The Role of Architectural Design in Promoting the Social Objectives of Zoos

A Study of Zoo Exhibit Design with Reference to Selected Exhibits in Singapore Zoological Gardens

by Michael Graetz

PART TWO - PHYSICAL ELEMENTS OF ZOO DESIGN

2.1 The Nature of the Moat

Moats are more than just animal barriers. At worst, the moat divorces the visitor from animals as much as mesh and bars. At best, they serve their containment function without visitors’ being aware of it and/or play a part in enhancing visitors' experience of animals.

Moats separate visitors from animals by some distance. This is good in some ways, especially for the animals, but it diminishes animals visually in size and may reduce visitors' involvement with the animals. This chapter examines the impact of moats from both sides and their role in modulating the visitor's experience.

Visitor Perceptions of Moats

Two best approaches to moats design from visitors' point of view are: (1) to make them invisible; and (2) to make them look like natural features. To treat moats in any other non naturalistic or abstract way is, as Polakowski calls it, “a non-argument”.[1] While it could be argued further that concealed moats are altogether the better option, designers need to realise how sophisticated visitors' powers of perceptions are. Concealment is thus not easily accomplished.

Concealing a moat involves not merely controlling the sight-lines of viewers but ensuring that no clues to the moat are present at all. The principle fault usually appears as habitat landscaping carried inconsistently or not at all across the moat to the visitors' side. Often it is a matter of the ‘habitat’ disappearing under the hooves and teeth and paws of the animals. Designers must assume, therefore, that casual observers can spot the line of demarcation[2].

For example, in the early 1980s an exhibit existed in Singapore Zoo for a browsing herbivore that achieved the illusion of no front barrier. Grass (Axonopus compressus) was the substrate each side, which sloped imperceptibly in to the dry moat. When brindled gnu (Connochaetes taurinus), a grazing animal, subsequently occupied the exhibit they transformed the landscape into barren earth and destroyed the illusion.

Expressing moats as geographical habitat features In contrast to total concealment is the idea of deliberately, or of necessity, showing the moat barrier--as a river, gorge, cliff or eroded landscape, for example. This approach can have two alternate intentions: (1) to enter the moat into the interpretive story-line of the exhibit and so convey the notion that animals in the wild are limited in their home-ranges by natural barriers; (2) to portray moats as a part of the habitat without visitors seeing them either explicitly or implicitly as a barrier.

In both approaches, the moat can fulfil functional or behavioural requirements of the animals. These may include rocky outcrops to climb on, water to swim or fish in, etc. and, most important, the limit of the animals' home range. Often, either of these approaches can often be more satisfactory than trying to conceal the barrier’s existence altogether. An advantage of concealment is that it does not matter what the moat looks like, dispensing with expensive landscape treatments. We have already noted the pitfalls of this notion. The best approach, in general, would be to hide the full extent of the moat. A modicum of habitat simulation (and immersion landscaping) can remove the remaining visual clues and prevent the moat drawing the eye, or appearing as a formidable barrier.

Psychological diminishment Nature thus inspires the ‘palette’ of moat treatments. However, their application is towards the end of playing down the moat's presence or extent. Concealing a moat’s depth should not be difficult, but visitors can judge width by the animals' distance. Perceptual illusions that simultaneously make moats appear narrower and animals appear larger will make the animal seem closer than it is[3].

The viewing geometry is possibly the most important factor in how wide a moat appears. If the visitor's line of sight is below the top level of the moat, then aiming for total concealment is possible.[4] As the moat comes into view with higher vantage points, it initially forms a small component of the view. Thus, the lowered viewpoint is an important technique that has another desirable consequence: it raises the animal, which then commands more respect and draws attention away from the moat.

A berm or other landform, or natural feature (such as a fallen tree) can also draw a discreet veil in front of the moat. This may be called for where lowering the vantage point of the visitor is not possible or desirable (where the animal is arboreal for example). Plants can achieve this also, but as mentioned, they may contrast too greatly with enclosures denuded by animals. Especially if plants within are chosen to withstand animal pressures and without purely to screen the moat, with no consideration of the whole effect.

