Homing of Peromyscus maniculatus in the Channelled Scablands of East-Central Washington

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Abstract
One hundred twenty-one Peromyscus maniculatus gambelii were used in conducting 203 homing trials from 30 different release points that ranged from 64 to 1976 meters from the trapping site. The habitat was open sagebrush and basalt cliffs; lakes and creeks enhanced the complexity and distinctiveness of the landscape. Homing performance decreased with increase in distance and was poor, even from short distances, across a large irrigation canal that served as an ecological barrier. Although males were better “homers” on the average, females were better for the longest distances, and no males returned from across the canal. The relationship between homing distance and percentage of returns is a curve with the following characteristics: an initial drop-off followed by a moderate decrease up to 550 to 600 meters, a subsequent steep drop-off, and a long tail. The initial drop-off probably depends on the proportion of mice without homing motivation (for example, transients). I argue that the second drop-off occurs at a distance equivalent to the limit of the life range of the majority of the individuals. Data from the literature are compared with this conclusion. The argument is supported by studies of spontaneous movements of mice and by comparing homing success of experienced and inexperienced mice. The shape of the observed curve for returns and theoretical considerations argue against the existence of an orientational sense. Homing studies on mice are considered to be a test of an unnatural situation for these animals and, therefore, an adaptive response cannot be expected. Data in the literature are discussed and I conclude that release beyond the life range of an individual results in disorientation that is expressed in behavioral changes. An intimate knowledge of a life range larger than the home range and an excellent memory are considered to be adaptive because natural events may force mice temporarily out of their otherwise suitable normal home range. It is expecte