UBC Theses and Dissertations
A habitat-use and dietary analysis of a monogastric versus a ruminant herbivore, on forested range Preston, Susan Karen
Interactions between feral horses and range cattle were studied on forested range of the Chilcotin Plateau in Central British Columbia from May, 1979 to August, 1980. Research objectives included collecting information on habitat-use, distribution and diet selection for horses and cattle, and habitat-use and distribution data only, for moose. Based on approximately equal, average defecation rates, the relative abundance of each species in the 200 km² study area, was estimated to be 89.7 percent cattle, 7.4 percent horses and 2.9 percent moose. The equine study population was organized into five harem groups, each composed of a single stallion with adult mares and immature animals of both sexes, ranging in group size from 5 to 14. Surplus adult males formed four bachelor groups of between one and four animals. A detailed analysis of all habitat types was not practicable nor considered essential in this study. The breakdown of the study area into seven general habitat types was based on macrovegetation associations which seemed to reflect broad habitat-use patterns and included open forest, semi-open forest, closed forest, meadow, shrub carr, interface zone and 'other' (e.g. roads). A botanical profile of the area, and concomitant plant collection, was done over the two summers of field work. Positive identification was achieved for 148 plant species, but no attempt was made to determine availability of the various species quantitatively. Fecal epidermal analysis was carried out on fecal samples collected for horses and cattle from June through September and for horses in winter. Results indicated at least 54 different plant species were used by the two herbivores. Eleven plant species were found to consitute 80% of the cattle diets and 86% of the horse diets, indicating at least 80% of the two herbivore diets were derived from only 7.4% of the available plant species. Horses utilized fewer plant species in the winter, and while the use of grasses was reduced, sedge and shrub-use increased. A system of random transects of between 18 to 25 km in length were used on a regular, consecutive basis to collect distribution and habitat-use data for horses, cattle and moose. Depending on the individual transects, a greater or lesser degree of spatial overlap was indicated for the three herbivores and the concentration of use in any area varied widely between species. The designated habitat types were measured along each transect and were assumed to reflect habitat availability for the entire study area. None of the three herbivores used the habitats in proportion to habitat availability. Both horses and cattle used meadow habitat disproportionately more (though not necessarily in the same locations), and cattle also indicated a preference for interface zone, while moose used open forest, closed forest and shrub carr disproportionately more.