LIGHT CHEERFUL MUSIC
The natural world is full of extraordinary animals
with amazing life histories,
yet certain stories are more intriguing than others.
The mysteries of a butterfly? fife cycle
or the strange biology of the Emperor penguin.
Some of these creatures were surrounded by fantastic myths
and misunderstandings.
Others have only recently re vealed their secrets.
These are the creatures that stand out from the crowd.
The curiosities that I find particuiarly fascinating.
MUSIC FADES TO SILENCE
EERIE MUSIC
In this programme, we investigate the stories of two animals
that owe their existence to human interference.
Killer bees that were created accidentally
when a wet! meaning breeding experiment went wrong.
And pizzly bears;
the resuit of polar bears and brown bears interbreeding.
How were these strange animals created
and are they unnatural mutants or valuable new hybrids?
This is a grizzly bear.
And that white one there is, of course, a polar bear.
But in between, there's a different kind of bear.
It's got the white coat of a polar bear,
except that, around the eyes, it's rather brown.
And its front legs are very brown.
It is, in fact, a hybrid.
The result of a mating between a polar bear and a grizzly bear.
And it's sometimes called a pizzly.
The first ever pizzty bears were born in a German zoo in 1876
after a polar bear and a grizzly, a type of brown bear,
were housed together.
Hybrid animals have frequently been born in captivity,
both intentionally and by accident.
Tigers and lions produce offspring catted Iigers
and donkeys and zebra babies known as zonkeys.
But usually these hybrid creatures are sterile
and are not well adapted for surviving in the wiid.
Animals, of course, usually mate with their own kind.
If different species are to interbreed and produce fertile young
they have to be extremely closely related.
Grizzly bear and polar bears
are certainly somewhat similar in appearance,
but are they, in fact, closely related?
In the bear family, the black species came first,
and then came the brown bear, and finally, the white polar bear.
This was thought to have happened about 4 to 5 million years ago,
but recent fossil evidence suggests that it may have happened as recently
as only half a million years ago.
So the polar bear is a relative/y recent species of bear.
One that branched off late in the bear family tree.
GENTLE MUSIC
Polar bears live high in the Arctic and are true carnivores.
They're slightly bigger in size than brown bears.
Their fur is creamy white, unlike the reddish brown grizzly,
not surprisingly, since they five in very different habitats.
Grizzly bears are found in North America and Northern Europe.
They're omnivores and eat some meat, nuts, grass and fruit.
Grizzly bears have rounded heads
and prominent shoulder humps that have evolved for digging.
Polar bears, on the other hand,
have more pointed heads, but no shoulder humps.
Their feet have hairy pads and short claws,
which helps to prevent them slipping on ice.
The grizzly has more obvious footpads
and much larger, curved claws.
We know that polar and grizzly bears can mate successfully,
but what sort of offspring do they produce?
For many years, zoos discouraged the breeding of pizz§y bears,
but recently there was a chance to study them in Germany.
In 2004, at Osnabruck Zoo,
a brown bear called Susi and a polar bear called Elvis
who'd shared an enclosure for 24 years,
unexpectedly produced wins.
The small brown cubs are bigger now and have changed colour.
The male, named Tapps, is brown,
and the female, Tipps, has a tighter coat.
But otherwise, they have traits inherited from both parents.
Long necks and visible tails, that are more typical of polar bears,
but also small shoulder humps
that are reminiscent of those of brown bears.
Their feet are intermediate in form
and their size is between the two,
smaller than a polar bear, but larger than a brown bear.
We know from Osnabruck Zoo
that when polar bears and grizzlies mate
they can produce pizziy cubs.
But what are the chances of these very different bears
meeting in the wild?
This is the grizzly bear's home range in North America.
Polar bears live higher up in the Arctic
so the two species are neighbours,
but ones with very different lifestyles and feeding habits
that restrict their ranges.
But their habitats are changing
as the climate is warming
and that's beginning to have an effect on the behaviour
of the two species in the wild.
In 2003,
a researcher working on a remote island
between Church?“ and the North Pole
discovered strange bear footprints in the snow
together with brown hairs.
The hair came from a grizziy. This was extraordinary.
The grizzly must have strayed hundreds of miles from its home
and travetied deep into polar bear territory.
So it was clear
that the chances of these cousins meeting and mating in the wild
was becoming a real possibility.
