0:00:10 > 0:00:14In the heart of Africa, straddling the borders of Rwanda, Uganda and Congo
0:00:14 > 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 > 0:00:35For over 50 years, they've been caught in the crossfire
0:00:35 > 0:00:42of a brutal civil war, fuelled by an ever-increasing human population.
0:00:42 > 0:00:46Yet still they survive, under constant surveillance
0:00:46 > 0:00:50from a dedicated group of people.
0:00:50 > 0:00:53A species in intensive care.
0:00:56 > 0:00:59Our cameras have been given privileged access
0:00:59 > 0:01:03to these amazing animals, revealing their secret lives.
0:01:09 > 0:01:14We'll experience the challenge of keeping an extended family together,
0:01:14 > 0:01:20the joy of growing up wild in a rainforest playground,
0:01:20 > 0:01:25the love of a father for his abandoned child.
0:01:26 > 0:01:28And above all,
0:01:28 > 0:01:33the extraordinary battle to save one of our closest relatives.
0:02:05 > 0:02:08For a million years, the Virunga Volcanoes
0:02:08 > 0:02:10have dominated the heart of Africa.
0:02:16 > 0:02:20A volatile presence in a volatile region.
0:02:32 > 0:02:35On their lush slopes, nourished with centuries of volcanic ash,
0:02:35 > 0:02:40lives the world's largest single population of mountain gorillas.
0:02:45 > 0:02:49Since Dian Fossey started her pioneering research
0:02:49 > 0:02:52here in Rwanda over 40 years ago,
0:02:52 > 0:02:55they've become one of the planet's most cherished animal communities.
0:03:09 > 0:03:13April is a dangerous month in the Rwandan Virungas.
0:03:16 > 0:03:19The long rains arrive, and the gorillas head down
0:03:19 > 0:03:24into the bamboo zone on the very edge of their protected area.
0:03:26 > 0:03:29It can be a perilous journey.
0:03:29 > 0:03:35The bamboo contains illegal snares set for forest antelope and pigs,
0:03:35 > 0:03:38but potentially lethal for gorillas.
0:03:49 > 0:03:53It's a worrying time for research scientist Felix Ndagijimana,
0:03:53 > 0:03:57who has trekked through the mist to a height of 4,000m.
0:04:01 > 0:04:03(GRUNTING)
0:04:18 > 0:04:23Continuing Fossey's work, Felix watches and records
0:04:23 > 0:04:28every detail of the gorillas' lives so they can be effectively protected.
0:04:34 > 0:04:39Today he's on the trail of silverback patriarch Cantsbee...
0:04:43 > 0:04:46..the leader of the biggest gorilla family in the world.
0:05:00 > 0:05:07This 46-strong group contains female consorts, junior silverbacks,
0:05:07 > 0:05:09adolescent blackbacks...
0:05:12 > 0:05:15...and a tiny newborn baby,
0:05:15 > 0:05:16just hours old.
0:05:21 > 0:05:26At 32, Cantsbee is one of the most successful silverbacks recorded
0:05:26 > 0:05:29since the research programme started in 1967.
0:05:29 > 0:05:32He was even named by Dian herself.
0:05:41 > 0:05:47Everybody thought that Puck, the mother of Cantsbee, was male
0:05:47 > 0:05:49until the day she gave birth.
0:05:49 > 0:05:52And when they told Dian Fossey, she said, "It can't be."
0:05:52 > 0:05:57So, from that day on, the name of the infant - Cantsbee.
0:06:00 > 0:06:05Three decades on, the bloodline continues.
0:06:17 > 0:06:20THUNDER
0:06:20 > 0:06:22The clouds are building.
0:06:22 > 0:06:25Soon Felix will follow the family on the difficult journey
0:06:25 > 0:06:30down the slopes towards the bamboo, recording every move they make.
0:06:45 > 0:06:48This privileged insight into their world is possible
0:06:48 > 0:06:53only because of Fossey's pioneering work with a process known as habituation,
0:06:53 > 0:06:57in which humans spend more and more time with the gorillas
0:06:57 > 0:07:00until they're completely accepted.
0:07:19 > 0:07:2640km north of the Virungas lies Uganda's Bwindi Impenetrable Forest.
0:07:32 > 0:07:36It's home to the rest of the world's mountain gorillas...
