Prairie Dogs - Talk of the Town Natural World


Prairie Dogs - Talk of the Town

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The North American prairies, home to the bison.

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But this film isn't about the bison.

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It's about a tiny creature that lives beneath the bison's feet...

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..the prairie dog.

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You might easily overlook the prairie dog,

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until it opens its mouth.

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SQUEAKING

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It's a little animal with a big voice.

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A team of scientists believe this noise

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is in fact a very complex language,

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which is remarkable for an animal many see as lowly vermin.

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So, what are they saying?

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To find out, scientists have devised a set of cunning experiments.

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But could these barks, squeaks and chirps really be a language?

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To our human ears, this just sounds like a lot of unnecessary noise,

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but to other prairie dogs it's all part of a jolly good conversation.

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That is, if you believe this man,

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prairie dog expert Professor Con Slobodchikoff.

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Prairie dogs have the most complex natural language

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that's been decoded so far.

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They have words for different predators, they have

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descriptive words for describing the individual features of predators,

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so it's a pretty complex language that has a lot of elements.

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A relative of the squirrel

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with a language second only to humans in its complexity?

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That's a bold claim.

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But Con has a problem.

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He's fighting an in-built prejudice against these little rodents.

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Convincing the wider world that prairie dogs are great linguists

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is proving a tough challenge.

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He believes if we just get to know them a little better,

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understand their world, then we might just see his point of view.

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Life as a prairie dog is complicated.

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It's not just a simple matter

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of eating grass and minding your own business.

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You have to share your space with lots of other prairie dogs.

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Every prairie dog is part of a big community called a town.

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The largest prairie dog towns stretch over tens of miles,

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their excavated homes pockmarking the prairie landscape.

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Living together requires impeccable social skills.

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Kissing is all the rage in prairie dog town.

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A little taste of saliva

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is like a calling card that helps identify a visitor.

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Prairie dogs, though, are nervous creatures,

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always on the lookout for signs of trouble across town.

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But what is there to worry about?

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Prairie dogs aren't the only animals living in the town.

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Squatters have moved into some of their vacant burrows.

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All these strangers make prairie dogs a little nervous.

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And so they should be.

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Prairie dogs are under attack from all quarters.

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There are times when they must feel besieged

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by animals that want to eat them.

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Even when they retreat to their underground burrows,

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the prairie dogs can't really relax.

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With no safety anywhere, above or below ground, prairie dogs

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have come up with a clever strategy for dealing with these threats.

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LOUD SQUEAKING

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They shout.

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Very loudly.

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Technically speaking, it's an alarm call.

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You might still be wondering why Con would choose

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such a humble subject to study animal language.

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After all, there are more likely animal linguists -

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whales or monkeys.

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But there was something about those prairie dog alarm calls

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that piqued his interest.

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With so many predators living in prairie dog town, Con wondered,

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do the prairie dogs have just one call,

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or do they have different calls for the different predators?

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There's only one way to find out.

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Con must test their calls.

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He's on his way to a remote ranch in the north of New Mexico.

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It's a haven for prairie dogs.

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Two species live here, Gunnison's and black-tails.

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Joining him are two of his students, Patricia Dennis,

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who will help record the calls,

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and Bill Briggs, who's devised a series of experiments

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to test the prairie dogs.

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Together, this team hopes to show once and for all

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that we have underestimated the little prairie dog.

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First of all, Con looks for signs of predators in his research area.

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Here's a badger excavation.

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This is very fresh.

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It probably happened in the last day or two.

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This is the way that badgers typically hunt.

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They'll excavate a prairie dog burrow and then go inside,

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and while the prairie dogs are sleeping,

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they will eat the prairie dogs

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and then they'll also sleep inside the burrow.

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They typically excavate a number of burrows

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all around us in a particular area, and then they move on

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to another place once they've eaten all the prairie dogs

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that live in a particular burrow system.

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The presence of predators is welcome news for Con.

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The prairie dogs should be on a state of alert,

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and that'll mean good alarm calls.

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SQUEAKING

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But waiting for predators to appear would be far too time-consuming.

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These imaginative scientists have a solution -

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they bring their own.

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Time to set up the first experiment.

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Bill must keep the dummy predator under wraps

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while he finds a suitable spot.

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Some prairie dogs are already a little spooked.

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Con uses his car as a screen to hide behind.

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It's important that no-one is visible.

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The predator is revealed...

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..a plastic coyote without any legs.

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It seems like an encouraging result.

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The prairie dogs are certainly being vocal.

