♪♪♪ NARRATOR: Ninety percent of the Earth's land mass is home to a creature so tenacious, yet so adorable that it rarely gets the respect it deserves.
There are over 100 kinds of domestic and wild rabbits and hares.
Their territories stretch from the Rocky Mountains to the deserts of Arizona.
From downtown Chicago to the northern reaches of Canada's frozen boreal forest.
And scientists are making some astounding discoveries about these often overlooked creatures.
BOONSTRA: The young bear that signature, these ghosts of predators past, in their biology.
NARRATOR: We take you deep into their changing world... SILVER: I just sent one child off to college.
This is like going off to college for rabbits.
NARRATOR: ...to experience the secret lives of rabbits and hares.
♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ NARRATOR: They live alongside us but a world apart.
They share our yards, and our neighborhoods, yet they remain a bit of a mystery.
We know so little about rabbits and hares that most of us couldn't tell them apart unless we saw them side by side.
Hares are substantially larger and have much longer legs and ears than rabbits.
Born in a nest, hairless and helpless, rabbits meet the world with their eyes and ears closed.
Even two weeks after birth, baby rabbits are still completely dependent on their mother.
Whereas hares are born right on the ground with their eyes wide open and a full coat of fur.
Unlike their defenseless cousins, baby hares, called leverets, are ready to run an hour after being born.
There are 31 different species of wild rabbits, and they are all so very different, with each species uniquely specialized to their habitat.
♪♪♪ Eastern cottontails are one of the most common rabbits on the planet -- so common that we rarely give them a second look.
But they have some remarkable talents and surprising behaviors that if we took the time to observe would amaze us.
As the sun goes down and the crowds disperse, eastern cottontails leave their daytime hiding places and come together for a common but rarely seen mating ritual called cavorting.
And cavorting is not for the faint of heart.
It's a full-body workout that involves Olympic-worthy high jumps, sexy moves and, above all, stamina.
First, the male locks eyes on his would-be mate, and sniffs the air to see if she might be receptive.
And then the dance begins.
With a quick hop into position they face off, followed by 'the rush,' where the male runs as fast as he can towards the female in an attempt to communicate his romantic intentions.
She jumps straight up in the air as he runs beneath her.
DYLAN: ♪ No, and I ain't lookin' to fight with you ♪ ♪ Frighten you or uptighten you ♪ ♪ Drag you down or drain you down ♪ ♪ Chain you down or bring you down ♪ ♪ All I really want to do ♪ ♪ Is, baby, be friends with you ♪ ♪♪♪ NARRATOR: If she's just not in to him, he tries dashing straight at her.
A risky move as she can now kick or bite him to tell him to back off, buddy.
The male often gives her a good sprits of urine as he passes, hoping to entice her into the dance.
But this can have the opposite effect, causing her to get even more aggressive.
♪♪♪ But if she is interested, the jump steps repeat faster and the leaps get higher.
The longer the dance goes on, the closer the female is to being ready to mate.
These rabbits are amazing athletes, but when it comes to fancy footwork, they've got nothing on their desert-dwelling cousins.
♪♪♪ ♪♪♪ When most of us think about rabbits and hares, we conjure up images of small helpless creatures that are merely an easy meal for a predator.
But they are so much more than that.
♪♪♪ Weighing in at over 9 pounds and standing almost 2 feet high, these are antelope jackrabbits.
Despite their name they are in fact hares, not rabbits.
Hares are much larger, and unlike rabbits who are relatively solitary creatures that only get together for mating, these antelope jackrabbits are known to gather in small groups to feed out in the open on cacti, mesquite leaves and grass.
Antelope jackrabbits are one of the largest hares in North America, and they're perfectly designed for their dry desert environment.
Their fur is highly reflective and insulated to help them deal with the harsh desert sun.
And the extensive network of blood vessels in their ears act as heat exchangers, shedding excess heat in climates that can easily reach over 105 degrees.
With big eyes placed on the upper part of their head, they are able to see predators coming from all directions, and their extraordinarily long ears can pick up sounds from 2 miles away.
