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The Unfeathered Bird – Katrina van Grouw

July 17, 2013


The Unfeathered Bird
Katrina van Grouw
Princeton University Press, NJ & Oxford, 2013, 287 pgs, $49.95.

This blog hasn’t posted book reviews in the past – we prefer to stick to issues concerning our chapter and local birds and not deluge our readers with email – but this book demands special attention. It is stunning, beautiful, mind-boggling, fascinating, and other space-hogging superlatives. It is not just a book, but a work of art, lovely, wonderful just to leaf through, drinking in the beauty and detail of hundreds of images. It is not just a work of art, it is a book, filled with fascinating bits of information, yet not random or disconnected, but woven together into a complete book. Even the print type is perfect: elegant, yet easily readable. I could go on, but I’d rather let you see some images and read some text for yourself. [Note – the images presented here do not do justice to the originals as they are both file-compressed and size-reduced.]

European Robin

European Robin with worm

The book is organized is what seems at first a peculiar manner, following the original 1758 Systema Naturae of Linnaeus. Not only does this work well, as the reader quickly realizes, but it awakens in us a new-found respect for Linnaeus’ magnificent obsession: to organize all living beings in a sensible manner, ending confusion for all time. The alterations to his structure made since then by legions of scientists are beyond count, but Linnaeus, for the most part, got it right. It is such alterations that author van Grouw chose to avoid, as she explains in her introduction:

My answer – a somewhat unorthodox one – was to turn modern classification on its head and to base my order of chapters on a system that is concerned only with outward structural appearances….rapacious birds, swimming birds, gallinaceous birds, and so on are grouped together according to convergent evolution….I’ve attempted to place groups that are superficially similar next to each other for ease of comparison. Thus storks are next to cranes and swifts next to swallows. The actual relationships are discussed within the text at some length.

Part One concerns generic avian structures: trunk, head, neck, hind limbs, wings, and tail.  The much longer Part Two illustrates and discusses most modern families, arranged into Linnaeus’ schema: Accipitres, Picae, Anseres, Grallae, Gallinae and Passeres. You’ll have to read the book to find out which family falls into which of these groups, but if you know what these six names refer to and guess where the families fall, you’ll be close. Hint: Anseres includes ducks and penguins; Passeres includes pigeons, swifts and passerines. The book explains why. And it works.

Let’s sample some artwork and text without my comments.

Woodpecker skull & tongue

Woodpecker skull & tongue – note groove around eye in right figure

Pgs 78-79 – Woodpeckers
The characteristic head shape of wood-pecking woodpeckers – with the braincase above the level of the bill – is another clue to their specialism. Simple but effective; this is to place the brain safely above the trajectory of impact. Any forces that do reach the cranium are absorbed by the thickened bone; its pockmarked surface a distinctive feature of woodpecker skulls. The skull of the excavating specialists also meets the neck at an almost perpendicular angle so that the bill faces the tree trunk rather than pointing vertically upward. This enables the bill to strike the wood at right angles to it with a smooth swinging motion like using a hammer and to avoid the jarring that would result from a forward thrust….They do, however, share one important attribute that has been the key to their success – an extensible tongue.  The basic structure of this organ is the same as in all birds: a tongue anchored to the floor of the mouth just in front of the opening to the windpipe, where it divides into two branches called hyoid horns. These “horns” extend backward along the inside of the lower jaw and behind the ear openings, hugging the back of the skull. In most birds the tongue cannot be extended beyond the tip of the bill, but woodpeckers, among others, are an exception. Their long tongue, tipped with various barbs or bristles and coated with sticky saliva from a well-developed salivary gland at the base of the jaw, can be shot out rapidly to trap insects. It’s all achieved by the action of the muscles surrounding the flexible and whip-like hyoid horns. But the horns do need to be considerably longer than those of other birds. So long are they in some species that they meet at the back of the head, extending right over the top of the cranium along a channel in the skull and may even twirl around the right eyeball or plunge into the right nostril. When the bird is feeding the slack in the hyoid horns is pulled sharply taut, thrusting the tongue forward.

Pg 122 – Grebes
The attractively striped chicks spend their first few weeks of life being carried on their parents’ back. Among more “normal” foodstuffs, the chicks are fed on feathers that the adults pluck from their breast and flanks. The adults eat these, too, and they are thought to serve as a wrapping for fish bones and other indigestible material ejected from the mouth as pellets.

Storm Petrel dancing on the water

Storm Petrel dancing on the water

Pg 130 – Storm petrels
In all petrels the upper arm and forearm bones are of approximately equal length. It’s the length of the hand that varies, and in general the larger the bird, the smaller the hand. Albatrosses have really long “arms” but small “hands.” But in storm petrels it’s the other way around. The section from the wrist to the wingtip is significantly longer than the bones of the upper and lower arm. They correspondingly have more functional primary flight feathers (attached to the hand) and fewer secondary flight feathers (attached to the arm) than do albatrosses. The breastbone, too, is long, and the wishbone curves outward to give the maximum area for the attachment of the well-developed flight muscles. Storm petrels may not be able to soar effortlessly for long periods like their long-winged cousins, but they can fly like butterflies and change direction with the slightest movement.

