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Rotterdam Zoo

Gorilla Island

Ben Westerveld, Hans Post, Carlyn Worstell (authors)
Gert-Jan Verboom (translation from Dutch)
Robert van Herk, Monika Fiby (editors)
Published 2004-12-9

 

UP LOCATION:

PO Box 532, , 3000 AM Rotterdam , The Netherlands
Phone: 031-010-443 1495
URL: http://www.rotterdamzoo.nl


UP KEY WORDS:

edible plants, feeding, shelter


UP ANIMALS:

Family:Species:Common Name:Capacity:
CercopithecidaeColobus guerezaColobus6
PongidaeGorilla gorillaWestern Lowland Gorilla10


UP DESCRIPTION:

The gorilla exhibit, part of Rotterdam's Africa area, consists of a large island for the gorillas and a smaller island where colobus monkeys are housed. Both islands are accessible to the colobus monkeys by way of swinging ropes. The existing indoor holding building (built in the 1960s) was maintained. Fortunately, this building is low to the ground and has a roof planting, so it is relatively unobtrusive. The gorillas are displayed on the outdoor island year-round. An existing, historic stable had to remain on the site and was remodelled to look like an African hut. It serves as a viewing area for visitors. There are three viewing areas around the island, carefully placed so that there is no cross-viewing and no view of the entire island from any one spot.

The island is lush and green with high grasses and plants. To create a natural appearance of the outdoor enclosure, a water moat or a wall of wooden poles form the barrier between visitors and animals. The wooden pole fence is equipped with electrical wire to prevent climbing. The moat is 4 meters in width, with a 45 degree angle so that, gradually, a depth of 1.80 meters is reached. Because gorillas may go in the water but cannot swim, a fence was placed in the center of the moat. This fence is electrically wired just above the water level. For additional safety, a 1 meter-wide swamp area, with bog plantings, was added to the width of the moat on the animal side of the moat. The water level in the moat is divided into two levels. A water pump keeps the water circulating which creates two small waterfalls. The water is aerated with a system that preserves water quality during the summer and keeps the water from freezing in the winter. Therefore, the gorillas can use the outdoor enclosure year-round. In order to encourage the gorillas to spend as much time as possible in the outdoor area, heated hiding caves and much vegetation was added for shelter from sun, rain, and cold, and a special enrichment-feeding program was developed to give the gorillas access to food at all times and to keep the island unpredictable (see "Management").
 

UP SIZE:

Space allocation in square meters:

useindoorsoutdoors     total exhibit    
accessible     total     accessible     total    
animals1,700
visitors800
others
total2,5002,500

 

UP COSTS:

Euro 454,000 including 1 % for design.

91,000 Euro were needed for preliminary preparation of the site - removing existing enclosures, relocating animals, diverting pipes, wiring, and removing pathways and vegetation. This process took about one month.
 

UP OPENING DATE:

15 June 2000
 

UP DESIGN:

Beginning: December 1998

  • Design: in house, Rotterdam Zoo

UP CONSTRUCTION:

Beginning: February 1999

  • General Contractor: Molhoek, Sleewijk, Netherlands
  • Artificial Vines: The Larson Company, Tucson, Arizona

UP LOCAL CONDITIONS:

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

 

UP PLANTS:

The overriding goal of the exhibit is to appear lush and green. Plants, including grass species known to be successful in Rotterdam’s climate were selected for the exhibit and are allowed to grow to natural heights. The same plant palette was used for both the animal area and visitor areas, to create a seemingly-seamless space. The planting plan was finalized early in the construction phase, so as soon as the contractor finished a part of the exhibit, the botanical department planted the vegetation. This way the exhibit would appear as green as possible when the exhibit was opened. In order to provide foraging opportunities and variety on the island, plants that are edible by gorillas, such as willow, were planted in different sections, with electric wire across the paths that lead to them. Periodically, the electric wire is taken down from a section to allow the gorillas to forage the plants. When one part of the area is stripped of the herbs by the gorillas, it is closed and another part is opened. Many large trees were planted to provide shade. The trees are protected by Berberis shrubs and electric wire until they reach further maturity. Plantings were also used to provide hiding opportunities for the animals, being placed, in some cases, between the visitor viewing area and the gorillas, so as not to present the animals to the visitors without any privacy.

