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E: Environment, Enrichment,
Education, & Endangered Species

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Welcome to E! This section is dedicated to the environment, enrichment, and education about animals and related topics. This page contains a history of enrichment.

History of Enrichment
by Arnold Chamove

In Victorian times there was a dramatic increase in the number of zoos. At that time people were only interested in seeing the new animals that were discovered from different parts of the world. As human disease was conquered and population growth became exponential, more zoos were developed all over the world and the criteria for good management of these animals then changed to one of breeding success. With the development of psychology and biology, people started studying these animals. At the same time, researchers were also looking at animals living in the wild. But until the 1960s, traveling from countries with developed research facilities to countries with large numbers of exotic wild animals was very expensive and so, not much fieldwork was done.

In the 1960's when much of the research on monkeys and on other animals that were housed in labs was conducted, it was soon discovered that there were a variety of experiences which were required for the normal development of a monkey. There weren't one or two things which if applied would produce a normal animal. There were different early experiences, or early conditions, which were necessary for the development of different types of normal behaviour. For example, for an animal to develop the correct patterns for clinging to other animals, they needed to be raised with at least one other animal, otherwise the innate cling response would be directed at one's self or at an inanimate object such as a diaper/nappy or soft toy.

To develop the correct direction for aggressive behaviour that is not directed to its own body, a young monkey must be put with at least one other animal (a monkey or even a dog) during daylight hours. But for an animal to develop normal patterns of social interaction, they need to be put with at least two other animals. One animal was not sufficient. The youngster needs to be raised with an adult animal or another youngster, which it can cling to as if it was its mother. For an animal to break the attachment that it has to its mother figure, (adult monkey, cage-mate or dog) there needs to be some break in the consistency of its interaction with that particular animal. If it is living always with the same animals, the two youngsters will cling together and they will never break that clinging pattern, the clinging pattern that a mother would break normally as their offspring gets older.

It was also found that if you wanted an animal which showed normal levels of aggression, it needed to be raised with a normal mother. If it was raised with other youngsters, it would be less aggressive than normal. If the youngster was raised with a mother that was not normal, who herself had perhaps been raised abnormally, the youngster would become more aggressive as a direct consequence of the aggression that it received from its mother.

So all of these different behaviour patterns which were observed in the youngsters, such as attachment, aggression, and sexual behaviour, could be influenced by different variables. Clinging is influenced by the number and pattern of animals that you were reared with. Aggression is influenced by the amount of aggression that you experience and both are affected by how confident you are. Sexual behaviour is influenced by a number of different experiences. You have to know that you are a monkey by being raised with other monkeys. You have to be able to get on with monkeys by being raised with more than two other monkeys and you have to have observed normal sexual patterns by being in a social group, etc.

Out of all of this research on the important aspects of early experience some interesting conclusions were drawn. From work with dogs, for example, it was discovered that there are important periods for the socialization of dogs. If you want a dog to be a normal dog, that is not to view human beings as part of its pack, you need to keep human beings away from it while it is young but give it experience with other dogs. If you want a dog to view human beings as part of its pack, then dogs need to have experience with humans before a particular age. If you want dogs to view cattle as part of its pack, and therefore be able to live with those cattle and protect the cattle from predators - wolves, coyotes, and even humans - then you need to raise those dogs with the cattle at critical ages.

A lot was learned about what was necessary to produce certain types of behaviour patterns, some of which were believed to be normal, and some of which people didn't know if it was normal or not. For example, in the fifties when the dog work was done and in the sixties when the monkey work was done, people didn't go into the wild and observe wild dogs, wild monkeys, wild cattle, wild chickens. But as the number of students increased, as the number of universities increased, and as travel became less expensive, people started to do these things and soon it was discovered what it is that normal wild dogs do. Of course, many people would say they don't want a normal wild-type dog. They don't want a dog which goes out and kills animals, which forms packs and hunts down animals eating them before they are even dead. The benchmark for normality (not desirability) was behaviour in the wild.

So the shift in zoos has changed from (a) exhibiting animals to (b) having animals which were able to breed in captivity, and now more recently to (c) animals which can show people what these animals are like in the wild. The modern zoo is meant to be a snapshot of the wild and to do this, people have had to discover what's important for these animals so that the animal will show normal behaviour. Comparisons have been made between animals in the wild with animals in the zoo. The new criteria for normal behaviour, has changed from breeding to that of wild behaviour. This is one criteria and probably the most widely accepted.