Their nocturnal habits are facilitated by their strong sense of smell – unusual in birds but common to most petrels whose well-developed olfactory apparatus is linked with the characteristic tubular nostrils. The birds use their sense of smell to locate and identify their nest site, find food, and even recognize one another. Indeed, most petrels have a pungent odor, but most breed in inaccessible areas such as islands and stacks, free from mammalian predators that would be able to detect them in this way. The aroma of storm petrels is sensual and complex; as enigmatic as the birds themselves.

Pg 178 – Storks
Considering storks as waterbirds, the carrion-eating habits of Marabou Storks seem rather incongruous. This habit was conveniently rationalized when researchers pioneering DNA hybridization techniques in the 1980s revealed the storks’ closest living relatives to be, not the herons, nor even the ibises and spoonbills, but the New World vultures.  In fact, some late nineteenth-century taxonomists had arrived at the same conclusion from a purely anatomical standpoint. The two groups certainly do share many similarities, including the bare facial skin and soaring flight. However, more recent molecular studies have blasted this theory – at least for now: Marabou Storks are probably not, after, long-legged vultures but simply rather vulturesque storks.

Pg 194 – Plovers
The plovers hunt by sight rather than by touch. In most, the bill is shorter, for aimed pecks rather than opportunistic probing, and their eyes are much larger than those of the sandpipers. In fact plovers are also nocturnal feeders, so having large eyes maximizes the amount of light hitting the retina. They also have a high density of rod cells in the eye, which aids vision under poor light conditions, though at the expense of some color perception. Like those of the woodcocks, plovers’ eyes are raised above the level of the cranium, but these are directed much farther forward to give the birds the good field of binocular vision they need. Stone curlews, too – same order, different family – have similarly large eyes to help with night feeding.
[End of excerpted portions]

You may have noticed that the images are not merely of bare bones lying there – most of them depict active birds, in motion, doing things. In my experience, this is utterly unique. Not only is the text graceful and uncluttered, but highly informative and always interesting. I’ve been a bird lover for almost 40 years, but I quite literally learned something new on every page. It’s a book, it’s a work of art, it’s both. It is unique.

All book reviews are supposed to be critical in nature and thus must point out shortcomings, even if they don’t amount to much. I had two points which I presented to the author, whose explanation follows my comment.

1. No drawing(s) at the beginning of the book of a generic bird with labels on all the various bones, organs & muscles mentioned in the text. Von Grouw replies: “I did consider the generic bird idea, but dismissed it early on as being unnecessary….Firstly, an illustration with pointer arrows labeling the different parts would be rather like a textbook diagram, which is the very thing I was trying to avoid. Everything in The Unfeathered Bird is a deliberate antithesis of the textbook stereotype! Secondly, you’ll notice that I went to great lengths to avoid the use of any jargon. This was to make readers who are unfamiliar with technical anatomical terms feel more comfortable reading the text and, again, to make it seem less like a textbook. So it would have seemed a bit strange to then label a diagram with technical terms that were not used in the text, or a bit unscientific to label it with descriptive terms that speak for themselves like ‘upper arm’ and ‘breastbone’.”

2. More complete index – the text was so interesting and useful that I was disappointed to find the index didn’t really cover it, only the pictures. Von Grouw replies: “…we (the publishers and myself) kept [the index] deliberately brief for the same reason – the avoidance of textbookishness and the desire to keep it simple. But if I’d made the Index bigger there would have been less room in my 304 pages for the content of the book, so something would have had to go. Every page was precious!”

My quibbles are minor; I find Von Grouw’s explanations entirely satisfactory.

The author lives in England not far from Oxford, is a former curator of the ornithological collections at London’s Natural History Museum, hikes in the nearby hills where she enjoys Neolithic and Iron Age earthworks, hill forts, flowers, butterflies and the occasional horse figure cut into white chalk downs. Her current project is Unnatural Selection, a similar book about about domesticated birds and mammals, which  she describes as “a sort of update of Darwin’s ‘Variations’ in which he used domesticated animals to explain evolution by natural selection.”  Following that will be a book about mammals, which I hope includes a few hominids.

Link to the book’s website:

The book is available at the Los Angeles Public Library but after reading it you’ll want to have your own copy. If my review hasn’t convinced you to buy it, here’s a Barnes & Noble  interview with the author, featuring many more pictures.   [Chuck Almdale]

One Comment
  1. ednalvarez permalink
    July 17, 2013 4:27 pm

    Great review and thanks. I almost didn’t open the email. I wish the ‘sender’ info said something enlightening rather than ‘comment _reply@’_ (mailto:reply@’) . There is so much ‘bad’ stuff out there that one has to be so careful in what is opened. Any way to change it? Thanks. EDNA


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