- Abstract Porcupine digs were counted in irrigated potato fields in the Negev desert of southern Israel. Dig rates in a sample 10-ha rectangular field increased from low levels in October to ≈30 per night beginning in mid-November and corresponded to the increasing availability of larger tubers. The temporal patterns suggest a lag in food switching, or the successive abandonment of natural food patches having low marginal value in relation to the increasing profitability of potatoes. In all three fields examined (40 ha), digs were concentrated along field peripheries and on sides furthest from artificial illumination. These patterns confirm previous findings on the predation-avoidance nature of porcupine surface activity. Total potato damage in the study area was estimated at 1.3 tons ha −1 , or 0.6% of the crop. We recommend: (a) adjustments in field shape to reduce edge and (b) the use of artificial lighting as two feasible means for passive damage control.