Food and fearscapes: responses of specialist and generalist rabbits to food and predation risks

Miranda Maurine Crowell

Small mammalian herbivores face many risks when foraging within food patches and across landscapes. Some risks are inherent in the food they consume (e.g., plant fiber and toxins) and other risks are imposed by their environment (e.g., temperature stress, predation). I explored how pygmy rabbits (Brachylagus idahoensis), sagebrush (Artemisia spp.) specialists and burrow obligates, and mountain cottontails (Sylvilagus nuttallii), habitat generalists, respond to perceived risk of predation, plant fiber, and plant toxins in captive feeding trials and field observations. First, I examined their perceived predation risk by measuring the proportion of basal diet consumed in food patches that varied in the amount and arrangement of concealment cover, and the distance from a burrow refuge, using double choice experiments. Next, I examined the perceived risk of consuming high-toxin, low-fiber sagebrush leaves compared with low-toxin, high-fiber sagebrush stems by pygmy rabbits and cottontails by offering whole sagebrush branches and separate bowls of leaves and stems in captive experiments, and by examining diets consumed and the size of stem diameters cropped by sympatric, free-ranging rabbits. Pygmy rabbits preferred food patches that offered greater total concealment, horizontal concealment, and were closer to their burrow refuge. Mountain cottontails preferred food patches that offered greater aerial concealment, but did not distinguish between patches based on total concealment and distance from a burrow refuge. These results suggest that pygmy rabbits perceived a higher risk of predation than cottontails, and relied more on hiding in their burrows than detecting and fleeing from predators. Free-ranging and captive pygmy rabbits consumed a greater proportion of sagebrush in their diet and cropped smaller diameter stems, allowing them to consume a greater proportion of sagebrush leaves, than did cottontails. This behavior is explained by their different abilities to detoxify monoterpenes in sagebrush and to deal with plant fiber. My findings demonstrate that pygmy rabbits and mountain cottontails perceive and respond to risks in their food and environment differently, which may be strong driving forces for food and habitat selection for specialist and generalist herbivores. The physiology and behavior of sympatric mammalian herbivores should be considered when planning conservation strategies for sagebrush-steppe landscapes.

Food and fearscapes: responses of specialist and generalist rabbits to food and predation risks

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