0:00:08 > 0:00:10In the heart of Africa,
0:00:10 > 0:00:13straddling the borders of Rwanda, Uganda and Congo,
0:00:13 > 0:00:16lies a remarkable mountain kingdom.
0:00:21 > 0:00:27It's home to the world's last 700 mountain gorillas.
0:00:32 > 0:00:34With so few left,
0:00:34 > 0:00:38they require constant surveillance from a dedicated band of humans.
0:00:44 > 0:00:47Our cameras have been given privileged access
0:00:47 > 0:00:49to these amazing animals by the people
0:00:49 > 0:00:52that record every detail of their lives.
0:00:56 > 0:00:59In this programme, we'll discover
0:00:59 > 0:01:02what it takes to be a dominant silverback.
0:01:06 > 0:01:10Every group needs one. GENTLE HOOTING
0:01:10 > 0:01:13Every male aspires to be one.
0:01:14 > 0:01:18The true leaders of the gorilla world.
0:01:22 > 0:01:27Join us as a teenage silverback fights to find his place in a group.
0:01:27 > 0:01:31An orphan's fate hangs in the balance.
0:01:33 > 0:01:36And the world's most successful silverback
0:01:36 > 0:01:39faces the biggest challenge of his life.
0:01:58 > 0:02:02Of the world's last 700 mountain gorillas,
0:02:02 > 0:02:07less than 65 are dominant silverbacks -
0:02:12 > 0:02:15every male gorilla's ultimate aim.
0:02:35 > 0:02:38And it's a prize worth fighting for -
0:02:40 > 0:02:44the right to father the next generation.
0:02:57 > 0:03:00Some males will never succeed.
0:03:02 > 0:03:05But that doesn't stop them trying.
0:03:08 > 0:03:11And no-one stays at the top for ever.
0:03:17 > 0:03:20From these 65 dominant silverbacks,
0:03:20 > 0:03:24one has remained at the top for longer
0:03:24 > 0:03:28and sired more offspring than any other.
0:03:32 > 0:03:35The true king of the volcanoes.
0:03:41 > 0:03:43His name is Titus,
0:03:43 > 0:03:47and today is his 35th birthday.
0:03:53 > 0:03:57Titus is now the oldest known silverback in the world.
0:04:06 > 0:04:10But his years as a great leader may be coming to an end.
0:04:13 > 0:04:17A silverback is only as successful as the group that he leads...
0:04:19 > 0:04:23..and Titus's group has been decimated.
0:04:29 > 0:04:32Three years ago, Titus led his group of 25
0:04:32 > 0:04:35to the very top of their volcano.
0:04:47 > 0:04:50He was driven there by a rival silverback
0:04:50 > 0:04:53set on taking Titus's crown.
0:04:56 > 0:05:02On top of their volcano kingdom, his group was forced to choose...
0:05:03 > 0:05:06..between Titus,
0:05:06 > 0:05:09the older, more experienced king,
0:05:09 > 0:05:12and the younger, stronger silverback.
0:05:29 > 0:05:3319 of his followers left with the challenger.
0:05:41 > 0:05:47Just six gorillas chose to stay loyal to the ageing Titus.
0:05:55 > 0:06:01Three years on, and Titus is about to face the biggest challenge of his life.
0:06:12 > 0:06:15This time, the threat will come from a gorilla
0:06:15 > 0:06:19much closer to him than anyone yet realises.
0:06:24 > 0:06:27CHEST BEATING
0:06:30 > 0:06:33Chest beats can carry for over a kilometre.
0:06:33 > 0:06:36CHEST BEATING
0:06:36 > 0:06:41They allow males to assess each other's size and strength.
0:06:43 > 0:06:45CHEST BEATING
0:06:46 > 0:06:50Somewhere out there is a large, strong silverback -
0:06:50 > 0:06:53and he's heading Titus's way.
0:07:07 > 0:07:1140 kilometres north, separated by swathes of farmland,
0:07:13 > 0:07:18there's a silverback at a very different stage of life from Titus.
0:07:25 > 0:07:29Rukina is in his prime.
0:07:31 > 0:07:35At 25 years of age, he controls his group
0:07:35 > 0:07:37with the confidence of a born leader.
0:07:47 > 0:07:50Rukina's home is Bwindi Impenetrable Forest.