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What's really wonderful about this is that other individuals are chiming in

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just in response to the vocalisation,

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so they don't even have to see the stimulus

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in order to know that this is a coyote, and they start yelling.

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Every call recorded must subsequently be analysed by Con.

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We can hear the difference in the calls

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between the different predators, but that's not really enough for us.

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What we really need is some sort of analytical tools

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for measuring what the frequency and time elements in the call are.

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And so this software here allows us to do this.

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This is our alarm call elicited for a coyote,

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and we can hear that it has a series of rhythmic chirps.

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We think that each prairie dog

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has its own individual, unique tonal qualities,

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just like humans have different voices and different voice prints.

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But even though each individual prairie dog might differ,

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all the prairie dogs have a common call

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for a coyote even within those individual voice print differences.

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So we think that when a prairie dog is calling for a coyote,

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they probably know who the prairie dog is that's calling,

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just the same way that we can on the telephone hear somebody's voice

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and immediately recognise it as a person that we know.

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SQUEAKY CHIRPING

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Everything is ready for experiment number two, the stuffed badger.

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Con and his team are very excited by this one.

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This is the first time they've ever tested a badger.

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Will the prairie dogs have a specific alarm call for it?

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The badger's out.

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LOUD SQUEAKING

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Well, the prairie dogs are certainly calling,

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but are these calls different from the earlier ones to the coyote?

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Con hopes so.

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Now the researchers must take a look at all the recordings

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from today's experiments.

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The badger call is an entirely new call for us.

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We've never recorded a call for a badger.

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So it's really exciting to look at the structure of this call

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and see what it looks like.

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And it looks very different

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from any of the other calls that we've recorded.

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SQUEAKING

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SQUEAKING

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HIGHER-PITCHED SQUEAKING

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To Con's expert ears and eyes, there is a difference both in their calls

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and in the shape of their sound graphs.

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The shape of each sound curve

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varies subtly, but is consistent for each predator.

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But to convince any would-be doubters,

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Con has another experiment planned.

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Over his 30 years of research, he's noticed that prairie dogs

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react in different ways to different predators.

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If the alarm calls for coyote and badger do indeed differ,

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then playing back the two calls

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to a group of prairie dogs should produce distinct responses.

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Bill's big speakers get fired up.

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HIGH-PITCHED SQUEAKING

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First, the alarm call for coyote.

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The prairie dogs react instantly.

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Having spooked one part of the colony with the loudest

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alarm call they've ever heard,

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the team moves on to an undisturbed spot

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to try out their second alarm call, the badger.

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SQUEAKING

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The reaction is very different.

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We had a terrific response, and for the coyote call

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they did just what they're supposed to do for a coyote.

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They ran to the burrows and stood at the lip of the burrows and watched.

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For the badger call, they ran to the lip of the burrows

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and crouched down, just like they're supposed to for a badger.

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So it was a terrific result.

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Adopting different tactics for different predators

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makes perfect sense.

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A coyote will hunt by surprise,

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so perhaps it's safest to sit up and keep an eye on it at all times.

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Badgers are the bulldozers of the predator world.

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They will dig into a prairie dog hole.

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Crouching down might be a way of hiding yourself

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so the badger doesn't choose your burrow.

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It's been a good day for the team.

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Every new alarm call is a new addition

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to their dictionary of prairie dog words.

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But there's still a long way to go

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in their quest to prove that prairie dogs have a complex language.

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It's early morning, and the prairie dogs are already up.

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Con and his team are back, and they're keen to try a new test,

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one that's a lot stranger than their earlier experiments.

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Con has a hunch that prairie dogs have unique calls for colours.

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It sounds a bit mad, but he's putting it to the test.

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(Patricia here's doing a coloured shirt experiment.

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(The idea here is to test the ability of the prairie dogs

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(to discriminate between different colours

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(and how they incorporate that information into their alarm calls.)

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No joy. The prairie dogs aren't calling.

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(I think one problem is that Patricia's not threatening enough.

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(She tends to walk slowly and is kind of relaxed about it.

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(I wonder if we could get Bill to wear a shirt.)

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Time to substitute Bill for Patricia.

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Bill's manly walk provokes a response.

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SQUEAKING

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But behind this quirky experiment is a bigger question.

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Could the prairie dog calls actually contain more information

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than just the identity of the threat?

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Could they be describing precisely what they see?

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Con believes the answer is yes.

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Throughout his 30-year study, he's found that changing the speed,

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direction and even the colour of a threat

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results in a change in the prairie dogs' alarm call.