Especially the high-pitched cry of a hawk.
Given the long spikes on nearly every plant in their habitat, a hare can often find a safe place to hide from aerial predators.
But these are no ordinary hawks.
They're Harris's hawks, the only raptors to hunt cooperatively in packs.
And each new member that joins the group raises the pack's chances of hunting success by 10%, leaving an antelope jackrabbit at a sizeable disadvantage.
♪♪♪ The group has sent out a scout to search for dinner.
When she spots suitable prey the signal goes out.
♪♪♪ And the birds move into hunting formation.
♪♪♪ ♪♪♪ The scout chases down the prey while her fellow birds flank her on the left and right to track it.
♪♪♪ ♪♪♪ No easy task because these hares are built for speed.
They can cover 20 feet in a single bound and clock in at over 45 miles an hour.
In this hot, prickly environment running full out is risky business.
But they have specially designed hind feet that allow them to zig and zag to evade predators.
They are so fast, and so nimble, it would be an incredible challenge for a single hawk to hunt one by herself.
So, acting like a relay team, the hawks pass the lead to each other to keep the pressure on as the hare tries to evade them, only to simultaneously converge on it from multiple directions, cutting off any escape.
♪♪♪ Sensing the trap, the hare dives under cover, hoping to wait out the danger.
♪♪♪ But the hawks have seen this play before.
Time to move to Plan B.
♪♪♪ One of them takes to the ground to flush the hare out into the open as the rest of the pack looks on.
♪♪♪ ♪♪♪ ♪♪♪ Running it right into the sweet spot.
♪♪♪ One wrong turn, one false step can spell the end.
♪♪♪ Even for an animal as formidable as an antelope jackrabbit.
♪♪♪ Predators are part of the natural cycle of life in the wild.
But native rabbits and hares are facing an even greater threat.
Habitat loss is bringing some native species to the brink of extinction.
♪♪♪ Native rabbits, like this New England cottontail, have become so rare that an entire team of biologists is working to try to stop their disappearance from the landscape.
SILVER: People would be surprised at how much work it takes to raise each individual rabbit.
You know, people are used to the idea that rabbits breed really easily.
They do breed easily, but they're also very fragile.
They need very specific conditions.
They're very shy. They need a lot of quiet.
They need a lot of benign neglect.
To date, we've bred, between the Roger Williams Park Zoo and the Queens Zoo, about 150 to not quite 200 rabbits over the course of six years.
So, every rabbit that we raise and that we release back into the wild is a potential ancestor for many, many more rabbits coming up into the future, so each one is really important to us.
NARRATOR: Today, a new batch of young rabbits that have only known life in captivity, are going on a journey that will change the course of their lives, and potentially their species, forever.
SILVER: Their world's about to change dramatically.
You know, I just sent one child off to college.
This is like going off to college for rabbits.
It's an extreme change.
NARRATOR: Like many wild rabbits, eastern cottontails are landscape specialists.
With their limited peripheral vision, they are most comfortable in a shrub thicket habitat.
SILVER: Over the last couple of decades the places where you find these rabbits has been reduced by as much as 85%. NARRATOR: Tens of millions of dollars are being spent to re-introduce New England cottontails back into their traditional stomping grounds between Maine and New York.
PERROTTI: Reality check is we have not found one in Rhode Island since 2006.
So we think they might be eradicated from Rhode Island.
Let's see here.
Let's check the ear tag, make sure it's one that's going to go.
I would be very, very afraid that if we did stop these efforts in the captive breeding and the reintroduction efforts that we could possibly lose the New England cottontail from our ecosystems.
That one's going.
NARRATOR: For over a thousand years, these native rabbits have been playing a vital role dispersing seeds and eating grasses and native plants so their disappearance has wide-ranging effects on the ecosystem.
PERROTTI: I like to look at nature like a bicycle wheel, right.
You get this brand new bike wheel out of the box, all of its spokes nice and tight and true.
