♪♪ Lisbon: What if we could follow animals in the wildest country without actually being there to observe them?

On one special ranch in Montana, we've been working on that approach for 10 years.

[ Elk sniffing ] [ Elk bugles in distance ] We use remote cameras, hundreds of them, all across the rugged backcountry.

Shot by shot, we've been able to witness how an entire wild community interacts.

♪♪ One life in particular has been truly special... ...a young female mountain lion has surprised us over and over.

[ Animal screeches ] Her life is full of danger... ...but also astonishing triumph.

Her name is Willow, and this is her story.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ Lisbon: I started tracking as a boy with my dad and my brother walking through the winter woods.

What really struck me was that there is a story in the snow.

That lit me up.

♪♪ I love the idea that I can piece together a story from what's left behind by the movement of animals on the forest floor when I'm away.

♪♪ ♪♪ ♪♪ This is MPG Ranch... ...over 15,000 acres of privately owned land in western Montana.

We don't actually ranch anything here.

We're more like a research institute... ...and we study everything from soil and plants, to the animals and how they all interact.

♪♪ I'm Joshua Lisbon, and for over a decade now, I've led a very unique mountain-lion study here.

It's unique because we don't handle cats, we don't collar cats, we don't want to disturb them in any way.

♪♪ When we find mountain-lion tracks, we go in the opposite direction.

We backtrack to find out where the cat came from.

That's how we discover their dens and find their kills.

And we also track ourselves, dropping waypoints when we see cat tracks so we can map how mountain lions are using the land.

We collect genetic samples as we go and keep tracker logs of everything we find.

♪♪ But our study is also unique because of all our motion-activated cameras.

♪♪ We've installed an extensive network across the entire ranch.

♪♪ ♪♪ Our goal is to see and not be seen.

♪♪ ♪♪ And the cameras have become our window into a mountain lion's very private world.

♪♪ Hirschauer: My name's Maggie Hirschauer and I've been with the mountain-lion project for three seasons now.

When we walk through the woods, we create these concentric rings around us that kind of call out our presence.

Being able to put cameras in the woods and go back and watch everything that happened in a specific spot is kind of a little miracle.

It's not the same as being there, but it lets you witness things that you could never otherwise see.

♪♪ ♪♪ ♪♪ ♪♪ I installed a camera today on a log that I've seen a fox come out of several times now.

It's a cool spot and I'm anxious to see what other animals I might find in the area.

♪♪ ♪♪ These cameras give us a glimpse into the lives of animals, the way that they interact with each other with different species, but also the way that they interact with the landscape and through time.

♪♪ ♪♪ Lisbon: When we first started putting cameras out, we had no idea that one of the first cats to walk in front of those cameras would allow us, over many years, to document all the moments to piece together her entire, extraordinary life.

In January of 2013, a family of lions took down a mule deer buck on the front side of the property, and this family group, to the best of our knowledge, is where the story for F-2, or Willow, begins.

[ Mountain lion chirping ] We have a mother and two young kittens on this kill, and we start really collecting solid DNA on this family group the following year.

[ Chirping continues ] One of the ways that mountain lions communicate with each other is through these chirping sounds.

[ Mountain lion chirping ] I've only ever heard this between females and their offspring, but they sound like birds.

[ Mountain lion chirping ] ♪♪ The kitten, F-2, came to be known as Willow, because as she grew up, she grew really tall, really thin, and that's how I'm able to pick her out when she shows up on camera.

And so, thinking of her as being willowy, I started calling her Willow.

♪♪ The ranch borders both private and public land where hunting is legal.

The mountain lions wander off our property onto these adjacent lands all the time.

And in the winter of 2014, Willow loses her mother and her sibling to hunters.

♪♪ ♪♪ [ Gunshot ] But Willow survives.

♪♪ We believe that she was still traveling with her mother at this time when she was orphaned.

♪♪ She then moves off the front side of the ranch into the more rugged and steep and secluded areas on the property.

Her first winter on her own.

♪♪ ♪♪ ♪♪ Tyler Carlin's been on the crew for a number of years.

He's amazing.

