Carpenter,
lumberjack,
surveyor, architect,
stonemason, hydro-engineer...
Man and beaver -
two of the most skilled and industrious creatures on earth.
In a battle of construction,
who really deserves the title 'Master Builder'?
The first contender for the title 'master builder'
is a dog-sized rodent found throughout the rivers and lakes of North America.
Beavers live and work in small, multi-talented teams.
This seven-year-old female is the foreman of a family gang,
which includes her male partner - as builder's mate
- and three adolescent apprentices.
Here, in the Rocky Mountains of Wyoming
they've got 6 months before winter arrives.
In that time they'll create a pond,
dig a network of canals, clear acres of trees
and construct a lodge with adjoining larder, using only local materials.
The beavers' toolbox includes claws with a vice-like grip
＃ chisels for teeth,
highly tuned ears and eyes for health and safety...
and a pair of dextrous paws.
A beaver is a green machine 每 fuelled by low-grade cellulose.
Its broad, flat tail is a rear engine that may run non-stop for 20 years.
It works efficiently on land and underwater,
and webbed feet deliver extra thrust for heavy loads.
Down the valley are the other contenders for the construction crown.
They too have their work cut out to finish before winter.
They too have a blueprint for a log cabin development.
But their toolbox includes a 20-ton crane,
a mechanical lumberjack
and a hydraulic-assisted forklift truck...
not to mention diesel-powered caterpillar-tracked excavators
and a 500 horsepower earth mover.
Their expert team is made up of surveyors
haulage experts, lumberjacks,
carpenters and stonemasons.
They've started laying the foundations for the first stage in the building process.
Upstream among the cottonwood trees,
the beaver crew have also started Stage one 每 constructing a dam.
They pile up stones and rocks to form a wall and cover it with woody debris.
The foreman and her family add more and more layers
and over a couple of weeks the stream is blocked.
Water backs up behind the dam to form a pond.
It's just the first stage in their 6-month schedule.
Each day a busy beaver can shift 10 times its own body weight
每 a total of around 500 pounds.
The beavers excavate the bed of their new pond,
making it deeper and using the mud like mortar to plug any holes in the wall.
Powered by strong hind legs and chunky forearms,
they pat, push and compress the dam to make it watertight.
As the dam becomes leak-proof, the water level rises upstream
and the beaver crew continue to bulldoze in new layers of material.
The dam-builders are programmed to react to the sound of trickling water.
They rush to block any leaks.
Working as a well-drilled team,
a beaver gang can build 5 feet of dam each day.
They won't stop until the river is completely blocked.
The largest beaver dam ever recorded was nearly a mile long.
Now builder turns surveyor...
the foreman checks the family's work for leaks.
It's taken several months' hard labour to construct a dam over 300 feet long
and the resulting pond now stretches more than a mile upstream
Stage one of the beaver project is complete
Downstream the earthmovers are on to Stage two
carving out a road for access to their site
A transport system is the second stage of the beaver blueprint too＃
but on this site there's no mechanical assistance.
The beavers use their claws and teeth to rip up mud and vegetation,
and their paws to shovel it into place.
In just a few days they can excavate an entire network of channels,
leading away from the main pond, far into their forest estate.
For safety reasons, beavers like to travel in the water
steering clear of predators like bears.
So instead of going overland, they take the water to the trees.
The longest channel ever measured ran for more than 1,300 feet
＃the builder and surveyor is also an expert hydro-engineer.
By blocking parts of the network,
the beaver can vary the water level in order to flood new areas and reach new trees.
And getting to the trees is what all this hard work was all about.
Trees are the raw material for Stage 3
每 building a home.
Meanwhile the beaver hydro-engineer becomes a lumberjack.
Four sharp incisors, powered by huge jaw muscles,
can whittle through a cottonwood tree in a matter of hours.
The beavers need to keep their wits about them while they work...
They listen to each creak and groan,
and to be on the safe side, often leave wind power to finish off the job
But inexperienced apprentices don't always time it right＃
squashed beavers are occasionally found.
Waiting for the wind means beavers can have 4 or 5 trees ready to go at any time
each one perhaps 3 feet in diameter and up to 100 feet tall.
A beaver lumberjack may chop more than 200 trees a year.
As a lumberjack's axe has a tough iron blade,
so the outer enamel of a beaver's teeth is reinforced.
The soft inner surface wears down more rapidly,
creating a chisel-like tree-cutting edge.
Chainsaws may become blunt,
but beavers teeth, like those of all rodents, are self-sharpening＃
they grow back as fast as they wear down.
The beaver's sense of smell is hundreds of times more sensitive than ours...
and they seem to use it to sniff out the tastiest, most nutritious trees.
The crew's hard work soon radically transforms the landscape
每 leaving a large gap in the forest.
Good lumberjacks don't leave a mess.
As soon as each tree falls, it's cleared away.
And for the beaver gang, it's payday.
They've flooded the forest so now they can swim to the trees＃
cut them down and reach the juicy leaves, twigs and bark at the top.
Time for the green machines to refuel.
The beaver strips the bark, and eats the best chips, up to 2 pounds a day.
Special micro-organisms in its guts digest this high-fibre food.
