Peak of the Lynx Cycle
A Canada Lynx (Lynx canadensis) spots me before I spot her, Katmai National Park & Preserve, Alaska.
Being back in Katmai in the fall felt great. Colorful fall foliage and a patchwork of lime, white, red, and green on the tundra produced a stunning landscape. I intended to experience it to the fullest as I searched for the elusive Canada Lynx during the peak of the lynx cycle.
After guiding three sequential bear photography workshops, I headed to the backcountry, away from Brooks Camp and all the people, searching for the elusive Canada Lynx (Lynx canadensis). I had seen a few lynx in Katmai in the past. Those sightings were few and far between.
I kept detailed records of where I had seen lynx or their sign. I intended to return to these areas to look for lynx, understanding that I still might strike out and not see any. When I learned that 2022 was a peak year in a 10-year cycle of lynx population densities. I had high hopes of seeing lynx.
While backpacking to my first camp, I saw my first lynx of the trip. A large gray male sat like a sphynx in the forest ahead of me. The sun had set long ago; it was too dark for any quality photography. However, experiencing this lynx on my first day in the backcountry gave me confidence.
I often tell myself not to “jinx” things by being overly optimistic. The next day I hiked for at least eighteen miles. No lynx were seen. Instead, I saw over 30 spruce grouse and about a dozen snowshoe hare. I also saw signs of lynx, along with wolf, moose, and of course, brown bear.
With sore feet, I followed a different approach the next day. Instead of covering many miles in search of lynx, I chose to sit and wait in areas where I had previously seen signs of them. After sitting quietly and waiting for a lynx to appear in four different places, I finally saw a lynx on the forest floor looking at me. As expected, the lynx saw me before I saw her.
One of my backcountry camps in Katmai with a great view of Naknek Lake
I was grateful for the abundant low bush cranberry (shown here) and blueberry that I ate in large quantities to supplement my diet.
This lynx cautiously watched me as I sat on the forest floor, allowing me to take plenty of photos in better lighting than my first lynx sighting of the trip. It was difficult to focus on the lynx through the dense vegetation. I sat motionless and waited for the lynx to move into openings where I could photograph it.
Being alone and hiking through the forests of Katmai gave me plenty of time to ponder the cyclic nature of lynx-snowshoe hare populations. In its simplest form, there is a predator-prey relationship between the lynx and snowshoe hare.
Canada lynx depend strongly on the snowshoe hare for food, making up for 35-97% of their diet. Every Lynx population relies primarily on the snowshoe hare, but the percentage in their diet fluctuates in different seasons and years, depending on hare abundance.
Northern snowshoe hare populations cycle every 8−11 years, sometimes spectacularly from as high as 2,300 hares per km\(^2\) to as low as 12 per km\(^2\). Wow!
Lynx numbers are closely linked to hare density(1)Hunter, Luke. Wild Cats of the World (p. 148). Bloomsbury Publishing., lagging one to two years behind with a three- to 17-fold drop, for example, from 17 lynx per 100km\(^2\) to 2.3 per 100km\(^2\).
The more I thought about this lynx-hare cycle; I had more and more questions.
Why did the hare population crash? They seemed to eat vegetation, and there was no shortage of greenery in all the years I have been to Katmai.
Why was the lynx so reliant on hares? What about all the grouse, squirrels, and other birds it could catch and eat?
Snowshoe hare was plentiful this year. I saw them frequently in the green and thick boreal forest in Katmai, still in their summer-fall brown fur.
The typical snowshoe habitat in Katmai National Park & Preserve is shown here.
Data from the Hudson Bay Company on Canada Lynx fur pelts from 1821 to 1910 show an average cycle of 9.6 years(2)
Elton C, Nicholson M. 1942. The ten-year cycle in numbers of the lynx in Canada. Journal of Animal Ecology 11: 215–244.. These lynx were trapped mostly in western Canada.
Fluctuations in the population density of Canada Lynx and the peak of the lynx cycle are highly correlated with the 10-year population density of the snowshoe hare. Canada Lynx is the only felid (cat) to exhibit cyclical population densities(3)Luke Hunter, Wild Cats of the World, Bloomsbury Natural History; 1st edition (September 24, 2015).
The correlation between snowshoe hare population density and lynx population density based on the Hudson Bay Company data is shown here reference. The lynx population cycle lags the hare by about 2 years.
In the summer, there sure seemed like plenty of vegetation for the snowshoe hares to eat. Every time I saw a hare, it was munching on green foliage. Perhaps it was during the winter when its food sources would be limited? This did not make sense in my area since there was no apparent 10-year cycle in the vegetation. I was stumped.
I carry a small Kindle with me to read during downtime. None of the references on my Kindle explained why the 10-year hare population density cycle existed.
