Hummingbirds are the tiniest of birds, yet they are some of the toughest, most energetic creatures on the planet. Their unique flying abilities give them unmatched maneuverability, but at the cost of a supercharged metabolism that keeps them on the edge of survival. Hummingbirds spend most their lives in fast forward, but now high-speed video lets us enter their world. Buy the DVD. This film premiered January 10, 2010.

They are the superhighways of the sky. Biologists call them “flyways,” and each spring and fall billions of birds hit these atmospheric roads for their annual migrations, which can stretch thousands of miles. The sandhill and whooping cranes seen on NATURE’s Flight School, for instance, travel up to 2,500 miles each way on their migrations, following the same flyways first pioneered thousands of years ago by their ancestors.

In general, flyways follow major landforms, such as mountain ridges, coastlines, or river valleys that act as natural funnels. And while every type of bird may have their own route, many birds use the same general channels. In North America, for instance, scientists recognize four major flyways: the Atlantic, the Mississippi, the Central, and the Pacific. Birds typically move north and south along these routes between their breeding grounds in Canada and the northern United States, and their wintering grounds in South and Central America.

Overall, about 80 percent of the some 650 species of birds that nest in North America migrate along these flyways — and the few remaining whooping cranes are part of the seasonal traffic jam. Each spring, the small flock of wild whoopers that nests in Canada’s Northwest Territories embarks on its 2,500-mile flight south to the Aransas National Wildlife Refuge in Texas. The journey takes up to 3 weeks. Now, as seen in NATURE’s Flight School, conservationists are using ultralight aircraft to help establish a new migrating flock that will travel between Florida and the upper Midwest. There is also a non-migrating flock of whooping cranes in Florida.

Operation Migration’s whooping cranes migrated from the Midwest to Florida.

While it might seem like the cranes fly a long way, their trip is nothing compared to the annual migration undertaken by the arctic tern. Each year, the small seabird takes a round trip that can top out at more than 20,000 miles, from the Arctic to the Antarctic and back again. Other sea birds routinely fly more than 10,000 miles on their migrations.

Each species handles their annual trips a bit differently. Some cut the journey up into short hops, flying low, and stopping frequently to rest or feed. Others, like many cranes, are able to use wind currents or “thermals” of hot air to soar vast distances. Some may fly as high as 30,000 feet to get the best breezes or to cross mountains. While some fly during the day, many others travel only by night.

In recent years, scientists have perfected the art of using radar and tags that transmit signals to satellites as they track birds on their remarkable journeys. This technology allows the researchers to see exactly where the birds are going, and how long it takes them. It also helps conservationists identify key resting and feeding grounds in need of protection.

The tracking studies even provide opportunities for the public to have a bit of fun by following specific birds through Web sites. Scientists studying satellite-tagged albatrosses in the Pacific, for instance, recently sponsored the “Big Bird Race,” which allowed gamblers to place bets on which bird would reach the destination first — with the profits going to albatross conservation. “Who knows, if enough money is raised with the “Big Bird Race” then maybe albatrosses may one day outnumber horses,” says Gemma Brass of Ladbrokes, the U.K.-based betting company that sponsored the race.

Intrepid avian creatures attain new heights in NATURE’s Extraordinary Birds.

The gift of flight would seem reason enough for humanity’s fascination with birds. But there’s even more to it than that. Birds are remarkable for a wide range of exceptional physical abilities, for their indications of intelligence, and — for some species — their surprising level of rapport with humans.

In the small Indian village of Kundha Kulam, for example, birds’ arrival are a sign to the townspeople that rain will follow and that their crops would soon thrive. While falconry — the art of training hawks, falcons and other birds of prey to hunt — exemplifies the partnership men and birds can develop.

Humans have also relied on the more prosaic pigeon. Although city dwellers may dismiss them as flying rats, no bird can top the pigeon for courage and service to humankind. Since pigeons have the ability to find their way “home,” many were used in dangerous, top-secret missions in World War I and II, delivering important messages to Allied troops behind enemy lines.

Discover more amazing birds — from hummingbirds and peregrine falcons to parrots and barn owls — on NATURE’s Extraordinary Birds.

To order a copy of Extraordinary Birds, please visit the NATURE Shop.

Online content for Extraordinary Birds was orginally posted November 2000.

Bumblebees bumble, butterflies dance, and dragonflies hover. But according to the conventional laws of flight, none of these high-flying insects should be able to get off the ground.

There are mathematical laws that explain how everything from luxury jets to paper gliders stay airborne, but for decades, engineers and scientists couldn’t make the rules explain how insects remain aloft.

Biologist R. McNeill Alexander of the University of Leeds in England once put it this way: “Insect flight cannot be explained by conventional aerodynamic principles.” One problem: while airplane wings don’t move, insect wings are constantly flapping, tilting, bending, and doing all sorts of complicated three-dimensional acrobatics the mathematical formulas can’t handle.

In recent years, however, McNeill and other scientists have begun to unravel the mystery of insect flight. One way they’ve done it is by building large-scale replicas of real insects, which they then “fly” in experimental wind tunnels. Cambridge University biologist Charles Ellington and colleagues, for instance, built “Flapper,” a kind of mechanical “Frankenmoth” that is ten times larger than its natural model, the hawkswing moth. By suspending “Flapper” in the wind tunnel and blowing smoke at it, they were able to see how the air swirled around the flapping wings. Photographs revealed that the wings created remarkable vortices that danced along the moth’s body, creating lift unlike that created by any high-tech jet — or predicted by any engineer. The studies also helped reveal why the hawkswing is one of the world’s fastest insects.

Other researchers are studying dragonflies, hoping to learn how these fast flyers are able to change direction so quickly. They too are building wind-tunnel models, in the hopes of learning secrets that will help them build more maneuverable fighter jets. But will the jets be able to stop on a dime and go backward, the way dragonflies do? Not likely, say the scientists. For the time being, insects remain champion flyers that even the most clever human engineer hasn’t figured out how to imitate.