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Last Updated on August 7, 2019, by eNotes Editorial. Word Count: 674

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In his book, Wiener provides great detail on birds, especially finches, of the Galapagos Islands. His book is based on the scientist studies of Peter and Rosemary Grant. The Galapagos Islands serve as one of the richest areas of scientific exploration, as the islands host many diverse species of animals, insects, birds, plants, and sea life.

The Grants, with a team of explorers, studied how important the shape and size of beaks are for the survival of birds:

The shape of a bird’s beak sets tight limits on what it can eat [...].

Each beak is a hand with a single permanent gesture. It is a general-purpose tool that can serve only a limited number or purposes. Wood-peckers have chisels. Egrets have spears. Darters have swords. Herons and bitterns have tongs. Hawks, falcons, and eagles have hooks. Curlews have pincers.

Wiener focuses on the beak of the finch, in particular:

[...] finches can’t put food in their mouths with their wings. They can’t use their claws either, any more than we can dine comfortably with our feet. They have to use their beaks. Beaks are to birds what hands are to us. They are the birds’ chief tools for handling, managing, and manipulating the things of this world.

Describing various birds in great detail, Wiener provides great insight into the diversity among birds, as seen in the following quote below:

There are about nine thousand species of birds alive in the world today, and the variety of their beaks helped confirm Paley’s belief in an inventive God.

The specialization of each beak per species is astounding, as one studies what each bird can or cannot do in its environment:

Flamingos’ beaks have deep troughs and fine filters, through which the birds can pump water and mud with their tongues. Kingfishers’ beaks have such stout inner braces and struts that a few species can dig tunnels in riverbanks by sailing headlong into the earth, over and over again, like flying jackhammers. Some finch beaks are like carpentry shops. They come equipped with ridges inside the upper mandible, which serve as a sort of built-in vise and help the finch hold a seed in place while sawing it open with the lower mandible.

This book provides tremendous details regarding the scientific steps taken by the Grants in order to obtain specific information about finches and their beaks:

The Grant team discovered that the ground finches were concentrating on about two dozen different species of seed. So the members of the team put each other these two dozen kinds of seeds between the points of a vernier calipers and measured them as carefully as they measured the birds’ beaks. They also measured the seeds’ hardness with the McGill nutcracker.

For accuracy, the Grants even visited the islands during different seasons, in order to study the bird activities and patterns:

The Grant team recaptured many of the birds they had caught during their first trip, and dangled them again in the spring balance. The finches had lost weight, and when the members of the team counted the seeds on the same plots as before, they could see why the birds might be hungry.

The Grant team even studied how the birds were affected by drought.

They know how variable the beaks are. They know how much the variations matter. They know how the plants were doing, what the weather was doing, how life on the island was squeezing the finches. They know all these figures with unprecedented precision, as well as the dimensions of the finches that made it through the drought and the finches that did not.

The incredible details of each bird and its beak made a difference in which ones survived difficult conditions of the environment over time:

In other words, among the males the biggest survived, and among females the biggest survived, but many more males survived than females. And what made the difference between life and death was often “the slightest variation,” an imperceptible difference in the size of the beak [...].