Dark areas in the field of view diminish and draw the eye less. The dark waters of an unfiltered wet moat can give this effect while edges of dry moats can simulate dark rock or earth. The converse is also true: bright areas within the exhibit will attract attention and appear closer. The pre-eminent use of this technique is in the Night Safari that literally puts animals in the spotlight.

Thus far the discussion has focused on achieving the illusion of not only being in the animals' habitat but being effectively in the animals' home range. The simple need to prevent visitors from really entering the animals' space--or falling in the moat--often subverts such illusions. In most zoos, bar less enclosures still have handrails to protect visitors (and animals). One solution to this is to replace the railing with a sufficiently wide planter with deterrent planting[5]. Again, the result may be perceptually the same as a handrail unless the planting is the same on both sides.

Singapore Zoo has used a variety of low impact safety features, many of which would not be possible in countries like the USA for example. They would be considered to hazardous or too much at risk of deliberate transgression. Among these are the following: depressing the planter level below the path so that the visitor is unsure how big the drop submerged in plants is; raising the planter with the wall formed as a natural feature; and various combinations of tensioned stainless steel cable on vertical or angled supports, painted matte black and merged with the vegetation. Often the most satisfactory method, which depends on risk, is simply to rely on visitors keeping to the path. The danger in opting for the most minimal method instead of accepting a compromise is that the handrail ruled out earlier may appear later, if the psychological approach fails.

Significance for Animals

Psychological significance. Very often an animal's pacing wears a track along the edge of the moat. This may be a sign of stereotypical behaviour (called locomotor stereotypy). It may also be a sign that the animal has insufficient space--why else would it describe the largest possible circuit allowed? It may also be a result of the normal behaviour of patrolling and marking the animal's territorial boundary.

Shepherdson explains “locomotor stereotypy” as a “thwarted escape response”[6]. Among the various reasons why animals should want to escape, too small an enclosure is not the most usual. Others are as follows: inability to act out normal behavioural repertoires; fighting with con-specifics; the existence of predators (such as wild pythons in the Zoo grounds); and awareness of something desirable outside the enclosure. These usually occur because the required features or circumstances are not present in the enclosure. Shepherdson further states that besides spatial volume, “edges” are also important for some animals such as chimpanzees. Thus the edge/area ratio may be more critical than enclosure area and be a measure of how “efficiently” animals use space.[7]

