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Compendium April 2008 (Vol 30, No 4)

Understanding Behavior: Use of Operant Conditioning to Facilitate Examination of Zoo Animals

by Sharon L. Crowell-Davis, DVM, PhD, DACVB

    Even in a profession known for its recalcitrant patients, examination and treatment of zoo animals can be especially challenging. However, appropriate use of operant conditioning can greatly facilitate this process when it is used to train animals to reliably exhibit specific behaviors. While such training is necessarily time-consuming, it can save time, money, and even patients' lives, as administering anesthetics by blow dart into a distressed, running animal presents a significant anesthetic risk.

    Terms and Conditions

    Operant conditioning is learning that occurs when behavior is affected by its consequences (see "How Animals Learn: Operant Conditioning," May 2006). The animal learns that if it does or does not immediately exhibit a given behavior when given a specific stimulus, called an eliciting stimulus, there will be a specific consequence: another certain stimulus, the controlling stimulus, either will be present or will discontinue. The term reinforcement refers to operant conditioning paradigms in which the likelihood of the behavior being repeated increases, while the term punishment refers to paradigms in which the probability of a behavior recurring decreases. The term positive means that the controlling stimulus is present or offered if the behavior occurs, while the term negative means that the controlling stimulus is absent or removed if the behavior occurs. In working with zoo animals, positive reinforcement, in which the animal repeats a behavior because it learns that the behavior results in a specific, desirable, or pleasant consequence, is most commonly used (see glossary).

    The primary operant conditioning technique used to train zoo animals is called shaping. In shaping via positive reinforcement, the animal is reinforced for behaviors that are progressively more and more like the desired end behavior (see the box for examples). This technique is used when the desired behavior, in its complete form, is unlikely to occur spontaneously so that it can be reinforced. Timing can sometimes be difficult, especially when working with wild animals, but use of a clicker or similar device can help. The clicker makes it possible for the trainer to make a brief, unique noise at the moment the animal engages in the desired behavior, regardless of whether it is possible to immediately provide a real or primary reinforcer. This sound becomes a secondary reinforcer: although a clicking sound is not normally something an animal would find pleasant or reinforcing, when it is consistently paired with a pleasant experience, it becomes a conditioned stimulus via classical conditioning (see "Classical Conditioning: Learning by Association," June 2006).

    Factors Affecting Training Success

    The primary reinforcer needs to be specific to the species and the individual animal. It should not just be desirable. It should be highly desirable. For some animals, a limited repertoire of reinforcers is fine, while for others, a variety of reinforcers, perhaps used in regular rotation, is more effective. For example, for a bobcat, chunks of meat are best, while bits of fish are acceptable. For otters, the opposite is true. Strawberries, grapes, and bits of apple are options for deer. Bears may respond best to an even more diverse set of offerings. As a general rule, simple "chow" or "kibble" will probably not be sufficiently motivating, nor will hay, if the animal is herbivorous.

    Many day-to-day factors also influence how well an animal responds to attempts at training. Hunger versus satiation is always important and can be even more relevant in a zoo environment, when training times must be coordinated with regular feeding times. Many animals perform best if they are hungry. Therefore, training sessions should not be conducted right after the animal has had a full meal. However, some animals become more aroused and agitated if they are hungry and will not perform well in this situation. Weather and time of year are also relevant. Training when it is very cold, very hot, or raining does not proceed well with many species because the animal, like the trainer, is uncomfortable in the unpleasant environmental conditions. Animals that hibernate, such as bears, are not likely to make progress during the winter. Nocturnal animals are not likely to make progress during the day and are best trained at night or, if their day/night cycle is reversed by artificial lighting, when the red light of their artificial night is on. Simple behaviors that the animal will not find aversive can sometimes be fully trained in a few sessions, while complex behaviors that the animal finds even mildly aversive may require months of work.

    When an animal has been successfully trained to perform a certain behavior, it is essential to maintain the behavior by regular practice. If training is discontinued, the behavior will eventually extinguish.

    Other Considerations

    Single Versus Multiple Trainers

    Selection and education of trainers is an important consideration. Some zoos have the budget to hire personnel whose regular job requirements specifically include conducting animal training. Other zoos are on a much tighter budget and cannot hire more personnel than are essential to take care of the animals' basic needs. In the second case, volunteer trainers may be able to fill the gap. Because consistency of training over a long period of time is essential to success, volunteers involved in such projects must be committed to several training sessions each week for an extended period. Multiple people can train the same animal to perform the same behavior. In fact, having multiple trainers can be beneficial because the animal is then more likely to exhibit the desired behavior to anyone rather than to just one person. If a single person exclusively does all of the training, the animal may not respond to anyone else, making it impossible to affect the animal's behavior if the single trainer is sick, on vacation, or otherwise absent.

    Commands and Communication

    If multiple trainers work with the same animal, they need to communicate on a regular basis regarding what training is being conducted and how the animal is progressing. They should select command words for specific actions that are simple for everyone to remember and are relatively unique to the vocabulary of the people interacting with the animal. For example, in the case of a tame doe that was resistant to restraint for physical examination, the word hug was selected as the command for it to stand still while someone held it. Gradual desensitization to being held was necessary, with the desired behavior being simply that the doe remain still. In the initial stages, the trainer reached around the doe's neck without making contact. If the doe remained still, it received a grape or other treat. Gradually, the trainer made increasing degrees of physical contact with the doe, beginning with a light touch and slowly progressing to firmer contact. At all times, the doe was rewarded for remaining still while increasing levels of contact and restraint were experienced.

    Training to Accept Undesirable Consequences

    Maintaining training of behaviors and interactions that do not involve eventual pain is easier than maintaining training of behaviors that occasionally result in pain. Nevertheless, the latter is possible (e.g., training a monkey to hold its arm out while a blood sample is taken). For such interactions, it is important that the behavior is well established with a large number of pleasant experiences before pain is experienced. After the animal experiences a painful consequence of the behavior, it should immediately be given a reinforcer, followed by continuing training with regular positive reinforcement. If modest pain is only occasionally experienced as a consequence of engaging in the behavior, while very pleasant consequences are experienced hundreds of times, maintenance of behaviors that facilitate diagnosis and treatment with minimal use of restraint and medications can be accomplished.

    Downloadable PDF

    Dr. Crowell-Davis discloses that she has received financial support from CEVA Animal Health and from Merial.

    NEXT: Canine Histiocytic Diseases


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