0:07:52 > 0:07:54Smaller than the Isle of Wight,
0:07:54 > 0:07:58and higher than the tallest mountain in Britain,
0:07:58 > 0:08:01it's home to about half the world's mountain gorillas.
0:08:05 > 0:08:08Bwindi lies in southern Uganda,
0:08:10 > 0:08:14just 40 kilometres north of the volcanoes
0:08:14 > 0:08:18where Titus and the other half of the population reside.
0:08:36 > 0:08:39On Rukina's trail is Martha Robbins,
0:08:40 > 0:08:45a pioneering scientist who's dedicated 20 years of her life
0:08:45 > 0:08:49to studying the world's last 700 mountain gorillas.
0:08:51 > 0:08:55I realise I definitely don't have the average day job.
0:08:55 > 0:08:57My commute involves walking into the forest,
0:08:57 > 0:09:01and this is the most amazing office anybody could have.
0:09:05 > 0:09:11Martha was the first researcher to gain the trust of a gorilla group in Bwindi,
0:09:11 > 0:09:16and today, she's still the only scientist studying this precious population.
0:09:18 > 0:09:22Research is important for many reasons that contribute to conservation.
0:09:22 > 0:09:27We need to understand their ecology, their social behaviour,
0:09:27 > 0:09:32and just how they develop over time, to help conserve them.
0:09:35 > 0:09:39Martha meticulously documents the lives of all the gorillas.
0:09:41 > 0:09:45But she's particularly interested in the fate of the silverbacks.
0:09:50 > 0:09:55One of the aspects that interests me the most is how males become dominant.
0:09:57 > 0:10:01All males, when they become adult, they turn silver.
0:10:01 > 0:10:03So all males become silverback,
0:10:03 > 0:10:05but not all males become leaders of a group.
0:10:07 > 0:10:09I sort of view it as, you know,
0:10:09 > 0:10:12in a business, very few people become the CEO.
0:10:12 > 0:10:16So becoming a dominant silverback's a very difficult thing.
0:10:19 > 0:10:22Rukina is a silverback at the very top of his game.
0:10:30 > 0:10:32It's the start of the dry season,
0:10:32 > 0:10:35and he's leading the group to their local swamp.
0:10:41 > 0:10:46They'll eat over 20 kilograms of vegetation a day.
0:10:51 > 0:10:52Rukina has guided them well,
0:10:55 > 0:10:59and the gorillas sing with delight at their new feast.
0:10:59 > 0:11:00GORILLAS CROON
0:11:10 > 0:11:14On the outskirts of the group, Martha spots a surprise visitor.
0:11:19 > 0:11:21It's junior silverback Marembo,
0:11:24 > 0:11:28a teenage male on the cusp of adulthood.
0:11:33 > 0:11:36He's a gorilla Martha knows well.
0:11:39 > 0:11:45Until a few months ago, Marembo lived happily in Rukina's group,
0:11:45 > 0:11:47a fine role model for the younger gorillas.
0:11:54 > 0:11:58But on becoming a teenager, his hormones took control
0:12:02 > 0:12:08and he struck out alone in search of females and a group of his own.
0:12:16 > 0:12:21Now he's back to try his luck against the dominant silverback, Rukina.
0:12:23 > 0:12:26Martha doesn't fancy his chances.
0:12:28 > 0:12:30Rukina's definitely still in his prime.
0:12:31 > 0:12:34Marembo's about 14, 15 years old,
0:12:34 > 0:12:38and he's got a way to go before he's...he's a threat.
0:12:44 > 0:12:48With his raging hormones and desire to be dominant,
0:12:48 > 0:12:51Marembo's return is sure to shake things up.
0:12:55 > 0:12:59And no-one quite knows how Rukina will react.
0:13:12 > 0:13:16While Martha's research in Uganda focuses solely on Rukina's group,
0:13:16 > 0:13:20further south, on the Rwandan volcanoes,
0:13:20 > 0:13:23a much larger operation is in action.
0:13:30 > 0:13:34Every day, teams of trackers, field staff and researchers
0:13:34 > 0:13:36climb the volcanoes to collect
0:13:36 > 0:13:41behavioural data from the nine different gorilla groups they study.