People who actually work in a zoo environment or work with animals would probably modify that requirement for normality. They would say the behaviour of the animals should not be obviously abnormal. Also it should fit in with whatever circumstances the animal should encounter. For example, they want a polar bear which doesn't show those abnormal pacing patterns common in polar bears, and yet doesn't attack humans. They want animals that fit in to the zoo environment, that are not a danger to their keeper, that while they don't eat the wide variety of foods which wild animals normally eat but still are healthy and apparently happy on the restricted diets which are available to zoo animals.

A similar thing would apply to people raising cattle, or sheep, or pigs, or chickens, or goldfish, or parrots. They want these animals to show no abnormal behaviour, such as the excessive aggression seen in chickens, the stereotyped behaviour that you see in pigs, such as chewing on metal bars, the chewing off of other pigs' tails. They also want them to show fast growth rates on the types of food that they are given and not normally aggressive. For example in cattle, if you are working in a pen with 50 cows, you don't want the cow to attack you. If a one-day-old calf is caught in a bog, you want to be able to go out and lift that calf out of the bog without the mother defending its calf from you as it would under wild conditions.

So when farming, you will want to change certain aspects of the behaviour of animals. You want to modify their responses to presumed predators by either not viewing you as a predator, or in countries where there are few predators and no wild predators such as New Zealand. You want them to show no anti-predator behaviour.

That's the background to enrichment. When the American Government followed the lead of several other Western governments and required that the psychological needs of animals in captivity be catered to, there began to be financial encouragement, and also a psychological encouragement for people to start looking at ways of improving captive environments. Another impetus for this increase in interest was to show zoo visitors the wide variety of normal behaviour that wild animals might show. Hal Markowitz in San Francisco began work to show zoo visitors active, interesting animals not normally seen in zoos. He designed and constructed a number of complex pieces of equipment which would get animals to do normal and interesting things. For example, he had a device where a cricket sound would be given and a bear would get up and it would go over to a log and it would roll the log to one side, something else would happen and the bear would climb up a tree and this would activate something else and the bear would go over and get a piece of food. Instead of a bear lying in the corner sleeping, waiting for its food, the zoo visitors saw an active and interesting bear and this technique has been developed by Markowitz, his students, and others who have been influenced by him into a wide range of naturally appearing behaviour Cats which stalk and leap for quickly moving pieces of meat is another dramatic example.

One of the drawbacks with Markowitz's work is that devices are expensive and have to be tailored quite specifically to the particular animal. By drawback I mean a drawback to their widespread use. Nevertheless, they have been adopted widely and have also influenced the design of zoos. One of the most ubiquitous of this type of equipment is an artificial termite mound, a termite mound which is used to demonstrate termite fishing in chimpanzees. In the wild the chimpanzee takes a stick or a long piece of grass or bamboo or afromomum and breaking off the side branches, she strips it so it's a single rod and then inserts it into a termite mound, waiting for the worker termites to attack the branch. She then removes it eating the attached termites. What's been done in these artificial termite mounds is that some sticky, often sweet substance has been placed at the bottom of the holes. The animal inserts its rod into the holes, removes it and licks off the sticky food. There have been two assessments of these termite mounds, one of these in Edinburgh Zoo which was done soon after the mound was put in, and it was discovered that it was hardly ever used by the chimpanzees. So much so that the keepers stopped baiting it and it was not used at all. Another assessment done in London Zoo was more positive and showed that orangutans did in fact use it, if at a low rate. Zoos are persisting with artificial termite mounds, including those where the visitor can see what is happening inside the mound.

The reason for this journey into history is to give an idea of the type of information that is available if people are interested in enrichment. It also gives some idea of the information which is not available. It's only recently that people have been looking at the behaviour of wild animals. There are only a few studies, a very few studies, on the behaviour of wild horses. One of these is on the behaviour of Prezwalski horses and one of these is on the behaviour of the wild horses of the Camargue which are heavily managed. The now-wild Prezwalski horses are heavily influenced by animals that were brought into captivity and then later reintroduced into the wild area where Prezwalski horses were originally found. I know of no studies of wild zebras, although there may be some, and there are a few studies of wild horses where they exist. A population of such is in New Zealand, and on one or two islands where the animals have been left to go wild.