He puts in the longest days and hikes the longest miles and seems to find the coolest stuff.

So he's been really indispensable to the study for years.

Carlin: Went to Woodchuck 1 today to change cards and batteries in one camera and put up three more on other den sites.

I went to change supplies in the camera in the first den, which is located in the south part of Davis Creek.

Just before I got to the den, I saw pretty fresh bobcat tracks.

When I got to the den, there were tracks of a bobcat entering the den, then leaving it, leaving me to believe the den was empty.

As I was about to start messing with the camera, I heard a noise in the den and a cougar came charging out.

[Bleep] Apparently, there's another way into the den.

Checking the tracks later, the cougar came in from the top of the den.

I adjusted the camera angle for this additional entrance.

Ironically, no large mammals have approached the den from the front since I put the camera up in December, until last night at 6:00, when the bobcat came.

And then there was a cougar sleeping in it today.

Hirschauer: We put cameras on a fox den that we've known to be active.

Foxes will often start to come by the den in midwinter, usually around December, and check it out and mark it.

And eventually, they just seem to post up there and wait for a mate.

They can easily sleep for more than 12 hours at a time while they're waiting.

♪♪ Once they've found each other, they'll spend more time at the den, taking turns sleeping as they excavate and prepare the den for a litter of pups in the spring.

♪♪ ♪♪ Squirrels often continue to live in their nearby nests, even when the foxes are in residence, and they seem to co-exist.

Maybe the foxes even benefit from their vigilance and alarms about other predators.

The squirrel that lives near this den, like all squirrels, has favorite routes through the forest mapped out.

This one always runs up the log that lies to the side of the den.

♪♪ ♪♪ ♪♪ Lisbon: In the summer of 2015... ...Willow breeds with a male, and she has her first kitten in the fall, and her first offspring is F-9, who we call Sula.

The first footage we get of Sula is as a young kitten with her mother on a kill site in January of 2016.

She looks to be probably about 3 months old at this point, so we believe she was born sometime in the October or November range.

We were able to get cameras on a number of kills that had Willow and Sula together at these sites.

Carlin: Went back into the bottom of Davis to try to figure out if the cougars had a kill in there.

I found the kill about 100 yards downstream of the area where I'd seen all the tracks last night.

The dead deer is actually down in the creek, but it was killed on the second road to the north and then dragged there.

At the kill site, there are multiple beds and excessive evidence of play by the young, demonstrated by tracks running up leaning trees and jumping off and broken limbs all over.

I set up two cameras at the site.

♪♪ ♪♪ ♪♪ [ Mountain lion chirps ] ♪♪ ♪♪ ♪♪ ♪♪ Lisbon: Later in 2016, Willow and Sula are still roaming around together.

♪♪ And then, in the fall of 2016, Willow has her second litter.

And their number designations are F-16 through F-19 and so we just collectively called them the teens.

Average dispersal age is 15 months.

To have two litters back-to-back, one fall following the other is not normally how it goes, because suddenly that mother is now in a position where she has newly dependent kittens and a still dependent juvenile.

And so now you have a mixed family group of different ages.

Only two of the teens actually survived that winter, F-17 and F-19.

So Sula is probably about a year old when the new kittens are born.

We started getting this footage out of Davis Creek of this mixed family group together.

We have this really distinctive large ponderosa, and this family group goes past it, and we can see clearly that Sula is following Willow and the teens, and they're all traveling together.

[ Mountain lions chirping ] At this point, we really weren't sure, what the future was going to hold for Sula.

[ Chirping continues ] She was, obviously, very dependent on her mother.

She continued to follow her around even into the next tracking season.

We worried she wouldn't be able to make it on her own and become a successful hunter.

♪♪ Mountain lions are stalk-and-ambush predators.

They're never very far from their prey.

♪♪ ♪♪ ♪♪ ♪♪ Mountain lions are incredibly secretive.

They move through the landscape, generally at a walk, and they move really quietly through the forests.

And they can freeze at any point... ♪♪ ...and then they'll get really, really close to their prey and then close that distance with a burst of speed.

♪♪ ♪♪ Hirschauer: I'd say elk are one of the more spectacular animals out there.