0:13:45 > 0:13:48The teams are from Karisoke Research Center,
0:13:48 > 0:13:50established over 40 years ago
0:13:50 > 0:13:52solely to study mountain gorillas.
0:14:02 > 0:14:07Come rain or shine, these gorillas are visited every day,
0:14:07 > 0:14:09on Sundays, holidays and even Christmas,
0:14:09 > 0:14:14making them some of the most studied animals on the planet.
0:14:17 > 0:14:22Only through detailed, long-term observations like these
0:14:22 > 0:14:25can the lives of mountain gorillas really be understood
0:14:29 > 0:14:32and this precious population preserved.
0:14:45 > 0:14:51At the head of this 70-strong team is 32-year-old Felix Ndagijimana.
0:15:10 > 0:15:16Felix is on his way to see gorilla king Titus. All is not well.
0:15:19 > 0:15:21Felix has met the mystery silverback
0:15:21 > 0:15:23responsible for the distant chest beats.
0:15:25 > 0:15:29He's young, strong and alone.
0:15:31 > 0:15:33LOW-PITCHED EXHALATIONS
0:15:34 > 0:15:38Felix knows if this silverback meets the ageing Titus,
0:15:38 > 0:15:41there'll be trouble. THROATY GROWLING
0:15:43 > 0:15:46Always, you don't know what the outcome's going to be.
0:15:46 > 0:15:49You know, sometimes it just gets like very physical -
0:15:49 > 0:15:51they will fight and bite each other.
0:15:56 > 0:16:01Just 100 metres away, Titus and his group are feeding,
0:16:01 > 0:16:05oblivious to the impending threat.
0:16:13 > 0:16:18Titus may be old, but he's no stranger to adversity.
0:16:24 > 0:16:28He's survived through some incredible ups and downs,
0:16:30 > 0:16:33each one recorded by his human observers
0:16:33 > 0:16:36since the very day he was born.
0:16:41 > 0:16:43From these notes, we can reconstruct
0:16:43 > 0:16:46the story of Titus's extraordinary life.
0:16:53 > 0:16:56When Titus was four years old,
0:16:56 > 0:16:58barely weaned from his mother's milk,
0:16:58 > 0:17:03he witnessed the brutal murder of his father.
0:17:08 > 0:17:10The great silverback
0:17:10 > 0:17:15was shot in the chest while defending Titus and his family from poachers.
0:17:24 > 0:17:26The group was sent into turmoil.
0:17:26 > 0:17:28Without a dominant silverback,
0:17:28 > 0:17:31the gorillas became frightened and confused.
0:17:32 > 0:17:35In the chaos, Titus's mother fled.
0:17:39 > 0:17:42The four-year-old Titus was orphaned.
0:17:44 > 0:17:48Everyone believed his short life was over.
0:18:03 > 0:18:05But Titus didn't die.
0:18:13 > 0:18:17He was adopted by a totally unrelated silverback.
0:18:22 > 0:18:26The silverback treated Titus like a son.
0:18:26 > 0:18:28He was offered shelter
0:18:28 > 0:18:32and protected against the other males in the group.
0:18:34 > 0:18:36Titus is a born survivor,
0:18:36 > 0:18:41and he grew to be a great and powerful leader.
0:18:50 > 0:18:54Today, Titus has the same fighting spirit.
0:18:55 > 0:19:00But he's a grandfather figure, and his life has come full circle.
0:19:06 > 0:19:11In a remarkable twist of fate, he now cares for a young orphan gorilla
0:19:11 > 0:19:14whose mother has left the group.
0:19:23 > 0:19:27This orphan is alone in the world, as Titus was once,
0:19:31 > 0:19:36entirely dependent on the ageing silverback for warmth, shelter
0:19:36 > 0:19:39and, above all, protection.
0:19:45 > 0:19:49But Titus's age makes the pair vulnerable.
0:19:53 > 0:19:55The approaching silverback will attempt to
0:19:55 > 0:19:58seize control of the group... CHEST BEATING
0:19:58 > 0:20:02...and could kill an infant fathered by another male.
0:20:10 > 0:20:14The orphan's survival depends entirely on Titus's ability
0:20:14 > 0:20:17to remain at the head of his group,
0:20:17 > 0:20:20and fight off this impending threat.
0:20:58 > 0:21:02Martha leaves her house each morning at 7:00,
0:21:02 > 0:21:07and heads to where she left the gorillas the previous day...
