Yellowstone biologists use remote cameras to study wildlife in the park. These strategically placed cameras help to identify and learn about our more secretive wildlife residents, like cougars.
The cougar (Puma concolor), also known as mountain lion, is the one of the largest cats in North America and a top predator native to Greater Yellowstone. (The jaguar, which occurs in New Mexico and Arizona, is larger.) As part of predator-removal campaigns in the early 1900s, cougars and wolves were killed throughout the lower 48 states, including national parks. Wolves (Canis lupus) were eradicated and, although cougars were largely eliminated from Yellowstone, the species survived in the West because of its cryptic nature and preference for rocky, rugged territory where the cats are difficult to track. Eventually the survivors re-established themselves in Yellowstone in the early 1980s, possibly making their way from wilderness areas in central Idaho.
Population
Prior to wolf reintroduction (1987–1993), Yellowstone National Park’s northern range was occupied year-round by an estimated 15 to 22 cougars, including adults, subadults, and kittens. There were 26–42 cougars estimated after wolf establishment (1998–2005). In 2014, a new study began which seeks to estimate population abundance in the same region using noninvasive genetic-survey methods. Biologists estimated between 29 and 45 individuals resided across the northern portion of Yellowstone (all age and sex classes combined) between 2014 and 2017 (Anton 2020). Currently, population estimation is underway using a remote camera survey grid methodology with preliminary results indicating a stable population since 2017. Since 2016, Global Positioning Collars (GPS) are used to study movements, predation, and population monitoring on 4–7 individuals a year.
While disease and starvation are occasional causes of cougar deaths, competition with other cougars or predators, and human hunting (during legal seasons outside protected areas), are the main causes of cougar mortality. Habitat fragmentation and loss are the main long-term threats to cougar populations across the western United States.
Behavior
Cougars live throughout the park in summer, but few people ever see them. The northern range of Yellowstone is prime habitat for cougars because snowfall is light and prey always available. Cougars follow their main prey as they move to higher elevations in summer and lower elevations in the winter.
Adult male cougars are territorial and may kill other adult males in their home range. Male territories may overlap with several females. In non-hunted populations, such as in Yellowstone, the resident adult males living in an area the longest are the dominant males. These males sire most of the litters within a population; males not established in the same area have little opportunity for breeding.
Although cougars may breed and have kittens at any time of year, most populations have a peak breeding and birthing season. In Yellowstone, males and females breed primarily from February through May. Males and females without kittens search for one another by moving throughout their home ranges and communicating through visual and scent markers called scrapes. A female’s scrape conveys her reproductive status. A male’s scrape advertises his presence to females and warns other males that an area is occupied. After breeding, the males leave the female.
In Yellowstone, most kittens are born June through September. Female cougars den in a secure area with ample rock and/or vegetative cover. Kittens are about one pound at birth and gain about one pound per week for the first 8–10 weeks. During this time, they remain at the den while the mother makes short hunting trips and then returns to nurse her kittens. When the kittens are 8– 10 weeks old, the female begins to hunt over a larger area. After making a kill, she moves the kittens to the kill. Before hunting again, she stashes the kittens. Kittens are rarely involved in killing until after their first year.
Most kittens leave their area of birth at 14 to 18 months of age. Approximately 99% of young males disperse 50 to 400 miles; about 70–80% of young females disperse 20 to 150 miles. The remaining proportion of males and females establish living areas near where they were born. Therefore, most resident adult males in Yellowstone are immigrants from other areas, thus maintaining genetic variability across a wide geographic area.
In Yellowstone, cougars prey upon elk (mostly calves) and deer. They stalk the animal then attack, aiming for the animal’s back and killing it with a bite to the base of the skull or the throat area.
A cougar eats until full, then caches the carcass for later meals. Cougars spend an average of 3–4 days consuming an elk or deer and 4–5 days hunting for the next meal. Cougars catch other animals—including red squirrels, porcupines, marmots, grouse, and moose—if the opportunity arises.
Cougars are solitary hunters who face competition for their kills from other large mammals. Even though a cached carcass is harder to detect, scavengers and competitors such as bears and wolves sometimes find it. In Yellowstone, black and grizzly bears will take over a cougar’s kill. Coyotes will try, but can be killed by the cougar instead. Wolves displace cougars from approximately 6% of their elk carcasses.
Although cougars and wolves once co-existed across much of their historical range, ecological research on each species has often had to be conducted in the absence of the other. By assessing pre- and post-wolf reintroduction data, biologists can learn about the ecological relationships between the two species. As social animals, wolves use different hunting techniques than the solitary cougar, but the two species prey on similar animals. While prey is abundant this competition is of little concern, but, a decrease in prey abundance could lead to an increase in competition between these carnivores.
