Michael A. Mandell
Department of Biology, Carleton College, Northfield, MN, USA, 55057
Abstract. Pollinator behavior is of great importance to plants in terms of pollination frequency and the degree of outcrossing. Resource density (flower density) may affect the foraging behavior of pollinators, which would then have effects for the plant. In areas where floral density is high, the pollinator may not have to range far in search of food. This would probably lead to a high likelihood of pollination but at the cost of short-distance pollen dispersal and a consequent decrease in the degree of outcrossing. The converse is likely to be true in areas of low floral density. This study attempted to determine the relationship between flower density and pollinator behavior (visitation rates) in the Neotropical plant Heliconia pogonantha and the hummingbirds that pollinate it. Hummingbird visitation rates were significantly higher in the areas of high Heliconia density than in the lower density plots. Although each inflorescence in the high density plot was visited more frequently, the higher visitation rate implied that the path followed by a hummingbird is shorter in these areas. This would lead to pollen being transported shorter distances from the parent plant than in the low density plots. The effects of this tradeoff on Heliconia fitness are not clear, as there is no evidence on how inbreeding depression affects this species.