Some monkeys have been studied extensively in the wild, particularly animals which have been able to be habituated. Perhaps the most famous series of studies is the chimpanzee by Jane Goodall, colleagues, and students. The macaque and baboon have been studied extensively because it's possible to habituate the animals and approach them in conditions of good visibility. The difficult to observe pygmy chimpanzee has only recently begun to be studied. Other animals that are used in labs extensively for behavioral work are the marmosets and tamarins, and because these animals are also difficult to observe in the wild, very little work has been done on them in their natural state. Marmoset and tamarin monkeys are very small, smaller than a cat. These monkeys are difficult to see in their dense jungle environment which they inhabit. They prefer moving through the densest of vegetation, and the cotton-top tamarin is found only in Columbia, and because of the growing of the coca shrub, in Columbia, it is not considered safe to go into areas of undisturbed jungle. Because of the cocaine, most of the jungle, over 99% of it has been cut down and there are only these small isolated pockets, usually on private farms, which have been left. So for a number of reasons, many animals for which wild information would be highly desirable have not been studied.

Seeing abnormal behaviour patterns in captive animals has encouraged a number of people to try to alter their conditions in such a way as to eliminate these abnormal behaviour patterns. There's been a vigorous debate for years about whether abnormal behaviour patterns in animals indicate some compromise of their welfare, suggests that they are suffering, indicates they are unhappy. Or perhaps these abnormal behaviour patterns are an adaptation to the change in the environment. Mink repeatedly doing back-flips hour after hour in their cages, polar bears pacing back and forth, wearing down tracks in the concrete of their enclosure are examples. For clarity this idea could be extended to human beings. If you put a human being in a small cage, sized as the regulations for monkeys, that is, big enough so that this human being could stand fully erect and also lie down. Those are the minimum size regulations for most monkeys. So if you put a human being in an enclosure which was 2m tall and a floor area of 2m long and 1m wide, that individual would show abnormal behaviour patterns. The individual might show pacing. Now, one argument is that the pacing is simply an adaptation to that environment. The polar bear pacing is simply the way that a polar bear walks when it's in a small enclosure. When it's in the wild it shows "pacing" over a long distance, over kilometers. A mink shows jumping patterns in the wild. It can't show jumping patterns in its cage so it jumps up and does back-flips. One argument is that this behaviour is not abnormal, does not show any distress. It's simply the way mink have of exercising. Other people say it shows some type of distress, welfare compromise. A human being chewing gum is their adaptation to chewing food when no food is available or they don't want to eat food. Is it abnormal behaviour? Does it indicate distress? To answer that question, people have looked to objective or independent measures of distress.

If you measure an animal in a cage before it shows these stereotype repetitive behaviour, you will see an increase in its heart rate, or you may get an increase in sweating, or some other indicator that the animal is under some sort of stress, that the animal is upset in some way. But, when you measure it after it shows these repetitive behaviour, it appears as if it has calmed down. My guess is the same thing would happen in humans in a small jail chewing gum. Many of these repetitive, one-per-second behaviour, like the rocking behaviour of animals or of humans seen in either mental hospitals or in hospitals for mental handicap, seem to be related to one-per-second bursts of brain activity which indicate a calmness. I remember my sister when we were kids lying in bed at night and repetitively hitting her head against the pillow at a one-per-second rhythm, and also in toning a little rhyme that she would sing to a one-per-second beat. This is very common in kids! Is it abnormal? Is it something which one wants to eliminate? Thumb sucking in children is another example. The debate goes on but those who feel it is undesirable seem to be winning the debate.

In the 1980s people were observing a number of abnormal behaviour in zoo animals, behaviour which would distress people who came to see them. They would see animals such as orangutans who were immobile the whole day, or they would see animals that were pacing back and forth, in a repetitive action such as polar bears, lions, and tigers. For a number of reasons, this was considered undesirable. So people began to get the idea of enriching their environment to change their behaviour from abnormal to normal. Zoo personnel already had some idea of the basic nutritional requirements and the basic social requirements in order to produce animals which would reproduce, and which could exist in a social group. Now, the goal was to produce animals in an exhibit which would interest people and which would educate people, and which would show the animals in a situation which the zoo could be proud of, could defend. And for a number of people who would keep exotic animals as pets, and the same thing would apply. They would want to keep these animals in a way of which they could be proud, and also they wanted to keep these animals in a way so that the animals appeared happy, appeared well-adjusted, and would show some of the behaviour, perhaps even many of the behaviour that they would show in the wild. And this attitude has spread to people who keep dogs and cats and more recently even budgies/parakeets, parrots, goldfish, hamsters, rats, mice, gerbils and reptiles.

