F51, an adult female mountain lion currently followed by Panthera’s Teton Cougar Project, has given birth to three litters in three years, which as far as we know, is something of an anomaly. F51 immigrated into our study area from some unknown place and we started tracking her at the very start of 2011, just before she gave birth to her first litter (5 kittens!). In fall 2012, she separated from her kittens when they were 14 months old, and then she gave birth to three kittens, just 16 months after her first litter. Wolves killed two kittens from her 2012 litter when they were very young, and when her last remaining kitten was just nine months old, they went their separate ways. We were completely baffled as to why such a young mountain lion was on her own (typically kittens disperse at about 18 months in our study area), but the answer revealed itself a month later. Just ten months after her 2012 litter, F51 gave birth to four new kittens in 2013. Absolutely amazing, and completely unexpected.
Watch the video below of F51′s 2013 litter when we discovered them (unexpectedly, during routine filed work looking for mountain lion kills). They are two days old.
Fecundity. I’ve always liked the sound of the word, and how it feels when I say it. According to Merriam-Webster’s Collegiate Dictionary, fecundity means “fruitful in offspring.” For biologists, fecundity is a measure of how fruitful is a species. It’s also essential knowledge in understanding species ecology and creating effective conservation plans for species that need support. For wildlife researchers, quantifying fecundity is something of a holy grail, because it requires such a significant time and energy investment, a quest if you will.
What information is needed to determine fecundity for an animal, you might ask? First, we need to know how many offspring are born at a time. Is it typically one offspring, like humans, or twins like pronghorn? Second, we need to know how often a single female gives birth. Females of many species give birth every year, or several times a year, in cases such as meadow voles and cottontail rabbits. Last, we need to know how long females typically live in a population to estimate how many times she might give birth during her lifetime. Seems so simple!
Now let’s consider mountain lions. Cougars are cryptic carnivores that earn a living by remaining invisible to their prey. They live like shadows on the landscape, weaving in between us, often unseen. They wander vast areas as they hunt and survive, making it challenging to predict where they are at any given point in time. Mountain lions are difficult to see on a normal day, but especially tricky to see when giving birth. And mountain lions live eight to 12 years, and sometimes longer (except in hunted populations). So how do we go about finding cougar dens, documenting the length of time between cougar litters, and determining the average length of time a female cougar survives in the wild?
It would be a near impossible task, if not for technology that allows us to follow mountain lions in the field—I’m talking about the collars researchers place on animals. Modern GPS collars allow us to not only pinpoint the location of an animal, but to do so in near-real time, because GPS locations are transferred through satellites to computers in our dingy field offices.
But let’s jump to what we’re learning on the Teton Cougar Project, one of few long-running projects on mountain lions. Unfortunately, many research projects are short—typically the length of a MS or PhD program—and thus determining fecundity for a species like mountain lions is impossible. Projects like the Teton Cougar Project are so special because they are so rare.
Over 13 years, we’ve visited the natal dens of 18 different females to document litter size, and recorded inter-birth durations for nine females for which we documented two to three consecutive litters. Here, in the Southern Yellowstone Ecosystem in northwest Wyoming, female mountain lions give birth to an average of three kittens (range two to five) on average every 27 months (range 10 to 39 months). It’s amazing how so much work and so many miles hiked can be summarized in just a sentence or two.
F51 is certainly our most “fruitful” female to date. Follow F51 and other mountain lions on facebook.
It’s akin to a light switch; it’s that stark. One day mountain lions inhabiting the Southern Yellowstone Ecosystem are predominantly killing mule deer, and the next day they all switch to killing elk. And then they kill elk for five to five and a half months before they switch back to deer.
It happens on a slightly different date each year. In 2013, it was November 14th, two weeks earlier than in 2012. There hasn’t been a deer killed by the cats we are tracking as part of Panthera’s Teton Cougar Project since that date, and we don’t expect we’ll find a deer killed by a project cougar until May. Nowhere in their vast geographic distribution do cougars exhibit such distinct summer and winter diets as in our study area.
Ungulate (a fancy word for a “hoofed mammal”) migrations, driven by the seasonal availability of forage that sustains them, result in large-scale redistributions of resources for carnivores. In response, carnivores adapt their foraging behaviors in systems with migrating prey.
