Pollinators sometimes play favorites when choosing plants to forage on, a behavior known as flower constancy. This behavior can be seen across many different types of pollinators, but is perhaps best known in honey bees and bumble bees.
As pollinators spend their days foraging for pollen and nectar, they have to make decisions about which flowers to visit. Flower constancy is displayed when the pollinator consistently chooses some plant species over others, or even some plant varieties over others, even when alternative choices exist in the same area.
In some cases, these alternative choices may provide even more nectar or pollen, but they are bypassed by the pollinator who is remaining faithful to the plant of its choice. Pollinators can show flower constancy within an individual foraging trip, or over a whole day, or sometimes even over their entire adult lifespan.
Why would a pollinator remain faithful to a certain plant species or variety? Scientists have four main ideas:
- Pollinators have limited memories, and can only store a limited amount of information about where and how to find flowers, so they keep returning to the same flowers over time.
- When a pollinator switches to a different type of flower, it has to learn a lot of new information, such as where to collect the pollen and nectar, and this learning can take time and energy.
- It is always risky to switch what you are doing – pollinators may stick to a flower because they know it contains pollen or nectar, and they not want to spend the time or energy trying to find something new and better.
- Pollinators may be faithful to certain flowers to avoid competition with other pollinators that are foraging on their preferred flowers.
Flower constancy is not always beneficial for a pollinator, as it could be missing out on other available resources, but it does benefit the plants! Plants are best pollinated when a pollinator shows flower constancy, transferring pollen across plants of the same species.
When pollinators visit many different plant species in the same trip, they can transfer pollen from different species, which won’t pollinate the plant. So in the end, regardless of why they do it, flower constancy is good for pollination!
Read more about bumble bees, a group of pollinators that display flower constancy, here.