Yeah, we could pull maybe one or two spokes out and that wheel might start to wobble.
We take too many out and the wheel is going to collapse.
This rabbit is one of those spokes in the New England wheel.
So we want to make sure that they're all intact.
You're not going to be in Kansas anymore, Dorothy.
They're not going to have the pampering care that our zookeepers give them every day.
They won't have their greens handed to them.
They're going to have to forage on their own.
That's when their life really changes, because now they have to evade predators, and, you know, be little rabbits.
♪♪♪ HOLMAN: When I pick up the rabbits, it's very quiet in the car.
And I'm listening to hear how active the rabbits are.
I'm curious if they're feisty, feeling ready to hit the ground running.
Because we don't know exactly how well they're going to do.
The 10 rabbits that we have in this car are a big percentage of the future and the success of the goals in New Hampshire and Maine, specifically, because we need rabbits to augment new habitat we've created.
♪♪♪ NARRATOR: It's now time for these young New England cottontails to be released into specially designed pens.
They'll stay here for a few weeks to give them a chance to learn about their world.
HOLMAN: You always want to turn off the electric before you approach the pen and go in.
We use it to keep the predators out.
We also have this metal flashing that's smooth, and that's to prevent animals that can climb up from getting any grip, and so they have to slide down.
NARRATOR: The pen may protect them from ground predators, but this is a training ground, so they are still exposed to threats from above.
♪♪♪ This is the moment of truth.
These young rabbits are finally going to get their first taste of life in the wild.
♪♪♪ ♪♪♪ There is so much to take in.
Their super sensitive noses twitch up to 120 times a second as they inhale a smorgasbord of new smells, and their ears act like satellite dishes tuning in a symphony of new sounds.
♪♪♪ HOLMAN: They're really uncertain about how to move, that they can move.
♪♪♪ It's very exciting when they finally start testing the waters and actually realize like, oh, I can jump out and go free.
Look what I can do, look, I can hop and I can bound. It's actually really exciting.
♪♪♪ NARRATOR: Our hidden cameras take you deep under cover to witness these naive rabbits' first brave hours in their new world.
♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ As night descends, their world shifts once again.
To survive, they need to learn to escape predators who see in the dark.
♪♪♪ ♪♪♪ ♪♪♪ Lucky for them, the thick vegetation of their preferred habitat offers protection from many that would harm them.
♪♪♪ HOLMAN: I'm really drawn to the hard-luck cases.
I'm an optimistic person, which I think is really critical for a species like this that requires so much stewardship by an entire community of people, and it's going to take time for us to be successful, and you need to celebrate the small successes and be able to continue on.
NARRATOR: This is but one of many species of native rabbits struggling to survive because it requires such a particular landscape.
But for another kind of rabbit, being able to survive in a highly specialized landscape may be its salvation.
♪♪♪ ♪♪♪ ♪♪♪ Deep in the swamps of Missouri, the mud and moisture combine to create an ideal habitat for stranger things.
♪♪♪ ♪♪♪ This is a place where the swamp creatures are so secretive they rarely get a glimpse even of each other.
♪♪♪ In this bizarre environment, it's surprising to find rabbits.
But these aren't any old bunnies.
♪♪♪ These are swamp rabbits, a unique species that is the largest cottontail on the planet.
And these animals have an incredible super power.
♪♪♪ ♪♪♪ ♪♪♪ Their size gives them increased buoyancy and musculature to be great swimmers.
They are so comfortable in the water that they easily move about flood plains and swamps to evade predators, find food and mates.
♪♪♪ Swamp rabbits are shy creatures.
In fact, so little is known about them that this is the first time they have ever been filmed swimming.
♪♪♪ Unlike other native rabbits whose populations are on the decline, these guys are faring much better.
♪♪♪ And as long as there is a swamp or waterway open, they can bunny paddle their way to new territory up and down the Mississippi Valley.
♪♪♪ ♪♪♪ And once they hit land, they're just as impressive.
♪♪♪ They leap more like deer than rabbits.
They are the iron men of the rabbit world.
