (sometimes shredded paper is taken into the enclosure from night dens) are removed and damaged plants tidied up. Vegetation growing near electric fencing needs to be regularly pruned to prevent it touching the wire and the shorting system. Fertiliser and mulch are added as required. Plants are replaced as necessary, and where possible, non-African species are being replaced by African species. One species used, Senecio mikanoides, has proven very prolific and is regularly thinned. This maintenance takes place between 8.00 am and 9.30 am prior to the gorillas being released into the exhibit.

Provision of browse material (freshly cut branches) provides an alternative to gorillas ripping branches off trees within the exhibit. Novel food items such as coconuts or "puzzle feeders" also help to reduce the gorillas pre-occupation with vegetation planted in the enclosure. Pellet feeds mixed with mulch stimulate foraging activity of a "non-destructive" nature. A feed of greens is offered every afternoon.

A post-and-rail fence has been placed on the planted area. Low fencing has also been installed along paths to prevent people straying onto gardens. On busy days, zoo personnel patrol the area
to ensure that no problems arise.



The transfer of gorillas from a rather stark and barren area to the rainforest exhibit created the opportunity for comparative studies. During 1990, two studies were undertaken, one focused on gorilla behaviour and the other on visitor perception of the apes (Burton, 1990; Ford, 1990). The results provide information about the success and effectiveness of the exhibit.

Results of the gorilla behaviour comparison indicated a significant increase in activity when the gorillas were first released into their new exhibit. However, levels of activity decreased over time, although the amount of local activity (foraging and eating) was greater in this exhibit than the previous exhibit, and the amount of captivity-related activity was less in this exhibit. Overall, the behaviour repertoire was greater in this exhibit.

Another project focused on visitor perception of gorillas. School students voluntarily completed a questionnaire seeking information about their understanding of gorillas. Some students viewed gorillas in the old ape complex while others viewed gorillas in the new Gorilla Forest. Response to questionnaires indicated that the naturalistic exhibit elicited more positive feelings and respect for the animals in this enclosure than was the case for the stark ape complex. Also, students are more likely to correctly nominate species sympatric with gorillas at the naturalistic exhibit and place a greater value on the importance of field research. Students were more positive about the adequacy of the zoo at the naturalistic exhibit. Finally, students demonstrated an increased awareness of the need for habitat preservation when they viewed gorillas in the naturalistic exhibit rather than the old exhibit.

The activity of the gorillas was closely monitored by keepers and horticultural staff and formed the basis for a study by a zoology student. It did not take long to identify preferred food items, including Ficus benghalensis, Barnbusa sp, Hedychium gardnerianum and Sparmannia africana, and those species that were left alone, such as Acanthus sp and Senecio tamoides. Species with prickly foliage, notably African boxthorn Lycium fercissimum and gorse Ulex europaeus, were introduced to the exhibit in an attempt to reduce damage to plants. The combination of prickly foliage and electric fencing works effectively to protect vegetation and plants with varying degrees of prickly foliage continue to be tested in the exhibit. Vegetation has grown around the electric
fencing, screening it from visitors.



Visitor education is the primary conservation focus of the exhibit.



An artificial Moreton Bay fig tree (Ficus macrophylla) was cast from a specimen growing in the Royal Botanic Gardens, Melbourne.



© Melbourne Zoo, 1990


Site Plan

Site Plan

© Melbourne Zoo, 1990


Picture Views

Picture Views

© Melbourne Zoo, 1992


Young Gorilla

Young Gorilla

© Melbourne Zoo, 1999


View towards the exhibit

1. View towards the exhibit

© Monika Fiby, 2017


Caves and Waterfall

2. Caves and Waterfall

© Monika Fiby, 1990


Lush Vegetation

3. Lush Vegetation

© Monika Fiby, 1990


Dry moat

4. Dry moat

© Monika Fiby, 2017


Path along the exhibit

5. Path along the exhibit

© Stephanie Nolz, 2010


Planted immersion

6. Planted immersion

© Stephanie Nolz, 2010


Main Viewpoint

7. Main Viewpoint

© Monika Fiby, 1990


Shaded viewing area

8. Shaded viewing area

© Stephanie Nolz, 2010


Closure during pregnancy

9. Closure during pregnancy

© Jon Coe, 2017


Ficus Tree Window

10. Ficus Tree Window

© Monika Fiby, 2017


Food Foraging

11. Food Foraging

© Monika Fiby, 1990


Enrichment objects

12. Enrichment objects

© Jon Coe, 2011


Room to Run

13. Room to Run

© Monika Fiby, 1990


Moat and wall

14. Moat and wall

© Stephanie Nolz, 2010


Mock Rock Work

15. Mock Rock Work

© Monika Fiby, 1990


Exhibit back side

16. Exhibit back side

© Monika Fiby, 2017


Keeper looks on . . .

17. Keeper looks on . . .

© Monika Fiby, 1990



18. Signage

© Monika Fiby, 2017


Interpretation area

19. Interpretation area

© Monika Fiby, 2017


Be a gorilla!

20. Be a gorilla!

© Stephanie Nolz, 2010


'Ranger station'

21. 'Ranger station'

© Monika Fiby, 2017


Hot Wire

22. Hot Wire

© Monika Fiby, 1990


Gorilla-Determined Path

23. Gorilla-Determined Path

© Monika Fiby, 1990


A Water Dragon Friend

24. A Water Dragon Friend

© Monika Fiby, 1990