0:07:40 > 0:07:44..and to a scientist carrying the work of Dian Fossey into new territory...
0:07:48 > 0:07:52...American Martha Robbins.
0:08:00 > 0:08:04Bwindi contains only 300 mountain gorillas,
0:08:04 > 0:08:08and there are another 380, 400 in the Virunga Volcanoes.
0:08:08 > 0:08:13We could put the entire population of Bwindi onto a jumbo jet.
0:08:13 > 0:08:16It might be difficult to get them onto a jet, but...
0:08:17 > 0:08:20And when you think about how few there are,
0:08:20 > 0:08:24every birth really does matter, and every gorilla is very important
0:08:24 > 0:08:28to maintaining this very unique, special population.
0:08:34 > 0:08:37Like Fossey in Rwanda, Martha has carefully habituated
0:08:37 > 0:08:40mountain gorillas to her presence.
0:08:44 > 0:08:47Now, after a dozen painstaking years,
0:08:47 > 0:08:53the 14 animals in her research group trust her completely.
0:09:02 > 0:09:05At the moment, she's particularly interested
0:09:05 > 0:09:10in a 15-year-old junior silverback, Marembo,
0:09:10 > 0:09:12an ape at a crossroads in his life.
0:09:19 > 0:09:22Marembo's really at that age where he needs to start being
0:09:22 > 0:09:26a big, mature silverback, but at the same time, he still likes to play.
0:09:29 > 0:09:31One of the things that's really nice when you see gorillas
0:09:31 > 0:09:34of very different age playing
0:09:34 > 0:09:37is that the older ones really temper themselves down.
0:09:39 > 0:09:41They'll play quite gently with the younger individuals.
0:09:52 > 0:09:55Marembo isn't a child any more.
0:09:55 > 0:10:00For several weeks, he's been spending more and more time alone.
0:10:03 > 0:10:08He seems ready to break from his family and try life on his own.
0:10:09 > 0:10:11But it's a big decision.
0:10:14 > 0:10:18And like a human teenager leaving home for the first time,
0:10:18 > 0:10:19he feels torn.
0:10:34 > 0:10:38The Rwandan town of Ruhengeri at the foot of the Virunga Volcanoes
0:10:38 > 0:10:42is the centre for all gorilla operations.
0:10:49 > 0:10:52The National Park headquarters is here.
0:10:58 > 0:11:00And the Karisoke Study Center...
0:11:02 > 0:11:06..a hive of activity for trackers, field staff
0:11:06 > 0:11:08and research scientists like Felix.
0:11:13 > 0:11:16It's also the headquarters of the Mountain Gorilla Veterinary Project...
0:11:19 > 0:11:22..a team of skilled specialists closely monitoring
0:11:22 > 0:11:24the health of every known gorilla.
0:11:30 > 0:11:33Their work extends across the three countries
0:11:33 > 0:11:38that share the world's last 700 mountain gorillas.
0:11:43 > 0:11:48On the Rwandan side, the biggest priority is little Umoja.
0:11:50 > 0:11:53She's a small three-year-old female
0:11:53 > 0:11:56and never strays far from her father, Kwitonda,
0:11:56 > 0:12:00one of the oldest silverbacks in the National Park.
0:12:08 > 0:12:11It's a touching relationship,
0:12:11 > 0:12:14but the youngster's life hasn't been easy.
0:12:14 > 0:12:19Recently, as Kwitonda tried to prevent a rival male from stealing his females,
0:12:19 > 0:12:23Umoja was caught in the crossfire and badly injured.
0:12:31 > 0:12:36Her life was saved only by the timely intervention of vet Magda Braum.
0:12:40 > 0:12:45Here was Umoja, with a badly injured wrist,
0:12:45 > 0:12:48and intestines are hanging out of her tummy.
0:12:51 > 0:12:53She was bitten and she was thrown high in the air,
0:12:53 > 0:12:55fell down, was bitten again.
0:12:55 > 0:12:57So they were pretty sure that she was dead.
0:13:01 > 0:13:06Magda operated on the spot, and Umoja was returned to her mother,
0:13:06 > 0:13:10who gently nursed her back to a fragile health.
0:13:10 > 0:13:14Because what we've done was important, but I think
0:13:14 > 0:13:18without what she has done, there was absolutely no chance of surviving.