♪♪♪ Rabbits and hares, by their very nature, have some astonishing abilities that allow them to exploit the ever-changing world in ways that few others can.
Thousands of miles away, archaeologists are making some groundbreaking discoveries that could change the way we think about rabbits.
♪♪♪ The story of not just one animal's life but the history of an entire species can be deciphered from rabbit bones likes these.
♪♪♪ Archaeologists are only now beginning to realize how rich a find this is and how it can foretell the future for native rabbits and hares.
♪♪♪ HART: When I look at the face of this rock shelter, I look for white streaks like this because this is bird poop, and I know that birds have been sitting on these perches for thousands of years, eating their prey and dropping bones like this down below.
Abrigo de los Escorpiones, the Shelter of the Scorpions, is a really unique site not just for Baja or even for North America but globally because it's one of the richest deposits of animal bones, anywhere in the world, for the past 10,000 years.
NARRATOR: Thousands of years ago, the rabbit and hare population declined dramatically throughout a vast expanse of western North America.
But not at this site.
HART: When we looked at this deposit, we were expecting to see that same decline, and instead what we saw was the rabbit and hare population exploded.
And I was very surprised by that, and when I compared the rabbit and hare population to El Niño frequency over the past 10,000 years, there was a really close match, and I got really excited.
I was like, 'Oh, my gosh, we just found a link between El Niño and rabbits.'
This is the first time anybody's seen any link between a major climatic phenomenon anywhere in the world and any vertebrate population, anywhere.
NARRATOR: Rabbits and hares are uniquely qualified to take advantage of changing global weather patterns like El Niño.
The influx of rainwater stimulates a dramatic increase in vegetation, meaning more food for hungry rabbits and hares.
HART: Their gestation times are very short, and they can respond really quickly, to any burst of vegetative growth.
And so their population can really explode fast.
A lot faster than, you know, some of the bigger animals that are found around here.
One kind of silver lining on the cloud of climate change is even though El Niño can have drastic effects on roads and dams and all sorts of other infrastructure, the influx of water and vegetation does a lot of good for a lot of animal species like rabbits and hares.
NARRATOR: Some of the bones in this graveyard undoubtedly came from domesticated rabbits as well as wild because humans began breeding rabbits as pets as early the 1800s.
Ever since, rabbits have been specifically bred for their gentle companionship and cherished for their beauty.
♪♪♪ ♪♪♪ ♪♪♪ Once a year, rabbits from all over North America and as far away as Japan are brought together to compete for the coveted title of Best in Show.
♪♪♪ STEWART: Individuals who say that a rabbit is a rabbit is a rabbit, they haven't been to an American Rabbit Breeders' Association rabbit show.
We have 49 different breeds with hundreds of combinations of color varieties.
Each breed is unique, so you look at everything from a Flemish giant that weighs 25 pounds to a 2-pound Netherland dwarf.
It's just the difference between a Great Dane and a Chihuahua.
There's something for everyone.
NARRATOR: Over 3,000 people and 17,000 rabbits have come to this convention, a kind of Westminster Dog Show for the rabbit set.
And they've all come to compete.
MALDONADO: I think my competition is stiff.
You know, I have Opie here, who is -- he's been doing great.
He's had a phenomenal year. His dad is the number one French lop in the country this year.
So he's got a pretty good chance of holding his own.
COLEMAN: So this is a Tan.
What I really like about these guys is they're more rambunctious than a lot of other rabbits.
I don't like a lot of rabbits that are like, Oh, I'll just sit here and do my thing, you know.
The Tans are like, I'm my own kind of unique special, and I do what I want when I want it, and you're not going to tell me otherwise.
STEWART: The English angoras, they are the vision of opulence.
They're covered, they're dripping with the tassels, the face, and a lot of times people say they look like the tribbles off of 'Star Trek.'
CHU: Yeah, it's important to have a pretty face like this one.
So the most important thing for an English angora is to have a very round body, a very good density.
It does not have a 'wow' factor if the coat is not as long as, say, 10 inches.