They're highly social and so fast and strong, and their bugles in the fall are one of the most haunting sounds you'll ever hear.

[ Elk bugling ] ♪♪ It's always been amazing to me that mountain lions, not only are capable of killing elk, but that they do so regularly.

[ Elk bugling in distance ] There's a fair bit of risk to a lion in going after prey that bold and powerful, and you'd think that they would just stick to smaller deer.

But adult lions in their prime seem to have no problem killing elk, even bull elk.

And that's a lot of meat, especially if you're feeding dependent young.

Lisbon: We have hundreds of cameras on the landscape that have been collecting imagery for 10 years.

We've caught mountain lions hunting... four times.

♪♪ ♪♪ ♪♪ [ Elk bugling ] ♪♪ ♪♪ ♪♪ ♪♪ Mountain lions end up providing food resources for a lot of things, because mountain lions will be subordinate to a pack of wolves or bears, so they'll run off a kill and leave that and feed everybody else.

[ Bear panting, groaning ] ♪♪ But in terms of fox or coyote or badgers or any smaller creatures coming in, a mountain lion is going to be dominant, and a mountain lion is going to defend that kill.

We see fox coming in and they're -- they're really skittish.

They're they're on high alert.

They'll feed a little bit, and they'll look around, they'll feed a little bit, and they'll look around.

And it's because they're under threat.

♪♪ They know that they're trying to sneak a meal.

You're putting yourself in a risky situation.

♪♪ ♪♪ ♪♪ We have instances of mountain lions running bobcats off kills.

♪♪ We have documented them killing coyotes on multiple occasions, to the point where sometimes I feel like they're out to get them.

And we just last winter documented a mountain lion, uh, killing a badger.

And what we think happened was the badger came in to try to get a meal and was surprised by the mountain lion.

♪♪ Ultimately, all of these animals are inhabiting the same landscape, and they encounter each other frequently.

♪♪ ♪♪ In the fall of 2018, Willow has another litter of kittens.

She uses an area that we call the Mistletoe Den, it's a bed site, really.

They don't spend a lot of time there.

They pass through.

It provides some shelter.

We maintain a camera there year-round, and so we see an incredible amount of animals making use of this spot.

♪♪ ♪♪ ♪♪ We picked this spot out because we get some of the youngest mountain-lion footage that we've had of kittens.

She's the only mountain lion we know of who uses this spot, and she must have a natal den somewhere nearby.

We get this imagery of Willow with two kittens.

We assume she only has two kittens in this litter.

However, it turns out that she may have a lot more.

So not long after that, on a Saturday morning, I get this call from Tyler.

And he is just beside himself excited.

He's like, "Oh, my God.

Oh, my God.

You have got to see what I just got off of this camera."

♪♪ It's February, it's six degrees, it's the middle of the night, there's three feet of snow on the ground... ...and an elk walks into frame with a mountain lion hanging off of its neck, with Willow hanging off of its neck.

♪♪ ♪♪ We have a female mountain lion -- say she's 100 pounds -- taking down a spike bull elk -- we'll say he's 400 pounds... ...and she's wrestling him down by strangling him slowly while this elk is trying to stomp her and kick her and throw her.

If she gets injured, she can potentially not hunt for a while.

If she can't recover, she's done for, and her kittens are done for.

This is incredibly risky, and they do it all the time.

And we happened to catch it on video.

♪♪ ♪♪ And Willow manages to drop this elk directly in front of her den.

As the daylight footage starts to appear, all these little kitten heads are popping up and they've got rounded-out bellies and bloody faces.

And we realize that Willow has six kittens.

And this is -- this is unheard of.

♪♪ ♪♪ The family group feeds on that elk for a week, maybe a little bit more.

What we begin to see is that they're moving between different den sites in the area.

We have these three dens that are really close to each other.

They're less than half a mile apart.

And we see Willow at one point leave the kill site, she goes off on her own to scout one of these other dens... ♪♪ ...and then returns a couple of days after with all of her kittens in tow.

[ Mountain lion chirps ] The average litter size for a mountain lion is one to four, with an average survival rate of one to two individuals.

