PREDATION OR STARVATION - CONSEQUENCES OF FORAGING DECISIONS BY PORCUPINES (ERETHIZON-DORSATUM)

Data on starvation and predation in porcupines (Erethizon dorsatum) we re gathered over a 5-year period to examine hypotheses about foraging. I predicted that predation would be greater in open habitats than in closed habitats, small porcupines would be more vulnerable to predatio n than large ones, and nutritionally stressed porcupines would trade-o ff increased risk of predation for decreased risk of starvation. Over 90% of predator-killed porcupines were located in open grasslands or j uniper shrublands, suggesting that open areas were higher in risk than wooded, riparian areas. High rates of predation in open areas in late winter supported the hypothesis of a trade-off between nutrition and predation risk. Mountain lions (Puma concolor) preyed on porcupines at a higher rate than did coyotes (Canis latrans), but predation by moun tain lions was independent of body size of porcupines (small samples p recluded analysis of predation by coyotes). These data reveal how pred ation and starvation influence populations of porcupines. Further, dat a indicate that poor nutritional status can drive animals to forage in risky habitats where predation is high.