Now the canal network comes into its own＃ as a bustling highway.
Branches are shipped from every corner of the property
每 it's a major logistical operation.
The journey ends here 每
at the beavers' winter storage depot, in the middle of the pond.
This larder must be filled within the next few weeks.
It's all paws to the pump
now the beavers' rear motor goes into overdrive.
Another wide load is delivered to the depot,
and stored in the deepest part of the pond,
where cold water will keep the food fresh.
Each branch is pushed right down into the mud.
The larder contains rations for the fast-approaching winter months
Winter is a crucial deadline 每
one the beaver builders can't afford to overrun.
As dusk falls, down the valley the contractors take off for the weekend
but the beaver crew don't miss a beat.
On the night shift, beavers seem to have an even greater sense of urgency
unlike the neighbours.
Productivity increases,
and they often bundle up 5 or 6 branches in a single load.
Not all the branches are stored in the larder
some are diverted for a different purpose
The beaver crew is ready to construct the final stage and crowning glory of their blueprint
their equivalent of a log cabin 每 a 'lodge'.
Over the past few months the family have lived in temporary accommodation
每 a hole in the riverbank.
But now they build a timber framework house
and render the outside with mud and sticks.
Down the valley the man-made log cabins are already underway...
but will this team finish before winter kicks in?
A beavers' lodge can be more than 40 feet across and 10 feet high
每 that's bigger than a double garage.
Once the basic framework is in place,
it's overlaid with yet more vegetation and sticks.
Each member of this crew can turn their paw to anything.
The plasterer arrives with mud to bind the walls and insulate against the cold.
Wattle and daub is a very effective technique.
But how does the beaver crew know when to start on the lodge?
They take their cue from the rising water levels
once the pond reaches a certain depth they automatically switch energies
from dam construction to building a home.
More and more logs are ferried in
Before they use the logs, the beavers strip the bark and eat it
每 nothing goes to waste.
All this manual labour helps to keeps these builders super fit
每 a beaver can lift its own bodyweight in timber.
From start to finish, it takes just 20 days to build the lodge,
using around 3 tonnes of raw materials.
The beavers' home is high-security
- protected by a moat, with several concealed underwater entrances.
Inside, the beavers carve out individual chambers
每 this is where they have their young.
Beavers give birth in spring, to 3 or 4 babies or kits,
each one about the size of a guinea pig.
The lodge is made up of 3 rooms, each with a private entrance to the pond.
The nursery, and then the sleeping quarters
This one is taken by a pair of muskrats 每 they're permanent squatters!
The third room is the beaver family's feeding chamber.
With last year's young still at home, it's a full house.
All these beaver bodies create a kind of central heating.
The humidity and warmth does, however,
mean that fungi grow like rising damp under the reed carpet.
With front and back door access underwater
the inhabitants can come and go hidden from prying eyes.
As well as being a cosy family home,
this is now a prime piece of detached waterfront property
每 complete with landscaped garden.
Lodge, larder, pond and channels are all finished.
The beavers are on schedule.
Their deadline is in sight and the building is almost complete.
Down the valley the other team is lagging behind＃
But they do have one big advantage
每 their project has planning permission.
Busy beavers can cause problems.
In the past and still today,
the beavers' fixation with building has led them to butt heads with man.
Flooding agricultural land has put beavers on the most wanted list
Farmers regularly clear small dams, but larger ones require more drastic measures
Months of hard work are often blown sky high.
But these resilient rodents have proved more than a match for the dam busters.
They quickly move in again to repair, renovate and re-flood the fields.
This persistence can be fatal.
Because they return to fix a leaking dam,
the beavers can easily swim right into a trap.
But in recent years, the beavers' building skill has been more appreciated
Beavers are now moved from sites where they're not wanted
and released into new areas as wildlife and wetland managers.
Beavers create much more than just a family home.
The beaver pond also serves as a firebreak during forest fires
and a run-off when the river floods.
It's a fishing lake and recreation area too.
In the right place the beaver is a model tenant
and free handyman, a true eco-engineer,
producing a mosaic of habitats that are suitable for many other species.
Man and beaver are sharing their waterways
but in the battle of construction, who's the winner?
Down the valley, snow has stopped the contractors in their tracks.
They've missed their deadline...
This lodge will now lie empty until spring.
The well-coordinated beaver team, on the other hand,
have hit nature's tight deadline.
As the temperature drops,
the true value of their painstaking preparations becomes clear.
Thanks to their hydro-engineering know-how
the family is ready for the winter freeze
This is the true test.
If they hadn't dug their pond just deep enough to stop it freezing solid,
the lodge entrance would have been icebound.
And with the forest inaccessible, the adjoining larder is a lifesaver.
It means the beavers can nip out for food throughout the colder months
without having to venture far into the woods
The beaver builders have designed the perfect winter refuge...
safe and well-stocked with food 每 ideal for raising chips off the old block.
It's a spacious home, where all the family can sit out winter
snug and warm.
And if the central heating gets too high,
the occupants can let off steam through an extractor vent.
So who, in this valley, wins the title 'Master Builder'?
No contest 每 it's the beaver.
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