The fact that we have a mother raising six, whether there is some form of adoption that takes place, or she just has six kittens is unbelievable.

We begin to realize that Willow is moving her young to this other den site and then back and then to another den site and then back, and the kittens will sometimes move independently back to the kill site and then will return to another den.

At different points, we see kittens get left behind for a little while, get picked back up by Mom.

What we're realizing is that the kittens are not as tethered to their mother as you would expect.

They're surprisingly independent, but this has consequences.

[ Mountain lion chirps ] Twice we find kittens get left behind -- one time, for a very short period of time.

The mother returns, picks that kitten back up, and they move on.

♪♪ But, later in the winter, we have this footage of a kitten that's left at a den site for an extended period of time... [ Mountain lion chirping ] ...and goes out and cries for its mother and goes back into the den and comes out and cries for its mother, and does this repeatedly.

[ Mountain lion chirping ] ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ The kitten finally just wanders off... ...and that's where the footage ends.

♪♪ [ Mountain lion chirping ] ♪♪ [ Thunder rumbles ] ♪♪ ♪♪ ♪♪ Hirschauer: Springtime out here is just incredible.

♪♪ Cute baby animals are bumbling around everywhere.

♪♪ ♪♪ ♪♪ After about four weeks, the fox pups first venture above ground.

♪♪ ♪♪ Once the pups are mobile, the male doesn't seem to stick around long, and the female takes over the hunting duties.

She spends a lot of time out hunting, and they are amazing hunters.

Over and over again, she goes out and comes back with meals for the pups.

♪♪ ♪♪ The pups are pretty competitive and voracious when feeding time comes around.

♪♪ The mother can't divide up the meals, and so they learn to be aggressive if they want to eat.

♪♪ ♪♪ Lisbon: We had Willow and the six kittens on camera in February when we first meet them.

We were worried about this abandoned kitten.

Was it lost?

Did it survive?

But then we get really clear imagery again in April.

We see then that the entire group is reunited.

♪♪ The mother must have come by and picked that straggler kitten up.

♪♪ This is a single mother raising six kittens.

♪♪ And then we keep seeing them here and there and here and there through Davis Creek and in different places, and she manages to raise this group to adulthood.

Willow's the only one hunting for this group, and hunting is a dangerous business if you're a mountain lion.

The risks are enormous and it could end her and it could end her family.

And she has to do this consistently to feed this giant family.

♪♪ Male mountain lions don't really contribute to raising and feeding their kittens, and as a result, their story can be harder to piece together.

We seem to lose the territorial male every year in this study to hunting.

Last year we had this really distinctive cat come on to the ranch, M-44.

He's short, he's squat, and his ears look like they were damaged from frostbite.

So, he's very distinctive.

And he stands out.

♪♪ And then later in the spring, he shows up again at a fox den.

And so, we see these kits playing outside just before he comes through... ...and then we actually see the mother fox sitting at the den with the lion in view in the background, and she's barking a warning at it.

[ Fox barking ] ♪♪ ♪♪ ♪♪ Hirschauer: Mountain lions can be a real danger to foxes and especially young foxes.

But M-44, passed by and the next day the foxes were back about their business.

♪♪ ♪♪ Over the course of a season, it's fun to see how the foxes react to the various animals that move through the woods around them.

♪♪ ♪♪ Lions, bears, coyotes, and wolves are all potentially dangerous and you can see the active interest the mother takes when she smells the other predators that have passed by.

It's dangerous for her to leave the pups alone while she hunts, but there's no other way for her to provide the food that they need and that she needs.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ Two of the pups were killed, and another two were not seen again.

The remaining pup only showed eye shine at night in one eye and seems to have lost or damaged the other one.

The lion appears to have been a transient cat that was just passing through.

It covered up the pups like it was caching a food source and returned to pluck fur and feed that evening and the next day.

But then the mother moved the pups bodies and the cat moved on.

♪♪ ♪♪ The mother and remaining pup moved, but the mother came back three more times.

♪♪ Each time she went and looked into the main, den entrance.

