Kyra Hoerr (BMC ’20) blogs on her recent trip to do mistletoe fieldwork in the U.K.

My name is Kyra and I’m in my final year of undergraduate studies at Bryn Mawr College working in Dr. Record’s research lab. I’m interested in ecology and philosophy of science, specifically in understanding how we can model biological complexity. I’ve been working with Sydne and Rob Salguero-Gomez (Oxford University Department of Zoology) on a mistletoe demography project for about a year now and I recently visited Oxford for two weeks to help with some of the fieldwork.

The cool thing about mistletoe—and one of the reasons it’s important to study—is that it’s hemi-parasitic. This means that the plant can obtain resources both from photosynthesis and from its host tree. At the moment there’s not a lot of data on parasitic plants, but they’re important to understand because their life history strategies may differ from non-parasitic species. For example, because mistletoe plants don’t need to invest as much energy into a root system to obtain water, we might expect them to have more energy to invest in reproduction than non-parasitic plants. The main hypothesis we’re investigating in this study is that mistletoe will demonstrate weaker trade-offs in reproduction and survival than non-parasitic plants.

Investigating this hypothesis involves a lot of tromping around in the woods with various pieces of expensive equipment. On a typical day in the field, Rob, Yash, and I carried two drones, two scopes, at least one tripod, a camera, and two iPads out into the woods looking like a group of over-prepared hikers. Once we arrived at a tree, we would take a picture of it from the same spot the picture was taken last year. This makes it easier to tell which mistletoes have died and which are still on the tree. After we took pictures with the iPad, camera, and drone, we would use the scopes to identify whether the mistletoes had fruit on them to determine whether they were reproductive. And finally, we would scan the tree to find new recruits—young plants that could have only a few leaves.

Back at Bryn Mawr I spend a lot of time in the lab staring at the pictures from the field. Using the software ImageJ I can measure the relative growth of the plants from the pictures we take each year. For the past year I’ve been using these images to gather information on the growth, survival, and reproduction of each individual mistletoe over the course of several years. I’ve started to use these data in integral projection models (IPMs) that will help us to understand the demography of these populations.

One of my favorite parts of doing fieldwork this year was realizing how well I’ve gotten to know each of the host trees. Just from looking at the branching patterns and distribution of mistletoe, I can tell you the ID number of almost all 25 of them. I even have some favorite mistletoe plants (mistletoe number 38 on Tree 128 is especially cute). Spending so much time looking at mistletoe plants on a computer screen has helped me to find even very small plants when I’m out in the field. It’s a very odd skill, but one that I’m very proud to have.