0:21:07 > 0:21:11a walk of anything from 90 minutes to four hours.
0:21:47 > 0:21:51Martha's keen to catch up with the young silverback, Marembo,
0:21:51 > 0:21:56last seen following Rukina and the family into the swamp.
0:22:01 > 0:22:04On the edge of the group, Martha finds a silverback
0:22:04 > 0:22:06lying in the shade.
0:22:09 > 0:22:15It's the teenager, Marembo, and it looks like he and Rukina
0:22:15 > 0:22:17have already come to blows.
0:22:17 > 0:22:21You can see the bite wound on the back of his head.
0:22:29 > 0:22:32He's had a tough time of his life.
0:22:33 > 0:22:35He would like to be dominant, but he certainly
0:22:35 > 0:22:38has a long way to go before he's strong enough.
0:22:39 > 0:22:41And Rukina's really in his prime,
0:22:41 > 0:22:45so he may try and stay on the edge, or he may leave.
0:22:45 > 0:22:47We'll have to see.
0:22:51 > 0:22:53While young Marembo sulks under the bushes,
0:22:53 > 0:22:59dominant silverback Rukina enjoys a real gorilla delicacy...
0:23:03 > 0:23:04..Dead wood.
0:23:11 > 0:23:16The wood is high in sodium, a precious mineral for gorillas.
0:23:18 > 0:23:21As the gorillas gather, it gives Martha a chance
0:23:21 > 0:23:25to have a look at the dominance hierarchy within the group.
0:23:28 > 0:23:31Sometimes you'll see somebody just sitting on the edge
0:23:31 > 0:23:33and you think they're just resting,
0:23:33 > 0:23:35but actually they're waiting their turn.
0:23:37 > 0:23:41Marembo keeps a respectful distance from Rukina.
0:23:45 > 0:23:47He's very much bottom of the pile.
0:23:51 > 0:23:53Even the females rank above him.
0:23:57 > 0:24:01If Marembo stands any chance of becoming a gorilla leader,
0:24:01 > 0:24:06he needs to start at the bottom and work his way up.
0:24:09 > 0:24:10And he's spotted his first target.
0:24:18 > 0:24:21This male was orphaned as an infant.
0:24:21 > 0:24:25He's the most timid member of Rukina's clan.
0:24:28 > 0:24:32It's teenage Marembo's big moment.
0:24:40 > 0:24:45He positions himself between the male and the rest of the group.
0:24:45 > 0:24:49It's a cheap trick to show Marembo's dominance.
0:24:55 > 0:24:59Eventually, the nervous male scoots past.
0:25:03 > 0:25:06For Marembo, it's a small triumph.
0:25:06 > 0:25:10At least he's dominant over someone!
0:25:13 > 0:25:171 gorilla down, 13 to go.
0:25:22 > 0:25:25GORILLA CALLING
0:25:25 > 0:25:27CHEST BEATING
0:25:27 > 0:25:29Back on the volcanoes,
0:25:29 > 0:25:33Felix is on his way to find silverback king Titus.
0:25:33 > 0:25:35SHRIEKING
0:25:38 > 0:25:39But there's trouble.
0:25:39 > 0:25:42HOOTING
0:25:53 > 0:25:57The big, challenging silverback is now amongst the group.
0:25:58 > 0:26:01He's set on one thing...
0:26:06 > 0:26:08...seizing Titus's throne.
0:26:25 > 0:26:27HOOTING AND DRUMMING
0:26:28 > 0:26:31The intruder displays to show Titus his strength.
0:26:36 > 0:26:39But Titus can't be intimidated.
0:26:39 > 0:26:41If he gave up now,
0:26:41 > 0:26:45the rival silverback would kill the young orphan in his care.
0:26:52 > 0:26:57The orphan must stay close to Titus for protection.
0:26:59 > 0:27:03But Felix knows the gorilla king is past his prime.
0:27:07 > 0:27:11Titus is old. He's lost a lot of muscles
0:27:11 > 0:27:16and you can see that his movement, when he's moving he's very slow.
0:27:20 > 0:27:23Titus now faces a potentially fatal decision.
0:27:26 > 0:27:32There are two options. One is run, and the other one is stay and fight.