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We think that each one of these chirps contains a noun-like word

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and it also contains adjective-like words,

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which describe the colour, the size, and all of that is

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put together into one of these single chirps,

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pretty much the same way that we would put together a sentence.

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So, we might say, "A tall, skinny coyote with yellow fur,"

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and the prairie dogs manage to put all of this into a single chirp.

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In other words, prairie dogs can cram into one short call

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the same amount of information found in a human sentence.

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How do they do it?

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Con suspects the answer lies in the fine detail of their calls.

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Each alarm call or each chirp is a series of stacked harmonics,

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that you can see one on top of the other,

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but instead of being actual multiples of the base frequency,

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they're actually modulated by the vocal apparatus of the prairie dog,

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and that's what contains the information that this is a coyote

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as well as the general colour and size and shape of the coyote.

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So prairie dogs can subtly alter the meaning of their chirp

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by varying each harmonic.

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It's an amazing way of tightly packaging information.

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All these findings demonstrate

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this is an animal we have grossly underestimated,

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that the prairie dog is much more complex than we thought.

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This is no surprise to the man

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who has doggedly championed prairie dogs his entire career.

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Everything about prairie dogs points to them being complex animals -

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even their homes.

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This is a prairie dog hole.

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It is part of an elaborate burrow system that is underground.

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The hole goes down maybe about between one and three metres,

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and then the entire burrow system

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stretches out for anywhere between three and five metres,

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with a fairly elaborate structure.

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There's a bathroom chamber where they pee and poop

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and there's a nest chamber where they sleep.

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There's also side chambers, where one prairie dog coming down

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meets another prairie dog coming up,

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and one of them backs into a side chamber

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so that the other one can go past,

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just like two cars on a narrow, winding mountain road.

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The prairie dog burrow system

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is remarkably sophisticated in its engineering.

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These rodents can excavate an extensive

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tunnel network that connects as many as six entrance holes.

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And it's deep underground where the pups are born in spring.

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Blind and without fur, they huddle together for warmth and security.

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This underground world of prairie dogs is rarely observed.

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It will be five weeks

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before the pups are ready to leave their nursery chamber.

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When that moment arrives, Con will be there.

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The pup calls will be crucial to his work.

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Above ground, the mounds are designed

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to funnel rain away from the holes and so keep their burrows dry.

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The hard work by these mining rodents

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has created a vast infrastructure

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that makes the prairies attractive for other animals.

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Many different species of all shapes and sizes

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have come to rely on prairie dogs for their lodging.

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Only recently have we come to recognise that without prairie dogs,

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the prairies would be lost for ever.

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They're important to all life on the prairies,

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including lots of animals that want to eat them.

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Con believes this relationship with other animals is the main reason

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why prairie dogs have developed a complex language.

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So what happens to the language if you take away all the predators?

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There's only one place where he can find the answer to that...

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..at a zoo.

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These prairie dogs have been in captivity all their lives.

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They've never seen predators.

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So what will happen when Bill and Patricia introduce

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their dummy predators?

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Will these captive prairie dogs

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have a call for threats they've never seen before?

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The coyote makes its entrance.

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SQUEAKING

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Well, they're certainly calling.

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But are they saying, "Coyote"?

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Right now, we've got about eight mics in here to make sure that we've got

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no problems with echoes or any other aberrations,

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and we're recording the prairie dogs' call to a coyote.

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And I'm watching here on the computer screen to look at the spectrograph

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to see how it's formed. And to tell you the truth,

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it's completely different than what we're used to.

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We still have individual chirps, but they have no definition to them.

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They're completely different, and it's really surprising to see.

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They're making a noise,

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but it doesn't sound like a prairie dog word.

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Now it's the badger's turn.

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Is he doing anything or just looking at it?

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There's two prairie dogs right now calling.

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There's one calling at the badger

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and another prairie dog by the metal grate.

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I've got a badger sitting out there,

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and we've got two prairie dogs calling for it.

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And the spectrograph is just amazing.

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It's nothing like we've seen before.

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We've got the chevrons, but there's no structure to them.

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Their calls are like a scream.

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It's an alarm, but without any meaning.

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It suggests they only develop their words

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after repeated exposure to predators.

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If so, that's learning,

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and that's a key characteristic of a proper language.

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Bill and Patricia's results from the zoo

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show that animals who have been in a zoo setting for at least nine years,

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who have not heard any predator calls,

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probably lose their predator calls or lose the ability to make those calls.