0:13:25 > 0:13:29But this wasn't the end of Umoja's problems.
0:13:33 > 0:13:35Before she'd completely recovered,
0:13:35 > 0:13:38her mother deserted the group for a rival silverback...
0:13:42 > 0:13:46..leaving Kwitonda as Umoja's sole carer.
0:13:53 > 0:13:57A female gorilla would normally give round-the-clock care
0:13:57 > 0:13:59to her offspring for up to five years.
0:14:02 > 0:14:04This is a big job for the male.
0:14:06 > 0:14:09The gorilla vets and the National Park team
0:14:09 > 0:14:13are now keeping an intense watch on the abandoned infant and her father.
0:14:17 > 0:14:21They know that as the rains arrive and the nights become colder,
0:14:21 > 0:14:24she'll miss the warmth of her mother.
0:15:02 > 0:15:06In the Virungas of Rwanda, the world's largest group of mountain gorillas,
0:15:06 > 0:15:11led by silverback Cantsbee, are heading down the volcano
0:15:11 > 0:15:15towards the bamboo zone on the edge of their protected area.
0:15:32 > 0:15:38As the clouds roll in, it will bring rain, prompting fresh shoots on the bamboo.
0:15:41 > 0:15:44But there are dangers here.
0:15:53 > 0:15:58Beyond the bamboo is the most densely populated area in Africa,
0:15:58 > 0:16:02with an average of 350 people per square kilometre.
0:16:11 > 0:16:14The gorillas are encircled by humanity.
0:16:14 > 0:16:18The two forest islands of Bwindi and the Virungas
0:16:18 > 0:16:20are under enormous pressure.
0:16:26 > 0:16:30When the gorillas get close to people, they're exposed to human diseases...
0:16:35 > 0:16:39..and the risk of being caught in an illegal snare.
0:16:52 > 0:16:55Gorillas go to the bamboo zone twice a year,
0:16:55 > 0:17:01at the beginning of the rainy seasons, so in April and in December.
0:17:01 > 0:17:05So this is when they leave other areas where they range
0:17:05 > 0:17:09to feed on the bamboo, which is one of their favourite foods.
0:17:10 > 0:17:13The gorilla patriarch must be careful.
0:17:15 > 0:17:18The danger from undetected snares is high.
0:17:24 > 0:17:29With 46 gorillas to protect, he's got a tough job on his hands.
0:17:37 > 0:17:41He has support from four junior silverbacks...
0:17:47 > 0:17:50..and eight feisty younger blackback males...
0:17:52 > 0:17:56GORILLAS SCREAM
0:17:59 > 0:18:02..not all of whom can be trusted.
0:18:06 > 0:18:10This young blackback is breaking the rules.
0:18:11 > 0:18:15It's a privilege normally reserved for the dominant silverback.
0:18:25 > 0:18:29But Cantsbee needs to reward his lieutenants,
0:18:29 > 0:18:31and sex is a powerful incentive
0:18:31 > 0:18:35to keep them in line and the group together.
0:18:38 > 0:18:42The dominant silverback needs to concentrate on the dangers
0:18:42 > 0:18:44from the outside world.
0:19:00 > 0:19:03The family are entering the bamboo zone...
0:19:09 > 0:19:11..and they have company.
0:19:56 > 0:20:01Fortunately, in this case it's the National Park's anti-poaching patrol,
0:20:01 > 0:20:05acting on a tip-off that snares have been set in this area.
0:20:05 > 0:20:10Most of the snares are actually found in the bamboo.
0:20:12 > 0:20:15They are very, very difficult to spot.
0:20:15 > 0:20:20They have to, you know, look very carefully to find these snares.
0:20:24 > 0:20:28We destroy around 1,000 snares each year.
0:20:30 > 0:20:36People come in the forest and set snares for other animals,
0:20:36 > 0:20:43for buffaloes, for antelopes, but gorillas end up getting caught in those snares.
0:20:46 > 0:20:50Poaching has always been a problem in the Virungas.
0:20:58 > 0:21:02In 1977, Dian Fossey's favourite gorilla, Digit,
0:21:02 > 0:21:08was murdered and decapitated by poachers as he tried to defend his family.
0:21:12 > 0:21:17Things have improved since then, but poaching is still a big problem.
