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Most hermaphroditic, many-flowered plants should suffer reduced fitness from within-plant selfing (geitonogamy). Large inflorescences are most attractive to pollinators, but also promote many flower visits during a single plant visit, which may increase selfing and decrease pollen export. A plant might avoid the negative consequences of attractiveness through modification of the floral display to promote fewer flower visits, while retaining attractiveness. This report shows that increasing only the variance in nectar volume per flower results in fewer flower visits per inflorescence by wild hummingbirds (Selasphorus rufus) and captive bumble bees (Bombus flavifrons) foraging on artificial inflorescences. Inflorescences were either constant (all flowers contained the same nectar volume) or variable (half the flowers were empty, the other half contained twice as much nectar as in the constant flowers). Both types of inflorescence were simultaneously available to foragers. Risk-averse foraging behaviour was expressed as a patch departure preference: birds and bees visited fewer flowers on variable inflorescences, and this preference was expressed when resource variability could be determined only by concurrent sampling. When variance treatments were clearly labelled with colour and offered to hummingbirds, the departure effect was maintained; however, when preference was measured by inflorescence choice, birds did not consistently prefer to visit constant inflorescences. The reduced visitation lengths on variable inflorescences by both birds and bees documented in this study imply that variance in nectar production rates within inflorescences may represent an adaptive trait to avoid the costs of geitonogamy.

The costs and benefits associated with feeding in the vicinity of a predator should vary within and among species, depending on an individual's vulnerability to a predator. In this paper, we investigate how willingness to risk exposure to a predator in order to gain access to food is expressed within groups of fish. We provided groups of six individually marked brook sticklebacks (Culea inconstans) and fathead minnows (Pimephales promelas) with the opportunity to feed in safety, or in the presence of a single predator (walleye, Stizostedion vitreum). Sticklebacks and fathead minnows are commonly found in the same locations at the same time, but sticklebacks also possess armour and spines that provide defence against some predators. Despite this morphological variation, patterns of individual behaviour were consistent between species. While feeding close to the predator, there was a positive relation between the size of the individual and the proportion of food consumed. No relation existed on the side farthest from the predator. These data suggest that fish may risk exposure to predators to exploit size-related differences in vulnerability to gain a competitive advantage for access to food.

Much empirical work has examined whether foraging animals distribute themselves across patches of resources according to an ideal free distribution (IFD). Most studies consider situations with 2 patches, where choice of one patch is synonymous with rejection of the alternative. In this paper, we use computer simulations to determine the effect of the number of patches on achievement of an IFD. Identical foragers were allowed to move between patches so as to maximize their intake rate. To generate departures from an IFD, we assigned all foragers a perception limit of prey numbers such that they could not perceive differences in patch quality that exceed this limit. Foragers would choose randomly from the patches among which they could perceive no differences. We found that, for the same perception limit, departures from an IFD were greatest in the 2-patch situation. In addition, we are less likely to detect perception limit-generated deviations from an IFD (or even a random distribution) in greater than 2-patch situations unless we examine cases in which there are large among-patch differences in quality. Hence, lab and field studies that incorporate the greater realism achieved by using more than 2 patches must be cautious about falsely accepting the hypothesis of an IFD, particularly if the causes of deviations from an IFD are independent of the

Pollinators usually maintain directionality while moving through a flower patch, presumably to increase foraging success by minimizing revisitation of previously- emptied flowers. Two alternative directionality-generating mechanisms have been proposed: foragers may keep track of their arrival direction at a flower or cluster of flowers and prefer to depart in the same direction (the arrival hypothesis), or they may show little change in orientation while foraging at a flower or flower cluster and prefer to depart in the direction they are last facing (the last-faced hypothesis). Rotation of a flower or inflorescence while the forager is feeding on it will unequivocally distinguish the two hypotheses