Arctic foxes resort to cannibalism as they struggle to find food in a warming world.
It's just one of the never-before-seen behaviors in Sir David Attenborough's latest series - Mammals.
It deals with how these animals adapt to a world that is rapidly changing the dominant mammal - man.
We also see otters frolicking on Singapore's busy roads and lemurs clinging to toothbrush trees in an attempt to cool off in the rising temperatures.
Mammals is demanding viewing material, but it also shows the unprecedented resourcefulness of the world's most successful animals.
In the last, sixth episode of the series, Sir David Attenborough says:
"If we make the right decisions, we can protect the future not only of our mammal relatives, but of all life on Earth."
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The series appeared 20 years after the original series called Život siasar.
During that time, technology has advanced significantly, allowing the BBC's Nature Newsroom and its partners to record sequences that were previously thought to be impossible.
The opening episode of the series was filmed entirely in the dark - revealing how an African leopard uses specially adapted vision to hunt sleeping monkeys.
"Thermal cameras today are amazing, the detail you can see is amazing. You can see the fur, you can see the animal's whiskers, technology has opened up a whole new world for us," explains Scott Alexander, producer of the show.
In order to record some sequences, the team had to make an extra effort.
For the fourth episode, "Cold," special sleeping pods were made so that the camera crew could stay on the ice in Svalbard, Norway for days while tracking a polar bear.
As a result, the team was able to film a polar bear hunting reindeer deep on land - a behavior thought to have been acquired because melting sea ice made it harder for it to hunt seals.
"It illustrates the flexibility of polar bears to compensate for the loss of hunting opportunities for marine, mammalian prey," says associate professor John Whiteman, of Old Dominion University and principal investigator of the International Polar Bear Conservation Organization, who also advised the authors of the series.
But he adds that studies have shown that this prey is not enough to replace the calories they need.
"And that's why the most important action that can be taken to protect polar bears as a species is to fight climate change."
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'Evolution in Real Time'
In the two decades that have passed since the previous series, the scale of human expansion also catches the eye.
Since 2000, almost 1,9 million square kilometers of habitat has been lost - about eight times the size of the UK - and one of the biggest causes is food production.
"Today, almost half of the world's habitable land is used for agriculture. Across Southeast Asia, vast palm oil plantations are replacing pristine forests," Attenborough warns us in the second episode of "The New Wild."
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Deforestation means food sources for local wildlife such as pig-tailed macaques are decreasing.
But, despite that, the episode brings an incredible story of their survival.
A family of macaques was filmed entering a palm oil plantation and catching the rats that now live there.
"These pig-tailed macaques were mostly vegetarians, and now they're becoming carnivores," episode producer Lydia Baines told BBC News.
"Animals have to adapt in real time, it's practically live evolution. Darwin would have been absolutely fascinated by this," she added.
But not all mammals are so successful.
In one episode, we learn that rising temperatures in the Arctic have caused the sea to freeze later in the year, and without sea ice, polar bears and arctic foxes cannot hunt.
For one fox, the wait was too long and the team thinks she died of starvation, and the hunger forced the other foxes to feed on her.
In another devastating scene, baby howler monkeys are orphaned when their parents mistake them for an electrified fence of tree branches.
In addition to being heartbreaking, filming animals has also led to scientific discoveries.
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Dr Kristina Cooper, senior lecturer in animal physiology at Curtin University, Perth, worked with the BBC's Natural History Unit to help them track the animals for episode five.
While fitting transmitters to the animals for the series, they heard the hedgehogs making sounds to each other underground - a phenomenon that had only been heard once before and had never been filmed.
The discovery led to a new scientific study by Dr. Cooper and her team.
She says this research is crucial if we want to protect animals.
"So if we understand how animals function and how they satisfy all the needs, then we will have an idea of how they might respond to a changing world.
"Then we can take steps to protect the species," she explained.
The series returned to some of the mammals filmed for the original series to see how human intervention helps them survive.
The blue whale was critically endangered until a ban on whaling allowed its population to recover.
Series Mammals is investigating how they now face a new threat from shipping, but scientists' work to track them is helping to introduce safety measures such as slower waterways.
Scott Alexander says this shows how we can work together with mammals to help each other.
"For me, the message of the show is that the planet is fantastic, that we should do everything we can to protect it so that we can live together with these animals and share this incredible diversity," he says.
Watch the video: How a polar bear sees the world around it
Broadcasting of the series Mammals starts on BBC One at 19pm UK Summer Time on Sunday.
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