But would their offspring survive?
Research on captive pizzly bears suggested that they could.
The hair of brown bear, polar bear and pizzly bear
are quite different, not only in colour, but in structure.
Here are cross sections of a hair from each of them.
The brown bear has a central canal,
which is filled with a honeycomb structure.
The polar bear, that central canal is almost empty,
making that hair good for insulation,
just what you need in a cold climate.
And the pizzly bear is a sort of compromise between the two.
The central canal has just a little in filling, so you might say
that it's not bad for cold temperatures and not bad for warm.
GENTLE INNOCENT MUSIC
Possessing a mix of characteristics of both parent bears
could actually help the hybrids survive in a rapidly changing world.
Their hunting ski/ls have also become more variable.
Tlpps and Tapps sometimes fish like brown bears,
but at other times behave like poiar bears.
Stamping, for instance.
Polar bears push down on ice to break it during their search for seals.
The Osnabruck pizziies perform a similar action.
This mixture of physical and behavioural characteristics
suggest that pizzties may be we?! equipped to survive in the wild
if conditions in the Arctic continue to change.
And in 2006, this notion became reality.
An odd-looking bear was shot
during a polar bear hunt in Northern Canada.
It was small, hunched and had dark smudges around its eyes and muzzle.
DNA testing showed that its mother was a polar bear
and its father a grizzly that had traveiied further north
and was hundreds of miles beyond its normal range.
So pizzly bears aren't just the result of captive breeding.
Several have been reliably identified in the wild,
though none have yet been caught alive.
But as the climate warms, so brown bears are moving north
and polar bears coming south.
And their close genetic relationship
means that not only can they interbreed,
but the offspring are likely to be fertile.
The ranges of these bears are now increasingly overlapping.
SEAGULL CRIES
It's now not uncommon to see polar and grizzly bears feasting together
when there's plenty of meat around as there is after a whale hunt.
So are we seeing a new development in the evolutionary history of bears?
In April 2010, biologists in the Northwest Territories of Canada
shot a dangerous polar bear.
It was strange in appearance
and DNA analysis showed something very significant.
This was a second generation pizzly bear.
The result of a female grizzly mating with a polar bear.
As global warming continues to diminish the Arctic sea ice habitat,
climate scientists believe that the polar bear
will struggle to survive as a species.
But at least some of the polar bear traits will be preserved
in these strange-looking hybrids.
So pizziy bears are not bizarre Frankenstein-iike creatures.
They're valuable new hybrids that may become increasingly common.
Next, the story of a familiar creature
that had a shocking change of character
when a well-meaning experiment went disastrously wrong
and created a hybrid killer bee.
SHRILL MUSIC
BEES BUZZING
In the 1960s and 70s, bees hit the headlines.
Huge swarms were attacking people and livestock
for no apparent reason.
The bees launching these attacks were, in fact, honey bees.
The sort from which we've been collecting honey for centuries.
In the Western world, monks traditionally kept bees for honey
and for the wax that they used to make candles.
For centuries, bees have had an association with human beings
and passive, easy-to-handle bees have been selectively bred.
So the European honey bee became a tolerant, well-tempered bee.
BEES BUZZING
So why would a species of bee
that has lived amiably alongside people for so long
suddenly change its nature?
The temperament of a bee colony is determined by that of the queen bee.
The one seen here marked with the blue spot.
She fays aft the eggs in the hive.
An aggressive queen will produce very ferocious workers,
while a passive queen produces calmer ones.
European honey bees are generally very passive.
TENSE MUSIC
African bees, however, are very different.
They have evolved to sting and attack large predators that raid their nests.
And to defend themselves from man,
who disturbs them when collecting honey.
Nonetheless, they're very hardworking.
They manage to produce substantial quantities of honey
in dry habitats
where good quality flowers are often hard to find.
In the 1950s, honey production in Brazil was failing.
And it was thought that African bees might be abte to help.
So a Brazilian scientist, Dr Warrick Kerr,
who was a specialist in bee genetics, was consulted.
The Brazilian Ministry of Agriculture asked Kerr
if he could obtain some African queens to experiment with
in order to breed a bee that combined the passive nature of the European bee
with the higher productivity of the African bee.
The bees there had originated from stock
imported to North America by British colonists.
Although these bees were productive in the North,
the more tropical climate of Central and South America
didn't suit them so well.