0:21:35 > 0:21:39In Uganda, teenage silverback Marembo and most of his group
0:21:39 > 0:21:42have moved into the trees.
0:21:49 > 0:21:54Unlike their cousins 40km away in Rwanda,
0:21:54 > 0:21:56these gorillas spend a lot of time up here,
0:21:56 > 0:21:58and it's where they find much of their food.
0:22:01 > 0:22:05That means climbing is an important skill to master.
0:22:48 > 0:22:52Junior silverback Marembo is on the edge of the family,
0:22:52 > 0:22:55his eyes fixed on the dominant male.
0:22:58 > 0:23:02In a group of this size, there's only room for one leader...
0:23:04 > 0:23:08..and a teenager can feel increasingly marginalised.
0:23:10 > 0:23:15Males have sort of two strategies as to how to become the leader of the group.
0:23:15 > 0:23:19They can either leave the group and become a solitary male
0:23:19 > 0:23:22and try to attract females and form their own group, or they'll try to become
0:23:22 > 0:23:26dominant from within the group, where slowly, over time,
0:23:26 > 0:23:28they'll try to outrank the dominant male.
0:23:43 > 0:23:47Mating rights are monopolised by the dominant silverback...
0:23:49 > 0:23:52...and since the leader has no real need for him in the group,
0:23:52 > 0:23:57Marembo isn't permitted access to receptive females.
0:24:05 > 0:24:08(It's quite likely they'll mate maybe once every hour,
0:24:08 > 0:24:11(once every hour and a half, two hours, today.)
0:24:17 > 0:24:21If the junior silverback wants to pass on his genes,
0:24:21 > 0:24:24his best option is to leave.
0:24:39 > 0:24:46In Rwanda, abandoned infant Umoja stays close to her father, Kwitonda.
0:24:52 > 0:24:56Since her mother left the group for another male,
0:24:56 > 0:24:59she's become completely dependent on her remaining parent.
0:25:02 > 0:25:04Kwitonda is an experienced silverback,
0:25:04 > 0:25:08but he's relatively new to Rwanda, having crossed the border from Congo
0:25:08 > 0:25:11with his family six years ago.
0:25:17 > 0:25:22The land he left behind has seen much strife for gorillas and people.
0:25:27 > 0:25:32In 2007, a gorilla family was brutally murdered here...
0:25:33 > 0:25:37...their deaths almost certainly a result of the fierce competition
0:25:37 > 0:25:40for the forest's precious resources.
0:25:54 > 0:25:59Many of Kwitonda's family bear the scars of war.
0:25:59 > 0:26:04Missing fingers and limbs are the legacy of a time spent in a forest
0:26:04 > 0:26:07bristling with snares.
0:26:19 > 0:26:23But at the moment, the main concern for the silverback -
0:26:23 > 0:26:28and for the veterinary team that monitors her - is three-year-old Umoja.
0:26:34 > 0:26:37An infant of this age should be with her mother.
0:26:37 > 0:26:41Almost every life skill needed to survive in the forest
0:26:41 > 0:26:46is taught by females in an education lasting at least five years.
0:26:53 > 0:26:57A three-year-old should also keep a close physical connection
0:26:57 > 0:27:01with its mother, who will shield it from the extremes of the Virungas' weather.
0:27:13 > 0:27:16The quality of her father's childcare
0:27:16 > 0:27:21could make the difference between life and death for Umoja.
0:27:43 > 0:27:48A storm is brewing above the Virunga Volcanoes in Rwanda.
0:28:16 > 0:28:19It can rain here at any time,
0:28:19 > 0:28:24but from February to May, it pours almost every day.
0:28:37 > 0:28:41On the lower slopes of the volcanoes, the stands of bamboo
0:28:41 > 0:28:43are already producing new shoots.
0:28:58 > 0:29:00Cantsbee must remain vigilant.
0:29:03 > 0:29:08His 46-strong family is within metres of the park border
0:29:08 > 0:29:11and in danger from illegal snares.
0:29:16 > 0:29:18For now, though, he eats.
0:29:18 > 0:29:23It's something a gorilla needs to do for at least five hours a day.
0:29:34 > 0:29:37Bamboo on its own is too rich for gorillas.
0:29:37 > 0:29:40They need to mix it with other plants or they'll get diarrhoea.
0:29:49 > 0:29:52Bindweed is another popular delicacy.