In summer, carnivores in North America are quick to seize opportunities presented by the birth pulse of numerous, vulnerable, young ungulates. Whereas in winter, carnivores take advantage of the numerous ungulates struggling to survive harsh weather on lesser-quality forage and suffering poorer health. In the Southern Yellowstone Ecosystem, cougars do something more. Not only do local mountain lions follow trends in changing prey vulnerability, but they also track changing prey numbers.
Through November and December each year, thousands of elk descend upon the National Elk Refuge and surrounding Bridger-Teton National Forest and Grand Teton National Park lands in northwest Wyoming (as well as thousands of tourists to ride in sleighs drawn by sturdy horses to view them, but cougars generally steer clear of the tourists). Recent winter elk counts in the area number around 11,500 animals. This boon in prey numbers for local mountain lions coincides with the migration of mule deer out of our study area into the flat lands surrounding Jackson, WY and further south. Thus, it is not surprising that cougars here switch their focus from deer to elk with the Christmas season.
Cougar populations across North and South America are primarily non-migratory and hunt non-migratory prey. Nevertheless, where mule deer exhibit seasonal migrations, some cougars follow, exhibiting seasonal ranges themselves; other cougars remain in winter deer range through the summer, where deer persist, but at lesser numbers (Pierce et al. 1999, Cooley et al. 2008). In contrast, cougars here remain relatively stationary as ungulates migrate across the Southern Yellowstone Ecosystem, and kill different prey in different habitats in different seasons.
As they hunt through the year, mountain lions in the Southern Yellowstone Ecosystem also distribute a wealth in carcasses for scavengers, decomposers and floral communities, in more diverse locations than they would if ungulates didn’t come and go. Thus ungulate migrations in the Southern Yellowstone Ecosystem are not just vital to the dynamic health of the area, but a cornerstone piece needed to understand why local cougars do what they do throughout the year.
Cooley HS, Robinson HS, Wielgus RB, Lambert CS (2008) Cougar prey selection in a white-tailed deer and mule deer community. J Wildl Manage 72: 99-106.
Wolves are coursing, social predators that operate in packs to select disadvantaged prey in open areas where they can test their prey’s condition. Mountain lions are solitary, ambush predators that select prey opportunistically (i.e., of any health) in areas where slopes, trees, boulders, or other cover gives them an advantage. Thus, wolves and cougars inhabit and utilize different ecological niches, allowing them to spatially and temporally coexist; nevertheless, in the absence of wolves, cougars utilize areas traditionally assumed to be the sole dominion of coursing wolves. This suggests that where wolves are sympatric with cougars, wolves limit mountain lions.
In fact, wolves kill mountain lions. This has never been disputed. Wolves are considered the dominant competitors in most interactions between the species. Take for instance, the Hornocker Institute study of mountain lions in Northern Yellowstone led by Dr. Toni Ruth, in which researchers discovered the remains of three mountain lions killed by wolves. What is contentious is the idea that mountain lions might kill wolves.
Liz Bradley, a Montana Fish, Wildlife and Parks wolf biologist, reports that she has discovered five wolves killed by mountain lions in three years—all bearing the characteristic canine punctures in their skulls betraying the identity of the perpetrator. Some dispute her claims and point out that wolves fight each other too, especially adjacent packs, and that they also attack the head; skeptics believe a canine puncture in a wolf skull could be made by another wolf just as easily as a mountain lion.
The Teton Cougar Project operates in the Southern Yellowstone Ecosystem, and is one of very few long-term studies of mountain lions. Since the start of the project, wolves have trickled into the area, established territories and reproduced. In 2001, U.S. Fish and Wildlife Service surveys estimated that there were about 10 wolves in our study area, and that number steadily increased to as high as 91 in 2010. To date, we’ve documented five lions killed by wolves, all kittens, and all less than six months old while they were still relatively slow to climb and less than fully coordinated. But it was just last October that we finally documented the contrary. For the first time, a mountain lion we were tracking killed a wolf.
She’s a particularly feral mountain lion, F109, an adult female with three three-month-old kittens. All cougars are feral, of course, but there’s something unique about F109. She has “crazy” eyes, and always wanders the most rugged, inhospitable terrain. She was near impossible to catch in the first place. She’s a survivor.
