The Calming of American Bison (Bison bison) During Routine Handling

Jennifer L. Lanier
Dr. Temple Grandin

Department of Animal Sciences Colorado State University Ft. Collins, CO 80523-1171


American Bison (Bison bison) handling is often a stressful time for both the animal and its handlers. There is a some research regarding "in pasture" bison behavior, but little on behavior during handling. The rationale for low stress handling, other than ethical concerns, can be justified on purely economical grounds. Each mature female is currently worth $3000.00; each marketable male is valued around $1500.00. Consequently, each injury or death represents a sizable economic loss. In order to reduce inj uries to bison and handlers, the bison must remain calm while being handled. My studies have focused on bison behavior during handling in squeeze chutes, alleys, holding pens, trucks, etc. Zoos, ranches, parks and other organizations that work with bison have had similar problems during handling. These problems range from stampeding to intra-herd aggression to "suicide." What follows are some techniques that can be used to calmly handle these large, skittish animals.

Behavior: Genetics and prior experiences affect behavior. Behavior can be modified, via training or habituation, but if the animal is in a state of fear, panic will override the learned behavior. The first experience an animal has in a new situati on is the foundation for subsequent behaviors in similar situations. If the first time a bison enters a squeeze chute and bad things happen to him, he will be reluctant to re-enter the chute. But if the first few times he enters the chute and the experien ce is neutral or positive, he will be more inclined to reenter the chute. Likewise, if the last experience the animal has just prior to leaving a facility is positive, such as a highly palatable food reward, the animal will be more receptive to being work ed the next time.

Fear Indicating Behaviors: Fear behaviors are signs displayed by an animal as a result of being in a frightening, stressful situation. Cortisol, a stress hormone, is secreted in the blood of fearful animals. As care givers, we must be able to reco gnize these signs, interpret and respond appropriately to them. There is a continuum of fear based behaviors in all animals. Low fear is on one end of the continuum, followed by moderately fearful, highly fearful and finally tonic immobility. Bison are no exception. Some of the very subtle indicators of fear in bison are licking , blinking, huddling, a raised tail, circular movement (milling), backing up and balking. As the fear increases these behaviors become amplified and new behaviors emerge: labored breathing, frothing at the mouth, vocalizing, bulging eyes, running, pushing , goring, attacking, sitting as well as jumping or climbing out of their enclosure. The last stage of fear is tonic immobility. An animal that lays down inappropriately and does not respond to stimuli maybe in tonic immobility. For example, when you move a bison from the pen to the squeeze chute it lays down. In effect, this is a form of shock. The antelope that suddenly stops struggling while in the lions jaws is in tonic immobility.

Individual differences may affect the appearance of the fear-based behavior. One animal may naturally vocalize more readily than another animal. One animal may progress through the continuum faster than another animal. It must be kept in mind that behavio r is a combination of genetics and prior experiences.

Novelty: Novelty is something new, unusual or it can be a familiar object or situation, but presented in strange or unusual circumstances. For example, a feed dish blowing in the wind. Like beauty, it is in the eye of the beholder. What is novel t o one animal may be familiar to another. Sudden confrontation with a novel object or situation is extremely stressful. If an animal is allowed time to voluntarily investigate the novelty, it becomes an attractant. In the wild, novelty is often associated with danger, because any new situation, object or change in routine can be life threatening. Gradual habituation to novelty will transform novelty into a non-threatening part of daily existence. But initially, novelty is always treated with suspicion.

However, novelty can be an attractant if an animal is allowed to voluntarily approach it. Novelty can be used to lead bison from one area to another. A chair, hat, or paper cup strategically placed, can lure bison from a pasture to a pen or from an enclos ure into a barn. This technique is most effective if used during conditions that the bison perceives as normal and non- threatening. If an inanimate object is to be used, attaching it to a string will allow the handler to gradually and smoothly pull the o bject and the bison towards the desired location. A similar technique (used with cattle) is to drag an object with a lariat into the place you wish the animals to go.

