In 1995 we deployed 800 simulated nests equipped with nest mortality timers to assess temporal patterns of predation of duck nests in the Canadian prairies. Timers recorded 470 predation events (70% of 672 depredated nests). Predation was nonrandom throughout the day, with a peak occurring between 00:00 and 06:00. Coyote (Canis latrans) and red fox (Vulpes vulpes) depredated nests at similar times (mean 18:32 and 22:42, respectively), whereas mean depredation time was significantly later for striped skunks (Mephitis mephitis, 02:08). We failed to detect a difference in depredation interval for neighboring nests destroyed by striped skunk (median = 62 h 18 min, n = 15) vs. pairs of nests depredated by different species (red fox-skunk, skunk-coyote and coyote-red fox, median depredation interval = 123 h 1 min, n = 6). Simultaneous observation of radio-marked skunks revealed that skunks spent 2–25 min at simulated nests and became inactive after nest destruction in ca. 50% of cases. Based on observations of striped skunk behavior and nest-timer data, we suggest that density-dependent nest predation is caused by increased patch use rather than area-restricted search.