Fig. 7.1. Return visits made by hummingbirds to the original flower. In some trials the original flower was depleted after a single visit; in other trials it was not depleted. The alternative flower differed in either location or color/pattern features. Values are means and SE, n = 6 per group.
Rather than testing rules for decision-making in flower visits, recent workers have focused on the scale of spatial information remembered and used by rufous hummingbirds. Brown (1994) and Brown & Gass (1993) have shown that birds in the laboratory can use visual cues to predict which feeder of several will contain reward, even when the reward is at some distance from the relevant visual cue. Although these experiments demonstrate that hummingbirds can and do use visual cues in foraging, when birds are faced with making choices among flowers under conditions in which the spatial cues conflict with the flower's visual features (flowers 80 cm apart; Hurly & Healy 1996), the birds invariably chose to return to the flower that occupied the location previously visited, rather than the one bearing the color pattern of the rewarded flower. Several recent experiments have tried to determine which cues birds use to return to food locations by using this kind of dissociation method (e.g., Brodbeck 1994; Clayton & Krebs 1994). Typically, four possible feeders are presented in an array, all differing in their color/patterns. Only one feeder
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