Feathers define birds

Much of the pleasure we take from birds is tied to the science that envelops these amazing creatures. Science explains flight and song and navigation. It also explains feathers, the one thing that defines birds most specifically.

Feathers are essential to our perception of birds. But with or without birds, feathers have a most interesting life of their own. Author Thor Hansen has given us the story of feathers in a fascinating book entitled "Feathers: the Evolution of a Natural Miracle."

One way to keep track of things to be mentioned in a review like this is to underline and make margin notes. I find books to be beautiful, a centuries-old technology to carry man's thoughts and ideas, and destined, I'm certain, to be the only technology to offer a certain, permanent home to those thoughts and ideas. So, I don't write in books; I keep notes on a piece of paper.

My list begins with the first feathers. They were worn by a creature from the Mesozoic era, a reptile-cum-bird that left us only rare impressions of its singular creation. Archaeopteryx is its name. It appeared like magic when a piece of slate was split in an English quarry.

One of the quarrymen smuggled this fossil home, incidentally using it as payment to a doctor for treatment of a lung condition, a doctor with an interest in fossils. That was in 1861. It was, as author Hanson says, "the first full specimen of … an ancient animal with the skeleton of a reptile and the feathers of a bird." It went on to become one of the most famous and most studied fossils ever.

This ancient animal's Latin name is more than descriptive. It's beautiful and poetic, uncommon things for scientific names: Archaeopteryx – "ancient wing written in stone."

Did you know that you can eat feathers? Billions of pounds of feather waste produced by the chicken industry are consumed each year, not by us directly, but as a food additive for cattle and, yes, in chicken feed. Feather meal – boil the feathers, dry them, grind them up – also is a fertilizer used by organic farmers.

Feathers keep birds warm. They also help keep birds cool. Hanson used a dead flicker to demonstrate this. The bird was placed in the sun. In a few minutes the outside temperature of the bird was 102 degrees Fahrenheit. A thermometer slipped beneath the feathers registered only 87 degrees.

There are stories in this book, leading us from one element of science to the next. Hanson is a good storyteller. He does write of dull moments. Discussing man's early attempts to fly, he quotes from an early book on this pursuit: would-be pilots were "grievously hurt," "received injuries that resulted in his death," and was "killed on the spot."

Throughout the book he weaves history and myth into explanation and knowledge, a recipe for a most readable effort.

Hanson is a conservation biologist who has worked in Africa and Central America. His first book, "The Impenetrable Forest: My Gorilla Years in Uganda," won the 2008 USA Book News Award for nature writing.