Source: Nature: "Extraordinary Birds"
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The Rufous hummingbird is a small wonder that, with respect to body size, migrates farther than any other creature on earth. The brightly colored, feisty bird breeds from southern Alaska to northern California and then spends the winter in Mexico. Though their brains are approximately the size of a grain of rice, Rufous hummingbirds have an excellent memory for locating flowers from year to year. In this video segment from Nature, learn about the little brain and big journey of the Rufous hummingbird.
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As hummingbirds and other bird species evolved over time, they developed a variety of traits and skills beneficial to both the birds themselves and to the continuation of their species. The vast array of hummingbird species is an example of the result of these evolutionary processes. Certain birds have developed beaks allowing them to feed at particular flowers, others have cultivated brightly colored plumage, and yet others are known for the exceptional skills at navigation. Many highly skilled bird behaviors are innate - certain bird species are born with these abilities, as is the case of the homing pigeon’s innate homing ability. Scientists often do not know how these skills have been acquired in the population, except to note that these traits became advantageous for the birds as their populations evolved in their respective environments.
The Rufous takes success one step further. It’s the champion of hummingbird migration.
From their breeding grounds as far north as coastal Alaska, the birds head south down the Rockies to the mountains of Mexico to winter. Come spring, they take a western route north, flying up through California to their summer grounds in southwestern Canada and beyond.
This tiny bird travels farther for its body size than any other creature on earth. Round trip, it’s more than five thousand miles. Yet they navigate with such accuracy that the same birds are caught in the same field year after year. How is it possible?
Calder - …that information they are storing in a brain that’s about the size of Abe Lincoln’s head on a penny, and yet they are coming back precisely to the same filling station along the way, doing as well as this very nice portable, miniaturized GPS system that takes fixes off of five, six or so satellites and gets an exact position. We got birds with this little brain that are coming and doing the same thing and they don’t have a GPS, they couldn’t begin to carry off, a whole herd of them couldn’t carry this one machine.
Calder –…Rufous male adult …And there’s a couple of red feathers there, and right over there way off the side.
Remarkably, juvenile birds travel on their own. They do not learn the route from their parents, and their track south is very different than the path they will take north next spring.
This means that much of what they do must be genetically programmed, yet hummingbirds show surprising flexibility. They will delay their trip if flowers are late to bloom, and they will adjust their path and altitude to take advantage of yearly variations in their food supply. How they anticipate these changes, no one knows.
Calder is turning to technology for some answers. By extracting a few feathers, he obtains a minute amount of tissue. Using new developments in DNA sequencing, he will look for the keys to their amazing behavior in their genetic instructions.
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