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


UP FEATURES DEDICATED TO ANIMALS:

The animals are provided with much shade through the use of lush vegetation, including tall trees, and three cave shelters. Observations at Rotterdam and other zoos show that gorillas are more active in the shade than in the sun. The caves are heated so that they may be used for warmth in the winter, though, so far, animals don't seem to use them much for this purpose. More often, gorillas, especially adult males, are seen on top of the caves or logs where they enjoy a view of their surroundings. The animals also enjoy spending time in the small valley in the center of the island, which affords them some privacy. A large climbing structure of dead trees and special, natural-looking "vines" occupies one side of the island. The artificial vines are extremely durable and long-lasting because they contain strong wire inside. They are grey-colored, matching the color of dead trunks.
 

UP FEATURES DEDICATED TO KEEPERS:


 

UP FEATURES DEDICATED TO VISITORS:

The African hut provides a shady rest spot while viewing the gorillas. All visitor views are carefully placed to ensure good views of the animals, without being able to see the entire island, or other visitors, from the view points. All three caves face outward toward the visitors, so animals can be seen when inside them. The unpredictably-timed feeding boxes (see "Management") keep gorillas moving about the island through-out the day, searching for available food. The boxes are placed strategically to bring animals into view of visitors.

The secondary path that circumnavigates the island is easily accessible, though it is surrounded by lush vegetation on both sides. This is to make visitors feel that they are in the environment of the gorillas. A tertiary path is made of rugged logs, creating an adventurous path for children to explore.
 

UP INTERPRETATION:

Interpretation is mainly achieved through placing the public within the environment of the gorillas and showing animals performing their natural behaviors. In the African hut, African artifacts are shown alongside signage that tells of the struggle between humans and gorillas in Africa.
 

UP MANAGEMENT:

Gorillas, by nature, search for food on the ground. To encourage this behavior in the exhibit, steel boxes were put in the soil of the island. These boxes are gorilla-proof because the lid is held in place by an electro-magnet. When the power is turned off, the magnet releases the lid and the box can be opened by the gorilla. Twelve of these boxes are placed around the island. Each of them is connected separately to a time switch, so that the keeper controls when each box can be opened. Each morning, the keeper fills the boxes with food items and then sets times (on a timer located off-exhibit) for the boxes to automatically open. The time switches are set at different times each day, so gorillas must keep checking boxes throughout the day. The gorillas are allowed to go outdoors year-round, and brought indoors at night.
 

UP RESEARCH:


 

UP CONSERVATION:


 

UP LOCAL RESOURCES:


over_t.jpg
86K + description267K
Overview
©Rotterdam Zoo, 1996

 
site_t.jpg
76K106K
Site Plan
©Rotterdam Zoo, 2000

 
11_t.jpg
49K65K
Western Lowland Gorilla (1)
©Rotterdam Zoo, 2002

 
0_t.jpg
45K + description58K
African Hut Viewing Pavilion (2)
©Carlyn Worstell, 2002

 
1_t.jpg
44K + description60K
Inside the Hut (3)
©Carlyn Worstell, 2002

 
2_t.jpg
52K + description71K
Heated Cave Shelter (4)
©Carlyn Worstell, 2002

 
3_t.jpg
69K + description118K
Moat with Electric Wire (5)
©Carlyn Worstell, 2002

 
4_t.jpg
55K + description75K
Naturalistic Vines (6)
©Carlyn Worstell, 2002

 
5_t.jpg
53K + description71K
A Jungle Path (7)
©Carlyn Worstell, 2002

 
6_t.jpg
58K + description75K
Wooden Pole Fence (8)
©Carlyn Worstell, 2002

 
8_t.jpg
41K + description148K
Steel Feeding Box (10)
©Carlyn Worstell, 2002

 
9_t.jpg
48K + description152K
Feeding-Box Timer (11)
©Carlyn Worstell, 2002

 
10_t.jpg
52K + description72K
Unobtrusive Holding Building (12)
©Carlyn Worstell, 2002

 
7_t.jpg
41K + description52K
Indoors (13)
©Gert-Jan Verboom, 2004

 
12_t.jpg
44K + description57K
Indoor enclosure (14)
©Gert-Jan Verboom, 2004

 
13_t.jpg
18K18K
Litter for Enrichment (16)
©Monique van Leeuwen, 2003

 
14_t.jpg
17K17K
Lookout for silverback (17)
©Ina van Seeters, 2003

 

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