Wildlife ecologists study what motivates animal behavior, but they are often difficult to analyze. Ecosystems are incredibly complex, behaviors are determined by many internal and external factors, and the observation itself is not easy to do.
As wildlife ecologists, we know that when we observe wild animals, it is impossible for us to know the effect of our presence on the subject’s behavior – not to mention the difficulty of tracking animals in their environment, in particular those which traverse vast expanses of forest. We must therefore resort to stealth means.
In a recently published study, we discovered an effective method to monitor the behavior of one of the boreal forest’s most elusive predators: the Canada lynx. Although GPS tracking is not new, it is generally only used to observe the movement of wildlife.
In our case, we wanted to delve into the secret life of this mysterious feline and record its soundscapes. After several unsuccessful attempts and a few clever solutions, we found a way to attach a small microphone to our lynx collars – and it opened up a whole new world to us.
We were pleased to note that these recorders were very effective in capturing the behavior of lynxes: “cats living their cat life” (grooming, sleeping); social behavior (aggressive interactions, purring, long-distance social calls); and hunting behavior (chasing, killing, eating).
During our five-year research in the Kluane, Yukon region, we collected over 14,000 hours of audio recordings for 26 lynxes. After using a variety of data processing methods, we were able to identify with 87% accuracy – a feat – times when Canadian lynxes were successful in killing an animal.
In the past, knowing that a lynx had killed prey often required a full day of snowshoeing and intensive tracking during short winter days in the Yukon. By recording several lynxes, we were able to gather information around the clock, while keeping our feet warm by a wood stove in a rustic cabin.
In addition to audio recorders, we have also attached accelerometers – small devices that measure activity over time, such as can be found in FitBits. Combined with GPS tracking devices, these “biologging” technologies provide unprecedented insight into the complex behaviors of these felines.
Lynxes and hares
The hunting behavior of the lynx is of particular interest to us. The populations of Canada lynx and snowshoe hare follow a cycle of population increases and decreases. When hare populations are high, lynxes have a lot to eat. Then, the high number of lynx causes the decline of hare populations, which leads to a collapse of lynx populations. When hares are hunted less due to the decrease in lynx numbers, the population increases again, which starts the cycle again. All of this happens over a period of about eight to ten years.
Lynx populations are affected by fluctuations in their food supply, but these hunters are more adept at adapting than previously believed.
But things might be more complex: lynxes turn to other prey, like the red squirrel, when they run out of hares. Our custom-made collars help us understand when this change may occur and determine whether lynxes may respond in different ways to the decline in snowshoe hare numbers.
We were also surprised to see more social behavior than expected. Lynxes are known to be solitary animals that live and hunt alone for most of the year. But many of our collared lynxes, especially adult females, seemed to interact with each other quite often in groups of two or three: they slept, groomed, moved around and even hunted together.
Although our collars revealed this surprising social behavior, it seems that lynxes do not share their food: after hearing them kill a prey, we often hear many growls and growls, as if they were repelling attempts to approach the lynx. other lynxes. Does this social behavior influence their ability to find and kill prey? This is one of the many new questions we are asking ourselves about lynx behavior as we continue to explore the lives of these amazing boreal predators.