0:27:35 > 0:27:40The old leader is wise and he's brave.
0:27:40 > 0:27:46In a rare display of strength, he shows the intruder his intent.
0:27:49 > 0:27:52SHRIEKING AND GRUNTING
0:27:56 > 0:28:01Silverback king Titus isn't going to give up his group without a fight.
0:28:09 > 0:28:15While Titus faces the biggest challenge of his 35 years,
0:28:15 > 0:28:19in Bwindi, everyone is still waiting for rain.
0:28:44 > 0:28:48All the inhabitants are ranging further each day in search of food and water.
0:29:08 > 0:29:10LOWING
0:29:26 > 0:29:30Rukina and his group have been forced into dangerous new territory.
0:29:47 > 0:29:49Oh, he's got a big cut.
0:29:51 > 0:29:54Oh, he's got a very big cut on the top of his head.
0:29:55 > 0:29:56That has to hurt.
0:29:59 > 0:30:00Marembo's right here,
0:30:00 > 0:30:06and he's got a very big, new bite or cut on the top of his head.
0:30:06 > 0:30:11It's maybe about this long, so I think he's been in some fights.
0:30:18 > 0:30:20Marembo's deep wounds
0:30:20 > 0:30:24look to be made by the sharp canine teeth of another silverback.
0:30:28 > 0:30:31But these wounds weren't made by Rukina.
0:30:35 > 0:30:39Martha follows the trampled vegetation
0:30:39 > 0:30:42until she finds another silverback.
0:30:48 > 0:30:52It's a gorilla she doesn't recognise.
0:30:52 > 0:30:54It's definitely not Rukina.
0:30:59 > 0:31:01And he's not alone.
0:31:03 > 0:31:08Four hostile silverbacks are threatening Rukina's group.
0:31:21 > 0:31:24Rival males will fight to steal females...
0:31:26 > 0:31:28..and it looks like teenage Marembo
0:31:28 > 0:31:31got injured trying to prove himself defending the group.
0:31:35 > 0:31:40But Marembo isn't the only gorilla at risk from the rival males.
0:31:44 > 0:31:48Martha spots the youngest member of Rukina's group,
0:31:48 > 0:31:53eight-month-old Ponoka, and his mother, Tinda.
0:31:59 > 0:32:03Silverbacks will kill infants that are not their own...
0:32:03 > 0:32:05SHRIEKING
0:32:05 > 0:32:07..an act known as infanticide.
0:32:10 > 0:32:14Killing Ponoka would enable them to mate with the bereaved mother
0:32:14 > 0:32:17and sire offspring of their own.
0:32:26 > 0:32:30Ponoka and his mother are dangerously close
0:32:30 > 0:32:32to one of the rival silverbacks.
0:32:34 > 0:32:37It's the dominant male from the other group.
0:32:37 > 0:32:39With Tindamanyere and Ponoka being up here,
0:32:39 > 0:32:45the infant's very vulnerable, at that age, to infanticide.
0:32:54 > 0:32:58RUMBLING GROWL
0:33:13 > 0:33:18On the volcanoes, Felix is heading towards Titus.
0:33:22 > 0:33:24GRUFF EXHALATIONS
0:33:24 > 0:33:28He's received worrying news.
0:33:28 > 0:33:32Titus and the rival silverback have come to blows.
0:33:40 > 0:33:42The gorilla king appears to be unscathed...
0:33:44 > 0:33:48..but his rival is nursing two fresh wounds...
0:33:51 > 0:33:54..wounds made by Titus.
0:34:08 > 0:34:12Finally, Felix gets a good look at Titus's challenger.
0:34:14 > 0:34:16He recognises his face.
0:34:19 > 0:34:21It's Rano...
0:34:25 > 0:34:26..Titus's son.
0:34:31 > 0:34:34Banished from the group three years ago,
0:34:34 > 0:34:37he's now returned from the wilderness
0:34:37 > 0:34:39to claim his father's throne.
0:34:47 > 0:34:49In the years he's been gone,
0:34:49 > 0:34:53he's grown into a formidable silverback.
0:34:54 > 0:34:56HOOTING
0:35:01 > 0:35:04Rano piles on the pressure.
0:35:11 > 0:35:13Titus keeps him at arm's length.
0:35:23 > 0:35:26But Titus is too old to risk another fight...
