A component of my second year Behavioural Ecology module (BSX-2018) was carrying out an Oystercatcher practical in order to learn more about, and measure, vigilance.
Vigilance: ‘The action or state of keeping careful watch for possible danger or difficulties’.
Prior to the practical experiment, we learned about vigilance during a lecture. And, evidently, vigilance can easily be measured in animals through assessing the number of times the animal raises their head, thereby scanning their environment in search of predators aswell as other potential threats.
Noticeably, animals in larger groups are known to be less vigilant following the ‘many eyes hypothesis’, since there are more eyes available to scan for predators, and more bodies to count for safety in numbers, it significantly reduces the need for individuals to scan on their own accord. In comparison to animals staying on their own, who need to scan more frequently in order to search and to keep themselves safe.
In order to successfully carry out the experiment, we were each assigned three videos of Oystercatchers to watch which had been previously recorded on Bangor Harbour.
We watched each video for a duration of three minutes, recording the number of times the Oystercatchers were vigilant (raising their heads) to measure the head-up rate with the use of a clicker, to provide accuracy to the experiment by ensuring we didn’t take our eyes away from the screen. Simply, whenever the animal raised their head, we were to press the clicker to count the head up rate.
During the experiment, we also had to assess which diet the Oystercatcher had to understand whether this did or did not affect vigilance in the individuals. This was done by monitoring how deep the animals searched for food. Noting that the animals engaged in a range of different searching methods, including:
And the prey handling methods for Bivalves consisted of:
- Hammering (Dorsal)
- Hammering (Ventral)
The information gathered was then recorded in the class datasheet for each of the Oystercatchers we observed, to which we could compare with the results of other students. Though, this wasn’t a component required for the completion of the practical experiment.
During the next part of the experiment, we were informed on how to use R statistics for the first time. Admittedly, I’ve always been nervous around stats, but I loved grasping the concept of using a new software and stepping aside from SPSS, and I quickly felt confident with using the software. The practical handout was a blessing and our knowledgeable, and kind, lecturers were around and keen to issue support and guidance if and when we required it.
We made our way through the practical handout, each of us working at our own pace and facing our own individual (but expected) hurdles along the way. The experiment took approximately four hours to complete as we were issued with codes we had to transfer into the software in order to create a graph, which could simply be done by running the code.
Following on from this, we made our own codes and plotted different categories on the X and Y axis, thereby allowing us to formulate our own graphs which could then be used to gain an insight and a further understanding into different relationships between Oystercatchers and vigilance. For example, how the diet affects the head up rate, or how group size affects head up rate.
And then we simply had to perform a stats test for each of the 6 plots we had previously created in earlier steps. Which, again, could be done by simply creating a code, running it and noting down the important parts of the test, such as the p-value to determine whether each of the relationships were significant or insignificant.