| dc.description |
Behavioral stereotypies in captive animals have been defined as repetitive, largely invariant patterns of behavior that serve no obvious goal or function (Mason, 1991a; Ödberg, 1978). Stereotypies are commonly attributed to boredom or fear, and are typically "treated" by enriching captivity with distracting, appealing stimuli. These stimuli often include food presented at times other than regular feedings, and as a result, engage species-typical foraging behaviors that reduce stereotypies.
This thesis applies a "foraging loop" hypothesis to the behaviors of contrasting species of marine mammal carnivores, polar bears and walruses. Polar bears in the wild commonly spend the majority of each day traveling to locate prey; captive polar bears commonly spend several hours a day in locomotor stereotypies preceding their scheduled daily feeding time. Experiments 1-4 presented small samples of food and scents on several schedules, examining their effects prior to, during, and after the schedule. Most schedules reduced stereotypies and increased general activity prior to and during the schedule.
In contrast to the lengthy locomotor search of wild polar bears, walruses in the wild spend more time "grazing" in beds of mollusks on the ocean floor, using their flippers, vibrissae, and mouths to locate and suction out mollusks. Captive walruses spend the majority of their day circle swimming, and mouthing and sucking inedible objects in their enclosure. Experiments 5-6 found that introducing mats with food or "boomer balls" with food increased contact and activity and decreased stereotypic circle swimming and sucking relative to controls.
These data support three conclusions: (1) individual stereotypies appear based on incomplete, repeating loops of foraging behavior; (2) providing stimuli supporting a more complete sequence of search behaviors reduces stereotypies and increases non-stereotypic activity; and (3) a descriptive, analytic approach based on how foraging behaviors relate to the captive feeding procedures can facilitate understanding of stereotypies and suggest methods to reduce them. |
|