What is the situation which will make these animals happy? One way of asking an animal what it takes to make it happy is to give it a wide choice of situations and see which it picks, and that is certainly one way of asking an animal what makes it happy: What does it want, what does it prefer? If you give me the choice of Mars bars versus a well-balanced meal, I'd choose Mars bars any time. I love Mars bars. If you raise a chicken in a tiny cage, it will choose an environment similar to that cage when allowed to choose. That situation is what it has come to accept, what it feels comfortable in.

But why do we choose things which may not be good for us? If you see a pack of wild dogs killing an animal in the wild you will notice that the first thing that they eat is the liver. The reason for that is that liver is very high in fat and in wild animals there are very low levels of fat, so fat is a very desirable commodity. In much the same way fat is a desirable commodity for humans. Dogs are not as attracted to sugars as humans are but for humans living under primitive conditions, both fats and sugars are rare and are highly desirable commodities and access to honey and the location of bees' nests is a protected resource. The same thing with fats. Those bits of animals which have high levels of fats such as brains, heart and liver are the most prized part of a wild carcass. And the same thing is true for dogs and other predators. Now, in humans, people have exploited that fact and if you mix together fats and sugar with a bit of flavoring, you have chocolate! and there is a wide variety of flavored variants on the theme of fat plus sugar.

Humans and animals are biologically disposed to desiring such things and when they have high amounts of these things, it can lead to problems. And the same with dogs with dogs. They like meat with high levels of fats. Many people in the winter, particularly if they are feeding dry dog food offer their dog pure fat. Dry dog food has low levels of fats and the reason is that if you add fat to dry dog food the fat can go rancid unless there are chemicals added to that fat, and some people prefer not to do that. Many manufacturers prefer not to do that and so it is recommended that if you feed solely dry dog food that you add a certain amount of fat, particularly in the winter. That fat can be animal fats, it can be oils, butter, egg yolk, any source of fat, and you will find particularly in the winter that dogs will regulate the amount of fat that they want, and if you give them a huge piece of beef fat, I mean a huge piece of beef fat, they will eat a large amount the ! first day, less the second day, and then they will stop eating it. So particularly in the winter when dogs spend a lot of time outside or active, when they need a lot of fat to burn the calories to protect themselves against the cold, they like fat.

But in captivity where obesity might be a problem, you might want to reduce the amounts of fat. But one of the most attractive foods to a dog are foods which have high levels of fat. People are beginning to exploit that by providing doggie chocolates. A much less expensive, healthier and much more desirable thing is to cut up chunks of liver into small squares and put it in the oven under low heat for several hours, or in a microwave under low heat for several hours to get rid of the moisture, and what you end up with is very, very hard, very tasty liver chunks which will keep for a long period of time and dogs really like these. They have all the taste of liver with less fat and very little water.

In conclusion, what principles can we derive from the research and speculations of those interested in enrichment which can guide our thinking if we wish to 'enrich'?

We can ask an animal what it prefers, providing it has had wide enough experience to make an informed choice. We can observe the behaviour of wild counterparts to see
(a) the range of behaviour types,
(b) the amount of each type of behaviour that is seen, and
(c) what behaviour take up much of the day.
Making behaviour more 'normal' (wild-like) is an agreed good of enrichment. In animals where food gathering occupies over half the day, food-related activities are a good basis for enrichment. Many enrichment ideas seem to extend 'psychological space' - that is to encourage the animal to act as though it is in a larger enclosure than it really is. See what humans and then animals like and then observe your target animal in a similar situation.

About the Author: Dr Arnold S. Chamove has practical experience with laboratory animals as Director of Research. He has taught various courses related to Animal Behaviour, Clinical Techniques, and Research Methods. In addition Dr. Chamove has done collaborative research with H.F.Harlow on primate learning and social development, taught at Stirling University in Scotland and is currently at Massey University in New Zealand. He is the recipient of the Anderson Prize from the Laboratory Animal Science Association for his work on enrichment. Contact Dr. Arnold S. Chamove at:


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