Maybe someday we'll have a better idea of what animals think and feel.

♪♪ ♪♪ ♪♪ ♪♪ The following year, about a mile away, we were filming a bobcat.

It had found a dead deer and had been trying to navigate this surly moose with larger predators, to try to get in and scavenge this carcass.

♪♪ And one night, a one-eyed fox showed up on the scene.

It's impossible to say, but I like to think that at least one of those fox pups is still running around these mountains, doing fox things.

♪♪ Lisbon: In the fall of 2019, we found a kill, where a lion had brought down a spike elk in a wallow.

♪♪ And this presented us with a really unique situation, because these mountain lions were not able to get this elk out of the wallow.

They tried, because they don't like to get their feet wet, but they could not do it.

So they're forced to feed in the open, and we had this incredible filming opportunity.

♪♪ ♪♪ We were also able to collect DNA off of that site to determine which individuals were there.

And what we found was Sula... ...Willow's first kitten from five years ago... ...and Sula's three kittens.

♪♪ ♪♪ We also see an unrelated male come in and share this kill with Sula and her family.

For the first time, we have proof of resource sharing with non-related individuals.

♪♪ And this all worked out really well until they were able to drag the kill out of the wallow, consume it a little bit more quickly.

and as the food resource disappeared, we begin to see tolerance diminish between the related and unrelated individual.

♪♪ ♪♪ ♪♪ ♪♪ Never do we see anyone actually follow through with violence.

There's a lot of bluffing, there's a lot of noise, but they work it out, and they still share that kill.

♪♪ ♪♪ ♪♪ The next morning, we see the family group come in.

They're a tight unit, and we have that unrelated individual just removed a little bit.

Everybody's tense and competitive for scraps.

[ Mountain lion snarling ] [ Mountain lion hisses ] ♪♪ [ Mountain lion chirping ] ♪♪ ♪♪ And then we see the family group leave... ...and they go together... ...and a period of time passes... ...and then that lone male follows them down the exact same track.

♪♪ The conventional wisdom is that cats are very solitary and they won't share their food resources, and they're incredibly territorial.

And family members can fight amongst themselves at a kill.

But, ultimately, what we also see is a reciprocal relationship where if I'm successful and you're having no luck, I may share with you, and then that is returned.

[ Mountain lion hisses ] And so these relationships form, and it increases the potential survival for everyone.

We found a spot where a drainage constricts and becomes a prime travel corridor.

It's a favorite ambush spot for mountain lions.

And this year a cat managed to kill an cow elk and her calf.

When we found it, the calf was partially consumed, and the cow elk was cached whole.

The mountain lion at this kill was F-27, one of Willow's giant litter of six from a couple of years before.

We had cameras up on these two kills for many weeks, and one day another adult cat showed up.

It fed for an afternoon, and that night F-27 returned, and they fed in peace together.

They shared the kill through the night, and in the morning, the other cat was gone.

Genetic sampling revealed that cat to be Sula.

So, both cats are the offspring of Willow from litters a few years apart by different males.

We had no prior indication of them having ever encountered each other before, but it seemed pretty clear that our residents are all well aware of each other.

[ Mountain lion hisses ] It's just another example of how complex the social life of mountain lions really is.

[ Wind gusting ] ♪♪ ♪♪ Last winter, we put cameras up at all of Willow's known den sites and she never showed up.

Some other cats stopped by, and they investigated here and there, but we just never saw Willow.

And, yeah, there's something sad about thinking that that story has ended... ...but all things change.

Willow may be gone, but in a very real way, her offspring carry her story forward out here.

They're using the skills that she taught them to survive.

So I like to think of it that her story carries on.

[ Mountain lion chirps ] By any measure, Willow was an extraordinary cat.

It was a privilege to witness her life as we did... ...her amazing hunting skills... ...and her phenomenal success as a mother.

♪♪ And I've come to realize that all the animals out here, passing in front of these cameras, they have their own stories.

We just don't see them.

[ Elk bugling ] But when we can, we realize that they lead lives more complex and vastly richer than we imagine.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ To learn more about what you've seen on this "Nature" program, visit PBS.org.

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