Investigative behavior facilitates the behavioral development of horses by exposing the animal to new objects, environmental situations, and experi-ences. It permits the horse to become aware of its environment, not only to avoid hazards but also to learn traits important for its various biological activ-ities. For example, through investigative behavior the animal finds potential danger, food and water, social companions, comfortable resting sites, and pathways. Throughout much of each day, horses exhibit investigative behav-ior, often while in other types of activity.
By the end of the first half hour postpartum, foals frequently exhibit visual investigation of their surroundings using monocular as well as binoc-ular vision. While still in sternal recumbency, the foal rotates its head and eyes looking around and often fixes its gaze on nearby objects. During the second half hour following birth, the ears of the foal begin to independently rotate to investigate environmental sounds. By this time olfactory, tactile, and possibly gustatory senses have also commenced and are used in the pre-nursing investigative activity of the foal. Once the foal is standing, it moves cautiously nosing, sniffing, and licking objects in its immediate vicinity. Objects at or just above head height are especially explored, such as the mare’s forearm, girth, flank, gaskin, and perigenital region as well as tree trunks or stall walls. At this stage, contact along the dorsal part of the muzzle induces the sucking reflex, and the foal appears highly moti-vated to nurse.
Once the foal has successfully nursed, the objective of most of its sub-sequent investigative behavior seems more directed at environmental aware-ness than nursing. The foal investigates its mother’s body and the surroundings. It may nibble grass, straw, or fecal material. Each new object in the immediate vicinity is visually, auditorily, tactilely, olfactorily, and
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sometimes gustatorily investigated by extending the head, muzzle, and occasionally the tongue. Movements are generally slow and jerky.
As the foal grows and as positive experiences accumulate, the foal’s realm of exploration also increases. Negative experiences, where the foal has been hurt or frightened, cause the foal to be hesitant to experience sim-ilar events, and investigative activity may be temporarily inhibited. Yet, with each favorable experience, a foal seems eager to explore new aspects of its environment.
The mother usually limits the foal’s early social contacts and range of exploration. Once the foal commences peer play activities, the opportu-nity for furthering environmental exploration and broadening its experi-ences are greater. Foals which experience neonatal handling and halter training tend to exhibit far greater exploratory interest and confidence than their unhandled neonatal peers (Waring 1972).
Throughout their lifetime horses continue to become alert to new objects that appear in their environment. Also, new sounds as well as odors are, at least momentarily, investigated. A horse may orient its head in the direc-tion of the stimulus, whereby the ears and eyes are directed forward. If the stimulus is at a distance, the neck is usually raised, elevating the head. If the stimulus is nearby, the head may be flexed in a collected position for visual scrutiny, or the head may be extended and the neck lowered enabling the horse to smell and possibly touch the object. Caution often character-izes the horse’s investigation.
Investigative activity can occur without the horse orienting its head directly toward the stimulus source. For example, stimulation from one side of the horse may only cause the eye and ear on that side to rotate and investigate. If minor stimulation is behind the horse, the ears and eyes typically rotate in that direction without the head or body becom-ing reoriented (Figure 6.1). The more suspicious the stimulus the more the horse tends to orient its head and body toward the stimulation. Alert-ness by one member of a group often induces similar behavior in other group members.
Horses continue to investigate new objects, intruders, sounds, and odors until they appear to have determined if the stimulus requires additional action, such as flight or some social interaction. In most cases, the initially attentive horse returns to its previous activity subsequent to the brief inves-tigation of the stimulus. Often the investigative response is only a subtle eye turn or ear movement. At other times, especially with novel stimuli, the
alertness and investigative response of the horse is overt and unmistakable (Figure 6.2).
If new objects in the environment do not induce flight, they are gener-ally investigated at close range, often by circling the object. The distance they cease their approach and remain separated from the stimulus object is the approach distance. The distance reflects the horse’s degree of appre-hension. If a stimulus object approaches a horse, avoidance by the horse soon becomes evident; the distance is again dependent on the horse’s degree of foreboding. Zeeb (1963) found that the Dulmen horses he observed would closely approach and investigate a motionless human, but they main-tained a distance of 3 to 5 m when the person walked near them. The horses withdrew and would not approach a person moving in the manner of a quadruped with hands and feet contacting the ground.
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Figure 6.1: Subtle visual investigative response of a horse toward photographer while continuing to graze. (Photo courtesy of R.R. Keiper)
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Excrement of other horses is frequently investigated by young and adult horses of both sexes. The neck is lowered and head extended permitting sniffing of the site and sometimes direct contact. Sometimes a flehmen
Figure 6.2: Overt alertness and investigative responses of horses.
response is given where the head elevates and extends while the anterior portion of the upper lip curls dorsally. Following the investigation of fresh feces and urine, the investigating horse may move over the site and add its own excrement to the site before departing (Feist and McCullough 1976).
When one horse directly investigates another horse, it often approaches with neck elevated (sometimes even arched) while head, eyes, and ears ori-ent toward the recipiori-ent. At other times, the investigating horse circuitously approaches utilizing monocular vision. If both horses participate, naso-nasal contact is common, accompanied by sniffing and audible exhalation. Gen-erally other regions of the body are then investigated, such as the head and neck. If only one individual is motivated to investigate, it may concentrate on the flank or perianal region of the other horse. If neither horse becomes aggressive, they often remain near each other until distracted.
Horses exhibit similar investigative and approach behavior toward life-like models of horses and full-sized two-dimensional horse sketches (Grzimek 1943a). The more such test objects deviate from being horse-like in body form, the less horses respond as if the objects were conspecifics.
When a horse is in an approach-withdrawal situation, fear can prevent or impede close investigation. Avoidance is typical. Thus an anxious horse may be repelled by slight or even imaginary barriers, such as a pool of water or an open doorway; whereas, when calm the same horse may approach, investigate, and proceed without incidence.
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