0:35:30 > 0:35:32..and he's left with one option.
0:35:39 > 0:35:41He must flee...
0:35:45 > 0:35:49..and his small but loyal group follows.
0:35:54 > 0:35:56The long pursuit begins.
0:36:19 > 0:36:23Felix knows that Rano aims to drive the ageing Titus to exhaustion,
0:36:23 > 0:36:26then take the group himself.
0:36:27 > 0:36:31Sometimes he's behind them, he's displaying, he's following them.
0:36:31 > 0:36:33They're going to keep moving.
0:36:37 > 0:36:40The little orphan must stay out of Rano's reach.
0:36:42 > 0:36:44There'll be no time to eat
0:36:44 > 0:36:46and no time to rest.
0:37:15 > 0:37:18But Titus can't keep running for ever.
0:37:40 > 0:37:42SHE MURMURS
0:37:45 > 0:37:47In Bwindi, Martha is worried
0:37:47 > 0:37:51for the youngest and most vulnerable member of Rukina's group...
0:37:54 > 0:37:57..eight-month-old Ponoka...
0:37:59 > 0:38:03..last seen near a silverback from the hostile group.
0:38:08 > 0:38:11Now he's nowhere to be seen.
0:38:16 > 0:38:20Teenage silverback Marembo is on the front line,
0:38:20 > 0:38:23doing his best to keep the rival males at bay.
0:38:30 > 0:38:32SHRIEKING
0:38:34 > 0:38:38Martha has finally tracked down dominant silverback Rukina.
0:38:44 > 0:38:47And he's got problems of his own.
0:38:54 > 0:38:58Two of his females seem to be showing a little too much interest
0:38:58 > 0:39:01in the chest beats from the other group.
0:39:04 > 0:39:08Both of them are looking towards the sounds of the other group.
0:39:11 > 0:39:15These females may try to sneak away to join the other group.
0:39:17 > 0:39:20Rukina will do everything he can to stop them.
0:39:23 > 0:39:28This is a time where Rukina is likely to be very vigilant
0:39:28 > 0:39:31to make sure that these females stay with him.
0:39:36 > 0:39:40RHYTHMIC GRUNTING
0:39:40 > 0:39:45Rukina knows these females can't go anywhere while he's guarding them.
0:39:46 > 0:39:49So the wise leader holds his ground,
0:39:49 > 0:39:55while foolhardy Marembo does the fighting on his behalf.
0:39:58 > 0:40:00CHEST BEATS
0:40:05 > 0:40:09Surprisingly, young Marembo's efforts seem to be working.
0:40:11 > 0:40:16The chest beats from the other group fade away into the forest.
0:40:16 > 0:40:17CHEST BEATS
0:40:24 > 0:40:28Bruised and battered, Marembo is exhausted.
0:40:38 > 0:40:40But, for one little gorilla,
0:40:40 > 0:40:43Marembo's efforts have been worthwhile.
0:40:48 > 0:40:50Little Ponoka is back,
0:40:50 > 0:40:53none the worse for wear.
0:40:57 > 0:41:01But it's his mother that Marembo is trying to win favour with.
0:41:05 > 0:41:09And she doesn't seem the least bit impressed.
0:41:13 > 0:41:15It's only with the respect from the group
0:41:15 > 0:41:18that a silverback can become a great leader.
0:41:19 > 0:41:24Marembo's quest for dominance doesn't look good.
0:41:29 > 0:41:32GRUNTING AND CHEST-BEATING
0:41:34 > 0:41:37THEY TALK QUIETLY
0:41:40 > 0:41:44Back on the volcanoes, there's even more trouble for Titus.
0:41:44 > 0:41:49So the situation is that there's another silverback up there.
0:41:49 > 0:41:52The group is here and the other silverback is up there.
0:41:52 > 0:41:55It's not Rano, it's another silverback.
0:41:58 > 0:42:00CHEST BEATS
0:42:00 > 0:42:02GRUNTS REASSURINGLY
0:42:07 > 0:42:12Titus is under incredible pressure from his son Rano,
0:42:12 > 0:42:15and now there's another challenger for his crown.
0:42:17 > 0:42:21You can imagine how this is stressful for Titus.
0:42:26 > 0:42:28He already has to deal with this one,
0:42:28 > 0:42:30and then this other silverback here.