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The zoo animals have very non-specific noise-like calls,

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and so I think that this shows that learning is important

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in this animal language.

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This is a major discovery.

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Learning is a crucial element of every language.

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But can Con build on the zoo results

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and demonstrate learning is taking place out on the prairies?

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If prairie dogs are learning their calls,

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then it must be happening once the pups come above ground.

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This, after all, is the first time they'll see other animals.

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Testing their ability to learn will be the most important experiment

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of all to prove that prairie dogs have a complex language.

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Con's reputation and the reputation of all prairie dogs

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now depends on the pups.

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In early June,

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the pups are just taking their very first steps above ground.

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Bill is setting up an experiment with a new fake predator.

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This is a silhouette of an airborne predator, like a hawk.

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And we'll shoot this down this line to try and simulate a hawk attacking

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a prairie dog in the colony, and it should be pretty exciting to see.

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Well, this is pretty disappointing.

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We've done this experiment before in the past,

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and the animals at other sites

0:26:520:26:54

have given a characteristic hawk call and then they run to their burrows.

0:26:540:26:58

But here, they just simply run to their burrows

0:26:580:27:01

and they don't give a call.

0:27:010:27:02

Maybe they don't see any aerial predators

0:27:020:27:05

and so have no reason to give a hawk call.

0:27:050:27:07

But nevertheless, it's really disappointing.

0:27:070:27:11

Perhaps prairie dog pups are a lot cannier

0:27:110:27:13

than we give them credit for.

0:27:130:27:15

Maybe Bill's fake hawk wasn't quite realistic enough for them.

0:27:150:27:20

This is more like it.

0:27:320:27:35

A swooping hawk

0:27:350:27:36

is enough to create a state of panic in prairie dog town.

0:27:360:27:40

Many prairie dogs will go underground.

0:27:470:27:50

If the aerial approach isn't successful,

0:27:570:28:00

then the hawk has another strategy -

0:28:000:28:03

just sit and wait.

0:28:030:28:05

And wait.

0:28:110:28:13

The one thing you don't want to do is go above ground,

0:28:150:28:19

not when there's a big hawk outside.

0:28:190:28:22

But pups can be a little impatient.

0:28:220:28:27

A hawk can hold prairie dogs hostage like this for many hours.

0:28:270:28:33

Both the prairie dogs and the hawk want to feed.

0:28:330:28:37

It becomes a battle of wills.

0:28:370:28:40

Eventually, the pups claim victory.

0:29:030:29:05

Back at his study colony,

0:29:230:29:25

Con is worried that there aren't as many predators as he thought,

0:29:250:29:29

and that's making it difficult to record pup calls.

0:29:290:29:32

He needs to get the colony on a higher state of alert,

0:29:350:29:39

so he has a plan to stir things up a bit.

0:29:390:29:42

-Hi, Brent.

-Hey, Con. How you doing?

0:29:520:29:54

-It's good to see you.

-Good to see you.

0:29:540:29:56

-So, these are your dogs?

-Yeah, these are my two dogs.

0:29:560:29:58

And when they're not chewing on each other,

0:29:580:30:01

they like to go after varmints like prairie dogs!

0:30:010:30:03

The purpose of this is to get the prairie dogs

0:30:080:30:11

more used to having predators around.

0:30:110:30:14

This colony probably has not had very much predation,

0:30:140:30:18

and they aren't calling as much as I would like.

0:30:180:30:21

And so having the dogs running around gets them more alert

0:30:210:30:25

and gets them to call more for other stimuli,

0:30:250:30:28

like some of the other experiments that we're going to do.

0:30:280:30:31

This isn't the first time Con has introduced prairie dog to real dog.

0:30:330:30:39

What we've found in the past is that they do recognise individual dogs.

0:30:390:30:43

They can describe the shape of the dogs,

0:30:430:30:46

the size of the dogs and the coat colour of the dogs.

0:30:460:30:50

But have the dogs had the desired effect?

0:30:500:30:53

Have they stirred up this colony?

0:30:530:30:56

Only one way to find out.

0:30:560:31:00

The pups seem to be on high alert, but will they call?

0:31:140:31:19

Everything is in place.

0:31:280:31:30

Now it's all down to the pups.

0:31:300:31:33

The tension is becoming unbearable.

0:31:350:31:38

SQUEAKING

0:31:540:31:56

The plastic coyote has worked its magic again.

0:31:570:32:00

But are the pups actually saying, "Coyote"?