ADAMS: I got my first rabbit when I was in 5th grade, and I just fell in love.
This is a blue tort English lop, and he's about five months old, and they're just a great breed.
They're a bigger breed, but they kind of act like a puppy.
So they have a great personality, and just really good with kids.
NARRATOR: It's all well and good that you like your rabbit, but when it comes to a competition, it's what the judge thinks that's important.
JUDGE: ...those ears, about that shape.
Got a good start on that head, though, nice structure to the skull.
MAN: Got pretty good bone.
JUDGE: Very nice midsection.
JUDGE #2: Nice quality to that coat.
He has beautiful ears, beautifully rounded at the tips, could use just a little bit better substance to them though.
NARRATOR: 49 breeds of rabbits are assessed by different judges over the course of a very busy week.
The judges have their work cut out from them because some classes have over 2,000 different rabbits competing against each other to win best in breed.
ADAMS: It's very stressful knowing that there's that many rabbits to compete against.
You know, because you work all year for this.
I get very anxious on show day, just because there's a lot that goes into it.
When I watch the judge judge the rabbit I really look to see any, like, eyebrow raise, or you know, that 'oh' moment in their head, you know.
Just that little move of their head or something like that is how I'm like, 'Well, it's going to be good or it's going to be really bad.'
JUDGE: Okay, I've got a senior doe here.
Has good width to the ears, could use a little bit more length to the ears, I'd like to see them a little bit more spoon shaped, a little thicker at the tips.
Has good width to the shoulders, but peaks too far forward, slopes off on the hind and you get square and angular at the back of the hip.
Has good flesh condition, has decent coat condition, very nice color.
ADAMS: That was fast.
NARRATOR: In the end, Kyle and his rabbit came in third.
A good placing, but not enough to take them to the final show.
♪♪♪ TRESENRITER: The rabbit community is huge.
You may not know those people are there, but they are, and for events like this, the national convention, they come out of hiding for it.
NARRATOR: All the primping and preening, the blow drying and nerves have been leading to this, the pinnacle event of the convention -- Best in Show.
These judges must now evaluate all 49 of the best in breed winners.
It's a bit like comparing apples to oranges.
♪♪♪ But soon the field of 49 will get whittled down to just one rabbit.
SMITH: That would be like winning the Academy Award.
For rabbit breeders, that's the ultimate.
That is the ultimate award.
You join a club. You're part of history forever.
ANNOUNCER: Now we need to announce the best in show winner.
So the best in show open rabbit 2018 ARBA convention is the Silver Marten.
[ Applause ] STEWART: And when you've got 17 to 25,000 animals, you know, in the show, to be the one best in show winning animal, that's amazing.
Very few individuals have ever accomplished it.
♪♪♪ NARRATOR: For most of us, our love of rabbits began with fairy tales and childhood storybooks like 'Alice in Wonderland.'
♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ As Alice discovered, rabbits like this little guy can innocently travel down the rabbit hole and be magically transformed.
♪♪♪ EDWARDS: This is Grace.
She's a continental giant, and Grace is nine months old.
She'll grow quite a bit more.
They just grow at such a fast pace.
From six weeks, they're sort of this big, and they just get bigger and bigger and bigger.
And they don't stop until they're 18 months old.
Come on then, darling.
Let's move you along.
I'd like to think that it's a bit of an Alice in Wonderland.
I think that they're very special.
They're a lovely creature.
Very gentle, and these guys behave more like dogs than rabbits.
NARRATOR: Meet Darius, the longest rabbit in the world.
These rabbits of unusual size can take some getting used to.
EDWARDS: When they arrived, my family looked at them and said, 'Have you gone completely mad?'
And I said no. I said, 'I just think they're amazing.'
They're so tremendous.
You go over there.
The Continental Giant is the biggest rabbit you can ever get.
There are Continental Giants that aren't so big.
It's just that ours seem to be enormous.
NARRATOR: And Annette's rabbits are World Champions.