Later, after returning home and reading many scientific papers on this well-known population cycle, I learned more. The first thing is that the population cycle is not fully explained and is still somewhat of a mystery. Some interesting experiments where scientists controlled the available food and access to predators of hares shed some light.
- Predation of hares was found to be a more important factor in the population density of hares than food availability
- Lynx will travel very far (1000 km or more) to find higher densities of snowshoe hare
- The ratio of caloric intake to caloric expenditure for lynx from snowshoe hare predation is significantly more than smaller prey (one snowshoe hare equates to roughly 50 voles)
- Snowshoe hare reproduction rates decrease when the population density of hares increases
- There is synchrony in the hare population density cycles across large regions of Canada and Alaska. The current belief is that this is due to lynx migrating from areas of low hare density to high hare density — thereby synchronizing the cycles in population.
A male spruce grouse sits in a tree. These grouse are normally on the ground and burst into an explosive flight once they sense danger. Lynx need to sneak up on them quietly and pounce quickly.
This lynx approached me right after a wonderful visit with a wolf. The lynx seemed to seek safety from the wolf by hanging out with me. What an amazing thing to experience 10 minutes alone with a wolf within 15 feet of me, followed by a lynx.
When I focussed my camera on this lynx, it had a ghostly feel to it, making it hard to concentrate. Lynx are known as “ghosts of the forest.”
A snowshoe sits motionless in the dark boreal forest of Katmai.
The lynx must be very patient and persistent, waiting in place for an unsuspecting snowshoe hare to come by.
Here is an informational diagram I made on the snowshoe hare; click on a node to expand and scroll the map.
The research on the lynx-hare cycle emphasizes that the diet of the snowshoe hare is diverse and that many predators eat snowshoe hare. In addition to the lynx, goshawks, red-tailed hawks, great horned owl, boreal owl, northern hawk owl, wolf, coyote, fox, golden eagle, and wolverine all prey on the snowshoe hare (and other prey).
Since the lynx specializes, or strongly favors, preying on the snowshoe hare, the correlation between hare population density and lynx population density is strong.
The strange synchrony of hare population density across large regions is caused by the lynx traveling long distances (up to 1100 km) from areas of low snowshoe hare density to high hare population density. This long-distance movement by the lynx keeps the hare population density dynamics correlated over large spatial areas. Many of the lynx I saw this year in Katmai may have traveled far to reach the high-density snowshoe hare this year.
The lynx’s specialization on the snowshoe hare for its preferred food source is what ties the hare population’s cycle to the lynx. This predator-prey cycle is famously described in the Lotka-Volterra differential equations and is used as the canonical example in many ecological textbooks.
I am grateful that I could get out in the wilds and devote some time looking for lynx and thinking about this puzzling 10-year cycle, especially during the peak of the lynx Cycle. Knowing that these cycles are still occurring in nature is reassuring and interesting.
Great photos and commentary Ed! Thanks!
Thank you, Verne. I hope you are doing well.
Fascinating story of nature at ita’s best. If only humans would lean from it and not have continuous population growth. Thanks for sharing your story and wonderful pics too!
Thank you, Karl. Good point, I must admit that while I was searching for lynx and thinking about the population cycles I did also wonder about the human population growth — up, up, up, ….
An adventure indeed! Wonderful pictures and commentary. I’m curious to know what precautions you take for a brown bear encounter in the wild.
Thank you for reading the article, Bill, and for your question. I carry BEAR SPRAY with me, and I have an electric bear fence around my tent, mainly to protect my tent when I am not around. Just about every day/night, I ran into bears on my hikes. I calmly moved perpendicular to their direction and let them pass with no problems.
Wonderful images and commentary on your pursuit of the elusive and beautiful lynx.
Thank you, Mike. It was really fun to explore Katmai with you! I miss being up there.
Thank you for teaching us about the lynx and hare dynamics. So interesting. Your photographs are stunning and so beautiful. Thank you for sharing your experience. Watching the bear cams this year and seeing how much rain Katmai received. There would have been an abundance of vegetation for the hares. Wildlife have so much to teach us.
Thank you for reading the article, Margaret. Yes, the amount of rainfall this summer was amazing, I hope it helps all the wildlife eat well before the big sleep over the winter.
Ed, very educational article, great story telling and wonderful photos. Thank you for sharing. I still fondly remember my lesson on brooks river.
Thank you, Aditya, I am glad you enjoyed the article, thanks for reading and commenting on it.
This article is sooo great! Very educational! And, the photos are fantastic! How exciting for you to be out there doing what you love and exciting for us that you bring your experience back and share it with us! Thanks!
Thank you, Tammy. I a glad you enjoyed the article. It was a fabulous experience for me.