Today’s post was written by Mike Keogh. Since returning from a year in New Zealand, Mike has been working on fulfilling the pre-requisites for graduate school. He has a bachelor’s degree in Psychology but he is going back to school for Physical Therapy. When time allows, he enjoys hiking, paddle boarding,and traveling.
The fall 2019 semester’s Introductory Biology I course was one of the most unusual and rewarding class structures I’ve experienced. Course-based Undergraduate Research Experience, or CURE, was an experiment to see if the gap between the foundational learning of the classroom and the practical experience of field work could be bridged. I would argue it has been, the benefits of which go beyond our transcripts.
The focus of CURE, and that of The Gulls of Appledore Research Group, is the Great Black-Backed Seagull. Each summer, Dr. Courchesne and a group of students, be they middle-schoolers or biology majors at a major university, travel to Appledore Island to study the large colony of Great Black-Backed (and to a lesser extent, Herring) Gulls that live there. The researchers spend weeks mapping the island, plotting the locations of nests, recording eggs hatching, and monitoring the health and development of those fledgings.
In the pursuit of learning about and from the gulls, the researchers gently separate the proud parents from their chicks for just long enough to take blood samples, affix an identification band to the chick’s leg, and record any other pertinent data about the chick or the nest. Analysis of the blood samples offers a range of information about the gulls, such as identifying if the gull is suffering from a disease and enabling researchers to perform a white blood cell count. In our case, the white blood cells of interest were heterophils and lymphocytes. The ratio of these two white blood cells allows researchers to identify the level of stress experienced by the gull.
Yes, the gulls are stressed. While demanding managers and delayed trains don’t top their list of stressors, the gulls face many of the same dilemmas and issues as humans. Who to choose as a mate, where to settle down, how to care and provide for their young, and the ever-increasing consequences of climate change.
Some stressors can be measured fairly directly, but no stressor is without obstacles and confounding variables. These variables can mean tricky decisions, often without all the information. For example, “How does the distance from the high tide line to a gull’s nest effect that gull’s stress level?” may seem simple. The researchers would have to choose an area to focus on, go out at high tide to mark the water line, and then measure the distance from that line to each nest in their area of focus. But what if a nest is in thick brush? Just estimate? Will that hold up to peer-review? What if a nest is on a large rock? Does the researcher climb the rock and measure directly to the nest? Do they measure to the base of the rock and then up the height of the rock to the nest? Could they mark the locations of the nests in that area on a map and then use the distance scale to measure the distance from the high-tide line to each nest as if they were all on the same level? These kinds of questions may seem like someone playing devil’s advocate, but, in the field, they can quickly become major obstacles that require the researchers to make judgement calls that will impact their entire study.
This semester, our class was provided with blood smear slides collected from gulls in 2017. As a class, we decided that we would count heterophils and lymphocytes, two types of white blood cells, the ratio of which can indicate the stress level in the gulls. We also decided that it would require the examination of 6 fields (locations on the slide to examine with a light microscope) on each slide to get an accurate idea of how many heterophils and lymphocytes a given sample contained.
We got slides, got microscopes, and got counting. All of our fields were photographed using our phones and sent to Dr. Courchesne for confirmation. We finished with confirmed heterophil and lymphocyte counts for 42 gulls from 2017.
Using this data, I examined the relationship between heterophils and lymphocytes by calculating the difference between them and comparing that difference to the gull’s mass. My goal in doing so was to identify if there was any relationship between the mass of a gull and the stress level it experienced. If the data were to show a connection, such as gulls beyond a certain mass experiencing abnormally high levels of stress, more research could be conducted to examine what specific aspects of being a large gull caused the increase in stress.
However, my analysis revealed no special relationship concerning the difference between the heterophils and lymphocytes and the mass of the gulls. Only a single gull’s data was thrown out as an outlier being beyond three standard deviations from the overall average. Without that single outlier, the data points were spread relatively evenly across the spectrum of gull masses. This indicates that the masses of the gulls are not a major contributing factor to their overall stress level.
I was surprised that mass does not appear to be a major factor in the stress levels of the gulls. I would have thought being larger would mean needing more food, the gathering of which takes a lot of energy, thereby compounding the problem. I would be interested to find out if there are any physical features that do play a role in the stress levels of the gulls. Hopefully, I will be able to take advantage of The Gulls of Appledore Research Group’s internship opportunity to go to Appledore and conduct my own research to find out.