An email from a reader, complete with new pictures of cute wild cats, prompted me to throw this week’s spotlight on the Canada lynx.
There are four species in the genus Lynx, two of which (the Canada lynx, L. canadensis, and the bobcat, L. rufus) occur in North America. The bobcat—once lumped with the Canada lynx in a single species—is far more common in the U.S. Most Canada lynx live farther north, where they prey on snowshoe hares and other mammals. (The tandem and regular oscillations of lynx and hare abundance, with a cycle of about ten years, is a famous story in ecology, which, as far as I know, is still unexplained.) Like most wild cats, they’re shy and solitary, so their biology is not terribly well understood.
Both American lynxes are medium-sized cats (20-30 lb) with tufted ears, very short tails (hence the name “bobcat”), huge paws (which, as you’ll see in the video below, act as snowshoes in winter), and a bushy mane around the jowls that gives them a regal and leonine appearance:
Peter Vickery, a biologist and president of The Center for Ecological Research, kindly agreed to share his story (and the three following photos) about surveying the Canada lynx in his state:
I was invited by the Maine Dept. of Inland Fisheries and Wildlife and USFWS researchers to join them looking for Canada Lynx dens in northern Maine. The Lynx Team (MDIFW and USFWS) has been studying lynx in northern Maine for 11 years, documenting breeding and productivity, survivorship, and habitat use.
To determine productivity, the Team has put radio collars on a number of females. If the females are denning, their movements become very limited in May and early June. When the general area of a potential den is identified, several members of the Team try and locate the female using receivers. One member then goes in slowly to search for the den. This often requires a game of approach and departure. Once the team member gets reasonably close, the female lynx often moves off. The researcher then moves off and the lynx returns. By doing this several times and carefully following the female’s movements, the researcher can get a pretty good idea of the search area and then the slow process of working through dense regenerating clearcuts begins.
My impression and conversations with Team members indicate that dens are nearly always in regenerating clearcuts or heavy brushy blowdowns. Lynx clearly use clearcuts as denning habitat, presumably because the hare densities are high and nearby, and the dense cover provides excellent shelter for a den. The industrial forest in northern Maine appears to provide plenty of early successional habitat for hare and lynx.
On the day I joined the Team in mid-June, we failed to find a den in the morning because that particular female moved about in an irregular fashion and it was impossible to pinpoint a potential den site. We tried a careful sweep and found old den sites but it may have been that the female had moved the kits, as they often do once the kits are old enough to move.
The second den search was successful, as you can see. The Team uses medical gloves as they take a variety of measurements before the kits are returned to the den. The Team then monitors the female’s movements to make sure she returns to the den. The Team has never had a case of den abandonment. Sometimes the females are close enough, within 4 meters, to observe the Team handling the litter but they are usually some 30 – 50 meters from the den while the Team is present. I’m guessing the female does a huge amount of licking once she returns! Despite efforts to minimize human contact, there must be some foreign smell that a diligent mother would want to remove.
It appears that 2010 is a pretty good year for lynx productivity in Maine. Litters this year are in the 2 – 3 kit range where a few years previously some females didn’t have any offspring. Litter sizes were larger earlier in the study. Not surprisingly, the number of kits is very closely linked to hare densities. I can attest to reasonable hare numbers this year as I saw well over 150 animals on a 60 mile evening drive along the wood roads the night I left the Lynx Team.
The Lynx Team follows the family in the winter once there is snow on the ground. Because the adult female has a collar, the Team can find where they cross a wood road and then back track to determine how many young are still with the female. I was impressed that this was an effective way to monitor kit survivorship through the first winter. The Team always back tracks so they don’t interfere with the animals. Females separate from the young lynx as the new breeding season approaches in early spring.
Regrettably, this is the last year of the study. It’s clear they have gathered an enormous amount of important information relating to productivity and habitat use.
I was very grateful to accompany the Maine Lynx Team and was enormously impressed with their skill, perseverance, and care for the rare animals they were studying. This was a very dedicated and caring group of field biologists! It was a privilege to join them.
Here’s Peter with one of the babies:
I’ll close with one of the most impressive wildlife pictures I’ve ever seen: a lynx catching a snowshoe hare, photographed by Robert Walch for the Time-Life book The World’s Wild Places: The American North Woods (1972). Look at the size of those paws!
And two lynx videos. The first is the classic duel between lynx and snowshoe hare:
And here’s a seriously peeved lynx. The book Wild Cats of the World reports that these beasts make a variety of sounds, some of them completely unexpected. This one (which may be a bobcat) seems to be growling and bleating at the same time.
h/t: Peter Vickery, Scott Hedges