0:32:000:32:06

If, as Con suspects, the pups learn the alarm calls,

0:32:060:32:10

then at this early stage of their lives,

0:32:100:32:12

he wouldn't expect them to know the calls for different predators.

0:32:120:32:16

Every call recorded

0:32:180:32:20

will be subjected to stringent scientific analysis.

0:32:200:32:23

Look at the difference.

0:32:260:32:28

But at first glance, the findings look positive for Con.

0:32:280:32:32

Now, he does have the same number of calls per series,

0:32:320:32:35

it seems like, and the loudness and everything else is the same.

0:32:350:32:38

And maybe the loudness and the number of calls is something that is innate,

0:32:380:32:43

and maybe the structure is something...

0:32:430:32:45

Side by side, the adult and pup calls are very different.

0:32:450:32:49

SQUEAKING

0:32:490:32:50

We have here a pup

0:32:500:32:52

and an adult calling for the coyote.

0:32:520:32:55

They sound very different,

0:32:550:32:57

and they also look very different on the computer.

0:32:570:33:01

We can see here the adult call has a lot of structure in it

0:33:070:33:10

and it contains a lot of information.

0:33:100:33:13

The pup call, on the other hand, doesn't have very much information

0:33:130:33:17

in it and it changes in structure, just like babbling in little kids.

0:33:170:33:23

So this pup is gradually acquiring more and more structure.

0:33:230:33:27

As in any language,

0:33:270:33:28

the youngsters must practise getting the words right.

0:33:280:33:32

In human babies we call it babbling,

0:33:320:33:35

and it appears that prairie dog babies babble, too,

0:33:350:33:38

as they struggle to make the right call.

0:33:380:33:41

These results are good news for Con,

0:33:410:33:43

but they don't prove they're learning, not yet.

0:33:430:33:47

To really show that, they'll need to test the same pups later in the year

0:33:470:33:51

to see if their calls change over time.

0:33:510:33:55

For now, there's nothing the team can do

0:33:550:33:58

but wait for the pups to grow up.

0:33:580:33:59

That is, if they're able to grow up.

0:33:590:34:04

Prairie dog pups are an ideal snack for hungry predators.

0:34:060:34:11

You might think the alarm calls of prairie dogs would make

0:34:130:34:16

it particularly challenging for a predator to hunt them.

0:34:160:34:19

But that doesn't seem to worry this family of swift foxes.

0:34:190:34:23

They've made a home in a deserted prairie dog burrow

0:34:290:34:33

right in the middle of a colony.

0:34:330:34:35

The fox cubs aren't even attempting to keep a low profile.

0:34:360:34:40

It's almost as if they're deliberately taunting

0:34:420:34:45

their prairie dog neighbours.

0:34:450:34:47

With four energetic cubs, Mum has a busy time.

0:34:540:34:59

She must hunt regularly.

0:34:590:35:02

When she goes out hunting,

0:35:100:35:12

the prairie dogs soon sit up and take notice.

0:35:120:35:15

But they're remarkably quiet.

0:35:230:35:26

Alarm calls warn of a pending threat,

0:35:260:35:29

but if that threat comes too close, prairie dogs will often fall silent.

0:35:290:35:35

To call out now could prove fatal.

0:35:350:35:38

If a pup does indeed learn from its parents,

0:35:430:35:45

then knowing when to hold fire and retreat

0:35:450:35:48

could be one of the most valuable lessons of its life...

0:35:480:35:51

SQUEAKING

0:36:000:36:03

..or the end of its life, if it gets it wrong.

0:36:090:36:14

When one of your neighbours is killed,

0:36:210:36:23

it wouldn't seem unreasonable to expect a moment of quiet reflection.

0:36:230:36:29

But once the swift fox is out of sight,

0:36:340:36:38

something quite extraordinary happens in prairie dog town.

0:36:380:36:43

LOUD BARKING

0:36:430:36:46

It looks like the prairie dogs are experiencing a moment of madness.

0:36:460:36:50

This acrobatic display is in fact the jump-yip call.

0:36:520:36:58

It could be an all-clear signal when a threat or danger has passed.

0:36:580:37:05

Whatever the meaning, it's certainly infectious.

0:37:050:37:08

In late summer, the rains bring a flush of colour to the prairies.

0:37:230:37:28

For the prairie dogs, it's been a pretty boring diet until now,

0:38:110:38:15

but sunflowers will provide a tasty treat.

0:38:150:38:20

Each sunflower seed has twice the number of calories

0:38:210:38:24

as a blade of grass, so they're vital to the prairie dog pups

0:38:240:38:28

as they fatten up for the winter.