They've held the Guinness World Record four times, and Darius is still the world's reigning giant.
EDWARDS: Darius is over four foot when you stretch him out.
I don't know what it is, whether it's because they're brought up in a very laid-back atmosphere.
And I think that's why they just keep getting so big.
In here is some press.
This one, Roberto, one of our giants.
So there he is with me.
That's probably your best picture, isn't it?
People come from all over the world to see these guys.
And we sell babies all over the world.
Although there's a waiting list.
Each rabbit, all ours have got very different personalities.
Some like more fuss than others.
Come on, boy.
Just stop it. You're too old.
Darius, even though he's an old man now and can be a bit grumpy, he still likes his lady friends.
So he hasn't lost his sparkle.
He likes his romance.
Leave her alone.
You've been a naughty old man.
♪♪♪ NARRATOR: Rabbits are notorious for, well, their incredible ability to breed like bunnies.
Their proficiency in this area can wreak havoc for a whole host of animals, including humans.
♪♪♪ ♪♪♪ ♪♪♪ In a small town deep in the Rocky Mountains, a bounty of non-native bunnies are attracting some very unwelcome visitors.
♪♪♪ There is a fundamental difference between wild and domestic rabbits.
Domestic rabbits have had the fight-and-flight response bred out of them.
♪♪♪ ROOZENDAAL: I feel that the rabbits don't belong here.
You know? They've been introduced.
Obviously, someone once upon a time let them go, and they've just proliferated.
[ Train bell ringing ] HENDERSON: So years ago, a fellow I know confided to me that he had two rabbits that he thought were male rabbits and he gave them to his buddy.
And it turned out that they weren't two male rabbits.
They were a male and a female rabbit, and his buddy at some point got a little tired of the increasing bunny population in their house and so outside all the rabbits went.
ALLISON: I live right kind of at ground zero where the bunnies were released, and there have been times when there are literally thousands of bunnies, everywhere.
HENDERSON: I'm not sure that people would have predicted they'd do so well here, because it's a harsh climate in the winter, and a lot of predators around but they're resourceful little critters.
We actually have a fair number of the rabbits out in front of the vet clinic.
So I was on call one night and I got a phone call, from someone who said, 'Hi. I'm just out in front of the clinic, and I think your rabbits got out.'
And the next thing I said was, 'You're not from Canmore, are you?'
♪♪♪ ALLISON: So, Canmore is really unique because it's wedged between Banff National Park and Kananaskis Country.
So you have animals travelling between those two parks, so we have grizzly bears, wolves, cougars, all going through wildlife corridors in this area.
And so, they're coming close to town.
You know, I think any predator worth its salt would know that there's thousands of bunnies running around, so that's why they would get drawn into town.
HONEYMAN: Well, we have documented cases of grizzly bears, cougars, and coyotes chasing rabbits right in town, and either catching them or running around trying to catch them.
And you can imagine the issues that that causes.
There's a whole bunch of public safety concerns surrounding that.
ALLISON: There is basically zero tolerance for a cougar or a coyote that gets drawn into town to eat the bunnies.
And so if they start doing that and they are seen a lot, then a Conservation Officer will come by and they are euthanized.
NARRATOR: After 20 years, the town could no longer ignore their feral rabbit problem.
Something had to be done.
HONEYMAN: Rabbits are a really sensitive issue with residents, you know they're cute and they're furry and the idea of having to, kill one or we talked about sterilizing at one point, it just -- it was -- it became a political issue.
ROOZENDAAL: For a while it was quite polarizing.
And when they first talked about, you know, exterminating the rabbits, there was a very vocal group that didn't think that should happen.
DECOTEAU: If you are caught supporting keeping these bunnies alive then you are criticized for being part of the problem.
If you are on the other side, then you are criticized for not respecting the life of an animal.
NARRATOR: After much community debate and several different management attempts, including costly sterilization and relocation, the town settled on a culling program to try to keep their feral rabbit population in check.
But to this day, they haven't all been eliminated.
