Wildlife Field Methods: Preferences of Pollinators

Bee pollinating an invasive Himalayan blackberry, Photo by: Chris Trinies

Pollinators help propagate flowers by moving from flower to flower searching for nectar as an energy source, and taking pollen along with them. The most well-known pollinators are bees but “pollinator” refers to any species which habitually moves from flower to flower. Bees, beetles, bats, flies, moths, butterflies, and hummingbirds are all examples of pollinators in the Pacific Northwest. Because most plants cannot reproduce without the services of pollinators, it is crucial to both natural ecosystems and agricultural crops that pollinators are abundant and active.

Little beetle peeking out of a native Thimbleberry, Photo by: Chris Trinies

When foreign plant species are introduced to a non-native region, they may not have the same restrictions on growth as they do in their native habitat (i.e. no herbivores here will eat them) and can outcompete the native plant species which do feed local herbivores, and greatly reduce the amount of herbivore forage in the region. They can outcompete in many different ways, some have poisonous berries, and some grow so rapidly they crowd out competition, and is possible that some may reproduce at a greater rate. However, the easiest way for a plant to reproduce more is to attract more pollinators.

Budding invasive Himalayan blackberry, Photo by: Chris Trinies

This raised the question: Do the pollinators in the Sehome Hill Arboretum have a preference between native and introduced plant species?

We ran a study to find out!

We instructed members of the class observe different plants (some native, some introduced) and record how often the plant was visited by pollinators, then compared native and introduced plants. We didn’t get any statistically significant results, which means that we can’t say from our observations alone that is definitely a difference in pollinator visits per minute between native and introduced species of plants. This is either because our study wasn’t large enough or because pollinators in the arboretum just don’t have a preference. Considering how many other studies found that pollinators have preferences in plants, it’s more likely that our study just wasn’t large enough.

We certainly learned more about pollinators and about what plants are native to the area by doing this study than if we'd tried to do a manipulative study in a controlled setting. One example was that the beetles we found on the thimbleberry flowers completely caught us by surprise and changed how we did the observations. Looking up all the plant species in the field was something we’d never really done before either. All in all this study was a great learning experience for future field work.

Monarch butterfly, Photo by: Larry Keller, Flickr

Before this study I don't think any of us really would take the time to sit and watch pollinators buzz around. Once we had it was actually pretty incredible. Different types of pollinators do exhibit different behaviors! Whether that be in the different ways that they get around, the way that they interact with other pollinators, how they act when they land on flowers...there are just so many differences among pollinators that are truly something to marvel at. I would consider this as a kind of "stop to smell the flowers" kind of experience. When you take the time to observe something so seemingly small, it becomes more apparent just how abundant and important little critters like pollinators are.

To drive the point home, lets give the pollinators a little round of applause for contributing so many wonderful foods in our lives!