Diet of Black-Tailed Jackrabbits on Sandhill Rangeland in Colorado

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Abstract
The major foods in the diet of the black-tailed jackrabbit were western wheatgrass, alfalfa, 6 weeks fescue, sand dropseed, prickly pear and sand sagebrush. The diet followed definite seasonal trends that were influenced by forage maturity and availability. Grasses made up 50% of the yearly diet and were more frequently eaten during early spring and summer. Forbs constituted 30% of the yearly diet and were preferred during summer and early fall. Shrubs were 10% of the yearly diet and were eaten primarily during fall and winter. Forbs were preferred over grasses and seasonally important foods received higher preference indices than those that were eaten in all seasons. Competition for food between jack-rabbits and cattle was greatest in early spring when both animals preferred green forage. At other times they ate some of the same foods but not in the same proportions, so competition was not great for the plants that were preferred by cattle. Jackrabbits probably decrease the longevity of reseeded forage stands on rangelands and influence secondary succession on old fields and denudes ranges. When a grass-alfalfa mixture is used to reseed rangelands, it is possible that jackrabbits concentrate on seeded areas and disseminate the seeds of less desirable grasses and forbs while feeding, thus contributing to the invasion of these species.