We can’t tell you exactly what happened, but we can describe what we deciphered from the clues left behind in the snow. F109 was up high traversing steep, barren slopes, where we expected there was little game. Nevertheless, her location data indicated that she’d stopped and we suspected she’d made a kill. We slogged up the mountain to investigate, the ground bare of snow adjacent the road, but as deep as our thigh in the high bowl where she lingered. The entire area preceding her position was a mosaic of wolf tracks and trails. A wolf pack made up of adults, subadults and pups had criss-crossed the area, leaving barely a patch of snow without their sign.
Perhaps the wolves had challenged F109, or perhaps just one of them wandered too close to her kittens, or perhaps a pup felt like exploring on its own—trying to decipher the absolute pandemonium of tracks was beyond us. Whatever the circumstances, F109 captured and killed a pup born this year just above the chaos of wolf activity. By this time (November), wolf pups are sizable, their skulls larger than those of coyotes. We discovered the signs of struggle, the telltale blood in the snow, and the pup’s remains beneath a lonely subalpine fir: a pile of coal black fur, bone shards from the legs, and the skull, skinned but completely intact. F109 and her kittens had consumed the pup completely.
Thus far, our research has supported exactly what everyone expected: Wolves dominate mountain lions in most encounters. But, this recent exchange is particularly exciting. No longer can we say that wolves dominate mountain lions in all encounters. What circumstances led to F109 turning the tables, we do not know. Perhaps F109’s predecessors served as naïve intermediaries relearning to coexist with a dominant competitor, a species absent since 1926, when the last wolf was killed in Yellowstone National Park. Perhaps F109 is evidence that lions learn quickly and adapt, and that mountain lions will successfully coexist with wolves in the Yellowstone Ecosystem for generations to come.
Credits: Cat Watch
Mountain lion, cougar, puma, panther, catamount, léon, Puma concolor. These are among the many names used to describe this large, lithe, solitary felid that ranges from southernmost Alaska to the tip of Tierra del Fuego. Concolor means “single color” and is meant to describe the uniform pelage of adult animals. However, those of us who are intimate with real cougars will tell you that their pelage varies from orange-rust to tawny-yellow to slate gray depending upon locale, and that the various hues in a single cat’s coat are too many to count.
The cougar’s coat is an excellent place to begin, for it introduces the subjects of mountain lion natural history, some contradictory literature we might encounter, and some of what we don’t know about this charismatic carnivore. Allen et al. (2011) proposed that the various coat patterns observed in wild felid are strongly correlated with their habitat selection, providing both defensive and tactical camouflage. They concluded that uniformly-colored felids, like the mountain lion, were more associated with open, well-illuminated habitats, and that felids wearing spots and stripes were more associated with complex forests.
Yet, most research on cougars speaks to the contrary. Cougars are called “habitat generalists,” and utilize nearly every habitat stretching across their range. Nevertheless, research in North America has shown that cougars actually avoid open habitats, including deserts and grasslands, and prefer structured habitats like forests. So, we might ask ourselves whether adult cougars should be spotted instead?
Panthera, a US-based nonprofit organization dedicated to wild cat conservation, collaborates with National Geographic on their Big Cat Initiative, a strategic effort designed to aid the world’s most imperiled felids. Panthera’s flagship cougar project is found in northwest Wyoming, and is one of few long-term studies of this amazing species. The Teton Cougar Project was recently host to Steve Winters and Drew Rush, National Geographic photographers on assignment to capture images of wild mountain lions for a recent National Geographic article “Ghost Cats,” penned by Doug Chadwick. For more than a year, the pair of photographers worked with the TCP, and the rewards of their labor can be seen both online and in the December issue of the magazine.
Cougars are “umbrella” species used to identify and preserve wildlife corridors and natural landscapes, as well as keystone species vital to ecosystem health and diversity. Cougars capture the imagination; they are charismatic, controversial and draw attention across communities with polarized views and interests. Thus, cougar research is about communicating with diverse and often opposing demographics, and building bridges between polarized communities in an effort to erase old mythology that drives continuous persecution of this species.
Follow us on Facebook, where we continue to share images and videos of wild mountain lions captured as part of ongoing research efforts. And I’ll be adding updates on our research in future National Geographic blog posts—stay tuned.
Allen WL, Cuthill IC, Scott-Samuel NE, Baddeley R. 2011. Why the leopard got its spots: relating pattern development to ecology in felids. Proc. R. Soc. B 278: 1373-1380.
Credits: Cat Watch