By Marie Sophie Roy, Master’s student at Concordia University

Reindeer (Rangifer tarandus) are usually considered quiet animals. With their calm and watchful gaze, they often appear contemplative and reserved. Yet if you listen closely, a soft, distinct clicking sound accompanies their steps, barely audible beneath the whisper of the wind. But when mating season arrives, the silence breaks.

High-ranking male reindeer become markedly more vocal, emitting low, guttural sounds believed to attract females and signal social status. This increased acoustic signaling during the mating season allows us to investigate whether male reindeer exhibit flexible vocalizations depending on the nearby individuals. This modulation of vocal behavior based on the audience is known as the “audience effect.” The main objective of our fieldwork, carried out in fall 2024, was to explore this potential audience effect in male reindeer vocalizations. To achieve this, we had to 1) find the reindeer and 2) record their vocalizations.

Finding the reindeer

Given that animals of this size cannot be kept in laboratories, fieldwork was necessary to study reindeer. Fortunately, we had access to a semi-domesticated population of reindeer at the Kutuharju Reindeer Research Station in Kaamanen, Finland. These reindeer roam freely within spacious enclosures (~15 km²), offering a unique opportunity to observe their behavior in a natural setting.

Because the reindeer move freely across such a broad area, it is useful to have a tool to track them. In the past, telemetry was employed by fitting high-ranking males with VHF radio collars. Trackers using an antenna and receiver could pinpoint the direction the reindeer were moving. When close enough to receive a signal, a reading could be taken at any time.

This field season, however, we switched to real-time GPS collars linked to the Ranniot application, a positioning and navigation service design for tracking. The decision was made together with our Finnish collaborators, as local herders had recently adopted Ranniot, primarily because the collars are lighter and better support the welfare of the reindeer. Learning to use this new system came with a few challenges. Although our Finnish collaborators helped introduce the app on the first day, the app interface was only available in Finnish, a language completely foreign to those of us in the field collecting data. To make matters worse, it wasn’t fully compatible with iOS, leaving us with just one functional device for tracking. It also took us a few days to figure out the optimal time interval between position readings, which refers to how often a GPS position was recorded. The shorter the interval, the quicker we could find the reindeer, but that also meant burning through the battery faster.

On the first day, we spent hours reaching the last recorded position, only to find that the reindeer had already left. Unlike telemetry, where you can actively take readings when needed, the GPS system felt much more passive. You are essentially left waiting for the next reading, and that lack of control can be frustrating. So, there we were, standing around, waiting for the next update… and then sprinting off again to the next location! That said, once we figured out that a 15-minute time interval between readings worked best, the system turned into a useful tool. Being able to see our own position on the map helped us avoid tricky terrain like bogs or steep hills, letting us plan a more efficient route.

Recording the vocalization

Once the reindeer were located, the next essential requirement was having a reliable device to record their vocalizations. We brought along a Zoom H6 recorder paired with a shotgun microphone attachment. It was simple to use and easy to carry, which was important since we often had to move quickly and adjust our position to follow the animals.

To record male vocalizations, we also needed to be present during the mating season, known as the rut. While it typically occurs around October, its exact timing can vary from year to year. The local herders helped us choose the best time to be there to catch the rut at its peak.

After that, it was only a waiting game. We positioned ourselves on the outskirts of the mating group, staying close enough to capture good-quality audio without disturbing them. It required us to minimize movement and noise, while still being ready to follow the reindeer as they moved around. Most importantly, we had to endure the cold, hoping we wouldn’t freeze while waiting for the male to finally vocalize.

Despite these few challenges, the data collection went smoothly. We ended up staying for two weeks, during which we successfully collected numerous male vocalizations. It was an unforgettable experience, and I’m genuinely excited to see what insights this data will reveal!