Bryan Shao-Chang Wee

Avian species are seldom the topic of discussion in areas concerning behavioral enrichment, despite the manifestation of abnormal behaviors and presumed boredom in captive birds. Birds in captivity are liable to suffer from a number of stress-related health, and behavioral problems when placed in situations where social and environmental deprivations exist. This paper delves into the meaning of behavioral enrichment, the need for it in zoos today, and highlights several examples of how we can rise to meet the challenge of ensuring that both the physiological and psychological needs of birds in captivity are taken care of.

The last decade has brought about a change in the way many zoos exhibit animals. When Carl Hagenbeck founded the Hamburg Zoo in the 1920s, I doubt he ever imagined that his idea of using a combination of real, and fiberglass foliage in an attempt to re-create an animal’s native environment, would later propel zoological institutions worldwide into an era of emphasizing naturalistic settings for animal exhibits.

Creative exhibit design, short of replicating the animal’s native range, can induce a ‘sense of freedom’ in the mind of the visitor (Polakowski, 1987). The ability to visualize a bird cloaked in its natural surroundings would lead not only the visitor, but even zoo personnel to conclude, and reasonably so, that every provision had been made to maximize its well-being in captivity.

It is important to remember, however, that even if a bird were placed in a large, spacious aviary, complete with live plants, a naturally-occurring substrate, and fiberglass river to boot, it might still end up behaving in a monotonous manner. The size of an aviary and a very ‘natural’ interior in themselves, are not enough to guarantee adequate or appropriate behavioral enrichment. After all, the quality of a confined animal’s space is more important than the quantity (Thompson, 1996). It is all too easy to create a space that looks wonderful, yet gives the animal no more freedom of expression than it would have in a simple box (Tudge, 1991).

This is where behavioral enrichment plays its part in the contemporary zoo, by improving the physiology, and mental well-being of the animal.

Various proponents of enrichment for animals in captivity have approached this subject from many different angles. Chamove, in his article ‘Enrichment - past and future (1994)’, defines enrichment as the ‘return to normal (wild) behavior’. Others, on the other hand, see enrichment as ‘increasing exploratory behavior … and reducing stereotyped behavior’ (Bacon, 1992). Hence, suppose we placed a rubber ball in an aviary, and a bird ends up spending a considerable amount of time playing with it. Some would say that this cannot be considered as enrichment, since it is obviously not normal for birds to play with balls in the wild. Yet others would argue that, by virtue of it having reduced, say, feather-plucking in that bird for even the briefest of moments, the resulting ‘distraction’ caused by the rubber ball was definitely enriching.

The difference then, lies in how we would like to see the animal progress. If we are satisfied that the success of behavioral enrichment lies in the amount of interest the birds demonstrate in reacting with, and exploring their aviary, then the latter explanation would suffice. However, if we plan to take this a bit further with the intention of re-introducing the species into the wild, then it certainly would not hurt to re-assess our enrichment methods, to allow the animal more opportunities to engage in ‘normal’ activities, that which is reminiscent of its behavior in its native habitat.

What then, constitutes ‘abnormal’ behavior? We must expect some differences between behavior in captivity, and in the wild. After all, the ‘wild’ is not a single, uniform place, and each animal adapts to particular circumstances. So, we cannot assume that every behavior perceived in the wild is typical of its behavior under all ‘wild’ circumstances, and neither should we assume automatically, that any deviation from wild behavior in captivity is necessarily bad (Tudge, 1991). Therefore, I would think that abnormal behavior refers to stereotypy (repeating the same action over and over again without any apparent function or goal), to acts of excessive lethargy, perhaps over-grooming to the extent of feather-plucking, over-aggressiveness, over-eating, and a failure to breed, among others.

Behavioral enrichment is important because it assists in reducing the possibilities of abnormal behavior, increases the educational value of exhibits, helps to validate captive display, and can stimulate greater interest in the physical environment, leading to enriched social interactions between birds. Specifically, enrichment techniques optimize the levels of social and physical stimulation provided in captive environments to maximize reproductive potential, and ensure normal behavioral development (Shepherdson, 1994).

In the long run, however, behavioral enrichment does more than just provide welfare for the individual. As wild habitats continue to shrink, and human pressures on wildlife continue to rise, zoos are increasingly concerned with the conservation and wellbeing of groups (populations and species) as well as individuals (Shepherdson, 1994). These new and interrelated roles for enrichment have progressed from the predominantly individual-oriented approach to include goals like the conservation of culturally defined repertoires of behavior for research and education; and facilitating the reproduction of captive populations (especially endangered species). Furthermore, with the present emphasis on conserving entire ecosystems rather then individual species, zoos play an important role in the re-introduction of captive-bred animals into the wild. This has increased the need for the continued preservation of natural behaviors in captivity, a goal that is greatly aided by behavioral enrichment.