0:42:32 > 0:42:33It's too much for him.
0:42:33 > 0:42:36GRUNTING AND CHEST-BEATING
0:42:36 > 0:42:38I can see him.
0:42:40 > 0:42:42HE GRUNTS REASSURINGLY
0:42:42 > 0:42:45CHEST BEATS
0:42:59 > 0:43:03Rano's displays are becoming more frequent,
0:43:03 > 0:43:06but this time they're not directed at Titus.
0:43:13 > 0:43:16His chest beats carry across the mountain,
0:43:16 > 0:43:22telling the second challenger that Rano got here first.
0:43:29 > 0:43:32Rano's displays keep the new impostor at bay.
0:43:42 > 0:43:47Titus's son is stamping his claim on his father's group.
0:43:50 > 0:43:52CHEST BEATS
0:43:59 > 0:44:03Rano's campaign has been relentless,
0:44:03 > 0:44:05and it seems to be paying off.
0:44:09 > 0:44:14But what does this mean for the ageing king?
0:44:19 > 0:44:23Titus and the little orphan are exhausted.
0:44:26 > 0:44:29They've been on the move for ten days.
0:44:36 > 0:44:39Felix can see the tide turning.
0:44:41 > 0:44:44The orphan sticks close to Titus.
0:44:48 > 0:44:52But the ever-present threat from Rano is just metres away.
0:44:55 > 0:45:00And one of the young males seems to be accepting him into the group.
0:45:06 > 0:45:09For Titus, this is no longer a battle
0:45:09 > 0:45:11for the leadership of his group.
0:45:13 > 0:45:15It's become a battle for survival.
0:45:19 > 0:45:25His life and the life of the little orphan now hang in the balance.
0:45:44 > 0:45:49In Bwindi, Rukina and his group are waking to another sunny day.
0:46:18 > 0:46:21Martha spots teenage silverback Marembo.
0:46:28 > 0:46:34He descends from his treetop haven and reluctantly follows the group.
0:46:37 > 0:46:41His heroic efforts to keep them safe have been completely ignored.
0:46:46 > 0:46:50The group has found a tree covered in bracket fungi.
0:46:58 > 0:47:02As always, Rukina is first to help himself...
0:47:05 > 0:47:08..before moving off to enjoy his prize.
0:47:09 > 0:47:12MEWING
0:47:19 > 0:47:22Little Ponoka steps up to take his turn.
0:47:33 > 0:47:36Marembo watches from the sidelines.
0:47:40 > 0:47:44Even the youngest member of the group gets to feed before him.
0:47:46 > 0:47:50The injustice is too much for one gorilla to bear.
0:48:02 > 0:48:04As if to rub salt into the wound,
0:48:04 > 0:48:08Rukina is flaunting another privilege of the dominant silverback...
0:48:13 > 0:48:16..right under Marembo's nose.
0:48:27 > 0:48:30Rukina leads the group away into the forest...
0:48:31 > 0:48:34..very much a silverback in control.
0:48:40 > 0:48:44But, for once, Marembo doesn't follow.
0:48:46 > 0:48:49The teenage silverback chooses a different path...
0:48:52 > 0:48:55..and walks alone into the forest.
0:49:01 > 0:49:05Martha suspects that this time his departure is final.
0:49:12 > 0:49:18He's no match for Rukina and is off to seek an easier target.
0:49:25 > 0:49:30It may be Marembo will never become a gorilla leader.
0:49:31 > 0:49:34But one thing's for sure...
0:49:34 > 0:49:38like all young males, he'll never stop trying.
0:50:00 > 0:50:04On the volcanoes, there's no reprieve for Titus.
0:50:09 > 0:50:12The pressure from his son Rano is relentless.
0:50:14 > 0:50:19Felix has been monitoring Titus's health,
0:50:19 > 0:50:22and it's taken a turn for the worse.
0:50:26 > 0:50:30He's called in Magda, the gorilla doctor.
0:50:37 > 0:50:40She's part of an elite team of seven vets
0:50:40 > 0:50:44who treat the mountain gorillas if their lives are at risk.
0:50:50 > 0:50:53Today, Titus is her priority.
0:50:55 > 0:51:00He's exhausted and has picked up an injury.