Table I MOATED EXHIBITS IN SINGAPORE ZOO

EXHIBIT	EXHIBIT AREA	FRONT BARRIER				SIDE/REAR BARRIER
		Width	Depth	Water depth	Type	Height	Type
	(m2)	(m)	(m)	(m)		(m)
Macaw	16	1.2	0.3	0.3	Wet	1.2	Wall
Lion	1393	10.0	3.0	1.1	Wet	4.5	Fence
Sumatran Tiger	1124	7.6	3.8	1.5	Wet‡	4.5	Fence‡
African Hunting Dog	1096	10.0	3.0	1.1	Wet	4.5	Fence
Maned Wolf	551	3.5	2.3		Dry	2.1	Fence
Polar Bear	328	4.2	4.5		Dry‡	3.9	Wall
Asian Elephant	1381	2.1	1.5		Dry	1.5	Fence
Giraffe	2098	3.0	0.9		Dry	2.1	Fence
Malayan Tapir	468	1.0	1.2		Dry	1.8	Fence
White Rhinoceros/Eland	2306	2.7	1.0		Dry	1.8	Fence
Barbary Sheep/Axis Deer	759	3.0	1.2	1.2	Wet	2.1	Fence
Black Buck/Deer	2535	3.0	1.5		Dry	2.1	Fence
Gnu/Thompson Gazelle	1400	3.0	2.1		Dry ‡	2.1	Fence
Greater Kudu	1577	3.0	1.6		Dry	2.1	Fence
Guanaco	608	1.4	1.0		Dry	2.1	Fence
Nilghai	1070	3.0	1.5		Dry	2.1	Fence
Nyala	1446	3.0	1.5		Dry	2.1	Fence
Oryx/Zebra	885	2.4	1.0		Dry		Moat
Zebra	657	4.5	0.9	0.9	Wet	2.1	Fence
Capuchin Monkey	153	3.5	0.6	0.6	Wet		Island
Celebes Ape	303	3.0	0.9	0.9	Wet		Island
Chimpanzee	750	5.8	3.0	2.1	Wet	2.7	Fence*
Colobus & Patas Monkey	460	7.0	0.6	0.6	Wet		Island
de Brazza Monkey	100	3.0	0.7	0.6	Wet		Island
Brown & Ring-tailed Lemur	219	3.0	0.6	0.6	Wet		Island
Lion-tailed Macaque	300	3.0	0.6	0.6	Wet		Island
Mandrill	338	5.8	3.0	2.1	Wet	2.7	Fence*
Muelleri Gibbon	169	3.6	0.6	0.6	Wet		Island
Orang Utan	660	3.8	3.0	1.5	Wet		Island
Silver Leaf Monkey	706	5.0	0.6	0.6	Wet		Island
Spider Monkey	144	3.6	0.6	0.6	Wet		Island
White-handed Gibbon	129	3.6	0.6	0.6	Wet		Island
Californian Sealion	450	1.2	1.2		Dry		GFRC
Green Iguana	191	3.0	1.1	0.5	Wet	1.7	Wall
Komodo Dragon	414	2.1	2.1		Dry	2.1	Fence*
Malayan Monitor/Civet	270	1.2	1.7	0.5	Wet	1.7	Wall
Rhinoceros Iguana	75	1.7	0.9	0.5	Wet‡		Island
*Cladding on fence   ‡Includes overhang

Moats as physical barriers When moats work the animals accept them as something comprehensible--the limit of its home range. Moats fail when the animal finds it alien to its nature. Under these circumstances, moats work as containment systems because they are a physical barrier to the passage of animals. Consequently, moats are hazardous to animals attempting to escape. This manifests itself in drowning, falls or simply the animal being out of sight because it has got into the bottom of the moat. To avoid the latter, designers must also make a hazard of the act of getting in the moat. One of the commonest means employed is the non-lethal hazard of ‘hot’-wire[8]. Uncomfortable bases such as mud or stones may make dry moats unattractive. Preferably, however, animals should find it positively more attractive to remain within the enclosure proper.

Moat Design

Ascertaining gross dimensions. The most obvious question in planning an animal exhibit is to ask what form the barriers will take. Gross dimensions therefore will often occupy much initial discussion--width, depth, height above and below water level, some refinements such as overhangs (or outriggers), for example. Once decided, that is very often that. The design team will review the dimensions once it has decided a suitable form of construction, and it is very often left this way through to construction.

While getting the dimensions correct with respect to the animals is imperative, asking a different question initially may better serve the design. Some initial questions may be thus: what are, or should be, the relative levels at each edge of the moat? And: what variations in these may be required or desirable along the moat length? Once the team has studied these--or possibly once the designer has reported on these--it can address and vary the dimensions from the standard to suit the final levels or other requirements.

This question of levels is also one ground for the argument that there are no standard moat dimensions. Never-the-less, much has been published on this subject since Hagenbeck[9] baited lions and tigers to see how high and wide they could jump. This literature arises from the constant sharing of information between zoos, particularly when one zoo is approaching the design of a moat for a species that is new to it. An author who publishes barrier dimensions from his or her own zoo is sure to be well read. Zoos will usually interpret the information it solicits with caution and filters it through its own experience. A ‘time-savers standard’ would be a dangerous tool if taken with the same assurance that one would use such a reference for, say, car park dimensions.[10]

Some reasons why standard moat designs are not desirable are as follows:

1. Existing site levels may give an animal the advantage of a downhill jump. Conversely, an uphill jump may permit a reduced width.