Species composition of cougar-killed prey, including primary ungulate prey species and other prey across three research phases (phase I: 1987–1993; phase II: 1998–2004; and phase III: 2014–2019; sample sizes of kills detected are indicated in parentheses). xoxo
History
In the early 1900s, cougars were killed as part of predator control in the park and largely eradicated along with wolves in the 1930s. However, cougars naturally recolonized by the early 1980s.
From 1987 to 1996, the first cougar ecology study was conducted in Yellowstone National Park. The research documented population dynamics of cougars in the northern Yellowstone ecosystem inside and outside the park boundary, determined home ranges and habitat requirements, and assessed the role of cougars as a predator. Of the 88 cougars that were captured, 80 were radio-collared.
From 1998 to 2006, the second phase of that research was conducted. Researchers monitored 83 radio-collared cougars, including 50 kittens in 24 litters. Between 1998 and 2005, researchers documented 473 known or probable cougar kills. Elk comprised 74%: 52% calves, 36% cows, 9% bulls, 3% unknown sex or age. Cougars killed about one elk or deer every 9.4 days and spent almost 4 days at each kill. The study also documented that wolves interfered with or scavenged more than 22% of the cougar-killed ungulates. The monitoring associated with this project has been completed and all of the radio-collars have been removed, but years of data are still being analyzed. New research is underway to evaluate population abundance, predation patterns, and competition with other carnivores.
Very few cougar–human confrontations have occurred in Yellowstone. However, observations of cougars, particularly those close to areas of human use or residence, should be reported.
Cougar M198
Last January, one of Yellowstone's marked mountain lions went missing. Scientists traveled deep into the park to investigate. And that journey? It wasn't as straightforward as they thought it would be.
Music by Chad Crouch, Victrola Dog/Podington Bear Music
Dan Stahler: Test Test 1-2-3…OK we are live Narrator: This is Dan Stahler. And—I swear—Dan Stahler practically has fur in his blood. He studies wolves and elk…He’s the endangered species coordinator for Yellowstone National Park. And he’s the project lead for Yellowstone’s research on mountain lions—also called pumas or cougars—And last year, Dan and his team had a cougar mystery to solve. Dan Stahler: All right, Good Morning. It’s January 28th. Dan Stahler, Colby Anton, Nathan Varley heading on in to the Black Canyon of the Yellowstone to go investigate on our only cougar collared right now, M198. He’s a 3-year-old male. We’re gonna go check it out and see what we see. Narrator: First, a little background here on M198. The M stands for male and 198 is his identifying number. M198’s collar that Dan was talking about is very high tech. Dan Stahler: sort of FitBits if you will for cougars One of the things those collars can do is communicate with a satellite system to record the cat’s location on the landscape every 3 hours. Dan could log in on a computer, look at all those location points and see where M198 had been. Dan Stahler: We used those points to identify clusters on the landscape where he spent time. Then usually about a week after he was in that area we would go investigate. Narrator: Investigating the places where cougars have spent time turns out to be incredibly valuable. And it’s a little like a crime scene investigation that you see on TV. Dan and his team can comb the area for DNA, like hair and scat, to help identify individual cats … like how many are out there and who’s who. This non-invasive technique of getting at the demographics of a cougar population is a powerful tool for studying such secretive animals. Or, let’s say a cougar made a kill in that spot. And if so, was it a deer or an elk or a marmot… how old was the animal… was it healthy…how many animals did the cougar kill over a given period of time… these things tell scientists a lot about the food habits of cougars like M198 AND what their impacts might be on populations of prey species like deer or elk. Dan Stahler: We found where he’d killed an adult cow elk. It was the only animal he fed on for 20-some odd days. And that’s kinda typical of a male cougar. They can go a long time without feeding. They’ll make a kill, feed on it, then do their other cougar things and roam around. If the cat stops roaming around – if it stops moving altogether, then the collar sends Dan an alert. For M198, that alert meant that either the collar came off somehow, or it stopped moving because M198 was probably dead. And Dan and Colby and Nathan needed to figure that out. The problem was that the collar suddenly stopped transmitting GPS locations. So finding it was going to take a little work. Dan Stahler: Colby, it’s too bad we don’t have a more recent track on him, Colby. He’s either down low or he’s tucked in a rock in the boulder field which let’s hope isn’t the case. Who knows Colby, we might get lucky. Narrator: Let’s just say that they didn’t get lucky. M198 had made his way into what Dan calls the Promontory. It’s a gnarly boulder field with rocks the size of cars. Dan Stahler: There are lots of places a kitty could tuck away up here. Narrator: This explains why Dan and his team were unable to get GPS coordinates from M198’s collar. There was no way a collar could communicate with the satellites in outer space through that huge pile of rocks. But those collars also come