We documented the diurnal pattern of nectar volumes in flowers of seven Neotropical hummingbird-pollinated plant
species that were open to flower visitors and compared these standing crop data to nectar volumes in flowers protected
from visitors. Standing crop of nectar bore little relationship to nectar in bagged flowers either in terms of volume or
temporal pattern of availability. There was almost no nectar in open flowers except in those collected at dawn and
those of Aphelandra sinrlairiana; these were apparently too abundant to be depleted by visitors. Nectar volumes in
open flowers were even more variable than in bagged flowers. We argue that understanding the evolution of plant-
pollinator interactions requires understanding the relationship between nectar production and standing crop, as well
as the impact of high variability on decisions by foraging animals. We conducted experiments to determine the effect
of nectar removal on nectar production. Nectar removal via simulated legitimate visits had no impact on total pro-
duction in flowers of Pavonia, hertia, and Palirourea. For A. sinclairiana and Pentagonia, total nectar production in
visited flowers was reduced compared to unvisited flowers. Data from individuals of these last two species indicated
that the population-level pattern was assembled from individuals that responded differently to nectar removal: clearly,
understanding the evolution of nectar traits demands data from individuals. We argue that detecting patterns of plant
responses to nectar removal requires the context of floral characteristics (.g, longevity, ovule number, or pollinators).
Nectar removal via simulated nectar-robbing visits had no impact on total nectar production in A. sinclairiana but
reduced total production in hertia. Nectar robbing did not cause plants to invest more energy in nectar than they
would have the absence of robbing. Finally, we found no difference in seed set by robbed and unrobbed flowers of
A. sinckziriana Our results add to a growing body of literature suggesting that nectar robbers are not always detrimental
to plant fitness.