The food storage behaviour of the Northwestern crow (Corvus caurinus) was investigated on Mitlenatch Island, British Columbia. The crows stored mostly intertidal food, especially clams, crabs, fish and worms, on the hillsides surrounding the intertidal beach. They also carried food to other parts of the island, presumably to be stored. Storage sites included, in decreasing order of importance, grass clumps, moss banks and the sides of rocks. The choice of substrate is discussed in relation to its camouflaging effect. Food items were most often carried and stored singly. Some individuals carried two items at a time. On average, it took a crow 24.9 sec to hide a food item. The crows stored food in exclusive and non-exclusive areas. Exclusive areas were defended and associated with a nesting territory, whereas non-exclusive areas were not, resulting in several birds using them. Food items were almost always covered and it was shown experimentally that this significantly reduced the chance that the cached item was stolen. The availability, abundance, profitability and preservation qualities of the stored food were discussed. Storage seems to result from a relative scarcity of non-intertidal food at high tide early in the breeding season. During this period too, females are forming and laying eggs, and may depend on the stored food at high tide. The success of 3-colour-ringed crows in relocating their food caches was 76%. The birds appeared to have memorized the location of their food stores. Olfaction appeared to be unimportant for the detection of experimentally-hidden clams. Experiments demonstrated that single stored clams were found more slowly than clumped ones. The problem of stored food decomposition was studied and discussed in relation to the short-term storage strategy.