Traditionally, mammals, primates and carnivores have garnered the bulk of the attention, when discussing the importance of the environment, and enrichment techniques for captive animals. In Markowitz’s [1982] book where he discussed behavioral enrichment applications, only one of the 199 text pages was devoted to birds (King, 1993). It is a fact that birds lack a close evolutionary relationship with humans when compared to the primates, and this perhaps accounts for their presumed lower levels of intelligence. However, the awareness that we are equally responsible for providing enriched environments for birds in captivity is not growing simply because many of us are not looking at the big picture, that a bird is just as important as, say, a large mammal in an ecosystem.

One of the most important misconceptions concerning birds in captivity, in my opinion, lies in the enclosure size, relative to body size. Now, for most carnivores, the enclosure size relative to body size is small, meaning to say that a lion would look pretty cramped in a 40 x 50-foot enclosure. A bird in the same enclosure, on the other hand, would have a much bigger enclosure size relative to body size, even for a large parrot like a Macaw. In short, people tend to think that birds have ‘plenty of space’ because of their relatively smaller size. This however, is far from true. Some birds are migratory, others cover long distances in search of food. Still others have territories marked over hundreds of miles. The size of an animal does not necessarily determine the size of the required space. Rather, it should be dependent on their behavioral needs. Birds also need environments that closely resemble their native habitats to express their behavioral characteristics (Polakowski, 1987).

When this is lacking, birds can end up with a multitude of problems. The absence of certain key stimuli in the physical environment of captive animals can result in failure to express certain behavioral patterns (Thompson, 1996). Based on the theory of natural selection, the rarity of certain essential behavioral patterns may cause these patterns to become gradually ‘phased out’ in a species over a period of time. Research has also shown that animals kept in socially, and physically impoverished conditions tend to develop rigid, unvarying behavior patterns (stereotypic behavior), rather than remaining exploratory and alert to stimuli in the environment (Shepherdson, 1994). Needless to say, stereotypic behavior in confined birds is an indication of poor welfare.

Birds in captivity may exhibit behaviors that give false perceptions of control when their lives are deprived of enrichment. These behaviors serve as outlets for pent-up frustrations, and are usually redirected to other objects or individuals in the aviary. Some ways in which birds stimulate themselves in an impoverished environment would include excessive self-scratching or self-mutilation. I have seen a pair of Golden-capped Conures, Aratinga auricapilla pluck themselves till they were bald. Despite providing fresh browse for the Conures on a daily basis, they continued to feather-pluck incessantly, to the extent of de-feathering their offspring!

Boredom is the psychological response to an environment that fails to meet the animal’s needs for stimulation due to low stimulus diversity (Thompson, 1996). More often than not, birds that are placed in stimulus-poor environments end up with a lowered expectation of the level of stimulatory input from their surroundings. Hence, a preference for little or no change in their environment develops. In addition, birds that are confined to monotonous environments for prolonged periods, are also less likely to engage in active stimulation-seeking behavior, even when presented with the appropriate opportunity. These may help explain why the Golden-capped Conures failed to respond to the introduction of fresh browse. Yet another example of birds providing false perceptions of control would be sudden explosions of aggressiveness among animals that have lived together in apparent harmony. This can be viewed as a redirected response toward an uncontrollable situation. There have been occasions at the Jurong BirdPark when seemingly docile and well-tempered individuals turned upon their aviary-mates with a sudden viciousness previously not displayed.

Enrichment strategies fall roughly into two categories: those that work on an occasional, irregular basis, and those that sustain interest over a long period of time despite repeated use (Lewis, 1992). At the Jurong BirdPark, we have a number of enrichment tools at our disposal, most of which fall under the latter category.

The first category consists of strategies that rely on novelty, things like plastic chains and wooden "toys" suspended from the top of cages. At the Jurong BirdPark, we also provide parrots with different materials to play with and chew on including fresh branches and dried whole coconuts. The coconuts are tied to the sides of aviaries with metal wire, just so they remain hanging there giving hours of chewing pleasures even after the powerful mandibles of a macaw have begun to strip the husk off. However, based on the need to keep the birds stimulated on a daily basis as far as possible, we have taken the effort to come up with more long-term enrichment techniques, to allow for sustained interest in the display and holding aviaries.

At our most recent display exhibit, Parrot Paradise, where we showcase more than three hundred parrots from over a hundred different species, the birds are mainly housed in mixed species aviaries. This means that they are able to mix freely with other species from the same, regional geographic location. For example, we have housed the African Grey Parrot (Psittacus e. erithacus) with the Senegal Parrot (Poicephalus senegalus), and the Jardine’s Parrot (Poicephalus gulielmi) in one large communal aviary (under the heading ‘Rainforest Africa’).