Here, they were not so productive.
BIRDS SINGING AND BEES BUZZING
European honey bees normally live in temperate climates
where an abundance of flowering plants provide a lot of nectar.
So they're able to produce honey quite easily.
GENTLE TENSE MUSIC
But conditions were not like that in Brazil
and the European bees struggled to make honey in any quantity.
The habits of the African bee seemed more suited
to the South American climate.
Honey bees are very choosy feeders.
They will carefully select those flowers that have the strongest nectar,
the sweetest nectar, and I can demonstrate that.
Here is a little bee in a bee holder.
Let me first try her
with a dilute solution of sugar.
No reaction.
Now let me try her with a stronger solution.
A sweeter solution.
And out comes her proboscis.
It won't let go!
DAVID LAUGHS
Western European bees can afford to be choosy
because there's flowers with rich nectar available
for such a long period of time.
African bees have no such luxury.
They have to feed at times when there are very few flowers open anyway
and those that are, are not very rich in nectar.
So they are much more industrious.
Let's release you
so you can go back and collect some more nectar.
BEE BUZZES
It's gone.
Kerr planned to take the industrious, less fussy African bee
and combine it with the passive European bee
to produce one that would work hard but would not be aggressive.
He persuaded particularly successful African beekeepers
to let him have some of their most gentle and passive queens,
133 in all.
Unfortunately, a customs agent sprayed his bees with insecticide
and they all died.
Kerr then chose a second batch,
but this time, he didn't screen out the most aggressive bees.
47 of these queens survived,
but they were far too fierce to give to the local Brazilian beekeepers.
So Kerr decided to breed them with some with some gentler drones.
Doctor Kerr set up 35 colonies
in an isolated area of Eucalyptus forest near Sao Paolo.
And to prevent the queens from escaping
he used a device called a queen excluder.
It fits on top of the brood box here.
The bars are sufficiently wide apart to allow worker bees to pass through,
but not so wide that the queen can.
But he went away and you can't cater for human error.
In his absence, a local beekeeper came
and noticed that the worker bees passing through
were losing some of the pollen that they'd collected.
So he removed the queen excluders.
And by the time Doctor Kerr came back,
26 of the queens had escaped into the wild,
and were already swarming.
Swarming is the way bees naturally increase their population.
A queen bee leaves the hive, taking many of the workers with her.
A swarm gathers,
rests, and quickly relocates to form a new colony.
African bees swarm more than their European cousins
and frequently divide to form mu/t/irale colonies.
Kerri; escaped queens and the Aifloanised worker bees
inherited this tendency to swarm
and they spread quickly across South America.
BEES BUZZING
WIND BLOWING
It was assumed that the abundant native European bees
would weaken the escaped African bees' more aggressive nature,
but this didn't happen.
The African genes were strong and their behaviour dominated.
By 1965, most Brazilian hives had been devastated
and the aggressive Africanised bees swept their way through South America
and headed up into North America.
They started to attack people with little provocation
and sometimes fate! results.
Up to 90% of a colony would launch an attack
and even though their venom was no more potent than the European bee,
they sting in their thousands.
TENSE MUSIC
Horror movies pictured them as crazed killers with lethal stings.
But this was far from the truth.
In any case, it wasn't the African Dee's sting that was fatal,
it was their behaviour.
The escape of such aggressive bees in the wild
was devastating for Kerr's career.
Africanised bees spread as far as the lower parts of North America,
but here, their takeover hatted.
The more temperate climate didn't suit them.
TENSE MUSIC LIGHTENS
Kerfs intentions had been good
and he later dedicated his research to try and correct the probiem.
Eventually, Kerr did help to create productive, more passive bee,
as had originally been his plan.
And South America is now one of the world's largest exporters of honey.
MUSIC FADES
The creation of the so-called killer bee by Doctor Kerr's experiments
was indeed a grave mistake.
But in recent years a more gentle form of African bee has been bred
and it's also possible that the ferocity of the African bee
has now been turned to our advantage.
Elephants are said to be terrified of bees
and in recent years farmers in Africa
have started playing the sounds of swarming bees over their fields
and the elephants have kept away.
So, as well as pollinating plants, bees can actually protect them.
So both the Africahised honey bee and the pizzly bear are here to stay.
But these unusual hybrids owe their success,
in one way or another, to humans.