0:29:55 > 0:29:59Cantsbee rolls it into a neat wrap before tucking in.
0:30:07 > 0:30:10But this is a surprisingly tricky skill to master.
0:30:10 > 0:30:13CHOKES
0:30:14 > 0:30:17You must remember to keep the sticky bits on the inside.
0:30:39 > 0:30:42It's five in the afternoon, and the temperature's dropping fast.
0:30:45 > 0:30:47The weather is closing in.
0:30:53 > 0:30:56Adult gorillas rely on their shaggy coats
0:30:56 > 0:31:00to keep them warm in the damp high altitude.
0:31:00 > 0:31:03But infants need a mother's embrace,
0:31:03 > 0:31:06and that's one thing three-year-old Umoja doesn't have.
0:31:13 > 0:31:18Since her mother left, she's been in the sole care of her father, Kwitonda.
0:31:21 > 0:31:25But the park's veterinary team are still very concerned.
0:31:26 > 0:31:29The pair are under constant surveillance.
0:31:39 > 0:31:42Mountain gorillas care for other family members
0:31:42 > 0:31:45in an extraordinarily loving way.
0:31:51 > 0:31:55The bonds between dominant males and their offspring
0:31:55 > 0:31:58are the most powerful of all, and a mature silverback
0:31:58 > 0:32:02will go to incredible lengths to protect his genetic future.
0:32:05 > 0:32:11Now Umoja must survive the first stormy night of the rainy season alone.
0:32:14 > 0:32:16At three years old,
0:32:16 > 0:32:20Umoja should be getting lessons in nest-building from her mother.
0:32:30 > 0:32:33But since she left, only Kwitonda has been able to help her.
0:32:53 > 0:32:55For the older, more accomplished gorillas,
0:32:55 > 0:33:00branches are folded over to make fresh springy beds in the trees.
0:33:00 > 0:33:03This gets them away from the cold ground
0:33:03 > 0:33:05and puts a whole range of foods within reach
0:33:05 > 0:33:07in case they get hungry in the night.
0:33:14 > 0:33:18But it's a skill Umoja's father can't pass on.
0:33:18 > 0:33:22He's too heavy for the trees and nests on the ground.
0:33:29 > 0:33:34THUNDER
0:33:37 > 0:33:40While the other infants snuggle up to their mothers,
0:33:40 > 0:33:43Umoja struggles to complete a nest of her own.
0:33:48 > 0:33:51As the storm approaches and the light fades,
0:33:51 > 0:33:54Umoja is ill-equipped for the harsh weather.
0:33:54 > 0:33:57THUNDER
0:34:11 > 0:34:15This is no night for a three-year-old gorilla to be sleeping alone.
0:34:52 > 0:34:56The rains have also arrived in Uganda,
0:34:56 > 0:35:01where scientist Martha Robbins has noted a significant development.
0:35:09 > 0:35:12Young silverback Marembo has vanished.
0:35:15 > 0:35:21He's made the brave decision to break with his family and strike out on his own.
0:36:16 > 0:36:20A new day dawns clear and bright in Rwanda.
0:36:51 > 0:36:53It's 6am, and the veterinary team
0:36:53 > 0:36:58is making its way back towards the spot where Kwitonda's group spent the night.
0:36:58 > 0:37:03The whole team is worried about his motherless daughter, Umoja.
0:37:10 > 0:37:14Gorillas often wake late during the rainy season.
0:37:14 > 0:37:19All around, mothers and their infants emerge from their nests.
0:37:19 > 0:37:21But there's no sign of Umoja.
0:37:26 > 0:37:28GRUNTING
0:37:31 > 0:37:35Her silverback father, Kwitonda, is one of the last to wake.
0:37:35 > 0:37:39His huge bulk has kept him warm through the long, wet night,
0:37:39 > 0:37:43and he seems reluctant to leave the leafy nest.
0:37:45 > 0:37:47He's not alone.
0:37:53 > 0:37:55Umoja is at his side.
0:38:13 > 0:38:16The motherless infant must have climbed in during the long, wet night
0:38:16 > 0:38:19to share her father's warmth.
0:38:28 > 0:38:33Umoja gently grooms her father, an illustration of the powerful bond
0:38:33 > 0:38:35that the pair are building.
