Why are lynx and snowshoe hare populations closely connected?

The populations of the Canada lynx and the snowshoe hare are closely connected because the snowshoe hare serves as the lynx's primary food source, making up 35 to 100 percent of its diet. This relationship creates a cyclical pattern in their populations that spans approximately 10 years.1

As the density of the snowshoe hare increases, the lynx population follows with a lag of about one to two years. Conversely, when the hare population crashes, the lynx population declines as well. This dependency is so significant that the lynx's reproductive success is tied to the availability of the hare; if hare numbers are low, female lynx may not breed or may experience spontaneous miscarriages. Additionally, the lynx's geographic distribution is strictly limited by the presence of the hare, as the cat does not inhabit regions where the hare's density falls below a certain threshold. Ultimately, the lynx plays a key role in controlling the hare population, while the lynx's own numbers are regulated by the availability of its prey.1