amount of nectar, composition of nectar, etc. For example, birds visit red flowers with long, narrow tubes and much nectar, but are not as strongly attracted to wide flowers with little nectar and copious pollen, which are more attractive to beetles. When these characteristics are experimentally modified (altering colour, size, orientation), pollinator visitation may decline.

Although non-bee pollinators have been seen to be less effective at depositing pollen than bee pollinators one study showed that non-bees made more visits than bees