0:38:42 > 0:38:45The little gorilla still has difficult times ahead,
0:38:45 > 0:38:50but Kwitonda is growing into his role as a hands-on father.
0:39:04 > 0:39:06In Uganda, there's still no sign of Marembo,
0:39:06 > 0:39:09the missing junior silverback.
0:39:13 > 0:39:16Martha Robbins temporarily abandons her search
0:39:16 > 0:39:18to travel to the far side of the forest.
0:39:18 > 0:39:22Here, a new family of gorillas are being habituated.
0:39:28 > 0:39:33Getting gorillas used to humans is a long and difficult task.
0:39:33 > 0:39:36GORILLAS SCREAM AND GRUNT
0:39:36 > 0:39:40They're not naturally aggressive creatures...
0:39:41 > 0:39:46..but they won't tolerate people if they think they pose a threat,
0:39:46 > 0:39:50as the park staff here know only too well.
0:39:50 > 0:39:53You don't know what to expect from their group.
0:39:53 > 0:39:56They come charging with all their teeth out,
0:39:56 > 0:39:58and that's the silverback, usually.
0:39:58 > 0:40:02It comes, the dominant silverback, because it's trying to protect the group.
0:40:05 > 0:40:08This group demands caution.
0:40:08 > 0:40:12At 34 strong, they're the largest family in the forest,
0:40:12 > 0:40:15with no less than four huge silverbacks.
0:40:18 > 0:40:21Martha and the team must approach with care.
0:40:22 > 0:40:24Aaah!
0:40:24 > 0:40:27They move in, making reassuring noises.
0:40:27 > 0:40:32THEY GRUNT
0:40:32 > 0:40:35The family is now just a few metres ahead.
0:40:35 > 0:40:37GORILLAS SHRIEK
0:40:57 > 0:40:59That's an alarm bark, a fear bark,
0:40:59 > 0:41:01so there are some quite close.
0:41:11 > 0:41:17After the first aggressive reaction, the mood calms.
0:41:17 > 0:41:19The team move forward.
0:41:27 > 0:41:31They're all watching us all the time.
0:41:31 > 0:41:34It's like if you have new visitors or strangers into your house,
0:41:34 > 0:41:36you'd be very wary of what they were doing.
0:41:46 > 0:41:50The photographs record each gorilla's unique features.
0:41:54 > 0:41:56Eventually, they'll be given names too.
0:42:01 > 0:42:04Martha will advise the National Park team if and when the gorillas
0:42:04 > 0:42:06are ready to meet visitors.
0:42:08 > 0:42:13But for that to happen, they must be calm and confident.
0:42:13 > 0:42:16- The gorillas are used to the uniform.- To these nice uniforms.
0:42:17 > 0:42:20So now we have to get, like, two, four tourists,
0:42:20 > 0:42:25so that they try to get used to different faces with these uniforms.
0:42:27 > 0:42:30HUMANS GRUNT
0:42:33 > 0:42:36GORILLA SCREAMS
0:42:40 > 0:42:42The reaction of a mature female suggests
0:42:42 > 0:42:44they aren't quite ready for visitors just yet.
0:42:44 > 0:42:49But over the next few months, the gentle habituation process will continue
0:42:49 > 0:42:55until the silverback is as relaxed with humans as Kwitonda and Cantsbee.
0:43:08 > 0:43:12Tourist visits have become the life-blood of gorilla conservation
0:43:12 > 0:43:13in the forest and the volcanoes.
0:43:18 > 0:43:22It was an idea Dian Fossey initially rejected as being too intrusive.
0:43:26 > 0:43:31But over the years, carefully managed tourism has provided Uganda and Rwanda
0:43:31 > 0:43:34with the revenue to look after the gorillas
0:43:34 > 0:43:37and a critical income for the people,
0:43:37 > 0:43:41many of whom live on less than a dollar a day.
0:44:00 > 0:44:03In Rwanda, single father Kwitonda and his daughter
0:44:03 > 0:44:06are crossing the park's boundary wall.
0:44:14 > 0:44:18Motherless infant Umoja follows in her father's wake,
0:44:18 > 0:44:20ready to taste a new food.
0:44:23 > 0:44:27The three-year-old is now fixed on every move her father makes.
0:44:30 > 0:44:32But there's a difficult road ahead.