equipped with radio telemetry. And because the radio beacon transmits its signal directly to Dan’s handheld receiver, he could use THAT to zero in on M198. And the way that works: The closer Dan gets to the collar, the louder the blips -- the radio signal. Dan Stahler: OK we’re getting closer guys. Dan Stahler: It’s kind of a fun process because you try to read the signal but think about what the cat would do—how he would move through here. I don’t know they ARE cats. They do amazing things. It would be nothing for him to bounce through this boulder field, but you’d think he’d take a path that would be a little easier on him. Dan Stahler: OK I think I see some blood up ahead. I don’t know for sure. Yeah….I see where birds or something pecked at blood in the snow. Dan Stahler: Lot of tracks. He’s in there somewhere. Clicking in real nice on the telemetry now. It’s interesting. Something dramatic went on here. Because there’s blood all over the rocks…look at the stain on that lichen right there…there’s a bunch of cat hair stuck to the rock…. Dan Stahler: Wow. There’s caves all over the place in here….Wow. There’s blood way down. Holy smokes. Hey might be WAY down in here guys. Dan Stahler: Uh this is a pretty…well…(grunting)…a little spelunking! I didn’t think I’d be doing THIS today. Dan Stahler: Let’s hope he’s dead and not a wounded cat that’s not happy to see me. Narrator: Twenty feet under the earth, tracking a bloody cat, Dan and Nathat started to piece together a story of what might have happened to M198. Nathan Varley (talking to Dan): Did he get pinned in there by a bigger cat? Dan Stahler: Yeah bigger cat, maybe… Nathan Varley: …and they’re fighting…that’s nasty. Dan Stahler: That’s how toms die often. Nathan Varley: Lions are lions. They’re just so powerful Dan Stahler: And you know he’s a 3-year-old tom and was probably trying to establish himself in here and all it takes is one bigger tom to say nuh-uh. Dan Stahler: We’ll know. You know they crunch the skull… Nathan Varley: Oh wow. Brutal. Dan Stahler: …when they kill each other. I think we’ll see it in his head. Dan Stahler: Well, you know, he has an accelerometer collar. So we can look at the activity. We can look at the movements... We might even see signs of a chase taking place somewhere else once we get the data back from it. Nathan Varley: So like, ‘he ran over here and this is where the other cat caught up to him and pinned him in the rocks…” Dan Stahler: Mmmm Hmmmm Nathan Varley: That’d be pretty interesting, wouldn’t it? Dan Stahler: Yup Nathan Varley: That’d be really interesting…How ‘bout that? Dan Stahler: Yeah, like, what are the energetics of a cougar fight? Narrator: OK this is where the idea of the cougar FitBit really comes in. Scientists can use the information from accelerometer collars to understand a lot more about animal behavior and energetics – basically, how much energy it takes for an animal to live its life. This is pretty cutting edge stuff. Dan Stahler: So, our ability to study carnivores like cougars is changing all the time. We take advantage of new technologies that become available…And those of us who have iPhones or FitBits or any activity exercise monitoring machine, may have heard the term accelerometer because they’re all built to these devices. These collars have built in accelerometers that continuously measure the 3-D axis--the neck position--of the cat wearing the collar. So when the animal is walking or resting or pouncing on prey it will record a specific type of activity pattern This data has been calibrated with captive animals--captive cougars--wearing collars on a treadmill, jumping and pouncing on a training course … measuring how much oxygen they’re consuming and that translates to calories burned… Narrator: Calories in. Calories burned. This is the basis of energetics. Dan is collaborating with Colby Anton, a PhD candidate at UC Santa Cruz, on the energetics research. Dan says they will be able to link the data from the captive cougars to the wild cougars in Yellowstone. And biologists in the park have these same collars on wolves. Dan Stahler: …so we can compare the energetics of a stalking carnivore that lives mostly by itself – the cougar – compared to a group-living carnivore that chases after its prey – the wolf – and can see different patterns in their energetics that may have been shaped through evolution, might be shaped by current environmental conditions Narrator: Understanding how these animals respond to environmental conditions, how they survive…what they eat…where they go…how they affect each other and their prey… All of this goes beyond just understanding cougars or wolves. Dan Stahler: It’s really about understanding how the ecosystem works. I think those of us who work with these animals don’t think of ourselves as a wolf biologist or an elk biologist or a cougar biologist. We’re ecologists trying to understand the pieces that make this ecosystem function the way it does. Really, what we’re trying to do is understand Yellowstone—it’s importance to the world, its importance to science …to nature—through the lens of wolves and cougars and elk. So these collars have opened up that world in a much more accurate way. Narrator: And because they want to interfere with the lives of wild cougars as little as possible, Dan and Colby only fit a couple of cats with those collars. Which made M198’s even more important to get back. Dan Stahler: OK, hey I’m gonna listen to the telemetry. Dan Stahler: It’s 12:07. Don’t tell me that beacon turned off. Dan Stahler: That should