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Thesis--University of Wisconsin--Madison. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

For more than three and one-half years a study was made of the amount of locomotor activity of the northern flying squirrel, Glaucomys sabrinus (Shaw). These nocturnal animals were studied in captivity under both natural climatic (outdoor) and controlled artificial (indoor) environmental conditions. Over a sixteen month period, 1285 observations were made under all kinds of weather upon the time at which flying squirrels became active. The average "awakening" time was 35.4 minutes after sunset. Spontaneous locomotor activity, of both individual and groups of flying squirrels, were recorded under natural climatic conditions by means of activity wheels, a treadle-board activity recorder, and an electronic vibration amplifier. Under these outside conditions an inverse relationship exists between the level of activity and the intensity of the nocturnal illumination. Locomotor activity was at a high level between the last and first quarter phases of the moon and declined markedly at full moon, or just afterwards. The relationship appeared to be unaltered by temperature, vapor pressure, the season, or the sex of the animal. The internal physiological "clock" governing this activity cycle persisted even after nine months under constant environmental conditions in which only the light was manipulated to produce 2-3 month periods of continuous light, continuous darkness, or light-dark periods in normal or reversed sequences. In later experiments manipulation of artificial moonlight was used to produce in the animals cycles of activity corresponding to lunar cycles of normal duration and lengthened cycles of 40-days duration or shortened cycles as brief as 7-days in duration. Under 8-hours light and 8-hours darkness (a 16-hour day instead of a 24-hour day), responsiveness differed markedly from the previous experiments i. e. the animals became almost as active under illumination as under darkness. Only after two months under these conditions did daylight activity begin to decline. Whether or not the animals could eventually adapt to a 16-hour day was not determined. This study reveals a series of inherent physiological controls within the animal which govern the level of the spontaneous activity under varying natural climatic conditions and under controlled artificial experimental conditions. The flying squirrel is sensitive to slight changes in light intensity during the dark periods. By observing the responses to varying environmental photoperiods, an attempt was made to understand the inherent rhythms of activity of this species--whether these should be neural, endocrinological, or both. Most nocturnal animals respond mainly to olfactory stimuli. The activity of the flying squirrel is shown by this study to be intimately determined by illumination. / Science, Faculty of / Zoology, Department of / Graduate

Populations of diurnal tree squirrels in the Portland area were located by mail surveys, personal interviews, and field inspections. Pine squirrels were found to reside in thickly wooded residential areas with dense understories and running water nearby. Western gray squirrels occupied habitats in relatively quiet residential neighborhoods, in areas well supplied with mast crops. Western fox squirrels were found to coexist with gray squirrels in their preferred habitat, and also to thrive in park settings with few mast trees and high activity and noise levels. In areas occupied by both fox and gray squirrels, dominant-subordinate relationships were noted. Each species tolerated the others.

This study investigated alarm calls given by Uinta ground squirrels (Spermophilus armatus) in the presence of a ground predator. I observed predator responses of 18 groups of three to four squirrels each for an average of three trials apiece. r~y objectives were: (1) to describe prey-predator interactions resulting in alarm calls, and (2) to test the following hypotheses: 1. Each Uinta ground squirrel (by sex and age) has an equal probability of giving an alarm call at any time of the season. 2. All Uinta ground squirrels are equally likely to call regardless of their distance to a burrow, closest conspecific, and the predator. 3. Alarm calls are as likely to occur in the search stage of predation as in the pursuit stage. 4. Callers and noncallers are equally vulnerable to predation. I found that: ( 1) each Uinta ground squirrel (by sex and age) in the experimental population had an equal probability of giving an alarm call in the presence of a predator through the season, (2) callers and noncallers were equally close to burrows at the time of the call, (3) the caller was typically located farther away from its closest conspecific than noncallers at the time of the cal l, (4) the caller was significantly closer to the predator than were noncallers at the time of the call, (5) alarm calls occurred significantly more often in the pursuit stage of predation than in the search stage, and (6) noncallers suffered significantly more predation than did callers. There appeared to be little risk and energetic cost associated with calling. Squirrels that called usually were being pursued by the predator and were very close to a burrow when they called. The callers had little to lose and could increase their inclusive fitness by warning relatives of the presence of danger. This study dealt only with responses to ground predators. Squirrels are likely to respond differently to avian predators. It is suggested that responses of animals to avian and terrestrial predators should vary with the potential threat that the predator poses. The apparent inhibition of secondary calls is discussed. Once animals are aware of the presence of danger, there is no need for another animal to repeat the message and reveal its location to the predator.

Call number: LD2668 .T4 1937 E41

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Graduation date: 1991