No continent experiences seasonal change as extreme as North America.
From tornados that roar across the prairies, to Arctic air sweeping through the humid, southern swamps - this is a land where pioneering animals thrive.
In winter, lynx prowl the snowy Yukon for snowshoe hares, whilst Florida manatees seek hot springs to escape the freeze. In the creeks of Tennessee, fish build spectacular underwater pyramids to find a mate.
Fireflies light up the forests during summer nights, roadrunners cruise the spectacular deserts of Arizona and polar bears leap from rocks to hunt beluga whales.
Stories from filming
Number of days filming: 307
The crew, who weren't supposed to touch the manatees, ended up being rolled around by them in the water - evidently the manatees weren't following the same rule book!
Underwater filming tips - filming crew played the Jurassic Park theme tune to attract beluga whales
The crew were asked by several members of the public in the US whether some of the cameramen were dead as they lay face down in rivers still as statues filming chub
A polar bear picked up the crews boat anchor off the bottom and brought it up in its mouth!
Filming locations and species
1. Canada lynx - Canada 2. River chub - Tennessee 3. Black bear - Canada 4. Fireflies and orb-weaver spider - Mississippi and Ohio 5. Prairie dogs - South Dakota 6. Roadrunner - Arizona 7. Grey mullet and tarpon - Florida 8. Manatee - Florida 9. Polar bear and beluga whale - Canada
Facts on species featured
There are over 150 different species of fireflies in North America and each has its own characteristic flash code
Prairie dogs have a complex means of communication that's even better than that of chimpanzees and dolphins
Black bears can be 30% heavier in autumn than they are in spring
Manatee - these herbivores munch on food for almost half the day, eating ten percent of their body weight in plant mass every day
North America: did you know?
North America is over one hundred times the size of Great Britain
Temperatures can range from 50 degrees celcius to minus 40
In Canada’s Yukon territory, two metres of snow can fall in a single day
North America has over 10 thousand species of wildflowers
The tides along North America are the largest in the world, each time the tide retreats 7,000 square miles of extra coastline is uncovered in the space of just two hours
In the open plains from Canada to Mexico there are over a million square miles where there are no trees in sight
An interview with Chadden Hunter, producer of North America
What was your approach for the North America film?
North America will be a continent that a lot of people feel like they're familiar with. The challenge was to really surprise them: We wanted to make you the viewer realize that there's a whole side of North America you haven't seen. It's blessed with a lot of differing conditions, from the Arctic in the north to the subtropics in Florida, with some of the most dynamic weather on the planet. It has this north-south mountain range, the Rockies. In Europe and Asia and other northern hemisphere continents mountains running east-west block Arctic air from meeting the tropics. But in North America the mountains run north-south, which means that you get Arctic air pouring down and meeting tropical air. That means you get fantastic things like Tornado Alley, and some dramatic seasonal changes. Take the southern swamps: they actually freeze over at times. These swamps that we think are completely tropical, covered in lichen with alligators in them… well, we have footage of alligators in Louisiana completely frozen in, locked into the ice with just their nostrils poking through. They're on the edge of survival.
That fits in to our overarching story in the North America episode which is that animals there are like the pioneers because the conditions in North America can be so brutal. The onset of winter storms or tornadoes or other climatic conditions has meant that to survive there, animals have really had to show a pioneering spirit or do something above and beyond.
Can you give us an example?
A mother manatee has that - when the water gets so cold, it'll kill their calf. She has to take her calf on this epic hundred-mile journey through all the waterways and swamps and she has to remember where a certain hot spring is to basically keep her calf alive. Elsewhere we have the lynx hunting in the north. It's a small cat but it's pushed further north than any other cat species on the planet. These animals are pushing the boundaries.
What was the hardest sequence to film?
Probably the most technologically challenging sequence was the fireflies. North America has these famous firefly spectacles. The low light technology has just come of age so that we can really go into that dark world. We took some of that latest technology, but instead of just having a camera sat there and having a time lapse of fireflies looking like fairy lights, we wanted to make you feel like you're part of the firefly experience. So we used cable dollies [cameras running along wires] through the forest where we would glide a camera down the cable while shooting time lapse at low light, trying to pick up this wonderful secret world. It feels like you've got science fiction vision, and when composer Hans Zimmer first saw it he said, “I can't wait to do the music for that one.”