not have shut off…(sighs) I don’t hear it Colby… Narrator: Despite continuing the search through the caverns without the signal, Dan and Colby and Nathan could not. Find. The cat. Dan Stahler: That pisses me off…. I hate leaving here without this cat and knowing the end of this story. ¬ Dan Stahler: Damn it, Colby . Colby Anton: beacon. Dan Stahler: Pffft…Another typical day in wildlife biology. Narrator: I think most scientists will tell you that dealing with frustration and overcoming setbacks is something scientists get comfortable with pretty quickly. In fact Dan tells me that a few days later, they were back in that boulder field. Dan Stahler: …and that’s what we did we went back into the area and it was another frustrating search… < “It’s so interesting, we’re at the site but we can’t quite find him” sounds of effort, rocks sliding, Dan in the field saying “that’s just me moving some rock”> …And then there was one little spot where I noticed some hair stuck to the top of the rock a little bit of blood and it was just another little slit I the rock that I wasn’t able to catch before… Dan Stahler: …I squeezed through it… Dan Stahler: …and I looked down with the headlamp and… Dan Stahler: Definitely not moving. (Sighs) Here he is. Aww. 198. Damn it. So, here I am down in the lions den with 198. He is dead. He’s lying on his side. Blood all over him. Hard to say what happened here but it does look like he’s been attacked. Wow. He must have been beat up pretty good to come down here like that. Bummer. Hard to loose a cat like that. He was the 1st one of the study—but certainly we’ll learn something about him from this event, too (sighs). Narrator: M198 the very first Yellowstone cougar to contribute accelerometer data to the study. But maybe what’s even cooler, is that he is one of only two wild cougars in the world to have his entire genome sequenced. And this has implications for big cat research worldwide. Narrator: Back in his office, Dan talked about the death of M198. The necropsy revealed the cat was indeed killed by another cougar. Narrator off mic: And he was your first… Dan Stahler: It was very discouraging. But at the same time, you know, you appreciate the wildness of Yellowstone and the lives these animals live … …There are relatively few places where you can understand how all these carnivores coexist, compete, interact, and what those impacts may be on prey, scavengers or each other… Narrator: And you know, Yellowstone is pretty special that way. Thanks to focused efforts of native species restoration, the park is more carnivore-rich today than it’s been in over 100 years. Dan says that ecologically, this is great news because carnivores like cougars have a critical role to play. Dan Stahler: Cougars, like other top carnivores through the act of predation, which is a powerful ecological force, they have the capacity to shape and structure ecosystems. Narrator: But from a human-dimensions standpoint, things are still a little thorny when it comes to these top predators. Dan Stahler: If you look at carnivores in particular they have a long history of persecution… Narrator off mic: Where do you think that comes from? Dan Stahler: We have a long evolutionary history with carnivores. Our ancestors competed with them for space, for food…And so it’s probably very much built in to our brains…and it’s hard to shed that baggage that was probably shaped over eons of time…But even today there are still challenges living with carnivores. If you raise livestock, carnivores can be a threat to your way of life. If you’re a hunter, you might find that carnivores compete with you for areas on the landscape that you like to hunt. And for others, they embrace the fact that we live in a place today where we can hunt and recreate and still be in a place where there are carnivores. I certainly feel that way living here at the gateway to Yellowstone in Gardiner MT. It’s a privilege to be able to live in a place where we have so much… Narrator: It’s a place where natural processes--like a cougar fight to the death--still play out. And although it was hard to lose him, the ghost of M198 lives on – inside the larger context of what we know about cougars in Yellowstone. M198 had a story to tell. But there are other cats on this landscape and they have their own stories. Dan Stahler: We just finished picking up M198 and we have tracks on at least mom and one or two probably big kittens or yearlings…and we’re looking in the snow here and you can see here where the young ones were romping and chasing each other. Colby found a good bed site over here so he’s taking his forceps and collecting the hairs and putting them in a sample envelope hoping we get some follicles on the hair for genotyping the DNA of one of these little buggers. Dan Stahler: So we’re just leaving the site where Colby got some hairs and lo and behold a nice fresh scat…one of the yearlings, probably…they were goofing around in here…. Dan Stahler: Another quality DNA sample…we’ll collect this too. Narrator: For Yellowstone National Park, I’m Jennifer Jerrett.
Integrating snow-tracking surveys, DNA samples collected from hair, scat, and blood left by cougar, statistical modeling, GPS collars, and remote cameras are tools wildlife biologists like Dan Stahler use to estimate cougar population sizes in Yellowstone. GPS collars also are used to study predation patterns and interactions with other species. This video offers a glimpse into the work that goes into collaring a cougar.
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