0:44:32 > 0:44:36Half of all infants fail to reach maturity,
0:44:36 > 0:44:41and the lack of a mother's care means the odds are stacked against Umoja.
0:44:48 > 0:44:54The attraction here is eucalyptus sap, which gorillas find irresistible.
0:45:03 > 0:45:08Just 5km away, Cantsbee and his huge family
0:45:08 > 0:45:10have also crossed the wall.
0:45:18 > 0:45:20But there's a problem.
0:45:21 > 0:45:24Felix has found a gorilla that's been left behind.
0:45:32 > 0:45:35She's lying alone, curled up in a ball.
0:45:42 > 0:45:45Nyandwi, Cantsbee's sister.
0:45:48 > 0:45:50She's laying down and not doing anything,
0:45:50 > 0:45:53and this is, like, not a feeding session, everybody's feeding again,
0:45:53 > 0:45:58you can see that she's left behind when everybody's left, so she is perhaps sick.
0:45:59 > 0:46:03Separated from her family, she's vulnerable.
0:46:03 > 0:46:07Cantsbee's sister is in the heart of the dangerous bamboo zone
0:46:07 > 0:46:10with no protection.
0:46:12 > 0:46:15Since Felix can't stay in this part of the forest after dark,
0:46:15 > 0:46:20he can only hope that the female gorilla comes to no harm overnight.
0:46:44 > 0:46:48Not far away, the anti-poaching team prepares for a night under the stars.
0:46:53 > 0:46:56For many hours, they've swept the park for snares.
0:47:04 > 0:47:06In her forest home in Uganda,
0:47:06 > 0:47:11Martha records another day without the missing junior silverback, Marembo.
0:47:34 > 0:47:36At daybreak in Rwanda, the anti-poaching team are once again
0:47:36 > 0:47:43sweeping the park for the illegal snares that can prove fatal to gorillas.
0:47:55 > 0:47:59But, for one young female, it may be too late.
0:48:09 > 0:48:13The sick female, sister of gorilla patriarch Cantsbee,
0:48:13 > 0:48:15managed to rejoin the group.
0:48:15 > 0:48:18But as she passed through the bamboo zone,
0:48:18 > 0:48:20she caught her arm in a freshly laid snare.
0:48:20 > 0:48:23If it isn't removed, she could lose the whole limb
0:48:23 > 0:48:26and possibly even her life.
0:48:26 > 0:48:31Fortunately, Dr Lucy Spelman from the Mountain Gorilla Veterinary Project
0:48:31 > 0:48:33has joined the team.
0:48:44 > 0:48:47Before the snare rope can be cut from the gorilla's wrist,
0:48:47 > 0:48:52Dr Spelman needs to immobilise her with an anaesthetic dart.
0:48:52 > 0:48:54That's not an easy task.
0:48:59 > 0:49:05Intervening in a group of this size and strength is notoriously difficult.
0:49:07 > 0:49:12Silverback Cantsbee is supported by four huge lieutenants,
0:49:12 > 0:49:16all willing to put their lives on the line in defence of the family.
0:49:16 > 0:49:18THEY GRUNT
0:49:18 > 0:49:24If they become suspicious of Dr Spelman and the team, they will attack.
0:49:24 > 0:49:29THEY WHISPER
0:49:29 > 0:49:34This is a serious operation, and each member of the team is thoroughly briefed.
0:49:44 > 0:49:49But, for the procedure itself, Dr Spelman must go it alone.
0:49:49 > 0:49:54Fortunately, she's a wildlife vet with years of gorilla experience.
0:50:06 > 0:50:10Dr Spelman is now within a few metres of the group.
0:50:13 > 0:50:18Cantsbee rests further down the slope, while his injured sister sits alone,
0:50:18 > 0:50:22the rope snare clearly visible on her wrist.
0:50:30 > 0:50:32HE WHISPERS
0:50:57 > 0:51:00SHARP SNAP AND AGITATED GRUNTING
0:51:07 > 0:51:11Dr Spelman's taken the shot, but the young gorilla moved at the last minute
0:51:11 > 0:51:14and hasn't received the anaesthetic.
0:51:20 > 0:51:23Many hours of careful manoeuvres now lie ahead
0:51:23 > 0:51:25if the young gorilla's life is to be saved.
0:51:42 > 0:51:48In Uganda, Martha Robbins is on the trail of missing junior silverback Marembo.
