The Boom-Bust Cycle of Canada Lynx and Snowshoe Hare

The boom-and-bust cycle of hare and lynx populations has been documented for generations through Indigenous knowledge and “centuries of fur trapping data.” ¹³ Over the last several decades, however, researchers have observed fewer extreme population peaks than historically recorded.¹⁴ The reason for this change is not yet fully understood, but climate change is one possible contributing factor.¹⁵ According to Laurence Fox in Arctic Focus, Yukon is receiving approximately one-third less snow than it historically did.¹⁶ While this may negatively impact lynx, it can benefit one of our most adaptable predators: the coyote (Canis latrans).

A deeply misunderstood yet magnificent animal, the coyote is considered a keystone species, meaning it plays an essential role in maintaining ecosystem balance. I recently completed my master’s thesis on coyote ecology, and I would like to explain a little about how climate change affects the ways coyotes (and other predators, including lynx) interpret changing environmental cues, which can lead to behavioural adaptations.

I promise not to regurgitate my entire thesis here — I will not dive into behavioural adaptations in this article — but if this topic interests you, I encourage you to explore it further!

Wildlife relies on environmental cues, such as temperature and photoperiod (day length), to anticipate seasonal changes.¹⁷ Climate change, particularly earlier springs and delayed winters, along with artificial light at night, can create mismatches between these environmental cues and the behaviours they trigger. These mismatches can affect migration timing, phenology (which is especially relevant here), and reproduction timing — all of which are carefully synchronized so offspring are born when food availability is highest. Isn’t that neat?¹⁸

I mentioned phenology above. For example, phenology refers to the timing of seasonal biological events, such as when a hare moults its coat from brown to white (or vice versa) based on environmental cues. Each colour provides important camouflage within its surroundings. However, when climate change causes mismatches — such as shorter winters — hares may not moult at the appropriate time and can become stuck with a bright white coat against a brown landscape, or a brown coat against the snow.¹⁹ This makes them much easier for predators to detect.

However, even if a hare is sporting a brown coat during a snowy winter, it may still have an advantage against coyotes. Snowshoe hares and lynx both have large, furry footpads that are “adapted to float atop deep powder.”²⁰ Coyotes, on the other hand, have smaller footpads that sink into deep snow, meaning snowshoe hares can often outrun them in these conditions.²¹

But don’t worry too much about these sweet little hares, because once the snow has fully melted, they regain the upper hand in speed against both predators!²²