Vegetal habitat characteristics and annual dietary selection were examined for the pygmy rabbit in southeastern Idaho. Areas selected for habitation by pygmy rabbits had a significantly greater woody cover and height than other areas. Total grass-forb biomass was similar in rabbit and nonrabbit sites. Grass biomass was least and forb biomass greatest where pygmy rabbits were most abundant. Sagebrush was eaten throughout the year, although in lesser amounts in summer (51%) than in winter (99%). Grasses and forbs were eaten through the summer (39 and lo%, respectively) and decreased in the diet through fall to winter. Sagebrush is critical to the pygmy rabbit for both food and cover, although in this study, cover and height of woody vegetation appeared to be the critical features of the habitat selected for. This fact should be considered before brush removal treatments are applied within pygmy rabbit range.
Distance perception of depicted objects was examined as a function of photographic area of view. Subjects viewed slides of natural outdoor scenes and directly estimated the distances to specified objects. Area of view was manipulated by means of photographing each scene with lenses of five different focal lengths: 135, 80, 48, 28, and 17 mm. Distance perception along the pictorial depth plane was systematically transformed through changing the photographic area of view: the shorter the focal length of the camera lens, the wider the area of view, and the greater the perceived distance. Linear functions for each subject's distance judgments revealed a very high goodness of fit. Both the y-intercepts and the slopes increased as focal length decreased. The increasing y-intercepts suggest that viewers place themselves farther away from the depicted scene as focal length decreases, compensating for the advancing proximal edge. The increasing slopes suggest that distance information throughout the pictorial depth plane appears to change with focal length. The subjects also made direct judgments of foreground truncation, revealing that foreground truncation decreased as focal length decreased, but that this decrease did not account for the considerable expansion in distance perception.
Seventy-two Navajo ranchers were questioned about the role of mixed-breed dogs with their Rocks. Navajos call their dogs "sheep dogs" but, unlike sheep dogs used by other ranchers to assist in herding and moving the flocks, Navajo dogs functfon primarily as guardians of sheep and goats to whom they have developed social bonds. This attraction is a result of raising dogs essentially from birth in visual, olfactory, auditory, and tactile association with sheep and goats. A minimum of handling of pups reduces the likelihood that they will bond strongly to humans. Mixed-breed dogs of the Navajo appear to exhibit all behavioral traits believed to he important in protecting flocks from predators, especially coyotes: they are attentive, defensive, and trustworthy. If ranchers choose to employ dogs, the rather simple Navajo recipe for training may serve them well. Mixed-breed dogs could be quickly deployed in a variety of ranching situations to help reduce predation on livestock. Coyote (Canis latrans) predation on sheep (Ovis aries) and goats (Capra hireus) continues to be a source of economic concern throughout much of North America (Gee et al. 1977, U.S. Dept. of Interior 1978). Since the mid-1970's, scientists have trained, deployed, and evaluated the performance of several introduced breeds of Eurasian dogs (Canis familiaris)
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