| Summary: | This study was done, in the desert ridge known as the Pico-Johnson, in the state of Sonora, Mexico, which is considered as natural habitat for the desert bighorn sheep (Ovis canadensis mexicana). In this work, we evaluate the importance of the relationship, between the bighorn sheep and the topographic component of his habitat, by using use-availability techniques. Topography was divided in four subcomponents (Height, Slope, Aspect and Landform) which at the same time were divided in classes. For this study, the visual location of 20 bighorn sheep's (5 males and 15 females) marked with radiotransmition collars as well as unmarked sheep observations, were registered. It was considered as use the frequency of sheep observation, for one year and a half of monthly visits, registered within each subcomponent class. Availability was defined as the proportion in which the subcomponent classes were found throughout the study area. It was found that, the sheep, do not use, most of the habitat classes, in their exact proportions, that some are preferred (terrain’s higher than 300 meters, slopes higher than 60%, S-SW-W composite aspect and canyon slopes) and the rest of the classes either were avoided or used proportionally. Bedsites, were evaluated using the same technique, encountering very similar patterns. We developed a habitat quality model for the sheep, that emphasized topography, besides topography other habitat components evaluated were: vegetation, free water sources, precipitation, habitat discreteness and range expansion. Habitat quality classes were excellent, good, regular and poor. The model was validated, by using the frequency of sheep observation within the different habitat quality classes and considered as a good habitat quality predictor, on the basis that, 73.0% of the frequency observation, were done on areas classified by the model as excellent and good.
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