Animals with a nervous, excitable temperament are often the most attracted to novelty if they voluntarily approach it. These same nervous animals will be the most fearful if they are suddenly confronted with novelty.

Continuum of Pressure to Initiate Movement: A continuum of pressure is an incremental increase in the exposure of a novel or adverse stimulus to the animal in order to obtain positive movement. Slightly adverse stimuli may be a sound or an invasio n of the animal's flight zone. In this context it is not meant as pain or other physical discomfort. Noise and handler exposure are two techniques that work well as a continuum of pressure to facilitate desired forward movement. The idea behind a continuu m of pressure to initiate forward movement is to begin with a minimal amount and gradually increase it as needed. By starting with the lowest amount of pressure and working up to the amount that invokes the desired response, the handler is creating a calm and relatively positive experience for the animal. If the handler initiates animal movement by electric shock, yelling, or arm waving, which are all at the extreme end of the pressure gradient, the animal will immediately become fearful. This fear resul ts in a traumatic experience for the bison and often the handler.

Because of their ability to hear higher and lower frequencies than humans, subtle sounds are often effective to move animals forward. The best are novel noises; a rustling newspaper or plastic bag, snapping of the fingers, pennies in an aluminum can, or a shh, shh sound.

The flight zone is that distance from the animal to a threat that causes the animal to begin to move away from the threat. If the threat is outside the flight zone but still "nearby", the animal will turn and face the threat. As the threat approaches and reaches the boundary of the flight zone the animal will turn and begin to move away. Increasing pressure on the flight zone of the animal is effective in creating animal movement. However, too much pressure and the animal panics. The optimal handler posit ion is at the boundary of the flight zone. Knowledge of the flight zone allows the handler to manipulate animals in a low stress manner.

When working with bison in a field or large enclosure it is relatively easy to determine the flight zone. It is often more difficult to establish the boundaries of the flight zone in small areas such as pens, corrals and exhibits. The flight zone may be l arger than the pen. In these circumstances, it may be possible to work the edge of the flight zone from an outside pen. Once the bison is in a handling facility, such as a single file alley or a squeeze chute, the handler is usually deep within its flight zone. However, the bison will perceive the walls as a safety barrier between themselves and the handler, provided that the walls are solid and do not allow the bison to see handler movement. When a handler appears over the top of the wall the bison perce ive two things. First, the safety provided by the barrier has evaporated and suddenly the predator is in the flight zone. Second, the predator is large and looming. The animal can not flee. This results in fear and panic. It is at this point that bison wi ll most often engage in behaviors leading to injury or death to themselves or other herd-mates.

The following is an example of how a handler may utilize a sequence of increasing pressure to initiate forward movement in a lead-up chute.

A bison is in a lead-up chute. The handler should keep a low profile until she is positioned behind the point of balance (shoulder). She then slowly raises her head up over the solid wall. If the bison doesn't move, she makes a high frequency noise. If th is is ineffective she makes a louder high frequency noise. She does not bang on the lead-up wall. If there is still no result, she stands up a few inches. The handler then hold her arm out over the bison's rump, then moves her arm....

Each successive action of the handler increases the pressure on the animal and enhances the probability of forward motion. Three notes of caution: First, pausing between each successive attempt will allow the bison to react calmly and for you to assess wh at works for you and your animals at that moment. Second, application of too much pressure will cause an animal to bolt, backup or freeze. Third, use slow deliberate movements. Sudden jerky motions elicit fear, as bison associate them with a predator atta cking. Use of Light to Facilitate Forward Movement: Light can be a critical factor when moving bison from one area to another. By controlling the position and intensity of the lighting, the handler can reduce anxiety and induce the bison to move from one area to another. Most animals prefer to go from a dark area into a well-lit area, rather than from a well-lit area to a dark area, due to the sharp contrasts created. It is crucial to avoid strong contrasting lights, which cast shadows. Shadows are contrasts tha t cause most species to balk. Lighting that gives the effect of an overcast day, generally work the best. If a bison can not see what awaits him in an area, there is a normal reluctance to enter - a matter of survival. On the flip side, most animals feel safe once they are in a dark area. "If I can't see you then you can't see me."

