“…These feeding territories consist of over 200 flowers (Armstrong et al, 1987;Paton & Carpenter, 1984), and the owners vigorously defend them from conspecifics attempting to rob nectar. Because flowers may take some considerable time to replenish (Gass et al, 1976), a hummingbird may follow one or several strategies in order not to revisit recently emptied flowers: visiting flowers in a consistent pattern whereby Copyright 1995 Psychonomic Society, Inc. memory is required only for the pattern and not the flowers themselves ("trap-lining";Feinsinger, 1978), visiting clumps of flowers and remembering the clump visited but not the individual flowers themselves, and remembering the specific locations of individual flowers. Each of these possible strategies has been discussed previously, and there is support from optimality models and experimental tests for the first two (Davies & Houston, 1981;Gill & Wolf, 1977;Kamil, 1978).…”