Providing companionship is essential as it allows birds to engage in appropriate social interactions. Social partners are an infinite source of response-contingent stimulation, allowing an individual to interact with its surroundings to a much greater degree than if it were alone (Thompson, 1996). Hence, it would be preferable if birds were placed in social groupings rather than exhibits of single specimens. Care must be taken at all times, however, to ensure that species well-known for their aggressiveness are kept under a watchful eye, and that introduction cages are used when placing new birds into an aviary. With constant and careful observation, aggression can be minimized.

Another enrichment tool in Parrot Paradise is the use of specific substrates in all the display aviaries, once again depending on geographical location. The use of various types of substrate such as compost, sand, red clay, and wood chips adds to the structural diversity of the exhibit. Natural ‘soft’ materials like grass, earth, sand, and gravel are often preferred because they provide opportunities for the birds to dig and play (Polakowski, 1987). There is no doubt that soil-related substrates can present maintenance problems and harbor harmful organisms, if not handled or maintained properly. Nonetheless, with regular fecal analyses and diligent care, the result of having naturally occurring substrates in aviaries is well worth the effort.

Water is also used as an enrichment tool in several of our exhibits. At the Waterfall Aviary, mist is sprayed generously to create the illusion of being in a rainforest. Not only does this ameliorate the microclimate for the birds, more importantly, it provides a semblance of their natural environment. In addition, sprinklers at several of our exhibits provide the birds the opportunity to take showers, especially during the hot, humid afternoons. Reducing body and aviary temperatures is only part of it. The birds, especially lories, get a kick out of playing with the jets of water spraying down at regular intervals during the day. A few of them have even managed to ‘damage’ the water nozzles in their aviaries, so keen were they to explore the contraption.

Plants in our exhibits suffer from constant exposure to the bird’s individual behaviors. Activities such as chewing, digging, and scratching, can and will be fatal for most kinds of plants. Parrots especially, love to chew, this being one of their natural behaviors in the wild, where they spend hours breaking nuts open for food. In these cases, we place ‘browse’ or sacrificial plants, and branches into the aviaries to keep the birds occupied. It is always best to allow the animals their interactions rather than frustrate them (Simpson, 1992). At the end of the day, sacrificial browse saves the plants from annihilation (for a while at least!) while the birds, like parrots, are able to engage in a natural activity.

There are certain guidelines to follow if we wish to achieve effective behavioral enrichment. First and foremost, zoo personnel have to know the animals, their behavioral characteristics and their physiology. Without this important information, one cannot possibly hope to provide an accurate analysis of the animal concerned, or design an appropriate enrichment tool. Knowledge of animals in their wild environment and their response to different environmental stimuli is clearly fundamental (Shepherdson, 1992).

Flexibility and imagination are key ingredients in a successful enrichment recipe for captive animals. None of this will exist if the staff are not there to make it happen. This is all the more important considering a lot of the staff, like the keepers, spend the majority of their time with the animals. They, more than anyone else, would be able to note even the slightest of changes in behavior. Therefore, morale and enthusiasm among the staff is of the essence.

The exchange of ideas between institutions or individuals would also go a long way to improving enrichment techniques. Sometimes, all it takes is a different perspective or a ‘third person’ to give a particular technique an entirely new outlook. There exist in our midst, publications designed as vehicles to present enrichment ideas of all kinds, where zoos could contribute articles or offer fresh perspectives on current issues.

Most zoos nowadays work within severe financial constraints. We must always keep in mind that some enrichment techniques while excellent in theory, may prove too expensive to build or maintain. It would be wise then, to design enrichment tools that are cost-effective, without grandeur if possible, in order to exclude unnecessarily high material, and maintenance costs.

Behavioral enrichment, without question, is an all-important tool in the exhibition of captive animals. It improves the life of the individual or group by providing natural behavioral opportunities, and creates a stimuli-filled environment in an otherwise constant captive setting. However, it is important that we do not overlook the importance of first having an exhibit that resembles the animal’s native habitat. After all, enrichment of any sort should not be an afterthought or something added to compensate for deficiencies (Shepherdson, 1992). Indeed, it is a combination of both exhibit design and enrichment tools, in the right amounts, that will ultimately allow the animal to enjoy a better quality of life in captivity.

More important for zoos though, is that with naturalistic exhibit designs and appropriate enrichment tools, the educational impact of an exhibit in which a visitor can watch a pheasant foraging for insects on the forest floor, or a reptile moving to adjust its body temperature, far exceeds narratives that require us to imagine the animal’s behavior in the wild.

Over the years, we have progressed in husbandry techniques, in breeding strategies, in the understanding of animal psychology, and in the relations between humans and other animals. The onus is on us to use all that information and experience to justify the exhibition of captive animals by maximizing their educational utility, improving their quality of life and providing species-appropriate opportunities (in terms of exhibition and enrichment) in captivity.