2. Edge and bottom conditions affect the risk of escape. These are controllable, but a designer may use any number of treatments, each with potentially different effects on different species. These special conditions can include vegetation (deterrent etc.); water (soft, marshy or flooded); stones (of various sizes and angularity); and ‘hot’ wire (in various arrangements).

3. The shape, or sectional profile of the moat is infinitely variable from rectangular to ‘U’- or ‘V’-shaped. These may be asymmetrical (with a more-or-less vertical outer wall and reclining slopes on the inner, animal side). Maintaining a uniform profile throughout its length may not be possible or desirable and this variability will affect the moat's performance.

4. Species are not individuals. As much variation in ability may exist between con-specifics as between people. Later experiments1[11] exceeded Hagenbeck's findings with lions and tigers, so minimum absolute limits for a species are difficult to fix. One common characteristic that affects performance is whether the animals are wild-caught or zoo-bred. The latter are partly domesticated and thus less flighty and less fit1[12].

5. The human ‘culture’ of the zoo (and not entirely the attitude of the director alone) ultimately determines whether the approach to barrier design will be radical or conservative. This may also encompass the zoo's attitude towards its visitors. It may contemplate testing the lower limits of moat widths in the interest of giving visitors a closer, more dramatic view.

6. With the Night Safari, another factor arises. Nowhere else have nocturnal animals been displayed at night, confined in outdoor enclosures. Singapore Zoo adopted a conservative approach to moat dimensions in anticipation of more active nocturnal animals than in daytime displays. Keepers routinely move dangerous animals to more secure night quarters in zoos generally for this reason.

These cautions not withstanding, examining the barriers of Singapore Zoo in relation to other published data is still of interest. Table I shows the basic gross dimensions of most moats in Singapore Zoo, with the exhibit areas accessible to the animals.

Additional features and refinements.

The dimensions in table I are of course not the whole story. Apart from features already alluded to--top returns, ‘hot’ wire, muddy bottoms, smooth walls, height above and below water--questions of how to get animals out of moats and avoid their getting into difficulties arise: ramps or ladders to return to the exhibit or another yard; and ribbed and grooved surfaces or rough textures for secure footing. The ends of moats and their junctions with other barriers such as fences are also important details to resolve and keeping in mind the visual appearance of these measures.

The reference made to variation from standards does not convey the elaborateness of moat treatment either. This is such that working drawings of moats cannot fully describe them in the conventional sense. The designer/documenter can only give an impression of the desired result and it requires an exhibit constructor well versed in this type of work to interpret the intention. Typical details usually give only the permissible extremes, and the contractor needs to be as much an artist (or to employ them) as a builder.

Concluding Remarks

This chapter has discussed several approaches to moats with remarks on their respective merits. We should not, however, conclude that any general approach applies to all or even a range of situations. The problems of site, animals and visitor needs are so variable that to propose one approach is questionable on both functional and aesthetic grounds. ‘One approach’ means always aiming for concealment, or always simulating natural features. Either one is valid but probably not to the exclusion of the other. Visitors do not see exhibits in isolation and three related defects--boredom, predictability and exhibit fatigue--must be guarded against.

Thus, specific recommendations are not possible, but generally, designers should adopt a variety of approaches across a range of exhibits. These can include the following: surprising visitors with the illusion of being among the animals, or that the animals are free; conveying the message that the moat marks the animals' territory, which the visitor must respect; giving way to visitors' desire to get closer by using glass or other thin viewing barriers.1[13] Above all, the implications of a moat from the visitors' standpoint should not be considered as purely to provide an unimpeded view. Nor should we see it in isolation in considering the primary animal restraint role.