ALLISON: I've noticed that the only ones that have kind of lasted are right in the malls and right beside major restaurants or right in the corridor of the railway where there's just a lot of action and animals like cougars and coyotes just wouldn't be bold enough to go into those places, so I think they've just been pushed and pushed into those areas.
NARRATOR: As the town of Canmore learned the hard way, where there is prey, there are always predators.
♪♪♪ Here in Canada's northern wilderness, one of the most studied predator/prey relationships on the planet is slowly revealing its secrets.
♪♪♪ ♪♪♪ Canada lynx are remarkably adapted to live in the boreal forest, where snow can stay on the ground 9 months a year and the temperature often dips to 40 below.
But they are not the only creatures built for this tough environment.
Snowshoe hare, with their huge hind feet and snow-colored coat are custom-built for these harsh conditions.
And within their bite-size frame lies the heart of a lion.
A fighter who has a few tricks up their sleeve to survive in a world where they're on everyone's dinner menu.
♪♪♪ BOONSTRA: The relationship between lynx and hares is intimate.
And it's probably been going on for thousands of years.
Our hares are built, in some sense, they're adapted to this forest, and the lynx are entirely built to kill them.
♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ It's not just lynx.
It's great horned owls and goshawks and coyotes.
All hares that die, die at the tooth or talon of their predators.
♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ NARRATOR: This hare will remember the stress of this hunt, as well as the multitude of other times it must run for its life.
New science is showing how these traumatic memories affect the balance of power between hares and their predators.
As their predators reach peak levels, the hares react to the chronic stress by significantly slowing their reproduction.
Instead of 4 litters a year, they'll have only 2.
♪♪♪ Instead of the usual 20 babies, they will have only 7 or 8.
Just enough to sustain their population's long-term survival while starving out their predators.
BOONSTRA: The problem with lynx is, in these forests there's not a lot to eat, and when they kill the majority of the hares and the hares go down because reproduction collapses and there's a long low, there's nothing to eat, so the numbers drop like crazy.
The lynx will move to try to find someplace where there are other food sources.
They'll move 500 or 600 kilometers.
NARRATOR: But the hares are one step ahead of them.
Fear of predation leads hares to reduce their reproduction, en masse.
So wherever the lynx travel, hares are in short supply.
Traditionally there has been a 10-year boom/bust cycle between snowshoe hares and lynx.
Boonstra's ground-breaking research is showing that there is still more to learn about this age-old ritual.
♪♪♪ In the spring, when the hare's coat changes from snow white to brown, Boonstra really starts to understand the complex lives of snowshoe hares.
BOONSTRA: I've been studying these snowshoe hares for almost 40 years now, and I try to get inside their heads in terms of what they're feeling.
So, we had good evidence that they were stressed.
NARRATOR: That stress is severe, it affects their reproduction, but it also affects their progeny, through the hormones and through the placenta.
NARRATOR: Soon after birth, Boonstra uses intense gene analysis to try to decode the secret of how mother hares pass the message to delay reproduction on to their young.
BOONSTRA: The young bear that signature, these ghosts of predators past, in their biology, in their growth, in their reproduction.
During the decline phase, which lasts about two years, depending on how intense it is, maybe three, theoretically the hares should be bouncing right back.
NARRATOR: But they don't bounce back even when predator numbers are low.
Instead they continue to keep their population numbers down far longer than an experienced biologist like Boonstra would have expected.
In a widespread effort that spans generations of snowshoe hare, these shy creatures that are everyone's favorite meal manage to turn the tables on their predators and start to control the game.
To dramatically alter the course of their lives and the lives of their predators for generations to come.
♪♪♪ There is something about the power of predators that draws us in.
♪♪♪ But sometimes those that seem like the disposable extras in the scene, the innocent and vulnerable secondary characters, are just as captivating.
In fact, sometimes, they are the real stars of the show.
♪♪♪ For strength can take many forms.
♪♪♪ And these seemingly passive creatures are far more robust than ever imagined.
Some may even be the ultimate survivors.
♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪ ♪♪♪