0:51:04 > 0:51:07Felix leads Magda to the group.
0:51:07 > 0:51:11She makes reassuring noises to let them know she's coming.
0:51:15 > 0:51:18Oh, he's nursing his right hand.
0:51:23 > 0:51:25Instead of putting it like this, he puts it like this.
0:51:25 > 0:51:27There must be something here.
0:51:28 > 0:51:33Magda has spotted a deep wound across Titus's wrist,
0:51:33 > 0:51:35making it hard for him to walk.
0:51:35 > 0:51:38SHE GRUNTS REASSURINGLY
0:51:38 > 0:51:43Now you can see the wound under his knee, under his right knee.
0:51:43 > 0:51:44There's always a little worry,
0:51:44 > 0:51:47especially with the older silverback like that,
0:51:47 > 0:51:51that there can be infection, there can be some deeper tendon injury.
0:51:55 > 0:51:59The battle scars from Rano's campaign are starting to show.
0:52:04 > 0:52:06You can see that their tummies
0:52:06 > 0:52:08are not as full as they would be normally.
0:52:08 > 0:52:13This is siesta time, but they can't afford siesta now
0:52:13 > 0:52:17because they were running since morning, so now they have to eat.
0:52:27 > 0:52:32As a gorilla doctor, she hopes to save every animal.
0:52:34 > 0:52:38But some cases are beyond her control.
0:52:42 > 0:52:44Magda can do nothing.
0:52:44 > 0:52:50To anaesthetise and treat Titus now would mean a sure victory for Rano.
0:52:57 > 0:53:02It's with heavy hearts Magda and Felix leave Titus for the night.
0:53:07 > 0:53:10Nature must take its course.
0:53:14 > 0:53:19Back in his office, Felix records the events of the last few weeks...
0:53:22 > 0:53:27..the latest chapter in the 35-year story of Titus's life.
0:53:39 > 0:53:44Titus has shown what it takes to be a great silverback leader...
0:53:50 > 0:53:54..a gorilla who came from humble beginnings,
0:53:54 > 0:53:59who, on the slopes of the volcanoes, rose against much adversity
0:53:59 > 0:54:03to be the most successful silverback ever recorded.
0:54:14 > 0:54:16He's sired more offspring
0:54:16 > 0:54:21and lived longer than any other known mountain gorilla.
0:54:25 > 0:54:28He's protected his group until the end...
0:54:33 > 0:54:38..eventually hounded to exhaustion by his own son.
0:54:43 > 0:54:46I don't know how long Titus can keep going.
0:54:49 > 0:54:51This could be the end of Titus.
0:54:56 > 0:54:58But the legacy of Titus will live on.
0:55:04 > 0:55:09The fate of his group now rests with his own flesh and blood.
0:55:18 > 0:55:21At first light, Felix climbs the volcano
0:55:21 > 0:55:25to see Titus for what could be the last time.
0:55:27 > 0:55:29HOOTING
0:55:32 > 0:55:35Rano remains strong and determined.
0:55:37 > 0:55:41For weeks, he's intimidated, terrorised
0:55:41 > 0:55:44and wounded his own father.
0:55:46 > 0:55:49Soon the prize of dominance will be his.
0:56:05 > 0:56:08Titus has finally managed to rest...
0:56:17 > 0:56:21..surrounded by his most loyal followers.
0:56:26 > 0:56:30The little orphan gently cleans his wound.
0:56:44 > 0:56:47Titus is dying.
0:56:57 > 0:57:01Felix has borne witness to a momentous event...
0:57:05 > 0:57:07..the crowning of a new silverback...
0:57:14 > 0:57:18..and the last stand of the Silverback King.
0:57:54 > 0:57:56Next time on Mountain Gorilla...
0:57:59 > 0:58:03...we look at what the future holds for one of our closest relatives.
0:58:05 > 0:58:08Are they safe in our hands?
0:58:09 > 0:58:12Titus' group struggles to accept a new king...
0:58:14 > 0:58:16..and Rano leads them into trouble.
0:58:19 > 0:58:22And with Titus gone...
0:58:23 > 0:58:28..the little orphan's life hangs in the balance.
0:58:33 > 0:58:36Subtitles by Red Bee Media Ltd
0:58:36 > 0:58:39E-mail subtitling@bbc.co.uk