0:51:52 > 0:51:54He's now been absent for a week,
0:51:54 > 0:51:58a sure sign that he's finally made the break from his family.
0:52:07 > 0:52:11The group have made their way into the swamp at the heart of the forest,
0:52:11 > 0:52:15but there's no sign of Marembo or the dominant silverback.
0:52:28 > 0:52:33The leafy curtains part, and a gorilla appears.
0:52:33 > 0:52:37It's the dominant silverback, and he's looking agitated.
0:52:37 > 0:52:41Could his mood be linked with Marembo's disappearance?
0:52:57 > 0:53:00For now, the group has a single silverback.
0:53:05 > 0:53:09Now Marembo will eke out the life of a lone wanderer
0:53:09 > 0:53:14in the leafy depths of the forest, until, hopefully, securing a family of his own.
0:53:19 > 0:53:23For Martha, it's a poignant moment.
0:53:23 > 0:53:27She's known this young silverback since he was a playful juvenile.
0:53:32 > 0:53:35Yet she can't help hoping that he may yet return.
0:53:35 > 0:53:40I bet we'll see him a little bit over the next few months.
0:53:40 > 0:53:44It's very difficult to be a successful silverback.
0:53:44 > 0:53:46He's got a few rough years ahead of him,
0:53:46 > 0:53:48being a solitary male and trying to acquire females,
0:53:48 > 0:53:53but I think he's got a fair chance. We'll have to wait and see.
0:54:15 > 0:54:17In Rwanda, Felix is heading out early.
0:54:17 > 0:54:20He's hoping to catch up with Cantsbee's sister,
0:54:20 > 0:54:23who was caught in the illegal snare.
0:54:30 > 0:54:35There's good news. Dr Spelman managed to anaesthetise the gorilla
0:54:35 > 0:54:37and remove the snare.
0:54:47 > 0:54:50The family is heading back to the summit of the volcano.
0:55:03 > 0:55:06There's a familiar gorilla up ahead.
0:55:08 > 0:55:11It's Cantsbee's sister, and she looks healthy.
0:55:11 > 0:55:16This is Nyandwi here, and she's doing well since the snare was removed.
0:55:16 > 0:55:22She's back in the group, she's feeding, she has no problem at all.
0:55:24 > 0:55:26It's a great outcome for the team.
0:55:26 > 0:55:28A mountain gorilla has been saved,
0:55:28 > 0:55:32and Cantsbee's family is still 46 strong.
0:55:43 > 0:55:47Further down the volcano, single father Kwitonda has also decided
0:55:47 > 0:55:49to lead his family away from the bamboo.
0:55:56 > 0:55:59Following the silverback is an unfamiliar female.
0:56:06 > 0:56:10She sits removed from the others, nursing a tiny baby.
0:56:19 > 0:56:23This should mean certain death for an infant new to the group.
0:56:23 > 0:56:28Any dominant silverback would kill a baby that was not his own.
0:56:30 > 0:56:34Yet Kwitonda has not reacted.
0:56:37 > 0:56:40But this female is no stranger.
0:56:47 > 0:56:53It's Umoja's wayward mother, who deserted Kwitonda for a rival silverback,
0:56:53 > 0:56:55but she left pregnant with his child.
0:56:58 > 0:57:02Now she's returned to seek his protection.
0:57:09 > 0:57:14The hands-on father has a new son, and Umoja has her mother back.
0:57:19 > 0:57:22How things develop now remains to be seen.
0:57:27 > 0:57:29But one thing is certain...
0:57:32 > 0:57:35..the bond between the little gorilla and her father, Kwitonda,
0:57:35 > 0:57:39will remain strong for the rest of their lives.
0:57:49 > 0:57:51Next time on Mountain Gorilla...
0:57:53 > 0:57:55..the last stand of the silverback king.
0:57:57 > 0:58:00Titus, the oldest silverback in the Virungas,
0:58:00 > 0:58:05faces his destiny in a brutal showdown with a rival male.
0:58:06 > 0:58:09He struggles to protect his dwindling family
0:58:09 > 0:58:13as the hostile intruder piles on the pressure in a war of attrition.
0:58:18 > 0:58:24Felix can do nothing but watch as the realisation dawns -
0:58:24 > 0:58:27Titus's challenger is his son.