Solid Sides and Solid Tops: As mentioned above, bison feel secure in dark areas. The use of solid sides can greatly reduce the level of fear in bison while they are being worked. Solid sides provide darkness as well as the illusion of restraint. I f the animal can not see a place from which to escape, it will be less likely to attempt an escape. It is for this reason that a solid top prevents bison from climbing out of an alley or squeeze chute. This illusion of containment causes the definition of 'solid' to be a bit nebulous. For calm animals, solid sides only need appear solid, for excited or wild animals they must be solid.

Conversion of an existing open sided facility to a solid sided facility can be done with minimal expense and materials. Cardboard can be temporarily used to enclose a squeeze chute or the alley leading up to the squeeze chute. Attaching strips of cardboar d at a 45-degree angle to the outside of the bars on the squeeze chute will prevent the bison from seeing through the bars. Bison remain calmer if they are not able to see people or novelty inside their flight zone. This 45-degree angle will also enable t he handlers and vets access to the bison. It is important that the junction of the cardboard and the bar be pointing towards the head end of the squeeze chute. Check the position of the cardboard by standing inside the squeeze chute as if you were a bison entering the chute. If the cardboard prevents light from entering the chute and you can not see outside of the chute then the cardboard is correctly attached to the bars.

The critical areas in a handling facility for solid sides are those areas where people are inside the flight zone or where the level of stress and fear may be a factor in their behavior. The squeeze chute and the area immediately proceeding the chute are critical areas for solid sides. Solid sides are recommended in the holding area if: the holding area is relatively unfamiliar to the bison, the holding area is required to hold more animals than usual, or if the animals may become fearful while held in th e area.

Working Bison: Bison are herd animals and prefer to be with herd-mates rather than alone. A solitary animal is often fearful and aggressive, consequently, it is recommended to never isolate a bison from its group. Bison do not follow one another nose to tail as do some species such as cattle and eland, they tend to fan out and walk beside one another. Queuing single file of bison is an unnatural behavior and results in bison climbing over each other. Bison are often the calmest if they ar e held as a group and then individually moved from the crowd pen to the squeeze chute. A bison cow and her calf can be worked together.

The crowd pen should never be filled more than 1/3 full at any given time. By providing sufficient room, the bison are able to maintain their dominant order relative to one another. This reduces stress and intra-herd conflicts. When bison are tightly co nfined with other bison, their fear manifests as aggression in the form of goring and pushing those around them. Bison that are to be held in close proximity to other bison should be held with similar bison of the same age and gender. Sick animals should be held separately from healthy animals. Males and females should be held separately as should juveniles from adults.

Training: Training bison for routine husbandry procedures reduces stress. Training is an effective low cost technique for the prevention of injuries and deaths. Operant conditioning of bison has been quite successful. Training does not reduce wild type genetics. If bison are not conditioned for routine husbandry procedures, the genetically 'true' bison (wild types) are often culled by either "suicide" or by management. This is inadvertent domestication of bison.

Conclusion: Bison present a unique management situation. Pasture bison are typically calm, easygoing, gamboling animals. However, once confronted with a corral, alley, squeeze chute and ill informed handlers they become "wild beasts." The results are injured animals and handlers, loss of profits, and strained public relations. Zoos, parks and other conservation systems have bison herds for public education and enjoyment. It is important for these organizations to have healthy, vibrant herds.

A favorable public perception of captive animals is critical to park funding and reputation. Calm, beautiful, picture perfect animals are powerful advertisements for parks. The increasing awareness of animal welfare and rights issues means that routine procedures that were considered adequate in the past are no longer acceptable in today's society. Calm, knowledgeable, low stress handling techniques are essential.

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