0:38:280:38:30

Time to set up their final exams

0:38:360:38:38

and see how their vocabulary is shaping up.

0:38:380:38:41

Are they still babbling like babies, or talking like adults?

0:38:410:38:46

Out come the usual suspects.

0:38:460:38:49

SQUEAKING

0:39:110:39:13

That's wonderful. We've got a really distinct coyote call.

0:39:170:39:21

There's another one calling from across the colony.

0:39:210:39:25

OK, Bill, let's do the badger.

0:39:460:39:48

They're standing up where they're foraging and looking

0:40:020:40:05

to see where the badger is going, and that's different from the coyote.

0:40:050:40:09

For the coyote, they run to the lip of their burrow and stand there.

0:40:090:40:13

For the badger, they are a little bit more reluctant to

0:40:130:40:16

run to their burrow until they see which burrow the badger is going to.

0:40:160:40:20

The signs are all good.

0:40:220:40:23

They are at least reacting in the right way to the fake predators.

0:40:230:40:28

The pups seem to be in fine voice.

0:40:300:40:34

But have they learnt the proper words from the adults?

0:40:340:40:38

To find out, they must compare them with pup calls

0:40:400:40:43

from earlier in the year to see if they've changed.

0:40:430:40:47

So let's just play the call that we got from the pups for the badger...

0:40:470:40:51

-OK.

-..two months ago versus the calls that we got from them today.

0:40:510:40:56

Let's see if we can hear it.

0:40:560:40:58

SQUEAKING

0:40:580:41:00

Yeah, again, very non-structured calls early in the season

0:41:070:41:11

and highly structured calls later in the season.

0:41:110:41:13

Looking at this spectrogram, you really see the difference.

0:41:130:41:17

-You do.

-Very detailed in the adult call.

0:41:170:41:19

What we saw at the beginning of the season

0:41:190:41:21

was that the pups gave very non-specific, generic calls,

0:41:210:41:25

and now these same pups are giving highly structured calls.

0:41:250:41:29

So, clearly, the pups have learned in just two months

0:41:290:41:33

how to adapt their calls so that they sound the same as the adult calls.

0:41:330:41:37

Let's see the same thing with the coyote.

0:41:370:41:39

Yeah, let's do that for the coyote.

0:41:390:41:41

Here we go.

0:41:410:41:44

Wow.

0:41:440:41:46

Again non-specific, just squeaks versus a lot of acoustic structure.

0:41:460:41:52

That's really very impressive.

0:41:520:41:54

-The calls are longer duration, as well.

-Yeah.

0:41:540:41:57

Probably because they contain a lot more information in them.

0:41:570:42:01

I think this shows that learning is actually going on,

0:42:030:42:06

because clearly we went from very generic,

0:42:060:42:09

non-specific calls to very specific calls in just a short period of time.

0:42:090:42:15

And I don't think that there's another explanation

0:42:150:42:19

other than learning.

0:42:190:42:20

It is possible that there is a genetic programme

0:42:200:42:23

that causes the maturation of the vocal tract,

0:42:230:42:26

but I think that's relatively unlikely

0:42:260:42:28

compared to the possibility of learning.

0:42:280:42:31

It's a eureka moment for Con and for the prairie dogs.

0:42:320:42:39

They have passed all the language tests with flying colours.

0:42:390:42:42

For Con, these findings are more than just about science.

0:42:440:42:48

He hopes they'll make people look differently at prairie dogs

0:42:480:42:52

and not see them as just vermin.

0:42:520:42:54

Prairie dogs have a very complicated social system.

0:42:540:42:57

They have to have some sense of their relationships between each other

0:42:570:43:02

in order to maintain this social system.

0:43:020:43:05

They also have this complex language,

0:43:050:43:07

and they have to have some kind of intellectual structure

0:43:070:43:11

in order to be able to understand this language, as well.

0:43:110:43:14

So the two things combined says to us that prairie dogs

0:43:140:43:18

are really very complex animals.

0:43:180:43:20

After 30 years of research, Con has all the information he needs

0:43:200:43:25

to help prove his bold claim that prairie dogs

0:43:250:43:28

have the most sophisticated language in the animal world.

0:43:280:43:33

At last the prairie dogs can step from the shadow of the bison

0:43:360:43:40

and take centre stage as the true hero of the prairies.

0:43:400:43:44

And they have one man to thank for that.

0:43:440:43:47

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